[PATCH] Add $_as_string convenience function

[PATCH] Add $_as_string convenience function

[Simon Marchi]

This patch is a follow-up to "Add printf format specifier for printing
enumerator":

  https://sourceware.org/ml/gdb-patches/2016-02/msg00144.html

Instead of having a solution specific to the printf command, Pedro
suggested adding a general purpose function $_as_string() that would
cover this use case and more.

So, in order to print the textual label of an enum, one can use:

  (gdb) printf "Visiting node of type %s\n", $_as_string(node)
  Visiting node of type NODE_INTEGER

gdb/ChangeLog:

	* data-directory/Makefile.in (PYTHON_FILE_LIST): Install
	gdb/function/as_string.py.
	* python/lib/gdb/function/as_string.py: New file.

gdb/testsuite/ChangeLog:

	* gdb.python/py-as-string.exp: New file.
	* gdb.python/py-as-string.c: New file.

gdb/doc/ChangeLog:

	* gdb.texinfo (Convenience Functions): Document $_as_string.
---
 gdb/data-directory/Makefile.in            |  1 +
 gdb/doc/gdb.texinfo                       | 13 ++++++++++
 gdb/python/lib/gdb/function/as_string.py  | 39 ++++++++++++++++++++++++++++++
 gdb/testsuite/gdb.python/py-as-string.c   | 32 +++++++++++++++++++++++++
 gdb/testsuite/gdb.python/py-as-string.exp | 40 +++++++++++++++++++++++++++++++
 5 files changed, 125 insertions(+)
 create mode 100644 gdb/python/lib/gdb/function/as_string.py
 create mode 100644 gdb/testsuite/gdb.python/py-as-string.c
 create mode 100644 gdb/testsuite/gdb.python/py-as-string.exp

diff --git a/gdb/data-directory/Makefile.in b/gdb/data-directory/Makefile.in
index f6d959f..c05f379 100644
--- a/gdb/data-directory/Makefile.in
+++ b/gdb/data-directory/Makefile.in
@@ -74,6 +74,7 @@ PYTHON_FILE_LIST = \
 	gdb/command/prompt.py \
 	gdb/command/explore.py \
 	gdb/function/__init__.py \
+	gdb/function/as_string.py \
 	gdb/function/caller_is.py \
 	gdb/function/strfns.py \
 	gdb/printer/__init__.py \
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 4ec0ec1..0b249f4 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -10760,6 +10760,19 @@ checks all stack frames from the immediate caller to the frame specified
 by @var{number_of_frames}, whereas @code{$_caller_matches} only checks the
 frame specified by @var{number_of_frames}.
 
+@item $_as_string(@var{value})
+@findex $_as_string@r{, convenience function}
+Return the string representation of @var{value}.
+
+This function is useful to obtain the textual label (enumerator) of an
+enumeration value.  For example, assuming the variable @var{node} is of
+an enumerated type:
+
+@smallexample
+(gdb) printf "Visiting node of type %s\n", $_as_string(node)
+Visiting node of type NODE_INTEGER
+@end smallexample
+
 @end table
 
 @value{GDBN} provides the ability to list and get help on
diff --git a/gdb/python/lib/gdb/function/as_string.py b/gdb/python/lib/gdb/function/as_string.py
new file mode 100644
index 0000000..d55a466
--- /dev/null
+++ b/gdb/python/lib/gdb/function/as_string.py
@@ -0,0 +1,39 @@
+# Copyright (C) 2016 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import gdb
+
+
+class _AsString(gdb.Function):
+    """Return the string representation of a value.
+
+Usage:
+  $_as_string(value)
+
+Arguments:
+
+  value: A gdb.Value.
+
+Returns:
+  The string representation of the value.
+"""
+
+    def __init__(self):
+        super(_AsString, self).__init__("_as_string")
+
+    def invoke(self, val):
+        return str(val)
+
+_AsString()
diff --git a/gdb/testsuite/gdb.python/py-as-string.c b/gdb/testsuite/gdb.python/py-as-string.c
new file mode 100644
index 0000000..efdf988
--- /dev/null
+++ b/gdb/testsuite/gdb.python/py-as-string.c
@@ -0,0 +1,32 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2016 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+enum EnumType {
+  ENUM_VALUE_A,
+  ENUM_VALUE_B,
+  ENUM_VALUE_C,
+  ENUM_VALUE_D,
+};
+
+static enum EnumType enum_valid = ENUM_VALUE_B;
+static enum EnumType enum_invalid = 20;
+
+int
+main ()
+{
+  return 0;
+}
diff --git a/gdb/testsuite/gdb.python/py-as-string.exp b/gdb/testsuite/gdb.python/py-as-string.exp
new file mode 100644
index 0000000..4c7dd0d
--- /dev/null
+++ b/gdb/testsuite/gdb.python/py-as-string.exp
@@ -0,0 +1,40 @@
+# Copyright (C) 2016 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# This file is part of the GDB testsuite.  It tests the convenience
+# functions in as_string.py.
+
+load_lib gdb-python.exp
+
+standard_testfile
+
+if { [prepare_for_testing ${testfile}.exp ${testfile} ${srcfile}] } {
+    return -1
+}
+
+if ![runto_main] {
+    fail "Couldn't run to main."
+    return 0
+}
+
+if { [skip_python_tests] } { continue }
+
+proc test_as_string { } {
+    gdb_test "p \$_as_string(2)" "\"2\""
+    gdb_test "p \$_as_string(enum_valid)" "\"ENUM_VALUE_B\""
+    gdb_test "p \$_as_string(enum_invalid)" "\"20\""
+}
+
+test_as_string
-- 
2.7.2

Re: [PATCH] Add $_as_string convenience function

[Joel Brobecker]

> This patch is a follow-up to "Add printf format specifier for printing
> enumerator":
> 
>   https://sourceware.org/ml/gdb-patches/2016-02/msg00144.html
> 
> Instead of having a solution specific to the printf command, Pedro
> suggested adding a general purpose function $_as_string() that would
> cover this use case and more.
> 
> So, in order to print the textual label of an enum, one can use:
> 
>   (gdb) printf "Visiting node of type %s\n", $_as_string(node)
>   Visiting node of type NODE_INTEGER
> 
> gdb/ChangeLog:
> 
> 	* data-directory/Makefile.in (PYTHON_FILE_LIST): Install
> 	gdb/function/as_string.py.
> 	* python/lib/gdb/function/as_string.py: New file.

Neat. I think this deserves a NEWS entry!

Re: [PATCH] Add $_as_string convenience function

[Simon Marchi]

On 2016-03-04 18:07, Joel Brobecker wrote:
> Neat. I think this deserves a NEWS entry!

That would be the NEWS entry:

* New Python-based convenience function $_as_string(val), which returns
   the textual representation of a value.  This function is especially
   useful to obtain the text label of an enum value.

Re: [PATCH] Add $_as_string convenience function

[Eli Zaretskii]

> Date: Mon, 07 Mar 2016 09:54:33 -0500
> From: Simon Marchi <simon.marchi@polymtl.ca>
> Cc: gdb-patches@sourceware.org
> 
> On 2016-03-04 18:07, Joel Brobecker wrote:
> > Neat. I think this deserves a NEWS entry!
> 
> That would be the NEWS entry:
> 
> * New Python-based convenience function $_as_string(val), which returns
>    the textual representation of a value.  This function is especially
>    useful to obtain the text label of an enum value.

This is fine with me, thanks.

Re: [PATCH] Add $_as_string convenience function

[Pedro Alves]

On 03/04/2016 08:43 PM, Simon Marchi wrote:
> This patch is a follow-up to "Add printf format specifier for printing
> enumerator":
>
>    https://sourceware.org/ml/gdb-patches/2016-02/msg00144.html
>
> Instead of having a solution specific to the printf command, Pedro
> suggested adding a general purpose function $_as_string() that would
> cover this use case and more.
>
> So, in order to print the textual label of an enum, one can use:
>
>    (gdb) printf "Visiting node of type %s\n", $_as_string(node)
>    Visiting node of type NODE_INTEGER
>
> gdb/ChangeLog:
>
> 	* data-directory/Makefile.in (PYTHON_FILE_LIST): Install
> 	gdb/function/as_string.py.
> 	* python/lib/gdb/function/as_string.py: New file.
>
> gdb/testsuite/ChangeLog:
>
> 	* gdb.python/py-as-string.exp: New file.
> 	* gdb.python/py-as-string.c: New file.
>
> gdb/doc/ChangeLog:
>
> 	* gdb.texinfo (Convenience Functions): Document $_as_string.

LGTM, thanks for doing this.

Thanks,
Pedro Alves

Re: [PATCH] Add $_as_string convenience function

[Simon Marchi]

On 2016-03-10 15:19, Pedro Alves wrote:
> LGTM, thanks for doing this.
> 
> Thanks,
> Pedro Alves

Thanks, pushed (including the NEWS entry).