Re: [python] [patch] set/show extended-prompt

[Phil Muldoon <pmuldoon at redhat dot com>]

Tom Tromey <tromey@redhat.com> writes:

>>>>>> "Phil" == Phil Muldoon <pmuldoon@redhat.com> writes:
>
> Phil> This patch adds extended-prompt capabilities to GDB.  In addition
> Phil> it adds a prompt substitution library.  I made the extended-prompt
> Phil> lazily control the prompt_hook on setting, over controlling it
> Phil> unconditionally.  The rest of the function remains the same other
> Phil> than in-Python documentation as was found in Archer.
>
> The code bits are ok.
>
> This needs a NEWS entry.

Thanks, I have added Matt Rice's non-printing character suggestion.  So
that needs to be approved.  I've also added a NEWS entry, and removed
the white-spaces from the ChangeLog (bizarre, not sure how that
happened).

I've updated the documentation to reflect the required changes too.

OK?

Cheers,

Phil

2011-08-15  Phil Muldoon  <pmuldoon@redhat.com>
            Tom Tromey  <tromey@redhat.com>
            Matt Rice <ratmice@gmail.com>

        * python/lib/gdb/prompt.py: New file.
        * python/lib/gdb/command/prompt.py: New file.
        * NEWS: Document set extended-prompt and gdb.prompt library

2011-08-15  Phil Muldoon  <pmuldoon@redhat.com>

        * gdb.python/python.exp: Add extended-prompt tests.

2011-08-15  Phil Muldoon  <pmuldoon@redhat.com>

        * gdb.texinfo (Prompt): Add set/show extended-prompt
        documentation
        (Basic Python): Add prompt_hook anchor.
        (Python modules): Reword module text for reflect multiple modules.
        (gdb.prompt): Document gdb.prompt module.

--

diff --git a/gdb/NEWS b/gdb/NEWS
index 089e6ce..255a22e 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -23,6 +23,14 @@
   ** A prompt subsitution hook (prompt_hook) is now available to the
      Python API.
 
+  ** A new command set/show extended-prompt has been added.
+
+  ** A new Python module, gdb.prompt has been added to the GDB Python
+     modules library.  This module provides functionality for
+     escape sequentions in prompts (used by set/show
+     extended-prompt).  These escape sequences are replaced by their
+     corresponding value.
+
   ** Python commands and convenience-functions located in
     'data-directory'/python/gdb/command and
     'data-directory'/python/gdb/function are now automatically loaded
diff --git a/gdb/data-directory/Makefile.in b/gdb/data-directory/Makefile.in
index 11cf2e6..c04aea4 100644
--- a/gdb/data-directory/Makefile.in
+++ b/gdb/data-directory/Makefile.in
@@ -55,8 +55,10 @@ PYTHON_FILES = \
 	gdb/__init__.py \
 	gdb/types.py \
 	gdb/printing.py \
+	gdb/prompt.py \
 	gdb/command/__init__.py \
-	gdb/command/pretty_printers.py
+	gdb/command/pretty_printers.py \
+	gdb/command/prompt.py
 
 FLAGS_TO_PASS = \
 	"prefix=$(prefix)" \
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index b477cf3..af34e38 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -19620,6 +19620,35 @@ Directs @value{GDBN} to use @var{newprompt} as its prompt string henceforth.
 Prints a line of the form: @samp{Gdb's prompt is: @var{your-prompt}}
 @end table
 
+Versions of @value{GDBN} that ship with Python scripting enabled have
+prompt extensions.  The commands for interacting with these extensions
+are:
+
+@table @code
+@kindex set extended-prompt
+@item set extended-prompt @var{prompt}
+Set an extended prompt that allows for substitutions.
+@xref{gdb.prompt}, for a list of escape sequences that can be used for
+substitution.  Any escape sequences specified as part of the prompt
+string are replaced with the corresponding strings each time the prompt
+is displayed.
+
+For example:
+
+@smallexample
+set extended-prompt Current working directory: \w (gdb)
+@end smallexample
+
+Note that when an extended-prompt is set, it takes control of the
+@var{prompt_hook} hook.  @xref{prompt_hook}, for further information.
+
+@kindex show extended-prompt
+@item show extended-prompt
+Prints the extended prompt.  Any escape sequences specified as part of
+the prompt string with @code{set extended-prompt}, are replaced with the
+corresponding strings each time the prompt is displayed.
+@end table
+
 @node Editing
 @section Command Editing
 @cindex readline
@@ -21176,6 +21205,8 @@ provided, it is decoded the way that @value{GDBN}'s inbuilt
 @end defun
 
 @defop Operation {@value{GDBN}} prompt_hook current_prompt
+@anchor{prompt_hook}
+
 If @var{prompt_hook} is callable, @value{GDBN} will call the method
 assigned to this operation before a prompt is displayed by
 @value{GDBN}.
@@ -23887,11 +23918,12 @@ top of the source tree to the source search path.
 @subsection Python modules
 @cindex python modules
 
-@value{GDBN} comes with a module to assist writing Python code.
+@value{GDBN} comes with several modules to assist writing Python code.
 
 @menu
 * gdb.printing::       Building and registering pretty-printers.
 * gdb.types::          Utilities for working with types.
+* gdb.prompt::         Utilities for prompt value substitution.
 @end menu
 
 @node gdb.printing
@@ -23959,6 +23991,59 @@ Return @code{True} if @var{type}, assumed to be a type with fields
 Return a Python @code{dictionary} type produced from @var{enum_type}.
 @end table
 
+@node gdb.prompt
+@subsubsection gdb.prompt
+@cindex gdb.prompt
+
+This module provides a method for prompt value-substitution.
+
+@table @code
+@item substitute_prompt (@var{string})
+Return @var{string} with escape sequences substituted by values.  Some
+escape sequences take arguments.  You can specify arguments inside
+``@{@}'' immediately following the escape sequence.
+
+The escape sequences you can pass to this function are:
+
+@table @code
+@item \\
+Substitute a backslash.
+@item \e
+Substitute an ESC character.
+@item \f
+Substitute the selected frame; an argument names a frame parameter.
+@item \n
+Substitute a newline.
+@item \p
+Substitute a parameter's value; the argument names the parameter.
+@item \r
+Substitute a carriage return.
+@item \t
+Substitute the selected thread; an argument names a thread parameter.
+@item \v
+Substitute the version of GDB.
+@item \w
+Substitute the current working directory.
+@item \[
+Begin a sequence of non-printing characters.
+@item \]
+End a sequence of non-printing characters.
+@end table
+
+For example:
+
+@smallexample
+substitute_prompt (``frame: \f,
+                   print arguments: \p@{print frame-arguments@}'')
+@end smallexample
+
+@exdent will return the string:
+
+@smallexample
+"frame: main, print arguments: scalars"
+@end smallexample
+@end table
+
 @node Interpreters
 @chapter Command Interpreters
 @cindex command interpreters
diff --git a/gdb/python/lib/gdb/command/prompt.py b/gdb/python/lib/gdb/command/prompt.py
index e69de29..35e522e 100644
--- a/gdb/python/lib/gdb/command/prompt.py
+++ b/gdb/python/lib/gdb/command/prompt.py
@@ -0,0 +1,66 @@
+# Extended prompt.
+# Copyright (C) 2011 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/>.
+
+"""GDB command for working with extended prompts."""
+
+import gdb
+import gdb.prompt
+
+class _ExtendedPrompt(gdb.Parameter):
+
+    """Set the extended prompt.
+
+Usage: set extended-prompt VALUE
+
+Substitutions are applied to VALUE to compute the real prompt.
+
+The currently defined substitutions are:
+
+"""
+    # Add the prompt library's dynamically generated help to the
+    # __doc__ string.
+    __doc__ = __doc__ + gdb.prompt.prompt_help()
+
+    set_doc = "Set the extended prompt."
+    show_doc = "Show the extended prompt."
+
+    def __init__(self):
+        super(_ExtendedPrompt, self).__init__("extended-prompt",
+                                              gdb.COMMAND_SUPPORT,
+                                              gdb.PARAM_STRING_NOESCAPE)
+        self.value = ''
+        self.hook_set = False
+
+    def get_show_string (self, pvalue):
+        if self.value is not '':
+           return "The extended prompt is: " + self.value
+        else:
+           return "The extended prompt is not set."
+
+    def get_set_string (self):
+        if self.hook_set == False:
+           gdb.prompt_hook = self.before_prompt_hook
+           self.hook_set = True
+        return ""
+
+    def before_prompt_hook(self, current):
+        if self.value is not '':
+            newprompt = gdb.prompt.substitute_prompt(self.value)
+            return newprompt.replace('\\', '\\\\')
+        else:
+            return None
+
+_ExtendedPrompt()
diff --git a/gdb/python/lib/gdb/prompt.py b/gdb/python/lib/gdb/prompt.py
index e69de29..296df3a 100644
--- a/gdb/python/lib/gdb/prompt.py
+++ b/gdb/python/lib/gdb/prompt.py
@@ -0,0 +1,149 @@
+# Extended prompt utilities.
+# Copyright (C) 2011 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/>.
+
+""" Extended prompt library functions."""
+
+import gdb
+import os
+
+def _prompt_pwd(ignore):
+    "The current working directory."
+    return os.getcwdu()
+
+def _prompt_object_attr(func, what, attr, nattr):
+    """Internal worker for fetching GDB attributes."""
+    if attr is None:
+        attr = nattr
+    try:
+        obj = func()
+    except gdb.error:
+        return '<no %s>' % what
+    if hasattr(obj, attr):
+        result = getattr(obj, attr)
+        if callable(result):
+            result = result()
+        return result
+    else:
+        return '<no attribute %s on current %s>' % (attr, what)
+
+def _prompt_frame(attr):
+    "The selected frame; an argument names a frame parameter."
+    return _prompt_object_attr(gdb.selected_frame, 'frame', attr, 'name')
+
+def _prompt_thread(attr):
+    "The selected thread; an argument names a thread parameter."
+    return _prompt_object_attr(gdb.selected_thread, 'thread', attr, 'num')
+
+def _prompt_version(attr):
+    "The version of GDB."
+    return gdb.VERSION
+
+def _prompt_esc(attr):
+    "The ESC character."
+    return '\033'
+
+def _prompt_bs(attr):
+    "A backslash."
+    return '\\'
+
+def _prompt_n(attr):
+    "A newline."
+    return '\n'
+
+def _prompt_r(attr):
+    "A carriage return."
+    return '\r'
+
+def _prompt_param(attr):
+    "A parameter's value; the argument names the parameter."
+    return gdb.parameter(attr)
+
+def _prompt_noprint_begin(attr):
+    "Begins a sequence of non-printing characters."
+    return '\001'
+
+def _prompt_noprint_end(attr):
+     "Ends a sequence of non-printing characters."
+     return '\002'
+
+prompt_substitutions = {
+    'e': _prompt_esc,
+    '\\': _prompt_bs,
+    'n': _prompt_n,
+    'r': _prompt_r,
+    'v': _prompt_version,
+    'w': _prompt_pwd,
+    'f': _prompt_frame,
+    't': _prompt_thread,
+    'p': _prompt_param,
+    '[': _prompt_noprint_begin,
+    ']': _prompt_noprint_end
+}
+
+def prompt_help():
+    """Generate help dynamically from the __doc__ strings of attribute
+    functions."""
+
+    result = ''
+    keys = prompt_substitutions.keys()
+    keys.sort()
+    for key in keys:
+        result += '  \\%s\t%s\n' % (key, prompt_substitutions[key].__doc__)
+    result += """
+A substitution can be used in a simple form, like "\\f".
+An argument can also be passed to it, like "\\f{name}".
+The meaning of the argument depends on the particular substitution."""
+    return result
+
+def substitute_prompt(prompt):
+    "Perform substitutions on PROMPT."
+
+    result = ''
+    plen = len(prompt)
+    i = 0
+    while i < plen:
+        if prompt[i] == '\\':
+            i = i + 1
+            if i >= plen:
+                break
+            cmdch = prompt[i]
+
+            if cmdch in prompt_substitutions:
+                cmd = prompt_substitutions[cmdch]
+
+                if i + 1 < plen and prompt[i + 1] == '{':
+                    j = i + 1
+                    while j < plen and prompt[j] != '}':
+                        j = j + 1
+                    # Just ignore formatting errors.
+                    if j >= plen or prompt[j] != '}':
+                        arg = None
+                    else:
+                        arg = prompt[i + 2 : j]
+                        i = j
+                else:
+                    arg = None
+                result += str(cmd(arg))
+            else:
+                # Unrecognized escapes are turned into the escaped
+                # character itself.
+                result += prompt[i]
+        else:
+            result += prompt[i]
+
+        i = i + 1
+
+    return result
diff --git a/gdb/testsuite/gdb.python/python.exp b/gdb/testsuite/gdb.python/python.exp
index 832afc0..4da3c88 100644
--- a/gdb/testsuite/gdb.python/python.exp
+++ b/gdb/testsuite/gdb.python/python.exp
@@ -275,3 +275,29 @@ gdb_test_multiple "end" "end programming" {
 	pass "end programming"
     }
 }
+
+gdb_py_test_multiple "prompt substitution readline" \
+  "python" "" \
+  "import gdb.command.prompt" "" \
+  "end" ""
+
+gdb_test_multiple "set extended-prompt one two three " \
+    "set basic extended prompt" {
+    -re "\[\r\n\]one two three $" {
+	pass "set basic extended prompt"
+    }
+}
+
+gdb_test_multiple "set extended-prompt \\w " \
+    "set extended prompt working directory" {
+    -re "\[\r\n\].*gdb.*testsuite.* $" {
+	pass "set extended prompt working directory"
+    }
+}
+
+gdb_test_multiple "set extended-prompt some param \\p{python print-stack} " \
+    "set extended prompt parameter" {
+    -re "\[\r\n\]some param True $" {
+	pass "set extended prompt parameter"
+    }
+}