gdb/cp-support.c

/* Helper routines for C++ support in GDB.
   Copyright 2002, 2003 Free Software Foundation, Inc.

   Contributed by MontaVista Software.

   This file is part of GDB.

   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 2 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, write to the Free Software
   Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#include "defs.h"
#include <ctype.h>
#include "cp-support.h"
#include "gdb_string.h"
#include "demangle.h"
#include "gdb_assert.h"
#include "gdbcmd.h"

/* The list of "maint cplus" commands.  */

static struct cmd_list_element *maint_cplus_cmd_list = NULL;

/* The actual commands.  */

static void maint_cplus_command (char *arg, int from_tty);
static void first_component_command (char *arg, int from_tty);

/* Here are some random pieces of trivia to keep in mind while trying
   to take apart demangled names:

   - Names can contain function arguments or templates, so the process
     has to be, to some extent recursive: maybe keep track of your
     depth based on encountering <> and ().

   - Parentheses don't just have to happen at the end of a name: they
     can occur even if the name in question isn't a function, because
     a template argument might be a type that's a function.

   - Conversely, even if you're trying to deal with a function, its
     demangled name might not end with ')': it could be a const or
     volatile class method, in which case it ends with "const" or
     "volatile".

   - Parentheses are also used in anonymous namespaces: a variable
     'foo' in an anonymous namespace gets demangled as "(anonymous
     namespace)::foo".

   - And operator names can contain parentheses or angle brackets.
     Fortunately, I _think_ that operator names can only occur in a
     fairly restrictive set of locations (in particular, they have be
     at depth 0, don't they?).  */

/* NOTE: carlton/2003-02-21: Daniel Jacobowitz came up with an example
   where operator names don't occur at depth 0.  Sigh.  (It involved a
   template argument that was a pointer: I hadn't realized that was
   possible.)  Handling such edge cases does not seem like a
   high-priority problem to me.  */

/* FIXME: carlton/2003-03-13: We have several functions here with
   overlapping functionality; can we combine them?  Also, do they
   handle all the above considerations correctly?  */

/* Find the last component of the demangled C++ name NAME.  NAME
   must be a method name including arguments, in order to correctly
   locate the last component.

   This function return a pointer to the first colon before the
   last component, or NULL if the name had only one component.  */

static const char *
find_last_component (const char *name)
{
  const char *p;
  int depth;

  /* Functions can have local classes, so we need to find the
     beginning of the last argument list, not the end of the first
     one.  */
  p = name + strlen (name) - 1;
  while (p > name && *p != ')')
    p--;

  if (p == name)
    return NULL;

  /* P now points at the `)' at the end of the argument list.  Walk
     back to the beginning.  */
  p--;
  depth = 1;
  while (p > name && depth > 0)
    {
      if (*p == '<' || *p == '(')
	depth--;
      else if (*p == '>' || *p == ')')
	depth++;
      p--;
    }

  if (p == name)
    return NULL;

  while (p > name && *p != ':')
    p--;

  if (p == name || p == name + 1 || p[-1] != ':')
    return NULL;

  return p - 1;
}

/* Return the name of the class containing method PHYSNAME.  */

char *
class_name_from_physname (const char *physname)
{
  char *ret = NULL;
  const char *end;
  int depth = 0;
  char *demangled_name = cplus_demangle (physname, DMGL_ANSI);

  if (demangled_name == NULL)
    return NULL;

  end = find_last_component (demangled_name);
  if (end != NULL)
    {
      ret = xmalloc (end - demangled_name + 1);
      memcpy (ret, demangled_name, end - demangled_name);
      ret[end - demangled_name] = '\0';
    }

  xfree (demangled_name);
  return ret;
}

/* Return the name of the method whose linkage name is PHYSNAME.  */

char *
method_name_from_physname (const char *physname)
{
  char *ret = NULL;
  const char *end;
  int depth = 0;
  char *demangled_name = cplus_demangle (physname, DMGL_ANSI);

  if (demangled_name == NULL)
    return NULL;

  end = find_last_component (demangled_name);
  if (end != NULL)
    {
      char *args;
      int len;

      /* Skip "::".  */
      end = end + 2;

      /* Find the argument list, if any.  */
      args = strchr (end, '(');
      if (args == NULL)
	len = strlen (end + 2);
      else
	{
	  args --;
	  while (*args == ' ')
	    args --;
	  len = args - end + 1;
	}
      ret = xmalloc (len + 1);
      memcpy (ret, end, len);
      ret[len] = 0;
    }

  xfree (demangled_name);
  return ret;
}

/* This returns the length of first component of NAME, which should be
   the demangled name of a C++ variable/function/method/etc.
   Specifically, it returns the index of the first colon forming the
   boundary of the first component: so, given 'A::foo' or 'A::B::foo'
   it returns the 1, and given 'foo', it returns 0.  */

/* Well, that's what it should do when called externally, but to make
   the recursion easier, it also stops if it reaches an unexpected ')'
   or '>'.  */

/* NOTE: carlton/2003-03-13: This function is currently only intended
   for internal use: it's probably not entirely safe when called on
   user-generated input, because some of the 'index += 2' lines might
   go past the end of malformed input.  */

/* Let's optimize away calls to strlen("operator").  */

#define LENGTH_OF_OPERATOR 8

unsigned int
cp_find_first_component (const char *name)
{
  /* Names like 'operator<<' screw up the recursion, so let's
     special-case them.  I _hope_ they can only occur at the start of
     a component.  */

  unsigned int index = 0;

  if (strncmp (name, "operator", LENGTH_OF_OPERATOR) == 0)
    {
      index += LENGTH_OF_OPERATOR;
      while (isspace(name[index]))
	++index;
      switch (name[index])
	{
	case '<':
	  if (name[index + 1] == '<')
	    index += 2;
	  else
	    index += 1;
	  break;
	case '>':
	case '-':
	  if (name[index + 1] == '>')
	    index += 2;
	  else
	    index += 1;
	  break;
	case '(':
	  index += 2;
	  break;
	default:
	  index += 1;
	  break;
	}
    }

  for (;; ++index)
    {
      switch (name[index])
	{
	case '<':
	  /* Template; eat it up.  The calls to cp_first_component
	     should only return (I hope!) when they reach the '>'
	     terminating the component or a '::' between two
	     components.  (Hence the '+ 2'.)  */
	  index += 1;
	  for (index += cp_find_first_component (name + index);
	       name[index] != '>';
	       index += cp_find_first_component (name + index))
	    {
	      gdb_assert (name[index] == ':');
	      index += 2;
	    }
	  break;
	case '(':
	  /* Similar comment as to '<'.  */
	  index += 1;
	  for (index += cp_find_first_component (name + index);
	       name[index] != ')';
	       index += cp_find_first_component (name + index))
	    {
	      gdb_assert (name[index] == ':');
	      index += 2;
	    }
	  break;
	case '>':
	case ')':
	case '\0':
	case ':':
	  return index;
	default:
	  break;
	}
    }
}

/* If NAME is the fully-qualified name of a C++
   function/variable/method/etc., this returns the length of its
   entire prefix: all of the namespaces and classes that make up its
   name.  Given 'A::foo', it returns 1, given 'A::B::foo', it returns
   4, given 'foo', it returns 0.  */

unsigned int
cp_entire_prefix_len (const char *name)
{
  unsigned int current_len = cp_find_first_component (name);
  unsigned int previous_len = 0;

  while (name[current_len] != '\0')
    {
      gdb_assert (name[current_len] == ':');
      previous_len = current_len;
      /* Skip the '::'.  */
      current_len += 2;
      current_len += cp_find_first_component (name + current_len);
    }

  return previous_len;
}

/* Don't allow just "maintenance cplus".  */

static  void
maint_cplus_command (char *arg, int from_tty)
{
  printf_unfiltered ("\"maintenance cplus\" must be followed by the name of a command.\n");
  help_list (maint_cplus_cmd_list, "maintenance cplus ", -1, gdb_stdout);
}

/* This is a front end for cp_find_first_component, for unit testing.
   Be careful when using it: see the NOTE above
   cp_find_first_component.  */

static void
first_component_command (char *arg, int from_tty)
{
  int len = cp_find_first_component (arg);
  char *prefix = alloca (len + 1);

  memcpy (prefix, arg, len);
  prefix[len] = '\0';

  printf_unfiltered ("%s\n", prefix);
}

void
_initialize_cp_support (void)
{
  add_prefix_cmd ("cplus", class_maintenance, maint_cplus_command,
		  "C++ maintenance commands.", &maint_cplus_cmd_list,
		  "maintenance cplus ", 0, &maintenancelist);
  add_alias_cmd ("cp", "cplus", class_maintenance, 1, &maintenancelist);

  add_cmd ("first_component", class_maintenance, first_component_command,
	   "Print the first class/namespace component of NAME.",
	   &maint_cplus_cmd_list);
		  
}