Com: iocsh: Tab completion

Add tab completion for "help ...", record names, and "pdbbase"

modules/database/src/ioc/dbStatic/Makefile

@@ -28,5 +28,6 @@ dbCore_SRCS += dbYacc.c
 dbCore_SRCS += dbPvdLib.c
 dbCore_SRCS += dbStaticRun.c
 dbCore_SRCS += dbStaticIocRegister.c
+dbCore_SRCS += dbCompleteRecord.cpp
 
 CLEANS += dbLex.c dbYacc.c

modules/database/src/ioc/dbStatic/dbCompleteRecord.cpp

@@ -0,0 +1,161 @@
+/*************************************************************************\
+* Copyright (c) 2022 Michael Davidsaver
+* SPDX-License-Identifier: EPICS
+* EPICS Base is distributed subject to a Software License Agreement found
+* in file LICENSE that is included with this distribution.
+\*************************************************************************/
+
+#include <algorithm>
+#include <limits>
+#include <string>
+#include <set>
+
+#include <string.h>
+
+#include <epicsStdio.h>
+#include <dbAccess.h>
+#include "dbStaticPvt.h"
+
+namespace {
+
+// immutable C string slice.  (avoid allocating many temporary std::string)
+class CStr {
+    const char* p;
+    size_t l;
+public:
+    CStr() :p(NULL), l(0u) {}
+    CStr(const CStr& o) :p(o.p), l(o.l) {}
+    explicit CStr(const char* p) :p(p), l(p ? strlen(p) : 0u) {}
+    CStr(const char* p, size_t n) :p(p), l(n) {}
+
+    CStr& operator=(const CStr& o) {
+        p = o.p;
+        l = o.l;
+        return *this;
+    }
+
+    bool operator==(const CStr& o) const {
+        return l==o.l && (p==o.p || memcmp(p, o.p, l)==0);
+    }
+    bool operator!=(const CStr& o) const {
+        return !(*this==o);
+    }
+    bool operator<(const CStr& o) const {
+        size_t pl = std::min(l, o.l);
+        int cmp = memcmp(p, o.p, pl);
+        return cmp<0 || (cmp==0 && l < o.l);
+    }
+
+    bool empty() const { return !l; }
+    size_t size() const { return l; }
+
+    bool prefixOf(const CStr& full) const {
+        return full.l >= l && memcmp(full.p, p, l)==0;
+    }
+
+    CStr commonPrefix(const CStr& o, size_t startFrom=0u) const {
+        size_t n, N;
+        for(n=startFrom, N=std::min(l, o.l); n<N; n++) {
+            if(p[n]!=o.p[n])
+                break;
+        }
+        return CStr(p, n);
+    }
+
+    void chop_at_first_of(const char* sep, size_t startFrom=0u) {
+        size_t n;
+        for(n=startFrom; n<l; n++) {
+            char c = p[n];
+            for(const char *s = sep; *s; s++) {
+                if(c == *s) {
+                    l = n+1u; // include trailing separator
+                    return;
+                }
+            }
+        }
+    }
+
+    char* dup() const {
+        char* ret = (char*)malloc(l+1u);
+        if(ret) {
+            memcpy(ret, p, l);
+            ret[l] = '\0';
+        }
+        return ret;
+    }
+};
+
+} // namespace
+
+char** dbCompleteRecord(const char *cword)
+{
+    const CStr word(cword);
+
+    DBENTRY ent;
+
+    dbInitEntry(pdbbase, &ent);
+    try{
+        // iterating all record twice...
+
+        CStr prefix;
+        bool first = true;
+
+        // find longest prefix match
+        for(long status = dbFirstRecordType(&ent); !status; status = dbNextRecordType(&ent)) {
+            for(status = dbFirstRecord(&ent); !status; status = dbNextRecord(&ent)) {
+                const CStr name(ent.precnode->recordname);
+
+                if(!word.prefixOf(name))
+                    continue;
+
+                if(first) { // first match
+                    prefix = name;
+                    first = false;
+
+                } else {
+                    prefix = prefix.commonPrefix(name, word.size());
+                }
+            }
+        }
+
+        // with prefix size known, iterate again to find suggestions
+        typedef std::set<CStr> suggestions_t;
+        suggestions_t suggestions;
+
+        for(long status = dbFirstRecordType(&ent); !status; status = dbNextRecordType(&ent)) {
+            for(status = dbFirstRecord(&ent); !status; status = dbNextRecord(&ent)) {
+                CStr name(ent.precnode->recordname);
+
+                if(!prefix.prefixOf(name))
+                    continue;
+
+                name.chop_at_first_of(":<>{}-", prefix.size());
+                suggestions.insert(name);
+            }
+        }
+
+        dbFinishEntry(&ent);
+
+        char** ret = NULL;
+
+        if(!prefix.empty() || !suggestions.empty()) {
+            ret = (char**)malloc(sizeof(*ret)*(2u + suggestions.size()));
+            ret[0] = prefix.dup();
+            size_t n=1u;
+            for(suggestions_t::iterator it(suggestions.begin()), end(suggestions.end());
+                it!=end; ++it)
+            {
+                ret[n++] = it->dup();
+            }
+            ret[n] = NULL;
+        }
+
+        return ret;
+
+    } catch(std::exception& e){
+        fprintf(stderr, "dbCompleteRecord error: %s\n", e.what());
+        dbFinishEntry(&ent);
+        return NULL;
+    }
+
+}

modules/database/src/ioc/dbStatic/dbStaticPvt.h

@@ -115,6 +115,9 @@ PVDENTRY *dbPvdAdd(DBBASE *pdbbase,dbRecordType *precordType,dbRecordNode *precn
 void dbPvdDelete(DBBASE *pdbbase,dbRecordNode *precnode);
 void dbPvdFreeMem(DBBASE *pdbbase);
 
+DBCORE_API
+char** dbCompleteRecord(const char *word);
+
 #ifdef __cplusplus
 }
 #endif