[commit/Ada] Add handling of "ptype TYPE_NAME.FIELD0.[...].FIELDN" expressions

[Joel Brobecker <brobecker@adacore.com>]

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Hello,

The subject says it all. Before the patch, you could do:

   (gdb) ptype type_name

But if you wanted to get the type of one field inside that type,
you would hit a limitation:

   (gdb) ptype circle.pos
   Invalid attempt to select from type: "circle.pos".

The attached patch enhances the debugger to able to do the above.

2008-01-04  Joel Brobecker  <brobecker@adacore.com>

        * ada-exp.y (chop_separator): New function.
        (write_selectors): Rewrite to re-use chop_separator.
        (ada_nget_field_index, get_symbol_field_type): New functions.
        (write_var_or_type): Add support for "ptype TYPENAME.FIELD"
        expressions.

As usual when I can, I wrote a testcase:

2008-01-04  Joel Brobecker  <brobecker@adacore.com>

        * gdb.ada/ptype_field/pck.ads, gdb.ada/ptype_field/pck.adb,
        gdb.ada/ptype_field/foo.adb: New files.
        * gdb.ada/ptype_field.exp: New testcase.

All tested on x86-linux. Note that I used the multi_line function
again! Very useful :)

Checked in.

-- 
Joel

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Index: ada-exp.y
===================================================================
--- ada-exp.y	(revision 69)
+++ ada-exp.y	(revision 70)
@@ -1112,6 +1112,22 @@ chop_selector (char *name, int end)
   return -1;
 }
 
+/* If NAME is a string beginning with a separator (either '__', or
+   '.'), chop this separator and return the result; else, return
+   NAME.  */
+
+static char *
+chop_separator (char *name)
+{
+  if (*name == '.')
+   return name + 1;
+
+  if (name[0] == '_' && name[1] == '_')
+    return name + 2;
+
+  return name;
+}
+
 /* Given that SELS is a string of the form (<sep><identifier>)*, where
    <sep> is '__' or '.', write the indicated sequence of
    STRUCTOP_STRUCT expression operators. */
@@ -1121,10 +1137,8 @@ write_selectors (char *sels)
   while (*sels != '\0')
     {
       struct stoken field_name;
-      char *p;
-      while (*sels == '_' || *sels == '.')
-	sels += 1;
-      p = sels;
+      char *p = chop_separator (sels);
+      sels = p;
       while (*sels != '\0' && *sels != '.' 
 	     && (sels[0] != '_' || sels[1] != '_'))
 	sels += 1;
@@ -1154,6 +1168,70 @@ write_ambiguous_var (struct block *block
   write_exp_elt_opcode (OP_VAR_VALUE);
 }
 
+/* A convenient wrapper around ada_get_field_index that takes
+   a non NUL-terminated FIELD_NAME0 and a FIELD_NAME_LEN instead
+   of a NUL-terminated field name.  */
+
+static int
+ada_nget_field_index (const struct type *type, const char *field_name0,
+                      int field_name_len, int maybe_missing)
+{
+  char *field_name = alloca ((field_name_len + 1) * sizeof (char));
+
+  strncpy (field_name, field_name0, field_name_len);
+  field_name[field_name_len] = '\0';
+  return ada_get_field_index (type, field_name, maybe_missing);
+}
+
+/* If encoded_field_name is the name of a field inside symbol SYM,
+   then return the type of that field.  Otherwise, return NULL.
+
+   This function is actually recursive, so if ENCODED_FIELD_NAME
+   doesn't match one of the fields of our symbol, then try to see
+   if ENCODED_FIELD_NAME could not be a succession of field names
+   (in other words, the user entered an expression of the form
+   TYPE_NAME.FIELD1.FIELD2.FIELD3), in which case we evaluate
+   each field name sequentially to obtain the desired field type.
+   In case of failure, we return NULL.  */
+
+static struct type *
+get_symbol_field_type (struct symbol *sym, char *encoded_field_name)
+{
+  char *field_name = encoded_field_name;
+  char *subfield_name;
+  struct type *type = SYMBOL_TYPE (sym);
+  int fieldno;
+
+  if (type == NULL || field_name == NULL)
+    return NULL;
+
+  while (field_name[0] != '\0')
+    {
+      field_name = chop_separator (field_name);
+
+      fieldno = ada_get_field_index (type, field_name, 1);
+      if (fieldno >= 0)
+        return TYPE_FIELD_TYPE (type, fieldno);
+
+      subfield_name = field_name;
+      while (*subfield_name != '\0' && *subfield_name != '.' 
+	     && (subfield_name[0] != '_' || subfield_name[1] != '_'))
+	subfield_name += 1;
+
+      if (subfield_name[0] == '\0')
+        return NULL;
+
+      fieldno = ada_nget_field_index (type, field_name,
+                                      subfield_name - field_name, 1);
+      if (fieldno < 0)
+        return NULL;
+
+      type = TYPE_FIELD_TYPE (type, fieldno);
+      field_name = subfield_name;
+    }
+
+  return NULL;
+}
 
 /* Look up NAME0 (an unencoded identifier or dotted name) in BLOCK (or 
    expression_block_context if NULL).  If it denotes a type, return
@@ -1252,14 +1330,21 @@ write_var_or_type (struct block *block, 
 
 	  if (type_sym != NULL)
 	    {
-	      struct type *type = SYMBOL_TYPE (type_sym);
-
-	      if (TYPE_CODE (type) == TYPE_CODE_VOID)
-		error (_("`%s' matches only void type name(s)"), name0.ptr);
-	      else if (tail_index == name_len)
-		return type;
+              struct type *field_type;
+              
+              if (tail_index == name_len)
+                return SYMBOL_TYPE (type_sym);
+
+              /* We have some extraneous characters after the type name.
+                 If this is an expression "TYPE_NAME.FIELD0.[...].FIELDN",
+                 then try to get the type of FIELDN.  */
+              field_type
+                = get_symbol_field_type (type_sym, encoded_name + tail_index);
+              if (field_type != NULL)
+                return field_type;
 	      else 
-		error (_("Invalid attempt to select from type: \"%s\"."), name0.ptr);
+		error (_("Invalid attempt to select from type: \"%s\"."),
+                       name0.ptr);
 	    }
 	  else if (tail_index == name_len && nsyms == 0)
 	    {

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Index: gdb.ada/ptype_field.exp
===================================================================
--- gdb.ada/ptype_field.exp	(revision 0)
+++ gdb.ada/ptype_field.exp	(revision 71)
@@ -0,0 +1,70 @@
+# Copyright 2008 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/>.
+
+if $tracelevel then {
+    strace $tracelevel
+}
+
+load_lib "ada.exp"
+
+set testdir "ptype_field"
+set testfile "${testdir}/foo"
+set srcfile ${srcdir}/${subdir}/${testfile}.adb
+set binfile ${objdir}/${subdir}/${testfile}
+
+file mkdir ${objdir}/${subdir}/${testdir}
+if {[gdb_compile_ada "${srcfile}" "${binfile}" executable [list debug additional_flags=-gnat05 ]] != "" } {
+  return -1
+}
+
+# A convenience function that joins all the arguments together,
+# with a regexp that matches zero-or-more end of lines in between
+# each argument.  This function is ideal to write the expected output
+# of a GDB command that generates more than a couple of lines, as
+# this allows us to write each line as a separate string, which is
+# easier to read by a human being.
+
+proc multi_line { args } {
+    return [join $args "\[\r\n\]*"]
+}
+
+gdb_exit
+gdb_start
+gdb_reinitialize_dir $srcdir/$subdir
+gdb_load ${binfile}
+
+set bp_location [gdb_get_line_number "STOP" ${testdir}/foo.adb]
+runto "foo.adb:$bp_location"
+
+gdb_test "ptype circle" \
+         [multi_line "type = record" \
+                     "    pos: pck\\.position;" \
+                     "    radius: integer;" \
+                     "end record" ] \
+         "ptype circle"
+
+gdb_test "ptype circle.pos" \
+         [multi_line "type = record" \
+                     "    x: integer;" \
+                     "    y: integer;" \
+                     "end record" ] \
+         "ptype circle.pos"
+
+gdb_test "ptype circle.pos.x" \
+         "type = <\[0-9\]+-byte integer>" \
+         "ptype circle.pos.x"
+
+
+
Index: gdb.ada/ptype_field/pck.adb
===================================================================
--- gdb.ada/ptype_field/pck.adb	(revision 0)
+++ gdb.ada/ptype_field/pck.adb	(revision 71)
@@ -0,0 +1,23 @@
+--  Copyright 2008 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/>.
+
+package body Pck is
+
+   procedure Do_Nothing (C : in out Circle) is
+   begin
+      null;
+   end Do_Nothing;
+
+end Pck;
Index: gdb.ada/ptype_field/pck.ads
===================================================================
--- gdb.ada/ptype_field/pck.ads	(revision 0)
+++ gdb.ada/ptype_field/pck.ads	(revision 71)
@@ -0,0 +1,30 @@
+--  Copyright 2008 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/>.
+
+package Pck is
+
+   type Position is record
+      X : Integer;
+      Y : Integer;
+   end record;
+
+   type Circle is record
+      Pos : Position;
+      Radius : Integer;
+   end record;
+
+   procedure Do_Nothing (C : in out Circle);
+
+end Pck;
Index: gdb.ada/ptype_field/foo.adb
===================================================================
--- gdb.ada/ptype_field/foo.adb	(revision 0)
+++ gdb.ada/ptype_field/foo.adb	(revision 71)
@@ -0,0 +1,22 @@
+--  Copyright 2008 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/>.
+
+with Pck; use Pck;
+
+procedure Foo is
+   My_Circle : Circle := (Pos => (1, 2), Radius => 3);
+begin
+   Do_Nothing (My_Circle);  -- STOP
+end Foo;