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20120705 commit rest of changes for nameref variables

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This commit is contained in:
Chet Ramey
2012-07-10 09:38:15 -04:00
parent 23477ba0d3
commit 87c1f4ece2
4 changed files with 133 additions and 20 deletions
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builtins/set.def
+14 -7
View File
@@ -1,7 +1,7 @@
This file is set.def, from which is created set.c.
It implements the "set" and "unset" builtins in Bash.
Copyright (C) 1987-2011 Free Software Foundation, Inc.
Copyright (C) 1987-2012 Free Software Foundation, Inc.
This file is part of GNU Bash, the Bourne Again SHell.
@@ -724,7 +724,7 @@ set_builtin (list)
$BUILTIN unset
$FUNCTION unset_builtin
$SHORT_DOC unset [-f] [-v] [name ...]
$SHORT_DOC unset [-f] [-v] [-n] [name ...]
Unset values and attributes of shell variables and functions.
For each NAME, remove the corresponding variable or function.
@@ -732,6 +732,8 @@ For each NAME, remove the corresponding variable or function.
Options:
-f treat each NAME as a shell function
-v treat each NAME as a shell variable
-n treat each NAME as a name reference and unset the variable itself
rather than the variable it references
Without options, unset first tries to unset a variable, and if that fails,
tries to unset a function.
@@ -748,13 +750,13 @@ int
unset_builtin (list)
WORD_LIST *list;
{
int unset_function, unset_variable, unset_array, opt, any_failed;
int unset_function, unset_variable, unset_array, opt, nameref, any_failed;
char *name;
unset_function = unset_variable = unset_array = any_failed = 0;
unset_function = unset_variable = unset_array = nameref = any_failed = 0;
reset_internal_getopt ();
while ((opt = internal_getopt (list, "fv")) != -1)
while ((opt = internal_getopt (list, "fnv")) != -1)
{
switch (opt)
{
@@ -764,6 +766,9 @@ unset_builtin (list)
case 'v':
unset_variable = 1;
break;
case 'n':
nameref = 1;
break;
default:
builtin_usage ();
return (EX_USAGE);
@@ -777,6 +782,8 @@ unset_builtin (list)
builtin_error (_("cannot simultaneously unset a function and a variable"));
return (EXECUTION_FAILURE);
}
else if (unset_function && nameref)
nameref = 0;
while (list)
{
@@ -810,7 +817,8 @@ unset_builtin (list)
}
/* Only search for functions here if -f supplied. */
var = unset_function ? find_function (name) : find_variable (name);
var = unset_function ? find_function (name)
: (nameref ? find_variable_last_nameref (name) : find_variable (name));
/* Some variables (but not functions yet) cannot be unset, period. */
if (var && unset_function == 0 && non_unsettable_p (var))
@@ -837,7 +845,6 @@ unset_builtin (list)
NEXT_VARIABLE ();
}
/* Unless the -f option is supplied, the name refers to a variable. */
#if defined (ARRAY_VARS)
if (var && unset_array)
doc/bash.1
+53 -5
View File
@@ -5,12 +5,12 @@
.\" Case Western Reserve University
.\" chet@po.cwru.edu
.\"
.\" Last Change: Sun May 27 20:28:33 EDT 2012
.\" Last Change: Thu Jul 5 11:10:13 EDT 2012
.\"
.\" bash_builtins, strip all but Built-Ins section
.if \n(zZ=1 .ig zZ
.if \n(zY=1 .ig zY
.TH BASH 1 "2012 May 27" "GNU Bash 4.2"
.TH BASH 1 "2012 July 5" "GNU Bash 4.2"
.\"
.\" There's some problem with having a `@'
.\" in a tagged paragraph with the BSD man macros.
@@ -1235,6 +1235,39 @@ appended to the array beginning at one greater than the array's maximum index
associative array.
When applied to a string-valued variable, \fIvalue\fP is expanded and
appended to the variable's value.
.PP
A variable can be assigned the \fInameref\fP attribute using the
\fB\-n\fP option to the \fBdeclare\fP or \fBlocal\fP builtin commands
(see the descriptions of \fBdeclare\fP and \fBlocal\fP below)
to create a \fInameref\fP, or a reference to another variable.
This allows variables to be manipulated indirectly.
Whenever the nameref variable is referenced or assigned to, the operation
is actually performed on the variable specified by the nameref variable's
value.
A nameref is commonly used within shell functions to refer to a variable
whose name is passed as an argument to the function.
For instance, if a variable name is passed to a shell function as its first
argument, running
.sp .5
.RS
.if t \f(CWdeclare -n ref=$1\fP
.if n declare -n ref=$1
.RE
.sp .5
inside the function creates a nameref variable \fBref\fP whose value is
the variable name passed as the first argument.
References and assignments to \fBref\fP are treated as references and
assignments to the variable whose name was passed as \fB$1\fP.
If the control variable in a \fBfor\fP loop has the nameref attribute,
the list of words can be a list of shell variables, and a name reference
will be established for each word in the list, in turn, when the loop is
executed.
Array variables cannot be given the \fB\-n\fP attribute.
However, nameref variables can reference array variables and subscripted
array variables.
Namerefs can be unset using the \fB\-n\fP option to the \fBunset\fP builtin.
Otherwise, if \fBunset\fP is executed with the name of a nameref variable
as an argument, the variable referenced by the nameref variable will be unset.
.SS Positional Parameters
.PP
A
@@ -7279,10 +7312,10 @@ is greater than the number of enclosing loops, the last enclosing loop
(the ``top-level'' loop) is resumed.
The return value is 0 unless \fIn\fP is not greater than or equal to 1.
.TP
\fBdeclare\fP [\fB\-aAfFgilrtux\fP] [\fB\-p\fP] [\fIname\fP[=\fIvalue\fP] ...]
\fBdeclare\fP [\fB\-aAfFgilnrtux\fP] [\fB\-p\fP] [\fIname\fP[=\fIvalue\fP] ...]
.PD 0
.TP
\fBtypeset\fP [\fB\-aAfFgilrtux\fP] [\fB\-p\fP] [\fIname\fP[=\fIvalue\fP] ...]
\fBtypeset\fP [\fB\-aAfFgilnrtux\fP] [\fB\-p\fP] [\fIname\fP[=\fIvalue\fP] ...]
.PD
Declare variables and/or give them attributes.
If no \fIname\fPs are given then display the values of variables.
@@ -7346,6 +7379,15 @@ When the variable is assigned a value, all upper-case characters are
converted to lower-case.
The upper-case attribute is disabled.
.TP
.B \-n
Give each \fIname\fP the \fInameref\fP attribute, making
it a name reference to another variable.
That other variable is defined by the value of \fIname\fP.
All references and assignments to \fIname\fP, except for changing the
\fB\-n\fP attribute itself, are performed on the variable referenced by
\fIname\fP's value.
The \fB\-n\fP attribute cannot be applied to array variables.
.TP
.B \-r
Make \fIname\fPs readonly. These names cannot then be assigned values
by subsequent assignment statements or unset.
@@ -9868,7 +9910,7 @@ value is true unless a supplied
.I name
is not a defined alias.
.TP
\fBunset\fP [\-\fBfv\fP] [\fIname\fP ...]
\fBunset\fP [\-\fBfv\fP] [\-\fBn\fP] [\fIname\fP ...]
For each
.IR name ,
remove the corresponding variable or function.
@@ -9884,6 +9926,12 @@ is specified, each
.I name
refers to a shell function, and the function definition
is removed.
If the
.B \-n
option is supplied, and \fIname\fP is a variable with the \fInameref\fP
attribute, \fIname\fP will be unset rather than the variable it
references.
\fB\-n\fP has no effect if the \fB\-f\fP option is supplied.
If no options are supplied, each \fIname\fP refers to a variable; if
there is no variable by that name, any function with that name is
unset.
doc/bashref.texi
+49 -3
View File
@@ -1473,6 +1473,39 @@ in an associative array.
When applied to a string-valued variable, @var{value} is expanded and
appended to the variable's value.
A variable can be assigned the @var{nameref} attribute using the
@option{-n} option to the \fBdeclare\fP or \fBlocal\fP builtin commands
(@pxref{Bash Builtins})
to create a @var{nameref}, or a reference to another variable.
This allows variables to be manipulated indirectly.
Whenever the nameref variable is referenced or assigned to, the operation
is actually performed on the variable specified by the nameref variable's
value.
A nameref is commonly used within shell functions to refer to a variable
whose name is passed as an argument to the function.
For instance, if a variable name is passed to a shell function as its first
argument, running
@example
declare -n ref=$1
@end example
@noindent
inside the function creates a nameref variable @var{ref} whose value is
the variable name passed as the first argument.
References and assignments to @var{ref} are treated as references and
assignments to the variable whose name was passed as @code{$1}.
If the control variable in a @code{for} loop has the nameref attribute,
the list of words can be a list of shell variables, and a name reference
will be established for each word in the list, in turn, when the loop is
executed.
Array variables cannot be given the @option{-n} attribute.
However, nameref variables can reference array variables and subscripted
array variables.
Namerefs can be unset using the @option{-n} option to the @code{unset} builtin
(@pxref{Bourne Shell Builtins}).
Otherwise, if @code{unset} is executed with the name of a nameref variable
as an argument, the variable referenced by the nameref variable will be unset.
@node Positional Parameters
@subsection Positional Parameters
@cindex parameters, positional
@@ -3616,7 +3649,7 @@ results in permissions of @code{755}.
@item unset
@btindex unset
@example
unset [-fv] [@var{name}]
unset [-fnv] [@var{name}]
@end example
Remove each variable or function @var{name}.
@@ -3624,6 +3657,10 @@ If the @option{-v} option is given, each
@var{name} refers to a shell variable and that variable is remvoved.
If the @option{-f} option is given, the @var{name}s refer to shell
functions, and the function definition is removed.
If the @option{-n} option is supplied, and @var{name} is a variable with
the @var{nameref} attribute, @var{name} will be unset rather than the
variable it references.
@option{-n} has no effect if the @option{-f} option is supplied.
If no options are supplied, each @var{name} refers to a variable; if
there is no variable by that name, any function with that name is
unset.
@@ -3812,7 +3849,7 @@ zero if @var{command} is found, and non-zero if not.
@item declare
@btindex declare
@example
declare [-aAfFgilrtux] [-p] [@var{name}[=@var{value}] @dots{}]
declare [-aAfFgilnrtux] [-p] [@var{name}[=@var{value}] @dots{}]
@end example
Declare variables and give them attributes. If no @var{name}s
@@ -3864,6 +3901,15 @@ When the variable is assigned a value, all upper-case characters are
converted to lower-case.
The upper-case attribute is disabled.
@item -n
Give each @var{name} the @var{nameref} attribute, making
it a name reference to another variable.
That other variable is defined by the value of @var{name}.
All references and assignments to @var{name}, except for changing the
@option{-n} attribute itself, are performed on the variable referenced by
@var{name}'s value.
The @option{-n} attribute cannot be applied to array variables.
@item -r
Make @var{name}s readonly. These names cannot then be assigned values
by subsequent assignment statements or unset.
@@ -4303,7 +4349,7 @@ if any are not found.
@item typeset
@btindex typeset
@example
typeset [-afFgrxilrtux] [-p] [@var{name}[=@var{value}] @dots{}]
typeset [-afFgrxilnrtux] [-p] [@var{name}[=@var{value}] @dots{}]
@end example
The @code{typeset} command is supplied for compatibility with the Korn
variables.c
+17 -5
View File
@@ -2958,7 +2958,7 @@ dispose_variable (var)
}
/* Unset the shell variable referenced by NAME. Unsetting a nameref variable
unsets both the variable and the variable it resolves to. */
unsets the variable it resolves to but leaves the nameref alone. */
int
unbind_variable (name)
const char *name;
@@ -2969,13 +2969,23 @@ unbind_variable (name)
v = var_lookup (name, shell_variables);
nv = (v && nameref_p (v)) ? find_variable_nameref (v) : (SHELL_VAR *)NULL;
r = nv ? makunbound (nv->name, shell_variables) : 0;
if (r == 0)
r = makunbound (name, shell_variables);
r = nv ? makunbound (nv->name, shell_variables) : makunbound (name, shell_variables);
return r;
}
/* Unbind NAME, where NAME is assumed to be a nameref variable */
int
unbind_nameref (name)
const char *name;
{
SHELL_VAR *v;
v = var_lookup (name, shell_variables);
if (v && nameref_p (v))
return makunbound (name, shell_variables);
return 0;
}
/* Unset the shell function named NAME. */
int
unbind_func (name)
@@ -3073,6 +3083,8 @@ makunbound (name, vc)
else if (assoc_p (old_var))
assoc_dispose (assoc_cell (old_var));
#endif
else if (nameref_p (old_var))
FREE (nameref_cell (old_var));
else
FREE (value_cell (old_var));
/* Reset the attributes. Preserve the export attribute if the variable