-var-info-path-expression

[Vladimir Prus <ghost@cs.msu.su>]

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This patch implements new MI command, -var-info-path-expression,
that, given a variable object, returns full expression that corresponds
to it.  Both KDevelop and Eclipse have now code that guesses such
full expression, and that code is rather hacky, and not exactly correct.

Moreover, as soon as MI is taught to get the true type 
polymorphic C++ objects and display fields of the real type, such full expression 
cannot be computed in frontend at all.

The essence of this patch -- which expressions are returned in which cases -- are
ported without change from the Apple branch. The code structure is much
different though -- this patch capitalizes on MI refactoring patches I've posted
recently.

This is lightly tested by hand, I'll write automated tests later. There's no docs
either -- again, will be written after discussion.

There is a couple of issues with this patch:

	- I don't much like 'var-info-path-expression' name, but
	naming of MI commands is not very important.
	- I'm not sure why we can't report full expression in the
	output of -var-list-children. The code I have does not seem
	very computationally expensive.

Comments are appreciated.

- Volodya

	Implement -var-info-path-expression.
	* mi/mi-cmds.h (mi_cmd_var_info_path_expression):
	Declare.
	* mi/mi-cmds.c (mi_cmds): Register var-info-path-expression.
	* mi/mi-cmd-var.c (mi_cmd_var_info_path_expression): New.
	* varobj.c (struct varobj): New field 'path_expr'.
	(c_path_expr_of_child, cplus_path_expr_of_child)
	(java_path_expr_of_child): New.
	(struct language_specific): New field path_expr_of_child.
	(varobj_create): Initialize the path_expr field.
	(varobj_get_path_expr): New.
	(new_variable): Initialize the path_expr field.
	(free_variable): Free the path_expr field.
	(adjust_value_for_children_access): New parameter
	WAS_TYPE.
	(c_number_of_children): Adjust.
	(c_describe_child): New parameter CFULL_EXPRESSION.
	Compute full expression.
	(c_value_of_child, c_type_of_child): Adjust.
	(cplus_number_of_children): Adjust.
	(cplus_describe_child): New parameter CFULL_EXPRESSION.
	Compute full expression.
	(cplus_name_of_child, cplus_value_of_child)
	(cplus_type_of_child): Adjust.
	* varobj.h (varobj_get_path_expr): Declare.

[-- Attachment #2: path_expression__gdb_mainline.diff --]
[-- Type: text/x-diff, Size: 16939 bytes --]

--- gdb/mi/mi-cmds.h	(/patches/gdb/path_4_unify_cpp/gdb_mainline)	(revision 2940)
+++ gdb/mi/mi-cmds.h	(/patches/gdb/path_expression/gdb_mainline)	(revision 2940)
@@ -108,6 +108,7 @@ extern mi_cmd_argv_ftype mi_cmd_var_crea
 extern mi_cmd_argv_ftype mi_cmd_var_delete;
 extern mi_cmd_argv_ftype mi_cmd_var_evaluate_expression;
 extern mi_cmd_argv_ftype mi_cmd_var_info_expression;
+extern mi_cmd_argv_ftype mi_cmd_var_info_path_expression;
 extern mi_cmd_argv_ftype mi_cmd_var_info_num_children;
 extern mi_cmd_argv_ftype mi_cmd_var_info_type;
 extern mi_cmd_argv_ftype mi_cmd_var_list_children;
--- gdb/mi/mi-cmds.c	(/patches/gdb/path_4_unify_cpp/gdb_mainline)	(revision 2940)
+++ gdb/mi/mi-cmds.c	(/patches/gdb/path_expression/gdb_mainline)	(revision 2940)
@@ -155,6 +155,8 @@ struct mi_cmd mi_cmds[] =
   { "var-create", { NULL, 0 }, 0, mi_cmd_var_create},
   { "var-delete", { NULL, 0 }, 0, mi_cmd_var_delete},
   { "var-evaluate-expression", { NULL, 0 }, 0, mi_cmd_var_evaluate_expression},
+  { "var-info-path-expression", { NULL, 0 }, 0, 
+    mi_cmd_var_info_path_expression},
   { "var-info-expression", { NULL, 0 }, 0, mi_cmd_var_info_expression},
   { "var-info-num-children", { NULL, 0 }, 0, mi_cmd_var_info_num_children},
   { "var-info-type", { NULL, 0 }, 0, mi_cmd_var_info_type},
--- gdb/mi/mi-cmd-var.c	(/patches/gdb/path_4_unify_cpp/gdb_mainline)	(revision 2940)
+++ gdb/mi/mi-cmd-var.c	(/patches/gdb/path_expression/gdb_mainline)	(revision 2940)
@@ -380,6 +380,27 @@ mi_cmd_var_info_type (char *command, cha
 }
 
 enum mi_cmd_result
+mi_cmd_var_info_path_expression (char *command, char **argv, int argc)
+{
+  struct varobj *var;
+  char *path_expr;
+
+  if (argc != 1)
+    error ("mi_cmd_var_info_path_expression: Usage: NAME.");
+
+  /* Get varobj handle, if a valid var obj name was specified */
+  var = varobj_get_handle (argv[0]);
+  if (var == NULL)
+    error ("mi_cmd_var_info_path_expression: Variable object not found");
+  
+  path_expr = varobj_get_path_expr (var);
+
+  ui_out_field_string (uiout, "path_expr", path_expr);
+
+  return MI_CMD_DONE;
+}
+
+enum mi_cmd_result
 mi_cmd_var_info_expression (char *command, char **argv, int argc)
 {
   enum varobj_languages lang;
--- gdb/varobj.c	(/patches/gdb/path_4_unify_cpp/gdb_mainline)	(revision 2940)
+++ gdb/varobj.c	(/patches/gdb/path_expression/gdb_mainline)	(revision 2940)
@@ -97,6 +97,10 @@ struct varobj
   /* NOTE: This is the "expression" */
   char *name;
 
+  /* Alloc'd expression for this child.  Can be used to create a
+     root variable corresponding to this child. */
+  char *path_expr;
+
   /* The alloc'd name for this variable's object. This is here for
      convenience when constructing this object's children. */
   char *obj_name;
@@ -216,6 +220,8 @@ static char *c_name_of_variable (struct 
 
 static char *c_name_of_child (struct varobj *parent, int index);
 
+static char *c_path_expr_of_child (struct varobj *child);
+
 static struct value *c_value_of_root (struct varobj **var_handle);
 
 static struct value *c_value_of_child (struct varobj *parent, int index);
@@ -236,6 +242,8 @@ static char *cplus_name_of_variable (str
 
 static char *cplus_name_of_child (struct varobj *parent, int index);
 
+static char *cplus_path_expr_of_child (struct varobj *child);
+
 static struct value *cplus_value_of_root (struct varobj **var_handle);
 
 static struct value *cplus_value_of_child (struct varobj *parent, int index);
@@ -254,6 +262,8 @@ static char *java_name_of_variable (stru
 
 static char *java_name_of_child (struct varobj *parent, int index);
 
+static char *java_path_expr_of_child (struct varobj *child);
+
 static struct value *java_value_of_root (struct varobj **var_handle);
 
 static struct value *java_value_of_child (struct varobj *parent, int index);
@@ -281,6 +291,10 @@ struct language_specific
   /* The name of the INDEX'th child of PARENT. */
   char *(*name_of_child) (struct varobj * parent, int index);
 
+  /* Returns the rooted expression of CHILD, which is a variable
+     obtain that has some parent.  */
+  char *(*path_expr_of_child) (struct varobj * child);
+
   /* The ``struct value *'' of the root variable ROOT. */
   struct value *(*value_of_root) (struct varobj ** root_handle);
 
@@ -306,6 +320,7 @@ static struct language_specific
    c_number_of_children,
    c_name_of_variable,
    c_name_of_child,
+   c_path_expr_of_child,
    c_value_of_root,
    c_value_of_child,
    c_type_of_child,
@@ -318,6 +333,7 @@ static struct language_specific
    c_number_of_children,
    c_name_of_variable,
    c_name_of_child,
+   c_path_expr_of_child,
    c_value_of_root,
    c_value_of_child,
    c_type_of_child,
@@ -330,6 +346,7 @@ static struct language_specific
    cplus_number_of_children,
    cplus_name_of_variable,
    cplus_name_of_child,
+   cplus_path_expr_of_child,
    cplus_value_of_root,
    cplus_value_of_child,
    cplus_type_of_child,
@@ -342,6 +359,7 @@ static struct language_specific
    java_number_of_children,
    java_name_of_variable,
    java_name_of_child,
+   java_path_expr_of_child,
    java_value_of_root,
    java_value_of_child,
    java_type_of_child,
@@ -425,6 +443,7 @@ varobj_create (char *objname,
       char *p;
       enum varobj_languages lang;
       struct value *value;
+      int expr_len;
 
       /* Parse and evaluate the expression, filling in as much
          of the variable's data as possible */
@@ -469,7 +488,10 @@ varobj_create (char *objname,
 
       var->format = variable_default_display (var);
       var->root->valid_block = innermost_block;
-      var->name = savestring (expression, strlen (expression));
+      expr_len = strlen (expression);
+      var->name = savestring (expression, expr_len);
+      /* For a root var, the name and the expr are the same.  */
+      var->path_expr = savestring (expression, expr_len);
 
       /* When the frame is different from the current frame, 
          we must select the appropriate frame before parsing
@@ -757,6 +779,21 @@ varobj_get_gdb_type (struct varobj *var)
   return var->type;
 }
 
+/* Return a pointer to the full rooted expression of varobj VAR.
+   If it has not been computed yet, compute it */
+char *
+varobj_get_path_expr (struct varobj *var)
+{
+  if (var->path_expr != NULL)
+    return var->path_expr;
+  else if (is_root_p (var))
+    return var->name;
+  else
+    {
+      return (*var->root->lang->path_expr_of_child) (var);
+    }
+}
+
 enum varobj_languages
 varobj_get_language (struct varobj *var)
 {
@@ -1357,6 +1394,7 @@ new_variable (void)
 
   var = (struct varobj *) xmalloc (sizeof (struct varobj));
   var->name = NULL;
+  var->path_expr = NULL;
   var->obj_name = NULL;
   var->index = -1;
   var->type = NULL;
@@ -1401,6 +1439,7 @@ free_variable (struct varobj *var)
 
   xfree (var->name);
   xfree (var->obj_name);
+  xfree (var->path_expr);
   xfree (var);
 }
 
@@ -1683,13 +1722,21 @@ varobj_value_is_changeable_p (struct var
    Both TYPE and *TYPE should be non-null. VALUE
    can be null if we want to only translate type.
    *VALUE can be null as well -- if the parent
-   value is not known.  */
+   value is not known.  
+
+   If WAS_PTR is not NULL, set *WAS_PTR to 0 or 1
+   depending on whether pointer was deferenced
+   in this function.  */
 static void
 adjust_value_for_children_access (struct value **value,
-				  struct type **type)
+				  struct type **type,
+				  int *was_ptr)
 {
   gdb_assert (type && *type);
 
+  if (was_ptr)
+    *was_ptr = 0;
+
   *type = check_typedef (*type);
   
   /* If the parent is reference, we always strip the
@@ -1721,6 +1768,8 @@ adjust_value_for_children_access (struct
 	  if (value && *value)
 	    gdb_value_ind (*value, value);	  
 	  *type = target_type;
+	  if (was_ptr)
+	    *was_ptr = 1;
 	}
     }
 }
@@ -1733,7 +1782,7 @@ c_number_of_children (struct varobj *var
   int children = 0;
   struct type *target;
 
-  adjust_value_for_children_access (NULL, &type);
+  adjust_value_for_children_access (NULL, &type, NULL);
   target = get_target_type (type);
 
   switch (TYPE_CODE (type))
@@ -1826,10 +1875,13 @@ value_struct_element_index (struct value
    to NULL.  */
 static void 
 c_describe_child (struct varobj *parent, int index,
-		  char **cname, struct value **cvalue, struct type **ctype)
+		  char **cname, struct value **cvalue, struct type **ctype,
+		  char **cfull_expression)
 {
   struct value *value = parent->value;
   struct type *type = get_type (parent);
+  char *parent_expression = NULL;
+  int was_ptr;
 
   if (cname)
     *cname = NULL;
@@ -1837,8 +1889,13 @@ c_describe_child (struct varobj *parent,
     *cvalue = NULL;
   if (ctype)
     *ctype = NULL;
+  if (cfull_expression)
+    {
+      *cfull_expression = NULL;
+      parent_expression = varobj_get_path_expr (parent);
+    }
 
-  adjust_value_for_children_access (&value, &type);
+  adjust_value_for_children_access (&value, &type, &was_ptr);
       
   switch (TYPE_CODE (type))
     {
@@ -1858,6 +1915,12 @@ c_describe_child (struct varobj *parent,
       if (ctype)
 	*ctype = get_target_type (type);
 
+      if (cfull_expression)
+	*cfull_expression = xstrprintf ("(%s)[%d]", parent_expression, 
+					index
+					+ TYPE_LOW_BOUND (TYPE_INDEX_TYPE (type)));
+
+
       break;
 
     case TYPE_CODE_STRUCT:
@@ -1877,6 +1940,13 @@ c_describe_child (struct varobj *parent,
       if (ctype)
 	*ctype = TYPE_FIELD_TYPE (type, index);
 
+      if (cfull_expression)
+	{
+	  char *join = was_ptr ? "->" : ".";
+	  *cfull_expression = xstrprintf ("(%s)%s%s", parent_expression, join,
+					  TYPE_FIELD_NAME (type, index));
+	}
+
       break;
 
     case TYPE_CODE_PTR:
@@ -1892,6 +1962,9 @@ c_describe_child (struct varobj *parent,
 	 right.  */
       if (ctype)
 	*ctype = get_target_type (type);
+
+      if (cfull_expression)
+	*cfull_expression = xstrprintf ("*(%s)", parent_expression);
       
       break;
 
@@ -1899,6 +1972,8 @@ c_describe_child (struct varobj *parent,
       /* This should not happen */
       if (cname)
 	*cname = xstrdup ("???");
+      if (cfull_expression)
+	*cfull_expression = xstrdup ("???");
       /* Don't set value and type, we don't know then. */
     }
 }
@@ -1907,10 +1982,18 @@ static char *
 c_name_of_child (struct varobj *parent, int index)
 {
   char *name;
-  c_describe_child (parent, index, &name, NULL, NULL);
+  c_describe_child (parent, index, &name, NULL, NULL, NULL);
   return name;
 }
 
+static char *
+c_path_expr_of_child (struct varobj *child)
+{
+  c_describe_child (child->parent, child->index, NULL, NULL, NULL, 
+		    &child->path_expr);
+  return child->path_expr;
+}
+
 static struct value *
 c_value_of_root (struct varobj **var_handle)
 {
@@ -1961,7 +2044,7 @@ static struct value *
 c_value_of_child (struct varobj *parent, int index)
 {
   struct value *value = NULL;
-  c_describe_child (parent, index, NULL, &value, NULL);
+  c_describe_child (parent, index, NULL, &value, NULL, NULL);
   if (value != NULL)
     release_value (value);
 
@@ -1972,7 +2055,7 @@ static struct type *
 c_type_of_child (struct varobj *parent, int index)
 {
   struct type *type = NULL;
-  c_describe_child (parent, index, NULL, NULL, &type);
+  c_describe_child (parent, index, NULL, NULL, &type, NULL);
   return type;
 }
 
@@ -2066,7 +2149,7 @@ cplus_number_of_children (struct varobj 
   if (!CPLUS_FAKE_CHILD (var))
     {
       type = var->type;
-      adjust_value_for_children_access (NULL, &type);
+      adjust_value_for_children_access (NULL, &type, NULL);
 
       if (((TYPE_CODE (type)) == TYPE_CODE_STRUCT) ||
 	  ((TYPE_CODE (type)) == TYPE_CODE_UNION))
@@ -2093,7 +2176,7 @@ cplus_number_of_children (struct varobj 
       int kids[3];
 
       type = var->parent->type;
-      adjust_value_for_children_access (NULL, &type);
+      adjust_value_for_children_access (NULL, &type, NULL);
 
       cplus_class_num_children (type, kids);
       if (strcmp (var->name, "public") == 0)
@@ -2164,11 +2247,14 @@ match_accessibility (struct type *type, 
 
 static void
 cplus_describe_child (struct varobj *parent, int index,
-		      char **cname, struct value **cvalue, struct type **ctype)
+		      char **cname, struct value **cvalue, struct type **ctype,
+		      char **cfull_expression)
 {
   char *name = 0;
   struct value *value;
   struct type *type;
+  int was_ptr;
+  char *parent_expression = NULL;
 
   if (cname)
     *cname = NULL;
@@ -2176,24 +2262,30 @@ cplus_describe_child (struct varobj *par
     *cvalue = NULL;
   if (ctype)
     *ctype = NULL;
-
+  if (cfull_expression)
+    *cfull_expression = NULL;
 
   if (CPLUS_FAKE_CHILD (parent))
     {
       value = parent->parent->value;
       type = get_type (parent->parent);
+      if (cfull_expression)
+	parent_expression = varobj_get_path_expr (parent->parent);
     }
   else
     {
       value = parent->value;
       type = get_type (parent);
+      if (cfull_expression)
+	parent_expression = varobj_get_path_expr (parent);
     }
 
-  adjust_value_for_children_access (&value, &type);
+  adjust_value_for_children_access (&value, &type, &was_ptr);
 
   if (TYPE_CODE (type) == TYPE_CODE_STRUCT
       || TYPE_CODE (type) == TYPE_CODE_STRUCT)
     {
+      char *join = was_ptr ? "->" : ".";
       if (CPLUS_FAKE_CHILD (parent))
 	{
 	  /* The fields of the class type are ordered as they
@@ -2228,6 +2320,11 @@ cplus_describe_child (struct varobj *par
 
 	  if (ctype)
 	    *ctype = TYPE_FIELD_TYPE (type, type_index);
+
+	  if (cfull_expression)
+	    *cfull_expression = xstrprintf ("((%s)%s%s)", parent_expression,
+					    join, 
+					    TYPE_FIELD_NAME (type, type_index));
 	}
       else if (index < TYPE_N_BASECLASSES (type))
 	{
@@ -2245,6 +2342,15 @@ cplus_describe_child (struct varobj *par
 	    {
 	      *ctype = TYPE_FIELD_TYPE (type, index);
 	    }
+
+	  if (cfull_expression)
+	    {
+	      char *ptr = was_ptr ? " *" : "";
+	      *cfull_expression = xstrprintf ("((%s%s) %s)", 
+					      TYPE_FIELD_NAME (type, index),
+					      ptr,
+					      parent_expression);
+	    }
 	}
       else
 	{
@@ -2291,12 +2397,12 @@ cplus_describe_child (struct varobj *par
 	  if (cname)
 	    *cname = access;
 
-	  /* Value and type are null here.  */
+	  /* Value and type and full expression are null here.  */
 	}
     }
   else
     {
-      c_describe_child (parent, index, cname, cvalue, ctype);
+      c_describe_child (parent, index, cname, cvalue, ctype, cfull_expression);
     }  
 }
 
@@ -2304,10 +2410,18 @@ static char *
 cplus_name_of_child (struct varobj *parent, int index)
 {
   char *name = NULL;
-  cplus_describe_child (parent, index, &name, NULL, NULL);
+  cplus_describe_child (parent, index, &name, NULL, NULL, NULL);
   return name;
 }
 
+static char *
+cplus_path_expr_of_child (struct varobj *child)
+{
+  cplus_describe_child (child->parent, child->index, NULL, NULL, NULL, 
+			&child->path_expr);
+  return child->path_expr;
+}
+
 static struct value *
 cplus_value_of_root (struct varobj **var_handle)
 {
@@ -2318,7 +2432,7 @@ static struct value *
 cplus_value_of_child (struct varobj *parent, int index)
 {
   struct value *value = NULL;
-  cplus_describe_child (parent, index, NULL, &value, NULL);
+  cplus_describe_child (parent, index, NULL, &value, NULL, NULL);
   return value;
 }
 
@@ -2326,7 +2440,7 @@ static struct type *
 cplus_type_of_child (struct varobj *parent, int index)
 {
   struct type *type = NULL;
-  cplus_describe_child (parent, index, NULL, NULL, &type);
+  cplus_describe_child (parent, index, NULL, NULL, &type, NULL);
   return type;
 }
 
@@ -2398,6 +2512,12 @@ java_name_of_child (struct varobj *paren
   return name;
 }
 
+static char *
+java_path_expr_of_child (struct varobj *child)
+{
+  return NULL;
+}
+
 static struct value *
 java_value_of_root (struct varobj **var_handle)
 {
--- gdb/varobj.h	(/patches/gdb/path_4_unify_cpp/gdb_mainline)	(revision 2940)
+++ gdb/varobj.h	(/patches/gdb/path_expression/gdb_mainline)	(revision 2940)
@@ -87,6 +87,8 @@ extern char *varobj_get_type (struct var
 
 extern struct type *varobj_get_gdb_type (struct varobj *var);
 
+extern char *varobj_get_path_expr (struct varobj *var);
+
 extern enum varobj_languages varobj_get_language (struct varobj *var);
 
 extern int varobj_get_attributes (struct varobj *var);

Property changes on: 
___________________________________________________________________
Name: csl:base
 -/all/patches/gdb/path_3_unify/gdb_mainline
 +/all/patches/gdb/path_4_unify_cpp/gdb_mainline
Name: svk:merge
  d48a11ec-ee1c-0410-b3f5-c20844f99675:/patches/gdb/path_1/gdb_mainline:2869
 +d48a11ec-ee1c-0410-b3f5-c20844f99675:/patches/gdb/path_2_children/gdb_mainline:2879
  d48a11ec-ee1c-0410-b3f5-c20844f99675:/patches/gdb/path_3_unify/gdb_mainline:2930
 -d48a11ec-ee1c-0410-b3f5-c20844f99675:/patches/gdb/path_expression/gdb_mainline:2562
 +d48a11ec-ee1c-0410-b3f5-c20844f99675:/patches/gdb/path_4_unify_cpp/gdb_mainline:2937
  e7755896-6108-0410-9592-8049d3e74e28:/mirrors/gdb/trunk:157978