Update version numbers after tagging

Document the NTNDArray::getValueSize() fix.
Fix markdown errors, back-quoting identifiers with "_" chars.
Reformat the text to use semantic line breaks: https://sembr.org/

.readthedocs.yml

@@ -0,0 +1,17 @@
+# .readthedocs.yml
+# Read the Docs configuration file
+# See https://docs.readthedocs.io/en/stable/config-file/v2.html for details
+
+# Required
+version: 2
+
+# Build documentation in the documentation/ directory with Sphinx
+sphinx:
+  configuration: documentation/conf.py
+
+# Build documentation with MkDocs
+#mkdocs:
+#  configuration: mkdocs.yml
+
+# Optionally build your docs in additional formats such as PDF and ePub
+formats: all

Doxyfile

@@ -38,7 +38,7 @@ PROJECT_NAME           = normativeTypesCPP
 # could be handy for archiving the generated documentation or if some version
 # control system is used.
 
-PROJECT_NUMBER         =
+PROJECT_NUMBER         = 6.0.3-dev
 
 # Using the PROJECT_BRIEF tag one can provide an optional one line description
 # for a project that appears at the top of each page and should give viewer a
@@ -743,7 +743,7 @@ WARN_LOGFILE           =
 # spaces.
 # Note: If this tag is empty the current directory is searched.
 
-INPUT                  = include
+INPUT                  = src
 
 # This tag can be used to specify the character encoding of the source files
 # that doxygen parses. Internally doxygen uses the UTF-8 encoding. Doxygen uses
@@ -1008,7 +1008,7 @@ GENERATE_HTML          = YES
 # The default directory is: html.
 # This tag requires that the tag GENERATE_HTML is set to YES.
 
-HTML_OUTPUT            = documentation/html
+HTML_OUTPUT            = html/doxygen
 
 # The HTML_FILE_EXTENSION tag can be used to specify the file extension for each
 # generated HTML page (for example: .htm, .php, .asp).

configure/CONFIG_NTYPES_VERSION

@@ -0,0 +1,12 @@
+# Version number for the Normative Types API and shared library
+
+EPICS_NTYPES_MAJOR_VERSION = 6
+EPICS_NTYPES_MINOR_VERSION = 0
+EPICS_NTYPES_MAINTENANCE_VERSION = 3
+
+# Development flag, set to zero for release versions
+
+EPICS_NTYPES_DEVELOPMENT_FLAG = 1
+
+# Immediately after a release the MAINTENANCE_VERSION
+# will be incremented and the DEVELOPMENT_FLAG set to 1

configure/CONFIG_SITE

@@ -32,3 +32,5 @@ endif
 -include $(TOP)/../CONFIG_SITE.local
 -include $(TOP)/configure/CONFIG_SITE.local
 
+# MSVC - skip defining min()/max() macros
+USR_CPPFLAGS_WIN32 += -DNOMINMAX

configure/Makefile

@@ -10,6 +10,8 @@ include $(TOP)/configure/CONFIG
 # but continue the build even if conflicts are found.
 CHECK_RELEASE = YES
 
+CFG += CONFIG_NTYPES_VERSION
+
 TARGETS = $(CONFIG_TARGETS)
 CONFIGS += $(subst ../,,$(wildcard $(CONFIG_INSTALLS)))
 

documentation/RELEASE_NOTES.md

@@ -2,14 +2,42 @@
 
 This document summarizes the changes to the module between releases.
 
+## Release 6.0.2 (EPICS 7.0.10, December 2025)
+
+- Fix potential NULL pointer dereference in `NTNDArray::getValueSize()`
+
+## Release 6.0.1 (EPICS 7.0.3.1, October 2019)
+
+- Doxygen updates and read-the-docs integration.
+
+## Release 6.0.0 (EPICS 7.0.3, July 2019)
+
+- Reimplement `isCompatible()` methods to use a new internal validation API in
+order to make the implementation uniform, less repetitive and less strict.
+
+The new implementation is less strict in the sense that it considers types that
+can be converted into one another compatible with each other.
+For example, any `Scalar` is considered compatible with any other `Scalar`,
+regardless of the underlying type.
+Normative Types users are advised to use `getAs()` and `putFrom()` when
+getting/putting data from/into `PVScalar`s and `PVScalarArray`s.
+
+Also, `isCompatible()` methods now disregard field order and extra fields that
+are not part of the specification.
+
+This change is not expected to break any current server or client, but it will
+break existing clients that rely on the previous `isCompatible()` strictness
+once servers start to take advantage of `isCompatible()` now being less strict.
+
 ## Release 5.2.2
 
-- Fix NTTable::getColumnNames().
+- Fix `NTTable::getColumnNames()`.
 
 ## Release 5.2.1 (EPICS 7.0.2, Dec 2018)
 
-* No functional changes.
-* Removal of declaration for unimplemented PVNTField::createAlarmLimit() and elimination of unused variables.
+- No functional changes.
+- Removal of declaration for unimplemented `PVNTField::createAlarmLimit()` and
+elimination of unused variables.
 
 
 ## Release 5.2.0 (EPICS 7.0.1, Dec 2017)
@@ -22,39 +50,39 @@ build against the latest version of pvData.
 
 The main changes since release 5.1.1 are:
 
-* NTUnionBuilder: Add missing value() function
-* Updated document: Now document all Normative Types
+- NTUnionBuilder: Add missing `value()` function
+- Updated document: Now document all Normative Types
 
 
 ## Release 5.1.1
 
 The main changes since release 5.0 are:
 
-* Linux shared library version added
-* Headers and source locations have changed
-* Missing is_a implementations added
-* NTAttribute::addTags() is now non-virtual
-* New license file replaces LICENSE and COPYRIGHT
+- Linux shared library version added
+- Headers and source locations have changed
+- Missing `is_a()` implementations added
+- `NTAttribute::addTags()` is now non-virtual
+- New license file replaces LICENSE and COPYRIGHT
 
 ### Shared library version added
 
-Linux shared library version numbers have been added by setting SHRLIB_VERSION
-(to 5.1 in this case). So shared object will be libnt.so.5.1 instead of
-libpvData.so.
+Linux shared library version numbers have been added by setting `SHRLIB_VERSION`
+(to 5.1 in this case).
+The shared object will be `libnt.so.5.1` instead of `libnt.so`.
 
 ### Headers and source locations have changed
 
 Source has moved out of nt directory directly into src.
 
-Headers have been moved into a pv directory. This facilitates using some IDEs
-such as Qt Creator.
+Headers have been moved into a pv directory.
+This facilitates using some IDEs such as Qt Creator.
 
-src/nt/ntscalar.cpp -> src/ntscalar.cpp
-src/nt/ntscalar.h   -> src/pv/ntscalar.h
+- `src/nt/ntscalar.cpp -> src/ntscalar.cpp`
+- `src/nt/ntscalar.h   -> src/pv/ntscalar.h`
 
-### Missing is_a implementations added
+### Missing `is_a()` implementations added
 
-is_a(PVStructurePtr const &) implementation has been added for each type.
+`is_a(PVStructurePtr const &)` implementation has been added for each type.
 
 
 ## Release 5.0 (EPICS V4.5, Oct 2015)
@@ -62,41 +90,44 @@ is_a(PVStructurePtr const &) implementation has been added for each type.
 This release adds support through wrapper classes and builders for the
 remaining Normative Types:
 
-* NTEnum
-* NTMatrix
-* NTURI
-* NTAttribute
-* NTContinuum
-* NTHistogram
-* NTAggregate
-* NTUnion
-* NTScalarMultiChannel
+- NTEnum
+- NTMatrix
+- NTURI
+- NTAttribute
+- NTContinuum
+- NTHistogram
+- NTAggregate
+- NTUnion
+- NTScalarMultiChannel
 
-Release 5.0 therefore implements fully the
-[16 Mar 2015 version](http://epics-pvdata.sourceforge.net/alpha/normativeTypes/normativeTypes_20150316.html)
- of the normativeTypes specification.
+Release 5.0 therefore fully implements the 16 Mar 2015 version of the
+normativeTypes specification.
 
 Each wrapper class has an extended API:
 
-* is_a now has a convenience overload taking a PVStructure.
-* isCompatible, reporting introspection type compatibility, now has an overload
-  taking a Structure. The PVStructure version is retained as a convenience
-  method and for backwards compatibility.
-* An isValid function now reports validity of a compatible PVStructure's data
-  with respect to the specification.
+- `is_a()` now has a convenience overload taking a PVStructure.
+- `isCompatible()`, reporting introspection type compatibility, now has an
+  overload taking a Structure.
+  The PVStructure version is retained as a convenience method and for backwards
+  compatibility.
+- An `isValid()` function now reports validity of a compatible PVStructure's
+  data with respect to the specification.
 
 Other changes are:
 
-* Support for NTAttributes extended as required by NTNDArray
+- Support for NTAttributes extended as required by NTNDArray
   (NTNDArrayAttributes).
-* A new class for parsing NT IDs (NTID).
-* Resolution of the confusion between column names and labels in NTTable and
-  improved API. Function for adding columns is now addColumn rather than add.
-  New getColumnNames function provided.
-* isConnected is treated as an optional rather than a required field in
-  NTMultiChannelArray. isConnected() and addIsConnected() functions added to
-  wrapper and builder respectively.
-* Unit tests for all new classes.
+- A new class for parsing NT IDs (NTID).
+- Resolution of the confusion between column names and labels in NTTable and
+  improved API.
+  Function for adding columns is now `addColumn()` rather than `add()`.
+  A new `getColumnNames()` function provided.
+- `isConnected()` is treated as an optional rather than a required field in
+  NTMultiChannelArray.
+  `isConnected()` and `addIsConnected()` functions added to wrapper and builder
+  respectively.
+
+- Unit tests for all new classes.
 
 ## Release 4.0 (EPICS V4.4, Dec 2014)
 
@@ -107,26 +138,27 @@ It is a major rewrite of the previous versions of normativeTypesCPP.
 This release provides support through wrapper classes and builders for the
 following Normative Types:
 
-* NTScalar
-* NTScalarArray
-* NTNameValue
-* NTTable
-* NTMultiChannel
-* NTNDArray
+- NTScalar
+- NTScalarArray
+- NTNameValue
+- NTTable
+- NTMultiChannel
+- NTNDArray
 
 Each type has a wrapper class of the same name which has functions for checking 
-compatibility of existing PVStructures (isCompatible) and the reported types of 
-Structures (is_a), wraps existing PVStructures (wrap, wrapUnsafe) and provides
-a convenient interface to all required and optional fields.
+compatibility of existing PVStructures (`isCompatible()`) and the reported types
+of Structures (`is_a()`),
+wraps existing PVStructures (`wrap()`, `wrapUnsafe()`) and provides a convenient
+interface to all required and optional fields.
 
 Each type has a builder which can create a Structure, a PVStructure or a
-wrapper around a new PVStructure. In each case optional or extra fields can be
-added and options such as choice of scalar type can be made.
-
+wrapper around a new PVStructure.
+In each case optional or extra fields can be added and options such as choice of
+scalar type can be made.
 
 Additional features are:
 
-* Utility classes NTField and NTPVField for standard structure fields and
+- Utility classes NTField and NTPVField for standard structure fields and
   NTUtils for type IDs.
-* Unit tests for the implemented classes.
+- Unit tests for the implemented classes.
 

documentation/_static/css/custom.css

@@ -0,0 +1,7 @@
+.wy-side-nav-search {
+    background-color: #18334B;
+}
+
+.wy-side-nav-search input[type="text"] {
+    border-color: #18334b;
+}

documentation/conf.py

@@ -0,0 +1,77 @@
+# Configuration file for the Sphinx documentation builder.
+#
+# This file only contains a selection of the most common options. For a full
+# list see the documentation:
+# http://www.sphinx-doc.org/en/master/config
+
+# -- Path setup --------------------------------------------------------------
+
+# If extensions (or modules to document with autodoc) are in another directory,
+# add these directories to sys.path here. If the directory is relative to the
+# documentation root, use os.path.abspath to make it absolute, like shown here.
+#
+# import os
+# import sys
+# sys.path.insert(0, os.path.abspath('.'))
+
+
+# -- Project information -----------------------------------------------------
+
+project = 'normativeTypes (C++)'
+copyright = '2019, EPICS Controls.'
+author = 'EPICS'
+
+
+# -- General configuration ---------------------------------------------------
+
+# Add any Sphinx extension module names here, as strings. They can be
+# extensions coming with Sphinx (named 'sphinx.ext.*') or your custom
+# ones.
+extensions = [
+    'sphinx.ext.intersphinx',
+]
+
+# Add any paths that contain templates here, relative to this directory.
+templates_path = ['_templates']
+
+# List of patterns, relative to source directory, that match files and
+# directories to ignore when looking for source files.
+# This pattern also affects html_static_path and html_extra_path.
+exclude_patterns = ['_build', 'Thumbs.db', '.DS_Store']
+
+# Intersphinx links to subprojects
+intersphinx_mapping = {
+}
+
+
+# -- Options for HTML output -------------------------------------------------
+
+# The theme to use for HTML and HTML Help pages.  See the documentation for
+# a list of builtin themes.
+#
+html_theme = 'sphinx_rtd_theme'
+
+
+# Add any paths that contain custom static files (such as style sheets) here,
+# relative to this directory. They are copied after the builtin static files,
+# so a file named "default.css" will overwrite the builtin "default.css".
+html_static_path = ['_static']
+
+html_css_files = [
+    'css/custom.css',
+]
+
+master_doc = 'index'
+
+html_theme_options = {
+    'logo_only': True,
+}
+html_logo = "images/EPICS_white_logo_v02.png"
+
+html_extra_path = ['../html']
+
+
+# -- Run Doxygen ------------------------------------------------------------
+
+import subprocess
+subprocess.call('cd ..; mkdir -p html/doxygen; doxygen', shell=True)

documentation/index.rst

@@ -0,0 +1,17 @@
+NormativeTypes (C++) Library
+============================
+
+.. toctree::
+   :hidden:
+
+   EPICS Website <https://epics-controls.org>
+   EPICS Documentation Home <https://docs.epics-controls.org>
+
+
+.. toctree::
+   :maxdepth: 1
+   :caption: normativeTypesCPP
+
+   Reference Manual <ntCPP>
+   API Documentation <https://docs.epics-controls.org/projects/normativetypes-cpp/en/latest/doxygen>
+   Source Code Repository on GitHub <https://github.com/epics-base/normativeTypesCPP>

src/Makefile

@@ -47,7 +47,7 @@ LIBRARY = nt
 nt_LIBS += pvData Com
 
 # shared library ABI version.
-SHRLIB_VERSION ?= 5.2.2
+SHRLIB_VERSION ?= $(EPICS_NTYPES_MAJOR_VERSION).$(EPICS_NTYPES_MINOR_VERSION).$(EPICS_NTYPES_MAINTENANCE_VERSION)
 
 include $(TOP)/configure/RULES
 

src/ntaggregate.cpp

@@ -4,6 +4,8 @@
  * found in the file LICENSE that is included with the distribution
  */
 
+#include "validator.h"
+
 #define epicsExportSharedSymbols
 #include <pv/ntaggregate.h>
 #include <pv/ntutils.h>
@@ -194,83 +196,26 @@ bool NTAggregate::is_a(PVStructurePtr const & pvStructure)
 
 bool NTAggregate::isCompatible(StructureConstPtr const &structure)
 {
-    if (structure.get() == 0) return false;
-
-    ScalarConstPtr valueField = structure->getField<Scalar>("value");
-    if (valueField.get() == 0 || valueField->getScalarType() != pvDouble)
+    if (!structure)
         return false;
 
-    ScalarConstPtr nField = structure->getField<Scalar>("N");
-    if (nField.get() == 0 || nField->getScalarType() != pvLong)
-        return false;
+    Result result(structure);
 
-    FieldConstPtr field = structure->getField("dispersion");
-    if (field.get())
-    {
-        ScalarConstPtr dispersionField = structure->getField<Scalar>("dispersion");
-        if (!dispersionField.get() || dispersionField->getScalarType() != pvDouble)
-            return false;
-    }
-
-    field = structure->getField("first");
-    if (field.get())
-    {
-        ScalarConstPtr firstField = structure->getField<Scalar>("first");
-        if (!firstField.get() || firstField->getScalarType() != pvDouble)
-            return false;
-    }
-
-    field = structure->getField("firstTimeStamp");
-    if (field.get() && !ntField->isTimeStamp(field))
-        return false;
-
-    field = structure->getField("last");
-    if (field.get())
-    {
-        ScalarConstPtr lastField = structure->getField<Scalar>("last");
-        if (!lastField.get() || lastField->getScalarType() != pvDouble)
-            return false;
-    }
-
-    field = structure->getField("lastTimeStamp");
-    if (field.get() && !ntField->isTimeStamp(field))
-        return false;
-
-    field = structure->getField("max");
-    if (field.get())
-    {
-        ScalarConstPtr maxField = structure->getField<Scalar>("max");
-        if (!maxField.get() || maxField->getScalarType() != pvDouble)
-            return false;
-    }
-
-    field = structure->getField("min");
-    if (field.get())
-    {
-        ScalarConstPtr minField = structure->getField<Scalar>("min");
-        if (!minField.get() || minField->getScalarType() != pvDouble)
-            return false;
-    }
-
-    field = structure->getField("descriptor");
-    if (field.get())
-    {
-        ScalarConstPtr descriptorField = structure->getField<Scalar>("descriptor");
-        if (!descriptorField.get() || descriptorField->getScalarType() != pvString)
-            return false;
-    }
-
-    NTFieldPtr ntField = NTField::get();
-
-    field = structure->getField("alarm");
-    if (field.get() && !ntField->isAlarm(field))
-        return false;
-
-    field = structure->getField("timeStamp");
-    if (field.get() && !ntField->isTimeStamp(field))
-        return false;
-
-    return true;
+    return result
+        .is<Structure>()
+        .has<Scalar>("value")
+        .has<Scalar>("N")
+        .maybeHas<Scalar>("dispersion")
+        .maybeHas<Scalar>("first")
+        .maybeHas<&NTField::isTimeStamp, Structure>("firstTimeStamp")
+        .maybeHas<Scalar>("last")
+        .maybeHas<&NTField::isTimeStamp, Structure>("lastTimeStamp")
+        .maybeHas<Scalar>("max")
+        .maybeHas<Scalar>("min")
+        .maybeHas<Scalar>("descriptor")
+        .maybeHas<&NTField::isAlarm, Structure>("alarm")
+        .maybeHas<&NTField::isTimeStamp, Structure>("timeStamp")
+        .valid();
 }
 
 bool NTAggregate::isCompatible(PVStructurePtr const & pvStructure)

src/ntattribute.cpp

@@ -4,6 +4,8 @@
  * found in the file LICENSE that is included with the distribution
  */
 
+#include "validator.h"
+
 #define epicsExportSharedSymbols
 #include <pv/ntattribute.h>
 #include <pv/ntutils.h>
@@ -130,46 +132,22 @@ bool NTAttribute::is_a(PVStructurePtr const & pvStructure)
 
 bool NTAttribute::isCompatible(StructureConstPtr const & structure)
 {
-    if (structure.get() == 0) return false;
-
-    ScalarConstPtr nameField = structure->getField<Scalar>("name");
-    if (nameField.get() == 0 || nameField->getScalarType() != pvString)
+    if (!structure)
         return false;
 
-    UnionConstPtr valueField = structure->getField<Union>("value");
-    if (valueField.get() == 0 || !valueField->isVariant())
-        return false;
+    Result result(structure);
 
-    FieldConstPtr field = structure->getField("tags");
-    if (field.get())
-    {
-        ScalarArrayConstPtr tagsField = structure->getField<ScalarArray>("tags");
-        if (tagsField.get() == 0 || tagsField->getElementType() != pvString)
-            return false;
-    }
-
-    field = structure->getField("descriptor");
-    if (field.get())
-    {
-        ScalarConstPtr descriptorField = structure->getField<Scalar>("descriptor");
-        if (!descriptorField.get() || descriptorField->getScalarType() != pvString)
-            return false;
-    }
-
-    NTFieldPtr ntField = NTField::get();
-
-    field = structure->getField("alarm");
-    if (field.get() && !ntField->isAlarm(field))
-        return false;
-
-    field = structure->getField("timeStamp");
-    if (field.get() && !ntField->isTimeStamp(field))
-        return false;
-
-    return true;
+    return result
+       .is<Structure>()
+       .has<Scalar>("name")
+       .has<Union>("value")
+       .maybeHas<ScalarArray>("tags")
+       .maybeHas<Scalar>("descriptor")
+       .maybeHas<&NTField::isAlarm, Structure>("alarm")
+       .maybeHas<&NTField::isTimeStamp, Structure>("timeStamp")
+       .valid();
 }
 
-
 bool NTAttribute::isCompatible(PVStructurePtr const & pvStructure)
 {
     if(!pvStructure) return false;

src/ntcontinuum.cpp

@@ -4,6 +4,8 @@
  * found in the file LICENSE that is included with the distribution
  */
 
+#include "validator.h"
+
 #define epicsExportSharedSymbols
 #include <pv/ntcontinuum.h>
 #include <pv/ntutils.h>
@@ -122,42 +124,22 @@ bool NTContinuum::is_a(PVStructurePtr const & pvStructure)
 
 bool NTContinuum::isCompatible(StructureConstPtr const & structure)
 {
-    if (structure.get() == 0) return false;
-
-    ScalarArrayConstPtr baseField = structure->getField<ScalarArray>("base");
-    if (baseField.get() == 0 || baseField->getElementType() != pvDouble)
+    if (!structure)
         return false;
 
-    ScalarArrayConstPtr valueField = structure->getField<ScalarArray>("value");
-    if (valueField.get() == 0 || valueField->getElementType() != pvDouble)
-        return false;
+    Result result(structure);
 
-    ScalarArrayConstPtr unitsField = structure->getField<ScalarArray>("units");
-    if (unitsField.get() == 0 || unitsField->getElementType() != pvString)
-        return false;
-
-    FieldConstPtr field = structure->getField("descriptor");
-    if (field.get())
-    {
-        ScalarConstPtr descriptorField = structure->getField<Scalar>("descriptor");
-        if (!descriptorField.get() || descriptorField->getScalarType() != pvString)
-            return false;
-    }
-
-    NTFieldPtr ntField = NTField::get();
-
-    field = structure->getField("alarm");
-    if (field.get() && !ntField->isAlarm(field))
-        return false;
-
-    field = structure->getField("timeStamp");
-    if (field.get() && !ntField->isTimeStamp(field))
-        return false;
-
-    return true;
+    return result
+        .is<Structure>()
+        .has<ScalarArray>("base")
+        .has<ScalarArray>("value")
+        .has<ScalarArray>("units")
+        .maybeHas<Scalar>("descriptor")
+        .maybeHas<&NTField::isAlarm, Structure>("alarm")
+        .maybeHas<&NTField::isTimeStamp, Structure>("timeStamp")
+        .valid();
 }
 
-
 bool NTContinuum::isCompatible(PVStructurePtr const & pvStructure)
 {
     if(!pvStructure) return false;

src/ntenum.cpp

@@ -4,6 +4,8 @@
  * found in the file LICENSE that is included with the distribution
  */
 
+#include "validator.h"
+
 #define epicsExportSharedSymbols
 #include <pv/ntenum.h>
 #include <pv/ntutils.h>
@@ -121,34 +123,20 @@ bool NTEnum::is_a(PVStructurePtr const & pvStructure)
 
 bool NTEnum::isCompatible(StructureConstPtr const &structure)
 {
-    if (structure.get() == 0) return false;
-
-    NTFieldPtr ntField = NTField::get();
-
-    FieldConstPtr valueField = structure->getField("value");
-    if (!valueField.get() || !ntField->isEnumerated(valueField))
+    if (!structure)
         return false;
 
-    FieldConstPtr field = structure->getField("descriptor");
-    if (field.get())
-    {
-        ScalarConstPtr descriptorField = structure->getField<Scalar>("descriptor");
-        if (!descriptorField.get() || descriptorField->getScalarType() != pvString)
-            return false;
-    }
+    Result result(structure);
 
-    field = structure->getField("alarm");
-    if (field.get() && !ntField->isAlarm(field))
-        return false;
-
-    field = structure->getField("timeStamp");
-    if (field.get() && !ntField->isTimeStamp(field))
-        return false;
-
-    return true;
+    return result
+        .is<Structure>()
+        .has<&NTField::isEnumerated, Structure>("value")
+        .maybeHas<Scalar>("descriptor")
+        .maybeHas<&NTField::isAlarm, Structure>("alarm")
+        .maybeHas<&NTField::isTimeStamp, Structure>("timeStamp")
+        .valid();
 }
 
-
 bool NTEnum::isCompatible(PVStructurePtr const & pvStructure)
 {
     if(!pvStructure) return false;

src/ntfield.cpp

@@ -5,6 +5,7 @@
  */
 
 #include <pv/lock.h>
+#include "validator.h"
 
 #define epicsExportSharedSymbols
 #include <pv/ntfield.h>
@@ -31,198 +32,97 @@ NTField::NTField()
 {
 }
 
+Result& NTField::isEnumerated(Result& result)
+{
+    return result
+        .has<Scalar>("index")
+        .has<ScalarArray>("choices");
+}
+
 bool NTField::isEnumerated(FieldConstPtr const & field)
 {
-   if(field->getType()!=structure) return false;
-   StructureConstPtr structurePtr = static_pointer_cast<const Structure>(field);
-   FieldConstPtrArray fields = structurePtr->getFields();
-   StringArray names = structurePtr->getFieldNames();
-   size_t n = structurePtr->getNumberFields();
-   if(n!=2) return false;
-   FieldConstPtr f = fields[0];
-   if(names[0].compare("index")!=0) return false;
-   if(f->getType()!=scalar) return false;
-   ScalarConstPtr s = static_pointer_cast<const Scalar>(f);
-   if(s->getScalarType()!=pvInt) return false;
-   f = fields[1];
-   if(names[1].compare("choices")!=0) return false;
-   if(f->getType()!=scalarArray) return false;
-   ScalarConstPtr sa = static_pointer_cast<const Scalar>(f);
-   if(sa->getScalarType()!=pvString) return false;
-   return true;
+    Result result(field);
+    return isEnumerated(result.is<Structure>()).valid();
+}
+
+Result& NTField::isTimeStamp(Result& result)
+{
+    return result
+        .has<Scalar>("secondsPastEpoch")
+        .has<Scalar>("nanoseconds")
+        .has<Scalar>("userTag");
 }
 
 bool NTField::isTimeStamp(FieldConstPtr const & field)
 {
-   if(field->getType()!=structure) return false;
-   StructureConstPtr structurePtr = static_pointer_cast<const Structure>(field);
-   FieldConstPtrArray fields = structurePtr->getFields();
-   StringArray names = structurePtr->getFieldNames();
-   size_t  n = structurePtr->getNumberFields();
-   if(n!=3) return false;
-   FieldConstPtr f = fields[0];
-   if(names[0].compare("secondsPastEpoch")!=0) return false;
-   if(f->getType()!=scalar) return false;
-   ScalarConstPtr s = static_pointer_cast<const Scalar>(f);
-   if(s->getScalarType()!=pvLong) return false;
-   f = fields[1];
-   if(names[1].compare("nanoseconds")!=0) return false;
-   if(f->getType()!=scalar) return false;
-   s = static_pointer_cast<const Scalar>(f);
-   if(s->getScalarType()!=pvInt) return false;
-   f = fields[2];
-   if(names[2].compare("userTag")!=0) return false;
-   if(f->getType()!=scalar) return false;
-   s = static_pointer_cast<const Scalar>(f);
-   if(s->getScalarType()!=pvInt) return false;
-   return true;
+    Result result(field);
+    return isTimeStamp(result.is<Structure>()).valid();
+}
+
+Result& NTField::isAlarm(Result& result)
+{
+    return result
+        .has<Scalar>("severity")
+        .has<Scalar>("status")
+        .has<Scalar>("message");
 }
 
 bool NTField::isAlarm(FieldConstPtr const & field)
 {
-   if(field->getType()!=structure) return false;
-   StructureConstPtr structurePtr = static_pointer_cast<const Structure>(field);
-   FieldConstPtrArray fields = structurePtr->getFields();
-   StringArray names = structurePtr->getFieldNames();
-   size_t n = structurePtr->getNumberFields();
-   if(n!=3) return false;
-   FieldConstPtr f = fields[0];
-   if(names[0].compare("severity")!=0) return false;
-   if(f->getType()!=scalar) return false;
-   ScalarConstPtr s = static_pointer_cast<const Scalar>(f);
-   if(s->getScalarType()!=pvInt) return false;
-   f = fields[1];
-   if(names[1].compare("status")!=0) return false;
-   if(f->getType()!=scalar) return false;
-   s = static_pointer_cast<const Scalar>(f);
-   if(s->getScalarType()!=pvInt) return false;
-   f = fields[2];
-   if(names[2].compare("message")!=0) return false;
-   if(f->getType()!=scalar) return false;
-   s = static_pointer_cast<const Scalar>(f);
-   if(s->getScalarType()!=pvString) return false;
-   return true;
+    Result result(field);
+    return isAlarm(result.is<Structure>()).valid();
+}
+
+Result& NTField::isDisplay(Result& result)
+{
+    return result
+        .has<Scalar>("limitLow")
+        .has<Scalar>("limitHigh")
+        .has<Scalar>("description")
+        .has<Scalar>("format")
+        .has<Scalar>("units");
+
 }
 
 bool NTField::isDisplay(FieldConstPtr const & field)
 {
-   if(field->getType()!=structure) return false;
-   StructureConstPtr structurePtr = static_pointer_cast<const Structure>(field);
-   FieldConstPtrArray fields = structurePtr->getFields();
-   StringArray names = structurePtr->getFieldNames();
-   size_t n = structurePtr->getNumberFields();
-   if(n!=5) return false;
-   FieldConstPtr f = fields[0];
-   if(names[0].compare("limitLow")!=0) return false;
-   if(f->getType()!=scalar) return false;
-   ScalarConstPtr s = static_pointer_cast<const Scalar>(f);
-   if(s->getScalarType()!=pvDouble) return false;
-   f = fields[1];
-   if(names[1].compare("limitHigh")!=0) return false;
-   if(f->getType()!=scalar) return false;
-   s = static_pointer_cast<const Scalar>(f);
-   if(s->getScalarType()!=pvDouble) return false;
-   f = fields[2];
-   if(names[2].compare("description")!=0) return false;
-   if(f->getType()!=scalar) return false;
-   s = static_pointer_cast<const Scalar>(f);
-   if(s->getScalarType()!=pvString) return false;
-   f = fields[3];
-   if(names[3].compare("format")!=0) return false;
-   if(f->getType()!=scalar) return false;
-   s = static_pointer_cast<const Scalar>(f);
-   if(s->getScalarType()!=pvString) return false;
-   f = fields[4];
-   if(names[4].compare("units")!=0) return false;
-   if(f->getType()!=scalar) return false;
-   s = static_pointer_cast<const Scalar>(f);
-   if(s->getScalarType()!=pvString) return false;
-   return true;
+    Result result(field);
+    return isDisplay(result.is<Structure>()).valid();
+}
+
+Result& NTField::isAlarmLimit(Result& result)
+{
+    return result
+        .has<Scalar>("active")
+        .has<Scalar>("lowAlarmLimit")
+        .has<Scalar>("lowWarningLimit")
+        .has<Scalar>("highWarningLimit")
+        .has<Scalar>("highAlarmLimit")
+        .has<Scalar>("lowAlarmSeverity")
+        .has<Scalar>("lowWarningSeverity")
+        .has<Scalar>("highWarningSeverity")
+        .has<Scalar>("highAlarmSeverity")
+        .has<Scalar>("hysteresis");
 }
 
 bool NTField::isAlarmLimit(FieldConstPtr const & field)
 {
-   if(field->getType()!=structure) return false;
-   StructureConstPtr structurePtr = static_pointer_cast<const Structure>(field);
-   FieldConstPtrArray fields = structurePtr->getFields();
-   StringArray names = structurePtr->getFieldNames();
-   size_t n = structurePtr->getNumberFields();
-   if(n!=10) return false;
-   FieldConstPtr f = fields[0];
-   if(names[0].compare("active")!=0) return false;
-   if(f->getType()!=scalar) return false;
-   ScalarConstPtr s = static_pointer_cast<const Scalar>(f);
-   if(s->getScalarType()!=pvBoolean) return false;
-   f = fields[1];
-   if(names[1].compare("lowAlarmLimit")!=0) return false;
-   if(f->getType()!=scalar) return false;
-   s = static_pointer_cast<const Scalar>(f);
-   if(s->getScalarType()!=pvDouble) return false;
-   f = fields[2];
-   if(names[2].compare("lowWarningLimit")!=0) return false;
-   if(f->getType()!=scalar) return false;
-   s = static_pointer_cast<const Scalar>(f);
-   if(s->getScalarType()!=pvDouble) return false;
-   f = fields[3];
-   if(names[3].compare("highWarningLimit")!=0) return false;
-   if(f->getType()!=scalar) return false;
-   s = static_pointer_cast<const Scalar>(f);
-   if(s->getScalarType()!=pvDouble) return false;
-   f = fields[4];
-   if(names[4].compare("highAlarmLimit")!=0) return false;
-   if(f->getType()!=scalar) return false;
-   s = static_pointer_cast<const Scalar>(f);
-   if(s->getScalarType()!=pvDouble) return false;
-   f = fields[5];
-   if(names[5].compare("lowAlarmSeverity")!=0) return false;
-   if(f->getType()!=scalar) return false;
-   s = static_pointer_cast<const Scalar>(f);
-   if(s->getScalarType()!=pvInt) return false;
-   f = fields[6];
-   if(names[6].compare("lowWarningSeverity")!=0) return false;
-   if(f->getType()!=scalar) return false;
-   s = static_pointer_cast<const Scalar>(f);
-   if(s->getScalarType()!=pvInt) return false;
-   f = fields[7];
-   if(names[7].compare("highWarningSeverity")!=0) return false;
-   if(f->getType()!=scalar) return false;
-   s = static_pointer_cast<const Scalar>(f);
-   if(s->getScalarType()!=pvInt) return false;
-   f = fields[8];
-   if(names[8].compare("highAlarmSeverity")!=0) return false;
-   if(f->getType()!=scalar) return false;
-   s = static_pointer_cast<const Scalar>(f);
-   if(s->getScalarType()!=pvInt) return false;
-   f = fields[9];
-   if(names[9].compare("hysteresis")!=0) return false;
-   if(f->getType()!=scalar) return false;
-   return true;
+    Result result(field);
+    return isAlarmLimit(result.is<Structure>()).valid();
+}
+
+Result& NTField::isControl(Result& result)
+{
+    return result
+        .has<Scalar>("limitLow")
+        .has<Scalar>("limitHigh")
+        .has<Scalar>("minStep");
 }
 
 bool NTField::isControl(FieldConstPtr const & field)
 {
-   if(field->getType()!=structure) return false;
-   StructureConstPtr structurePtr = static_pointer_cast<const Structure>(field);
-   FieldConstPtrArray fields = structurePtr->getFields();
-   StringArray names = structurePtr->getFieldNames();
-   size_t n = structurePtr->getNumberFields();
-   if(n!=3) return false;
-   FieldConstPtr f = fields[0];
-   if(names[0].compare("limitLow")!=0) return false;
-   if(f->getType()!=scalar) return false;
-   ScalarConstPtr s = static_pointer_cast<const Scalar>(f);
-   if(s->getScalarType()!=pvDouble) return false;
-   f = fields[1];
-   if(names[1].compare("limitHigh")!=0) return false;
-   if(f->getType()!=scalar) return false;
-   s = static_pointer_cast<const Scalar>(f);
-   if(s->getScalarType()!=pvDouble) return false;
-   f = fields[2];
-   if(names[2].compare("minStep")!=0) return false;
-   if(f->getType()!=scalar) return false;
-   s = static_pointer_cast<const Scalar>(f);
-   if(s->getScalarType()!=pvDouble) return false;
-   return true;
+    Result result(field);
+    return isControl(result.is<Structure>()).valid();
 }
 
 StructureConstPtr NTField::createEnumerated()
@@ -339,4 +239,3 @@ PVStructureArrayPtr PVNTField::createAlarmArray()
 }
 
 }}
-

src/nthistogram.cpp

@@ -4,6 +4,8 @@
  * found in the file LICENSE that is included with the distribution
  */
 
+#include "validator.h"
+
 #define epicsExportSharedSymbols
 #include <pv/nthistogram.h>
 #include <pv/ntutils.h>
@@ -135,37 +137,19 @@ bool NTHistogram::is_a(PVStructurePtr const & pvStructure)
 
 bool NTHistogram::isCompatible(StructureConstPtr const &structure)
 {
-    if(!structure.get()) return false;
-
-    ScalarArrayConstPtr rangesField = structure->getField<ScalarArray>("ranges");
-    if(!rangesField.get() || rangesField->getElementType() != pvDouble) return false;
-
-    ScalarArrayConstPtr valueField = structure->getField<ScalarArray>("value");
-    if(!valueField.get()) return false;
-
-    ScalarType scalarType = valueField->getElementType();
-    if (scalarType != pvShort &&
-        scalarType != pvInt &&
-        scalarType != pvLong)
+    if (!structure)
         return false;
 
-    FieldConstPtr field = structure->getField("descriptor");
-    if(field)
-    {
-       ScalarConstPtr descriptorField = structure->getField<Scalar>("descriptor");
-       if (!descriptorField.get() || descriptorField->getScalarType() != pvString)
-           return false;
-    }
+    Result result(structure);
 
-    field = structure->getField("alarm");
-    if (field.get() && !ntField->isAlarm(field))
-        return false;
-
-    field = structure->getField("timeStamp");
-    if (field.get() && !ntField->isTimeStamp(field))
-        return false;
-
-    return true;
+    return result
+        .is<Structure>()
+        .has<ScalarArray>("ranges")
+        .has<ScalarArray>("value")
+        .maybeHas<Scalar>("descriptor")
+        .maybeHas<&NTField::isAlarm, Structure>("alarm")
+        .maybeHas<&NTField::isTimeStamp, Structure>("timeStamp")
+        .valid();
 }
 
 bool NTHistogram::isCompatible(PVStructurePtr const & pvStructure)

src/ntid.cpp

@@ -7,11 +7,11 @@
 #include <pv/ntid.h>
 #include <pv/typeCast.h>
 
-namespace epics { 
+namespace epics {
 
 namespace nt {
 
-    const static std::string BAD_NAME = "?"; 
+    const static std::string BAD_NAME = "?";
 
     NTID::NTID(const std::string & id)
     : fullName(id),
@@ -81,7 +81,7 @@ namespace nt {
             else
             {
                 name = fullName;
-            } 
+            }
         }
         return name;
     }
@@ -105,7 +105,7 @@ namespace nt {
             {
                 endMajorIndex = fullName.find('.', versionSepIndex+1);
                 majorVersionStr = (endMajorIndex != std::string::npos)
-                    ? fullName.substr(versionSepIndex+1, endMajorIndex-(versionSepIndex+1)) : 
+                    ? fullName.substr(versionSepIndex+1, endMajorIndex-(versionSepIndex+1)) :
                       fullName.substr(versionSepIndex+1);
             }
             else
@@ -150,7 +150,7 @@ namespace nt {
             {
                 endMinorIndex = fullName.find('.', endMajorIndex+1);
                 minorVersionStr = (endMinorIndex != std::string::npos)
-                    ? fullName.substr(endMajorIndex+1, endMinorIndex-(endMajorIndex+1)) : 
+                    ? fullName.substr(endMajorIndex+1, endMinorIndex-(endMajorIndex+1)) :
                       fullName.substr(endMajorIndex+1);
             }
             else
@@ -186,5 +186,3 @@ namespace nt {
 
 
 }}
-
-

src/ntmatrix.cpp

@@ -4,6 +4,8 @@
  * found in the file LICENSE that is included with the distribution
  */
 
+#include "validator.h"
+
 #define epicsExportSharedSymbols
 #include <pv/ntmatrix.h>
 #include <pv/ntutils.h>
@@ -139,43 +141,20 @@ bool NTMatrix::is_a(PVStructurePtr const & pvStructure)
 
 bool NTMatrix::isCompatible(StructureConstPtr const & structure)
 {
-    if (structure.get() == 0) return false;
-
-    ScalarArrayConstPtr valueField = structure->getField<ScalarArray>("value");
-    if (valueField.get() == 0 || valueField->getElementType() != pvDouble)
+    if (!structure)
         return false;
 
-    FieldConstPtr field = structure->getField("dim");
-    if (field.get())
-    {
-        ScalarArrayConstPtr dimField = structure->getField<ScalarArray>("dim");
-        if (dimField.get() == 0 || dimField->getElementType() != pvInt)
-            return false;
-    }
+    Result result(structure);
 
-    field = structure->getField("descriptor");
-    if (field.get())
-    {
-        ScalarConstPtr descriptorField = structure->getField<Scalar>("descriptor");
-        if (!descriptorField.get() || descriptorField->getScalarType() != pvString)
-            return false;
-    }
-
-    NTFieldPtr ntField = NTField::get();
-
-    field = structure->getField("alarm");
-    if (field.get() && !ntField->isAlarm(field))
-        return false;
-
-    field = structure->getField("timeStamp");
-    if (field.get() && !ntField->isTimeStamp(field))
-        return false;
-
-    field = structure->getField("display");
-    if (field.get() && !ntField->isDisplay(field))
-        return false;
-
-    return true;
+    return result
+        .is<Structure>()
+        .has<ScalarArray>("value")
+        .maybeHas<ScalarArray>("dim")
+        .maybeHas<Scalar>("descriptor")
+        .maybeHas<&NTField::isAlarm, Structure>("alarm")
+        .maybeHas<&NTField::isTimeStamp, Structure>("timeStamp")
+        .maybeHas<&NTField::isDisplay, Structure>("display")
+        .valid();
 }
 
 bool NTMatrix::isCompatible(PVStructurePtr const & pvStructure)

src/ntmultiChannel.cpp

@@ -6,6 +6,8 @@
 
 #include <algorithm>
 
+#include "validator.h"
+
 #define epicsExportSharedSymbols
 #include <pv/ntmultiChannel.h>
 #include <pv/ntutils.h>
@@ -13,7 +15,7 @@
 using namespace std;
 using namespace epics::pvData;
 
-namespace epics { namespace nt { 
+namespace epics { namespace nt {
 
 
 static FieldCreatePtr fieldCreate = getFieldCreate();
@@ -232,86 +234,27 @@ bool NTMultiChannel::is_a(PVStructurePtr const & pvStructure)
 
 bool NTMultiChannel::isCompatible(StructureConstPtr const & structure)
 {
-    if (!structure.get()) return false;
-
-    UnionArrayConstPtr valueField = structure->getField<UnionArray>("value");
-    if (!valueField.get()) return false;
-
-    ScalarArrayConstPtr channelNameField = structure->getField<ScalarArray>(
-        "channelName");
-    if (!channelNameField.get()) return false;
-    if (channelNameField->getElementType() != pvString) return false;
-
-    FieldConstPtr field = structure->getField("severity");
-    if (field.get())
-    {
-        ScalarArrayConstPtr severityField = structure->getField<ScalarArray>("severity");
-        if (!severityField.get() || severityField->getElementType() != pvInt)
-            return false;
-    }
-
-    field = structure->getField("status");
-    if (field.get())
-    {
-        ScalarArrayConstPtr statusField = structure->getField<ScalarArray>("status");
-        if (!statusField.get() || statusField->getElementType() != pvInt)
-            return false;
-    }
-
-    field = structure->getField("message");
-    if (field.get())
-    {
-        ScalarArrayConstPtr messageField = structure->getField<ScalarArray>("message");
-        if (!messageField.get() || messageField->getElementType() != pvString)
-           return false;
-    }
-
-    field = structure->getField("secondsPastEpoch");
-    if (field.get())
-    {
-        ScalarArrayConstPtr secondsPastEpochField = structure->getField<ScalarArray>("secondsPastEpoch");
-        if (!secondsPastEpochField.get() || secondsPastEpochField->getElementType() != pvLong)
-            return false;
-    }
-
-    field = structure->getField("nanoseconds");
-    if (field.get())
-    {
-        ScalarArrayConstPtr nanosecondsField = structure->getField<ScalarArray>("nanoseconds");
-        if (!nanosecondsField.get() || nanosecondsField->getElementType() != pvInt)
-            return false;
-    }
-
-    field = structure->getField("userTag");
-    if (field.get())
-    {
-        ScalarArrayConstPtr userTagField = structure->getField<ScalarArray>("userTag");
-        if (!userTagField.get() || userTagField->getElementType() != pvInt)
-            return false;
-    }
-
-    field = structure->getField("descriptor");
-    if (field.get())
-    {
-        ScalarConstPtr descriptorField = structure->getField<Scalar>("descriptor");
-        if (!descriptorField.get() || descriptorField->getScalarType() != pvString)
-            return false;
-    }
-
-    NTFieldPtr ntField = NTField::get();
-
-    field = structure->getField("alarm");
-    if (field.get() && !ntField->isAlarm(field))
+    if (!structure)
         return false;
 
-    field = structure->getField("timeStamp");
-    if (field.get() && !ntField->isTimeStamp(field))
-        return false;
+    Result result(structure);
 
-    return true;
+    return result
+        .is<Structure>()
+        .has<UnionArray>("value")
+        .has<ScalarArray>("channelName")
+        .maybeHas<ScalarArray>("severity")
+        .maybeHas<ScalarArray>("status")
+        .maybeHas<ScalarArray>("message")
+        .maybeHas<ScalarArray>("secondsPastEpoch")
+        .maybeHas<ScalarArray>("nanoseconds")
+        .maybeHas<ScalarArray>("userTag")
+        .maybeHas<Scalar>("descriptor")
+        .maybeHas<&NTField::isAlarm, Structure>("alarm")
+        .maybeHas<&NTField::isTimeStamp, Structure>("timeStamp")
+        .valid();
 }
 
-
 bool NTMultiChannel::isCompatible(PVStructurePtr const &pvStructure)
 {
     if(!pvStructure.get()) return false;
@@ -326,7 +269,7 @@ bool NTMultiChannel::isValid()
     if (getChannelName()->getLength() != valueLength) return false;
 
     PVScalarArrayPtr arrayFields[] = {
-          getSeverity(), getStatus(), getMessage(), 
+          getSeverity(), getStatus(), getMessage(),
           getSecondsPastEpoch(), getNanoseconds(), getUserTag()
     };
     size_t N = sizeof(arrayFields)/sizeof(arrayFields[0]);
@@ -338,7 +281,7 @@ bool NTMultiChannel::isValid()
         if (arrayField.get() && arrayField->getLength() != valueLength)
             return false;
     }
-    return true; 
+    return true;
 }
 
 

src/ntnameValue.cpp

@@ -4,6 +4,8 @@
  * found in the file LICENSE that is included with the distribution
  */
 
+#include "validator.h"
+
 #define epicsExportSharedSymbols
 #include <pv/ntnameValue.h>
 #include <pv/ntutils.h>
@@ -134,35 +136,19 @@ bool NTNameValue::is_a(PVStructurePtr const & pvStructure)
 
 bool NTNameValue::isCompatible(StructureConstPtr const & structure)
 {
-    if (structure.get() == 0) return false;
-
-    ScalarArrayConstPtr nameField = structure->getField<ScalarArray>("name");
-    if (nameField.get() == 0 || nameField->getElementType() != pvString)
+    if (!structure)
         return false;
 
-    ScalarArrayConstPtr valueField = structure->getField<ScalarArray>("value");
-    if (valueField.get() == 0)
-        return false;
+    Result result(structure);
 
-    FieldConstPtr field = structure->getField("descriptor");
-    if (field.get())
-    {
-        ScalarConstPtr descriptorField = structure->getField<Scalar>("descriptor");
-        if (!descriptorField || descriptorField->getScalarType() != pvString)
-            return false;
-    }
-
-    NTFieldPtr ntField = NTField::get();
-
-    field = structure->getField("alarm");
-    if (field && !ntField->isAlarm(field))
-        return false;
-
-    field = structure->getField("timeStamp");
-    if (field && !ntField->isTimeStamp(field))
-        return false;
-
-    return true;
+    return result
+        .is<Structure>()
+        .has<ScalarArray>("name")
+        .has<ScalarArray>("value")
+        .maybeHas<Scalar>("descriptor")
+        .maybeHas<&NTField::isAlarm, Structure>("alarm")
+        .maybeHas<&NTField::isTimeStamp, Structure>("timeStamp")
+        .valid();
 }
 
 bool NTNameValue::isCompatible(PVStructurePtr const & pvStructure)

src/ntndarray.cpp

@@ -7,6 +7,9 @@
 #include <algorithm>
 
 #include <pv/lock.h>
+#include <pv/sharedPtr.h>
+
+#include "validator.h"
 
 #define epicsExportSharedSymbols
 #include <pv/ntndarray.h>
@@ -18,9 +21,6 @@ using namespace epics::pvData;
 
 namespace epics { namespace nt {
 
-static NTFieldPtr ntField = NTField::get();
-
-
 namespace detail {
 
 static FieldCreatePtr fieldCreate = getFieldCreate();
@@ -71,7 +71,7 @@ StructureConstPtr NTNDArrayBuilder::createStructure()
                 ScalarType st = static_cast<ScalarType>(i);
                 fb->addArray(std::string(ScalarTypeFunc::name(st)) + "Value", st);
             }
-            valueType = fb->createUnion();                
+            valueType = fb->createUnion();
         }
 
         if (!codecStruc)
@@ -127,7 +127,7 @@ StructureConstPtr NTNDArrayBuilder::createStructure()
         returnedStruc = fb->createStructure();
 
         if (!isExtended)
-            ntndarrayStruc[index] = returnedStruc; 
+            ntndarrayStruc[index] = returnedStruc;
     }
     else
     {
@@ -192,95 +192,11 @@ NTNDArrayBuilder::shared_pointer NTNDArrayBuilder::add(string const & name, Fiel
     return shared_from_this();
 }
 
-
 }
 
 const std::string NTNDArray::URI("epics:nt/NTNDArray:1.0");
 const std::string ntAttrStr("epics:nt/NTAttribute:1.0");
 
-static FieldCreatePtr fieldCreate = getFieldCreate();
-static PVDataCreatePtr pvDataCreate = getPVDataCreate();
-
-class NTValueType
-{
-public:
-    static bool isCompatible(UnionConstPtr const &u)
-    {
-        if(!u.get()) return false;
-
-        if (u->getID() != Union::defaultId()) return false;
-        if (u->isVariant()) return false;
-
-        for (int i = pvBoolean; i != pvString; ++i)
-        {
-            ScalarType scalarType = static_cast<ScalarType>(i);
-            std::string name(ScalarTypeFunc::name(scalarType));
-            name += "Value";
-            ScalarArrayConstPtr scalarField = u->getField<ScalarArray>(name);
-            if (scalarField.get() == 0 ||
-                    scalarField->getElementType() != scalarType)
-                return false;
-        }
-
-        return true;
-    }
-};
-
-class NTCodec
-{
-public:
-    static bool isCompatible(StructureConstPtr const &structure)
-    {
-        if(!structure.get()) return false;
-
-        if (structure->getID() != "codec_t") return false;
-
-        ScalarConstPtr scalarField = structure->getField<Scalar>("name");
-        if (scalarField.get() == 0 || scalarField->getScalarType() != pvString)
-            return false;
-
-        UnionConstPtr paramField = structure->getField<Union>("parameters");
-        if (paramField.get() == 0 || !paramField->isVariant())
-            return false;
-
-        return true;
-    }
-};
-
-
-class NTDimension
-{
-public:
-    static bool isCompatible(StructureConstPtr const &structure)
-    {
-        if(!structure.get()) return false;
-
-        if (structure->getID() != "dimension_t") return false;
-
-        ScalarConstPtr scalarField = structure->getField<Scalar>("size");
-        if (scalarField.get() == 0 || scalarField->getScalarType() != pvInt)
-            return false;
-
-        scalarField = structure->getField<Scalar>("offset");
-        if (scalarField.get() == 0 || scalarField->getScalarType() != pvInt)
-            return false;
-
-        scalarField = structure->getField<Scalar>("fullSize");
-        if (scalarField.get() == 0 || scalarField->getScalarType() != pvInt)
-            return false;
-
-        scalarField = structure->getField<Scalar>("binning");
-        if (scalarField.get() == 0 || scalarField->getScalarType() != pvInt)
-            return false;
-
-        scalarField = structure->getField<Scalar>("reverse");
-        if (scalarField.get() == 0 || scalarField->getScalarType() != pvBoolean)
-            return false;
-
-        return true;
-    }
-};
-
 NTNDArray::shared_pointer NTNDArray::wrap(PVStructurePtr const & pvStructure)
 {
     if(!isCompatible(pvStructure)) return shared_pointer();
@@ -302,84 +218,62 @@ bool NTNDArray::is_a(PVStructurePtr const & pvStructure)
     return is_a(pvStructure->getStructure());
 }
 
-bool NTNDArray::isCompatible(StructureConstPtr const &structure)
-{
-    if(!structure.get()) return false;
-
-    UnionConstPtr valueField = structure->getField<Union>("value");
-    if(!NTValueType::isCompatible(valueField)) return false;
-
-    StructureConstPtr codecField = structure->getField<Structure>("codec");
-    if(!NTCodec::isCompatible(codecField)) return false;
-
-    ScalarConstPtr compressedSizeField = structure->getField<Scalar>("compressedSize");
-    if (compressedSizeField.get() == 0)
-        return false;
-
-    if (compressedSizeField->getScalarType() != pvLong)
-        return false;
-
-
-    ScalarConstPtr uncompressedSizeField = structure->getField<Scalar>("uncompressedSize");
-    if (uncompressedSizeField.get() == 0)
-        return false;
-
-    if (uncompressedSizeField->getScalarType() != pvLong)
-        return false;
-
-    StructureArrayConstPtr dimensionField = structure->getField<StructureArray>("dimension");
-    if (dimensionField.get() == 0)
-        return false;
-    StructureConstPtr dimElementStruc = dimensionField->getStructure();
-
-    if(!NTDimension::isCompatible(dimElementStruc))
-       return false;
-
-    NTFieldPtr ntField = NTField::get();
-
-    StructureConstPtr dataTimeStampField = structure->getField<Structure>(
-        "dataTimeStamp");
-    if (dataTimeStampField.get() == 0 || !ntField->isTimeStamp(dataTimeStampField))
-        return false;
-
-
-    ScalarConstPtr uniqueIdField = structure->getField<Scalar>("uniqueId");
-    if (uniqueIdField.get() == 0)
-        return false;
-
-    if (uniqueIdField->getScalarType() != pvInt)
-        return false;
-
-
-    StructureArrayConstPtr attributeField = structure->getField<StructureArray>( "attribute");
-    if (!attributeField)
-        return false;
-
-    if (!NTNDArrayAttribute::isCompatible(attributeField->getStructure()))
-        return false;
-
-
-    FieldConstPtr field = structure->getField("descriptor");
-    if (field.get())
+namespace {
+    Result& isValue(Result& result)
     {
-        ScalarConstPtr descriptorField = structure->getField<Scalar>("descriptor");
-        if (!descriptorField || descriptorField->getScalarType() != pvString)
-            return false;
+        result.is<Union>(Union::defaultId());
+
+        for (int i = pvBoolean; i < pvString; ++i) {
+            ScalarType type = static_cast<ScalarType>(i);
+            string name(ScalarTypeFunc::name(type));
+            result.has<ScalarArray>(name + "Value");
+        }
+
+        return result;
     }
 
-    field = structure->getField("alarm");
-    if (field.get() && !ntField->isAlarm(field))
+    Result& isCodec(Result& result)
+    {
+        return result
+            .is<Structure>("codec_t")
+            .has<Scalar>("name")
+            .has<Union>("parameters");
+    }
+
+    Result& isDimension(Result& result)
+    {
+        return result
+            .is<StructureArray>("dimension_t[]")
+            .has<Scalar>("size")
+            .has<Scalar>("offset")
+            .has<Scalar>("fullSize")
+            .has<Scalar>("binning")
+            .has<Scalar>("reverse");
+    }
+}
+
+bool NTNDArray::isCompatible(StructureConstPtr const &structure)
+{
+    if (!structure)
         return false;
 
-    field = structure->getField("timeStamp");
-    if (field.get() && !ntField->isTimeStamp(field))
-        return false;
+    Result result(structure);
 
-    field = structure->getField("display");
-    if (field.get() && !ntField->isDisplay(field))
-        return false;
-
-    return true;
+    return result
+        .is<Structure>()
+        .has<&isValue>("value")
+        .has<&isCodec>("codec")
+        .has<Scalar>("compressedSize")
+        .has<Scalar>("uncompressedSize")
+        .has<&isDimension>("dimension")
+        .has<Scalar>("uniqueId")
+        .has<&NTField::isTimeStamp, Structure>("dataTimeStamp")
+        .has<&NTNDArrayAttribute::isAttribute, StructureArray>("attribute")
+        .maybeHas<Scalar>("descriptor")
+        .maybeHas<&NTField::isAlarm, Structure>("alarm")
+        .maybeHas<&NTField::isTimeStamp, Structure>("timeStamp")
+        .maybeHas<&NTField::isDisplay, Structure>("display")
+        .valid();
 }
 
 
@@ -390,7 +284,6 @@ bool NTNDArray::isCompatible(PVStructurePtr const & pvStructure)
     return isCompatible(pvStructure->getStructure());
 }
 
-
 bool NTNDArray::isValid()
 {
     int64 valueSize = getValueSize();
@@ -434,10 +327,8 @@ int64 NTNDArray::getValueSize()
 {
     int64 size = 0;
     PVScalarArrayPtr storedValue = getValue()->get<PVScalarArray>();
-    if (!storedValue.get())
-    {
+    if (storedValue.get())
         size = storedValue->getLength()*getValueTypeSize();
-    }
     return size;
 }
 

src/ntndarrayAttribute.cpp

@@ -4,6 +4,8 @@
  * found in the file LICENSE that is included with the distribution
  */
 
+#include "validator.h"
+
 #define epicsExportSharedSymbols
 #include <pv/ntndarrayAttribute.h>
 #include <pv/ntattribute.h>
@@ -132,24 +134,25 @@ bool NTNDArrayAttribute::is_a(PVStructurePtr const & pvStructure)
     return is_a(pvStructure->getStructure());
 }
 
+Result& NTNDArrayAttribute::isAttribute(Result& result) {
+    return result
+        .has<Scalar>("name")
+        .has<Union>("value")
+        .maybeHas<ScalarArray>("tags")
+        .has<Scalar>("descriptor")
+        .maybeHas<&NTField::isAlarm, Structure>("alarm")
+        .maybeHas<&NTField::isTimeStamp, Structure>("timeStamp")
+        .has<Scalar>("sourceType")
+        .has<Scalar>("source");
+}
+
 bool NTNDArrayAttribute::isCompatible(StructureConstPtr const & structure)
 {
-    if (!NTAttribute::isCompatible(structure)) return false;
-
-    // descriptor required field for attibute in an ndarray
-    ScalarConstPtr descriptorField = structure->getField<Scalar>("descriptor");
-    if (descriptorField.get() == 0 || descriptorField->getScalarType() != pvString)
+    if (!structure)
         return false;
 
-    ScalarConstPtr sourcedTypeField = structure->getField<Scalar>("sourceType");
-    if (sourcedTypeField.get() == 0 || sourcedTypeField->getScalarType() != pvInt)
-        return false;
-
-    ScalarConstPtr sourcedField = structure->getField<Scalar>("source");
-    if (sourcedField.get() == 0 || sourcedField->getScalarType() != pvString)
-        return false;
-
-    return true;
+    Result result(structure);
+    return isAttribute(result.is<Structure>()).valid();
 }
 
 bool NTNDArrayAttribute::isCompatible(PVStructurePtr const & pvStructure)

src/ntscalar.cpp

@@ -4,6 +4,8 @@
  * found in the file LICENSE that is included with the distribution
  */
 
+#include "validator.h"
+
 #define epicsExportSharedSymbols
 #include <pv/ntscalar.h>
 #include <pv/ntutils.h>
@@ -152,42 +154,22 @@ bool NTScalar::is_a(PVStructurePtr const & pvStructure)
 
 bool NTScalar::isCompatible(StructureConstPtr const &structure)
 {
-    if (structure.get() == 0) return false;
-
-    ScalarConstPtr valueField = structure->getField<Scalar>("value");
-    if (valueField.get() == 0)
+    if (!structure)
         return false;
 
-    FieldConstPtr field = structure->getField("descriptor");
-    if (field.get())
-    {
-        ScalarConstPtr descriptorField = structure->getField<Scalar>("descriptor");
-        if (!descriptorField.get() || descriptorField->getScalarType() != pvString)
-            return false;
-    }
+    Result result(structure);
 
-    NTFieldPtr ntField = NTField::get();
-
-    field = structure->getField("alarm");
-    if (field.get() && !ntField->isAlarm(field))
-        return false;
-
-    field = structure->getField("timeStamp");
-    if (field.get() && !ntField->isTimeStamp(field))
-        return false;
-
-    field = structure->getField("display");
-    if (field.get() && !ntField->isDisplay(field))
-        return false;
-
-    field = structure->getField("control");
-    if (field.get() && !ntField->isControl(field))
-        return false;
-
-    return true;
+    return result
+        .is<Structure>()
+        .has<Scalar>("value")
+        .maybeHas<Scalar>("descriptor")
+        .maybeHas<&NTField::isAlarm, Structure>("alarm")
+        .maybeHas<&NTField::isTimeStamp, Structure>("timeStamp")
+        .maybeHas<&NTField::isDisplay, Structure>("display")
+        .maybeHas<&NTField::isControl, Structure>("control")
+        .valid();
 }
 
-
 bool NTScalar::isCompatible(PVStructurePtr const & pvStructure)
 {
     if(!pvStructure) return false;

src/ntscalarArray.cpp

@@ -4,6 +4,8 @@
  * found in the file LICENSE that is included with the distribution
  */
 
+#include "validator.h"
+
 #define epicsExportSharedSymbols
 #include <pv/ntscalarArray.h>
 #include <pv/ntutils.h>
@@ -161,39 +163,20 @@ bool NTScalarArray::is_a(PVStructurePtr const & pvStructure)
 
 bool NTScalarArray::isCompatible(StructureConstPtr const & structure)
 {
-    if (structure.get() == 0) return false;
-
-    ScalarArrayConstPtr valueField = structure->getField<ScalarArray>("value");
-    if (valueField.get() == 0)
+    if (!structure)
         return false;
 
-    FieldConstPtr field = structure->getField("descriptor");
-    if (field.get())
-    {
-        ScalarConstPtr descriptorField = structure->getField<Scalar>("descriptor");
-        if (!descriptorField.get() || descriptorField->getScalarType() != pvString)
-            return false;
-    }
+    Result result(structure);
 
-    NTFieldPtr ntField = NTField::get();
-
-    field = structure->getField("alarm");
-    if (field.get() && !ntField->isAlarm(field))
-        return false;
-
-    field = structure->getField("timeStamp");
-    if (field.get() && !ntField->isTimeStamp(field))
-        return false;
-
-    field = structure->getField("display");
-    if (field.get() && !ntField->isDisplay(field))
-        return false;
-
-    field = structure->getField("control");
-    if (field.get() && !ntField->isControl(field))
-        return false;
-
-    return true;
+    return result
+        .is<Structure>()
+        .has<ScalarArray>("value")
+        .maybeHas<Scalar>("descriptor")
+        .maybeHas<&NTField::isAlarm, Structure>("alarm")
+        .maybeHas<&NTField::isTimeStamp, Structure>("timeStamp")
+        .maybeHas<&NTField::isDisplay, Structure>("display")
+        .maybeHas<&NTField::isControl, Structure>("control")
+        .valid();
 }
 
 bool NTScalarArray::isCompatible(PVStructurePtr const & pvStructure)

src/ntscalarMultiChannel.cpp

@@ -4,6 +4,7 @@
  * found in the file LICENSE that is included with the distribution
  */
 #include <algorithm>
+#include "validator.h"
 
 #define epicsExportSharedSymbols
 #include <pv/ntscalarMultiChannel.h>
@@ -12,7 +13,7 @@
 using namespace std;
 using namespace epics::pvData;
 
-namespace epics { namespace nt { 
+namespace epics { namespace nt {
 
 
 static FieldCreatePtr fieldCreate = getFieldCreate();
@@ -228,86 +229,27 @@ bool NTScalarMultiChannel::is_a(PVStructurePtr const & pvStructure)
 
 bool NTScalarMultiChannel::isCompatible(StructureConstPtr const & structure)
 {
-    if (!structure.get()) return false;
-
-    ScalarArrayConstPtr valueField = structure->getField<ScalarArray>("value");
-    if (!valueField.get()) return false;
-
-    ScalarArrayConstPtr channelNameField = structure->getField<ScalarArray>(
-        "channelName");
-    if (!channelNameField.get()) return false;
-    if (channelNameField->getElementType() != pvString) return false;
-
-    FieldConstPtr field = structure->getField("severity");
-    if (field.get())
-    {
-        ScalarArrayConstPtr severityField = structure->getField<ScalarArray>("severity");
-        if (!severityField.get() || severityField->getElementType() != pvInt)
-            return false;
-    }
-
-    field = structure->getField("status");
-    if (field.get())
-    {
-        ScalarArrayConstPtr statusField = structure->getField<ScalarArray>("status");
-        if (!statusField.get() || statusField->getElementType() != pvInt)
-            return false;
-    }
-
-    field = structure->getField("message");
-    if (field.get())
-    {
-        ScalarArrayConstPtr messageField = structure->getField<ScalarArray>("message");
-        if (!messageField.get() || messageField->getElementType() != pvString)
-           return false;
-    }
-
-    field = structure->getField("secondsPastEpoch");
-    if (field.get())
-    {
-        ScalarArrayConstPtr secondsPastEpochField = structure->getField<ScalarArray>("secondsPastEpoch");
-        if (!secondsPastEpochField.get() || secondsPastEpochField->getElementType() != pvLong)
-            return false;
-    }
-
-    field = structure->getField("nanoseconds");
-    if (field.get())
-    {
-        ScalarArrayConstPtr nanosecondsField = structure->getField<ScalarArray>("nanoseconds");
-        if (!nanosecondsField.get() || nanosecondsField->getElementType() != pvInt)
-            return false;
-    }
-
-    field = structure->getField("userTag");
-    if (field.get())
-    {
-        ScalarArrayConstPtr userTagField = structure->getField<ScalarArray>("userTag");
-        if (!userTagField.get() || userTagField->getElementType() != pvInt)
-            return false;
-    }
-
-    field = structure->getField("descriptor");
-    if (field.get())
-    {
-        ScalarConstPtr descriptorField = structure->getField<Scalar>("descriptor");
-        if (!descriptorField.get() || descriptorField->getScalarType() != pvString)
-            return false;
-    }
-
-    NTFieldPtr ntField = NTField::get();
-
-    field = structure->getField("alarm");
-    if (field.get() && !ntField->isAlarm(field))
+    if (!structure)
         return false;
 
-    field = structure->getField("timeStamp");
-    if (field.get() && !ntField->isTimeStamp(field))
-        return false;
+    Result result(structure);
 
-    return true;
+    return result
+        .is<Structure>()
+        .has<ScalarArray>("value")
+        .has<ScalarArray>("channelName")
+        .maybeHas<ScalarArray>("severity")
+        .maybeHas<ScalarArray>("status")
+        .maybeHas<ScalarArray>("message")
+        .maybeHas<ScalarArray>("secondsPastEpoch")
+        .maybeHas<ScalarArray>("nanoseconds")
+        .maybeHas<ScalarArray>("userTag")
+        .maybeHas<Scalar>("descriptor")
+        .maybeHas<&NTField::isAlarm, Structure>("alarm")
+        .maybeHas<&NTField::isTimeStamp, Structure>("timeStamp")
+        .valid();
 }
 
-
 bool NTScalarMultiChannel::isCompatible(PVStructurePtr const &pvStructure)
 {
     if(!pvStructure.get()) return false;
@@ -321,7 +263,7 @@ bool NTScalarMultiChannel::isValid()
     if (getChannelName()->getLength() != valueLength) return false;
 
     PVScalarArrayPtr arrayFields[] = {
-          getSeverity(), getStatus(), getMessage(), 
+          getSeverity(), getStatus(), getMessage(),
           getSecondsPastEpoch(), getNanoseconds(), getUserTag()
     };
     size_t N = sizeof(arrayFields)/sizeof(arrayFields[0]);
@@ -333,7 +275,7 @@ bool NTScalarMultiChannel::isValid()
         if (arrayField.get() && arrayField->getLength() != valueLength)
             return false;
     }
-    return true; 
+    return true;
 }
 
 NTScalarMultiChannelBuilderPtr NTScalarMultiChannel::createBuilder()

src/nttable.cpp

@@ -5,6 +5,7 @@
  */
 
 #include <algorithm>
+#include "validator.h"
 
 #define epicsExportSharedSymbols
 #include <pv/nttable.h>
@@ -149,42 +150,32 @@ bool NTTable::is_a(PVStructurePtr const & pvStructure)
 
 bool NTTable::isCompatible(StructureConstPtr const & structure)
 {
-    if (!structure.get()) return false;
-
-    StructureConstPtr valueField = structure->getField<Structure>("value");
-    if (!valueField.get())
+    if (!structure)
         return false;
 
-    FieldConstPtrArray const & fields = valueField->getFields();
-    for (FieldConstPtrArray::const_iterator it = fields.begin();
-         it != fields.end(); ++it)
-    {
-        if ((*it)->getType() != scalarArray) return false;
+    Result result(structure);
+
+    result
+        .is<Structure>()
+        .has<Structure>("value")
+        .has<ScalarArray>("labels")
+        .maybeHas<Scalar>("descriptor")
+        .maybeHas<&NTField::isAlarm, Structure>("alarm")
+        .maybeHas<&NTField::isTimeStamp, Structure>("timeStamp");
+
+    StructureConstPtr value(structure->getField<Structure>("value"));
+    if (value) {
+        Result r(value);
+        StringArray const & names(value->getFieldNames());
+        StringArray::const_iterator it;
+
+        for (it = names.begin(); it != names.end(); ++it)
+            r.has<ScalarArray>(*it);
+
+        result |= r;
     }
 
-    ScalarArrayConstPtr labelsField = structure->getField<ScalarArray>("labels");
-    if (!labelsField.get() || labelsField->getElementType() != pvString)
-        return false;
-
-    FieldConstPtr field = structure->getField("descriptor");
-    if (field.get())
-    {
-        ScalarConstPtr descriptorField = structure->getField<Scalar>("descriptor");
-        if (!descriptorField.get() || descriptorField->getScalarType() != pvString)
-            return false;
-    }
-
-    NTFieldPtr ntField = NTField::get();
-
-    field = structure->getField("alarm");
-    if (field.get() && !ntField->isAlarm(field))
-        return false;
-
-    field = structure->getField("timeStamp");
-    if (field.get() && !ntField->isTimeStamp(field))
-        return false;
-
-    return true;
+    return result.valid();
 }
 
 bool NTTable::isCompatible(PVStructurePtr const & pvStructure)
@@ -197,7 +188,7 @@ bool NTTable::isCompatible(PVStructurePtr const & pvStructure)
 bool NTTable::isValid()
 {
     PVFieldPtrArray const & columns = pvValue->getPVFields();
-        
+
     if (getLabels()->getLength() != columns.size()) return false;
     bool first = true;
     int length = 0;

src/ntunion.cpp

@@ -4,6 +4,8 @@
  * found in the file LICENSE that is included with the distribution
  */
 
+#include "validator.h"
+
 #define epicsExportSharedSymbols
 #include <pv/ntunion.h>
 #include <pv/ntutils.h>
@@ -128,31 +130,18 @@ bool NTUnion::is_a(PVStructurePtr const & pvStructure)
 
 bool NTUnion::isCompatible(StructureConstPtr const &structure)
 {
-    if (structure.get() == 0) return false;
-
-    UnionConstPtr valueField = structure->getField<Union>("value");
-    if (valueField.get() == 0)
+    if (!structure)
         return false;
 
-    FieldConstPtr field = structure->getField("descriptor");
-    if (field.get())
-    {
-        ScalarConstPtr descriptorField = structure->getField<Scalar>("descriptor");
-        if (!descriptorField.get() || descriptorField->getScalarType() != pvString)
-            return false;
-    }
+    Result result(structure);
 
-    NTFieldPtr ntField = NTField::get();
-
-    field = structure->getField("alarm");
-    if (field.get() && !ntField->isAlarm(field))
-        return false;
-
-    field = structure->getField("timeStamp");
-    if (field.get() && !ntField->isTimeStamp(field))
-        return false;
-
-    return true;
+    return result
+        .is<Structure>()
+        .has<Union>("value")
+        .maybeHas<Scalar>("descriptor")
+        .maybeHas<&NTField::isAlarm, Structure>("alarm")
+        .maybeHas<&NTField::isTimeStamp, Structure>("timeStamp")
+        .valid();
 }
 
 bool NTUnion::isCompatible(PVStructurePtr const & pvStructure)

src/nturi.cpp

@@ -5,6 +5,7 @@
  */
 
 #include <algorithm>
+#include "validator.h"
 
 #define epicsExportSharedSymbols
 #include <pv/nturi.h>
@@ -149,45 +150,31 @@ bool NTURI::is_a(PVStructurePtr const & pvStructure)
 
 bool NTURI::isCompatible(StructureConstPtr const & structure)
 {
-    if (!structure.get()) return false;
-
-    ScalarConstPtr schemeField = structure->getField<Scalar>("scheme");
-    if (schemeField.get() == 0 || schemeField->getScalarType() != pvString)
+    if (!structure)
         return false;
 
-    ScalarConstPtr pathField = structure->getField<Scalar>("path");
-    if (pathField.get() == 0 || pathField->getScalarType() != pvString)
-        return false;
+    Result result(structure);
 
-    FieldConstPtr field = structure->getField("authority");
-    if (field.get())
-    {
-        ScalarConstPtr authorityField = structure->getField<Scalar>("authority");
-        if (!authorityField.get() || authorityField->getScalarType() != pvString)
-            return false;
+    result
+        .is<Structure>()
+        .has<Scalar>("scheme")
+        .has<Scalar>("path")
+        .maybeHas<Scalar>("authority")
+        .maybeHas<Structure>("query");
+
+    StructureConstPtr query(structure->getField<Structure>("query"));
+    if (query) {
+        Result r(query);
+        StringArray const & names(query->getFieldNames());
+        StringArray::const_iterator it;
+
+        for (it = names.begin(); it != names.end(); ++it)
+            r.has<ScalarArray>(*it);
+
+        result |= r;
     }
 
-    field = structure->getField("query");
-    if (field.get())
-    {
-        StructureConstPtr queryField = structure->getField<Structure>("query");
-        if (!queryField.get())
-            return false;
-
-        FieldConstPtrArray const & fields = queryField->getFields();
-        for (FieldConstPtrArray::const_iterator it = fields.begin();
-             it != fields.end(); ++it)
-        {
-            if ((*it)->getType() != scalar) return false;
-            ScalarType scalarType = std::tr1::dynamic_pointer_cast<const Scalar>(
-               (*it))->getScalarType();
-            if (scalarType != pvString &&
-                scalarType != pvInt &&
-                scalarType != pvDouble) return false;
-        }
-    }
-
-    return true;
+    return result.valid();
 }
 
 

src/pv/nt.h

@@ -31,7 +31,7 @@
 
 /** @page Overview Documentation
  *
- * <a href = "ntCPP.html">ntCPP.html</a>
+ * <a href = "../ntCPP.html">Normative Types (C++) Reference</a>
  *
  */
 

src/pv/ntfield.h

@@ -30,6 +30,8 @@
 
 namespace epics { namespace nt {
 
+struct Result;
+
 class NTField;
 typedef std::tr1::shared_ptr<NTField> NTFieldPtr;
 
@@ -149,6 +151,30 @@ private:
     NTField();
     epics::pvData::FieldCreatePtr fieldCreate;
     epics::pvData::StandardFieldPtr standardField;
+
+    // These won't be public just yet
+    static Result& isEnumerated(Result&);
+    static Result& isTimeStamp(Result&);
+    static Result& isAlarm(Result&);
+    static Result& isDisplay(Result&);
+    static Result& isAlarmLimit(Result&);
+    static Result& isControl(Result&);
+
+    friend class NTAggregate;
+    friend class NTAttribute;
+    friend class NTContinuum;
+    friend class NTEnum;
+    friend class NTHistogram;
+    friend class NTMatrix;
+    friend class NTMultiChannel;
+    friend class NTNameValue;
+    friend class NTNDArray;
+    friend class NTNDArrayAttribute;
+    friend class NTScalar;
+    friend class NTScalarArray;
+    friend class NTScalarMultiChannel;
+    friend class NTTable;
+    friend class NTUnion;
 };
 
 /**

src/pv/ntndarray.h

@@ -10,16 +10,16 @@
 #include <string>
 
 #ifdef epicsExportSharedSymbols
-#   define ntscalarArrayEpicsExportSharedSymbols
+#   define ntndarrayEpicsExportSharedSymbols
 #   undef epicsExportSharedSymbols
 #endif
 
 #include <pv/pvDisplay.h>
 #include <pv/pvControl.h>
 
-#ifdef ntscalarArrayEpicsExportSharedSymbols
+#ifdef ntndarrayEpicsExportSharedSymbols
 #   define epicsExportSharedSymbols
-#	undef ntscalarArrayEpicsExportSharedSymbols
+#	undef ntndarrayEpicsExportSharedSymbols
 #endif
 
 #include <pv/ntfield.h>
@@ -139,7 +139,7 @@ public:
      * and if so returns an NTScalarArray which wraps it.
      * This method will return null if the structure is is not compatible
      * or is null.
-     * 
+     *
      * @param pvStructure the PVStructure to be wrapped
      * @return NTScalarArray instance wrapping pvStructure on success, null otherwise
      */
@@ -150,7 +150,7 @@ public:
      * <p>
      * No checks are made as to whether the specified PVStructure
      * is compatible with NTNDArray or is non-null.
-     * 
+     *
      * @param pvStructure the PVStructure to be wrapped
      * @return NTNDArray instance wrapping pvStructure
      */
@@ -163,7 +163,7 @@ public:
      * version of NTNDArray through its type ID, including checking version numbers.
      * The return value does not depend on whether the structure is actually
      * compatible in terms of its introspection type.
-     * 
+     *
      * @param structure the pvStructure to test
      * @return (false,true) if the specified Structure (is not, is) a compatible NTNDArray
      */
@@ -176,7 +176,7 @@ public:
      * version of NTNDArray through its type ID, including checking version numbers.
      * The return value does not depend on whether the structure is actually
      * compatible in terms of its introspection type.
-     * 
+     *
      * @param pvStructure the PVStructure to test
      * @return (false,true) if the specified PVStructure (is not, is) a compatible NTNDArray
      */
@@ -187,7 +187,7 @@ public:
      * <p>
      * Checks if the specified Structure is compatible with this version
      * of NTNDArray through the introspection interface.
-     * 
+     *
      * @param structure the Structure to test
      * @return (false,true) if the specified Structure (is not, is) a compatible NTNDArray
      */

src/pv/ntndarrayAttribute.h

@@ -22,6 +22,7 @@
 
 namespace epics { namespace nt {
 
+struct Result;
 class NTNDArrayAttribute;
 typedef std::tr1::shared_ptr<NTNDArrayAttribute> NTNDArrayAttributePtr;
 
@@ -302,10 +303,13 @@ public:
 
 private:
     NTNDArrayAttribute(epics::pvData::PVStructurePtr const & pvStructure);
+    static Result& isAttribute(Result& result);
+
     epics::pvData::PVStructurePtr pvNTNDArrayAttribute;
     epics::pvData::PVUnionPtr pvValue;
 
     friend class detail::NTNDArrayAttributeBuilder;
+    friend class NTNDArray;
 };
 
 }}

src/validator.h

@@ -0,0 +1,277 @@
+/* validator.h */
+/*
+ * Copyright information and license terms for this software can be
+ * found in the file LICENSE that is included with the distribution
+ */
+#ifndef VALIDATOR_H
+#define VALIDATOR_H
+
+#include <string>
+#include <set>
+#include <algorithm>
+
+#include <pv/pvIntrospect.h>
+
+namespace epics { namespace nt {
+
+/**
+ * @brief Validation methods for NT types.
+ *
+ * @author bsm
+ */
+
+struct Result {
+    struct Error {
+        std::string path;
+        enum Type {
+            MissingField,
+            IncorrectType,
+            IncorrectId,
+        } type;
+
+        Error(std::string const & path, Type type)
+        : path(path), type(type) {}
+
+        bool operator==(const Error& other) const {
+            return type == other.type && path == other.path;
+        }
+
+        std::ostream& dump(std::ostream& os) const {
+            os << "Error(path=" << (path.empty() ? "<root>" : path) << ": ";
+
+            switch(type) {
+                case MissingField:  os << "missing";        break;
+                case IncorrectType: os << "incorrect type"; break;
+                case IncorrectId:   os << "incorrect ID";   break;
+            }
+            os << ")";
+            return os;
+        }
+    };
+
+    epics::pvData::FieldConstPtr field;
+    std::string path;
+    std::vector<Error> errors;
+
+    enum result_t {
+        Pass,
+        Fail,
+    } result;
+
+    Result(const epics::pvData::FieldConstPtr& field, const std::string& path = std::string())
+    : field(field), path(path), errors(), result(Pass) {}
+
+    Result() {}
+
+    Result& operator|=(const Result& other) {
+        result = std::max(result, other.result);
+        errors.insert(errors.end(), other.errors.begin(), other.errors.end());
+        return *this;
+    }
+
+    /**
+     * Returns whether this Result is valid.
+     *
+     * @return true if all tests passed, false otherwise.
+     */
+    inline bool valid(void) const {
+        return result == Pass;
+    }
+
+    /**
+     * Test that this Result's field is of a particular type 'T'.
+     *
+     * Appends an Error::Type::IncorrectType if the field is not of type 'T'.
+     *
+     * @return itself
+     */
+    template<typename T>
+    Result& is(void) {
+        if (!dynamic_cast<T const *>(field.get())) {
+            result = Fail;
+            errors.push_back(Error(path, Error::IncorrectType));
+        }
+        return *this;
+    }
+
+    /**
+     * Test that this Result's field is of a particular type 'T' and has
+     * an ID equal to 'id'.
+     *
+     * Appends an Error::Type::IncorrectType if the field is not of type 'T'.
+     * Appends an Error::Type::IncorrectId if the field does not have an ID
+     * equal to 'id'.
+     *
+     * @return itself
+     */
+    template<typename T>
+    Result& is(const std::string& id) {
+        T const *s = dynamic_cast<T const *>(field.get());
+        if (!s) {
+            result = Fail;
+            errors.push_back(Error(path, Error::IncorrectType));
+        } else if (s->getID() != id) {
+            result = Fail;
+            errors.push_back(Error(path, Error::IncorrectId));
+        }
+        return *this;
+    }
+
+    /**
+     * Test that this Result's field has a subfield with name 'name' and
+     * apply the function 'fn' to the subfield.
+     *
+     * Appends an Error::Type::IncorrectType if the field is not one of
+     * Structure, StructureArray, Union, UnionArray.
+     * Appends an Error::Type::MissingField if the subfield is not
+     * present.
+     *
+     * @return itself
+     */
+    template<Result& (*fn)(Result&)>
+    Result& has(const std::string& name) {
+        return has<epics::pvData::Field>(name, false, fn);
+    }
+
+    /**
+     * Test that this Result's field has an optional subfield with name
+     * 'name' and, if it has, apply the function 'fn' to the subfield.
+     *
+     * Appends an Error::Type::IncorrectType if the field is not one of
+     * Structure, StructureArray, Union, UnionArray.
+     *
+     * @return itself
+     */
+    template<Result& (*fn)(Result&)>
+    Result& maybeHas(const std::string& name) {
+        return has<epics::pvData::Field>(name, true, fn);
+    }
+
+    /**
+     * Test that this Result's field has a subfield with name 'name',
+     * apply the function 'fn' to the subfield and
+     * test that the subfield is of type 'T'.
+     *
+     * Appends an Error::Type::IncorrectType if the field is not one of
+     * Structure, StructureArray, Union, UnionArray.
+     * Appends an Error::Type::IncorrectType if the subfield is not of
+     * type 'T'.
+     * Appends an Error::Type::MissingField if the subfield is not
+     * present.
+     *
+     * @return itself
+     */
+    template<Result& (*fn)(Result&), typename T>
+    Result& has(const std::string& name) {
+        return has<T>(name, false, fn);
+    }
+
+    /**
+     * Test that this Result's field has an optional subfield with name
+     * 'name' and, if it has, apply the function 'fn' to the subfield and
+     * test that the subfield is of type 'T'.
+     *
+     * Appends an Error::Type::IncorrectType if the field is not one of
+     * Structure, StructureArray, Union, UnionArray.
+     * Appends an Error::Type::IncorrectType if the subfield exists and
+     * is not of type 'T'.
+     *
+     * @return itself
+     */
+    template<Result& (*fn)(Result&), typename T>
+    Result& maybeHas(const std::string& name) {
+        return has<T>(name, true, fn);
+    }
+
+    /**
+     * Test that this Result's field has a subfield with name 'name' and
+     * test that the subfield is of type 'T'.
+     *
+     * Appends an Error::Type::IncorrectType if the field is not one of
+     * Structure, StructureArray, Union, UnionArray.
+     * Appends an Error::Type::IncorrectType if the subfield is not of
+     * type 'T'.
+     * Appends an Error::Type::MissingField if the subfield is not
+     * present.
+     *
+     * @return itself
+     */
+    template<typename T>
+    Result& has(const std::string& name) {
+        return has<T>(name, false, NULL);
+    }
+
+    /**
+     * Test that this Result's field has an optional subfield with name
+     * 'name' and, if it has, test that the subfield is of type 'T'.
+     *
+     * Appends an Error::Type::IncorrectType if the field is not one of
+     * Structure, StructureArray, Union, UnionArray.
+     * Appends an Error::Type::IncorrectType if the subfield exists and
+     * is not of type 'T'.
+     *
+     * @return itself
+     */
+    template<typename T>
+    Result& maybeHas(const std::string& name) {
+        return has<T>(name, true, NULL);
+    }
+
+    std::ostream& dump(std::ostream& os) const {
+        os << "Result(valid=" << (result == Pass) << ", errors=[ ";
+
+        std::vector<Error>::const_iterator it;
+        for (it = errors.begin(); it != errors.end(); ++it) {
+            (*it).dump(os);
+            os << " ";
+        }
+        os << "])";
+        return os;
+    }
+
+private:
+    template<typename T>
+    Result& has(const std::string& name, bool optional, Result& (*check)(Result&) = NULL) {
+        epics::pvData::FieldConstPtr subField;
+
+        switch(field->getType()) {
+            case epics::pvData::structure:
+                subField = static_cast<epics::pvData::Structure const *>(field.get())->getField(name);
+                break;
+            case epics::pvData::structureArray:
+                subField = static_cast<epics::pvData::StructureArray const *>(field.get())->getStructure()->getField(name);
+                break;
+            case epics::pvData::union_:
+                subField = static_cast<epics::pvData::Union const *>(field.get())->getField(name);
+                break;
+            case epics::pvData::unionArray:
+                subField = static_cast<epics::pvData::UnionArray const *>(field.get())->getUnion()->getField(name);
+                break;
+            default:
+                // Expected a structure-like Field
+                result = Fail;
+                errors.push_back(Error(path, Error::IncorrectType));
+                return *this;
+        }
+
+        std::string subFieldPath(path.empty() ? name : path + "." + name);
+
+        if (!subField) {
+            if (!optional) {
+                result = Fail;
+                errors.push_back(Error(subFieldPath, Error::MissingField));
+            }
+        } else if (!dynamic_cast<T const *>(subField.get())) {
+            result = Fail;
+            errors.push_back(Error(subFieldPath, Error::IncorrectType));
+        } else if (check) {
+            Result r(subField, subFieldPath);
+            *this |= check(r);
+        }
+
+        return *this;
+    }
+};
+}}
+
+#endif

test/Makefile

@@ -72,6 +72,10 @@ TESTPROD_HOST += ntutilsTest
 ntutilsTest_SRCS = ntutilsTest.cpp
 TESTS += ntutilsTest
 
+TESTPROD_HOST += validatorTest
+validatorTest_SRCS = validatorTest.cpp
+TESTS += validatorTest
+
 TESTSCRIPTS_HOST += $(TESTS:%=%.t)
 
 include $(TOP)/configure/RULES

test/ntaggregateTest.cpp

@@ -78,7 +78,7 @@ void test_ntaggregate()
     // example how to set a value
     //
     ntAggregate->getValue()->put(1.0);
-    
+
     //
     // example how to get a value
     //
@@ -173,5 +173,3 @@ MAIN(testNTAggregate) {
     test_wrap();
     return testDone();
 }
-
-

test/ntattributeTest.cpp

@@ -173,5 +173,3 @@ MAIN(testNTAttribute) {
     test_wrap();
     return testDone();
 }
-
-

test/ntcontinuumTest.cpp

@@ -274,5 +274,3 @@ MAIN(testNTContinuum) {
     test_extra();
     return testDone();
 }
-
-

test/ntenumTest.cpp

@@ -84,7 +84,7 @@ void test_ntenum()
     choices[1] = "On";
     pvValue->getSubField<PVStringArray>("choices")->replace(freeze(choices));
     pvValue->getSubField<PVInt>("index")->put(1);
-    
+
     //
     // example how to get a value
     //
@@ -185,5 +185,3 @@ MAIN(testNTEnum) {
     test_wrap();
     return testDone();
 }
-
-

test/nthistogramTest.cpp

@@ -259,5 +259,3 @@ MAIN(testNTHistogram) {
     test_extra();
     return testDone();
 }
-
-

test/ntmatrixTest.cpp

@@ -151,7 +151,6 @@ void test_ntmatrix()
         display.setLow(-15);
         display.setHigh(15);
         display.setDescription("This is a test scalar array");
-        display.setFormat("%d");
         display.setUnits("A");
         pvDisplay.set(display);
     }
@@ -208,5 +207,3 @@ MAIN(testNTMatrix) {
     test_wrap();
     return testDone();
 }
-
-

test/ntmultiChannelTest.cpp

@@ -193,4 +193,3 @@ MAIN(testCreateRequest)
     test_wrap();
     return testDone();
 }
-

test/ntnameValueTest.cpp

@@ -254,5 +254,3 @@ MAIN(testNTNameValue) {
     test_extra();
     return testDone();
 }
-
-

test/ntndarrayAttributeTest.cpp

@@ -175,5 +175,3 @@ MAIN(testNTNDArrayAttribute) {
     test_wrap();
     return testDone();
 }
-
-

test/ntndarrayTest.cpp

@@ -21,8 +21,8 @@ void test_builder(bool extraFields)
     testOk(builder.get() != 0, "Got builder");
 
     builder->addDescriptor()->
-             addTimeStamp()->          
-             addAlarm()->  
+             addTimeStamp()->
+             addAlarm()->
              addDisplay();
 
     if (extraFields)
@@ -68,9 +68,9 @@ void test_all()
 
     PVStructurePtr pvStructure = builder->
             addDescriptor()->
-            addTimeStamp()->          
-            addAlarm()->  
-            addDisplay()->  
+            addTimeStamp()->
+            addAlarm()->
+            addDisplay()->
             add("extra1",fieldCreate->createScalar(pvString)) ->
             add("extra2",fieldCreate->createScalarArray(pvString)) ->
             createPVStructure();
@@ -120,5 +120,3 @@ MAIN(testNTNDArray) {
     test_wrap();
     return testDone();
 }
-
-

test/ntscalarArrayTest.cpp

@@ -167,7 +167,6 @@ void test_ntscalarArray()
         display.setLow(-15);
         display.setHigh(15);
         display.setDescription("This is a test scalar array");
-        display.setFormat("%d");
         display.setUnits("A");
         pvDisplay.set(display);
     }
@@ -243,5 +242,3 @@ MAIN(testNTScalarArray) {
     test_wrap();
     return testDone();
 }
-
-

test/ntscalarMultiChannelTest.cpp

@@ -180,4 +180,3 @@ MAIN(testCreateRequest)
     test_wrap();
     return testDone();
 }
-

test/ntscalarTest.cpp

@@ -159,7 +159,6 @@ void test_ntscalar()
         display.setLow(-15);
         display.setHigh(15);
         display.setDescription("This is a test scalar");
-        display.setFormat("%d");
         display.setUnits("A");
         pvDisplay.set(display);
     }
@@ -234,5 +233,3 @@ MAIN(testNTScalar) {
     test_wrap();
     return testDone();
 }
-
-

test/nttableTest.cpp

@@ -245,5 +245,3 @@ MAIN(testNTTable) {
     test_wrap();
     return testDone();
 }
-
-

test/ntunionTest.cpp

@@ -196,5 +196,3 @@ MAIN(testNTUnion) {
     test_regular_union();
     return testDone();
 }
-
-

test/ntutilsTest.cpp

@@ -33,5 +33,3 @@ MAIN(testNTUtils) {
     test_is_a();
     return testDone();
 }
-
-

test/validatorTest.cpp

@@ -0,0 +1,311 @@
+/*
+ * Copyright information and license terms for this software can be
+ * found in the file LICENSE that is included with the distribution
+ */
+
+#include <epicsUnitTest.h>
+#include <testMain.h>
+
+#include "../src/validator.h"
+#include <pv/ntndarray.h>
+#include <pv/pvIntrospect.h>
+
+using namespace epics::nt;
+using namespace epics::pvData;
+
+static epics::pvData::FieldCreatePtr FC;
+
+void test_is()
+{
+    testDiag("test_is");
+
+    // Result::is<Scalar> must be valid for Scalars of any type
+    for(int i = pvBoolean; i <= pvString; ++i) {
+        ScalarType t = static_cast<ScalarType>(i);
+        testOk(Result(FC->createScalar(t)).is<Scalar>().valid(),
+            "Result(Scalar<%s>).is<Scalar>().valid()", ScalarTypeFunc::name(t));
+    }
+
+    // Result::is<ScalarArray> must be valid for ScalarArray of any type
+    for(int i = pvBoolean; i <= pvString; ++i) {
+        ScalarType t = static_cast<ScalarType>(i);
+        testOk(Result(FC->createScalarArray(t)).is<ScalarArray>().valid(),
+            "Result(ScalarArray<%s>).is<ScalarArray>().valid()", ScalarTypeFunc::name(t));
+    }
+
+    {
+        // Result::is<Scalar> must be invalid for non-Scalar
+        Result result(FC->createScalarArray(pvInt));
+        result.is<Scalar>();
+        testOk(!result.valid(), "!Result(ScalarArray<pvInt>).is<Scalar>.valid()");
+        testOk1(result.errors.at(0) == Result::Error("", Result::Error::IncorrectType));
+    }
+
+    {
+        // Result::is<ScalarArray> must be invalid for non-ScalarArray
+        Result result(FC->createScalar(pvInt));
+        result.is<ScalarArray>();
+        testOk(!result.valid(), "!Result(ScalarArray<pvInt>).is<Scalar>.valid()");
+        testOk1(result.errors.at(0) == Result::Error("", Result::Error::IncorrectType));
+    }
+}
+
+void test_is_id()
+{
+    testDiag("test_is_id");
+
+    FieldBuilderPtr FB(FieldBuilder::begin());
+
+    {
+        // Both type and ID match for Structure
+        Result result(FB->setId("TEST_ID")->createStructure());
+        result.is<Structure>("TEST_ID");
+        testOk(result.valid(), "Result(Structure['TEST_ID']).is<Structure>('TEST_ID').valid()");
+    }
+
+    {
+        // Both type and ID match for Union
+        UnionConstPtr un(FB->
+            setId("TEST_ID")->
+            add("A", pvInt)->
+            add("B", pvString)->
+            createUnion()
+        );
+        Result result(un);
+        result.is<Union>("TEST_ID");
+        testOk(result.valid(), "Result(Union{A:int,B:string}['TEST_ID']).is<Union>('TEST_ID').valid()");
+    }
+
+    {
+        // Both type and ID match for Variant Union
+        Result result(FB-> createUnion());
+        result.is<Union>(Union::ANY_ID);
+        testOk(result.valid(), "Result(Union).is<Union>('%s').valid()", Union::ANY_ID.c_str());
+    }
+
+    {
+        // ID matches, type doesn't
+        Result result(FB->setId("TEST_ID")->createStructure());
+        result.is<Union>("TEST_ID");
+        testOk(!result.valid(), "!Result(Union['TEST_ID']).is<Structure>('TEST_ID').valid()");
+        testOk1(result.errors.at(0) == Result::Error("", Result::Error::IncorrectType));
+    }
+
+    {
+        // Type matches, ID doesn't
+        Result result(FB->setId("WRONG_ID")->createStructure());
+        result.is<Structure>("TEST_ID");
+        testOk(!result.valid(), "!Result(Structure['WRONG_ID']).is<Structure>('TEST_ID').valid()");
+        testOk1(result.errors.at(0) == Result::Error("", Result::Error::IncorrectId));
+    }
+
+    {
+        // Neither type nor ID match (ID is not even checked in this case since it doesn't exist)
+        Result result(FC->createScalar(pvDouble));
+        result.is<Structure>("SOME_ID");
+        testOk(!result.valid(), "!Result(Scalar).is<Structure>('SOME_ID').valid()");
+        testOk1(result.errors.at(0) == Result::Error("", Result::Error::IncorrectType));
+    }
+}
+
+void test_has()
+{
+    testDiag("test_has");
+
+    FieldBuilderPtr FB(FieldBuilder::begin());
+
+    StructureConstPtr struc(FB->
+        add("A", pvInt)->
+        add("B", pvString)->
+        createStructure()
+    );
+
+    std::string strucRepr("Structure{A:int,B:String}");
+
+    {
+        // Test that struc has both A and B, both being Scalars
+        Result result(struc);
+        result
+           .has<Scalar>("A")
+           .has<Scalar>("B");
+
+        testOk(result.valid(),
+            "Result(%s).has<Scalar>('A').has<Scalar>('B').valid()",
+            strucRepr.c_str());
+    }
+
+    {
+        // Test that struc does not have a field B of type ScalarArray
+        Result result(struc);
+        result
+           .has<Scalar>("A")
+           .has<ScalarArray>("B");
+        testOk(!result.valid(),
+            "!Result(%s).has<Scalar>('A').has<ScalarArray>('B').valid()",
+            strucRepr.c_str());
+        testOk1(result.errors.at(0) == Result::Error("B", Result::Error::IncorrectType));
+    }
+
+    {
+        // Test that struc does not have a field C
+        Result result(struc);
+        result
+           .has<Scalar>("A")
+           .has<Scalar>("C");
+        testOk(!result.valid(),
+            "!Result(%s).has<Scalar>('A').has<Scalar>('C').valid()",
+            strucRepr.c_str());
+        testOk1(result.errors.at(0) == Result::Error("C", Result::Error::MissingField));
+    }
+
+    {
+        // Test that 'has' fails for non-structure-like Fields
+        Result result(FC->createScalar(pvByte));
+        result.has<Scalar>("X");
+        testOk(!result.valid(), "!Result(Scalar<pvByte>).has<Scalar>('X').valid()");
+        testOk1(result.errors.at(0) == Result::Error("", Result::Error::IncorrectType));
+    }
+}
+
+void test_maybe_has()
+{
+    testDiag("test_maybe_has");
+
+    FieldBuilderPtr FB(FieldBuilder::begin());
+
+    StructureConstPtr struc(FB->
+        add("A", pvInt)->
+        add("B", pvString)->
+        createStructure()
+    );
+
+    std::string strucRepr("Structure{A:int,B:String}");
+
+    {
+        // Test that struc maybe has A and B, both being Scalars
+        Result result(struc);
+        result
+           .maybeHas<Scalar>("A")
+           .maybeHas<Scalar>("B");
+
+        testOk(result.valid(),
+            "Result(%s).maybeHas<Scalar>('A').maybeHas<Scalar>('B').valid()",
+            strucRepr.c_str());
+    }
+
+    {
+        // Test that if struc has a field B, it must be of type ScalarArray
+        Result result(struc);
+        result
+           .maybeHas<Scalar>("A")
+           .maybeHas<ScalarArray>("B");
+        testOk(!result.valid(),
+            "!Result(%s).maybeHas<Scalar>('A').maybeHas<ScalarArray>('B').valid()",
+            strucRepr.c_str());
+        testOk1(result.errors.at(0) == Result::Error("B", Result::Error::IncorrectType));
+    }
+
+    {
+        // Test that struc maybe has A (which it does) and B (which it doesn't)
+        Result result(struc);
+        result
+           .maybeHas<Scalar>("A")
+           .maybeHas<Scalar>("C");
+        testOk(result.valid(),
+            "Result(%s).maybeHas<Scalar>('A').maybeHas<Scalar>('C').valid()",
+            strucRepr.c_str());
+    }
+
+    {
+        // Test that 'maybeHas' fails for non-structure-like Fields
+        Result result(FC->createScalar(pvByte));
+        result.maybeHas<Scalar>("X");
+        testOk(!result.valid(), "!Result(Scalar<pvByte>).maybeHas<Scalar>('X').valid()");
+        testOk1(result.errors.at(0) == Result::Error("", Result::Error::IncorrectType));
+    }
+}
+
+Result& isStructABC(Result& result)
+{
+    return result
+        .is<Structure>("ABC")
+        .has<Scalar>("A")
+        .has<ScalarArray>("B")
+        .maybeHas<Scalar>("C");
+}
+
+void test_has_fn()
+{
+    testDiag("test_has_fn");
+    FieldBuilderPtr FB(FieldBuilder::begin());
+
+    {
+        StructureConstPtr inner(FB->
+            setId("ABC")->
+            add("A", pvInt)->
+            addArray("B", pvDouble)->
+            add("C", pvString)->
+            createStructure()
+        );
+
+        Result result(FB->add("inner", inner)->createStructure());
+        result.has<&isStructABC>("inner");
+
+        testOk(result.valid(), "Result({inner:<valid structABC>}).has<&isStructAbc>('inner').valid()");
+    }
+
+    {
+        StructureConstPtr inner(FB->
+            setId("ABC")->
+            add("A", pvInt)->
+            addArray("B", pvDouble)->
+            createStructure()
+        );
+
+        Result result(FB->add("inner", inner)->createStructure());
+        result.has<&isStructABC>("inner");
+
+        testOk(result.valid(), "Result({inner:<valid structABC w/o C>}).has<&isStructAbc>('inner').valid()");
+    }
+
+    {
+        StructureConstPtr inner(FB->
+            setId("XYZ")->
+            add("A", pvInt)->
+            addArray("B", pvDouble)->
+            createStructure()
+        );
+
+        Result result(FB->add("inner", inner)->createStructure());
+        result.has<&isStructABC>("inner");
+
+        testOk(!result.valid(), "!Result({inner:<structABC wrong id>}).has<&isStructAbc>('inner').valid()");
+        testOk1(result.errors.at(0) == Result::Error("inner", Result::Error::IncorrectId));
+    }
+
+    {
+        StructureConstPtr inner(FB->
+            setId("XYZ")->
+            add("A", pvInt)->
+            add("B", pvDouble)->
+            createStructure()
+        );
+
+        Result result(FB->add("inner", inner)->createStructure());
+        result.has<&isStructABC>("inner");
+
+        testOk(!result.valid(), "!Result({inner:<structABC wrong id and fields>}).has<&isStructAbc>('inner').valid()");
+        testOk1(result.errors.size() == 2);
+    }
+}
+
+MAIN(testValidator) {
+    testPlan(56);
+    FC = epics::pvData::getFieldCreate();
+    test_is();
+    test_is_id();
+    test_has();
+    test_maybe_has();
+    test_has_fn();
+    return testDone();
+}