[PATCH 6/9] parser: no longer use the "braceless" non-terminal

[Akim Demaille]

The purpose of this symbol was only to factor function calls.  As a
result the actions were indeed simpler, but the grammar was somewhat
uselessly obfuscated.  Get rid of this symbol, but introduce functions
to simplify dependencies.

There is no (intended) changes of behavior here.

* src/parse-gram.y (strip_braces, translate_code(
(translate_code_braceless): New.
(braceless): Remove, use "{...}" instead, and one of the previous
functions depending on the context.
(STRING, "%{...%}", EPILOGUE): Declare as <code>, instead of <chars>,
the difference between both is useless (well, I couldn't make sense of
it, even after having read the initial commit that introduced them).
(%union): Remove the now useless "chars" type.
Adjust the printers.
* src/scan-gram.l: Adjust.
---
 src/parse-gram.y | 117 +++++++++++++++++++++++++++++--------------------------
 src/scan-gram.l  |   6 +--
 2 files changed, 65 insertions(+), 58 deletions(-)

diff --git a/src/parse-gram.y b/src/parse-gram.y
index 8b57ce8..4c87c90 100644
--- a/src/parse-gram.y
+++ b/src/parse-gram.y
@@ -60,6 +60,22 @@
   #define YY_LOCATION_PRINT(File, Loc)            \
     location_print (Loc, File)
 
+  /* Strip initial '{' and final '}' (must be first and last characters).
+     Return the result.  */
+  static char *strip_braces (char *code);
+
+  /* Convert CODE by calling code_props_plain_init if PLAIN, otherwise
+     code_props_symbol_action_init.  Call
+     gram_scanner_last_string_free to release the latest string from
+     the scanner (should be CODE). */
+  static char const *translate_code (char *code, location loc, bool plain);
+
+  /* Convert CODE by calling code_props_plain_init after having
+     stripped the first and last characters (expected to be '{', and
+     '}').  Call gram_scanner_last_string_free to release the latest
+     string from the scanner (should be CODE). */
+  static char const *translate_code_braceless (char *code, location loc);
+
   static void version_check (location const *loc, char const *version);
 
   static void gram_error (location const *, char const *);
@@ -162,19 +178,10 @@
 %type <character> CHAR
 %printer { fputs (char_name ($$), yyo); } CHAR
 
-/* braceless is not to be used for rule or symbol actions, as it
-   calls code_props_plain_init.  */
-%union
-{
-  char *code;
-  char const *chars;
-};
-%type <chars> STRING "%{...%}" EPILOGUE braceless
-%type <code> "{...}" "%?{...}"
-%printer { fputs (quotearg_style (c_quoting_style, $$), yyo); }
-         STRING
-%printer { fprintf (yyo, "{\n%s\n}", $$); }
-         braceless "{...}" "%{...%}" EPILOGUE
+%union {char *code;};
+%type <code> "{...}" "%?{...}" "%{...%}" EPILOGUE STRING
+%printer { fputs (quotearg_style (c_quoting_style, $$), yyo); } STRING
+%printer { fprintf (yyo, "{\n%s\n}", $$); } <code>
 
 %union {uniqstr uniqstr;}
 %type <uniqstr> BRACKETED_ID ID ID_COLON PERCENT_FLAG TAG tag variable
@@ -266,12 +273,8 @@ prologue_declaration:
   grammar_declaration
 | "%{...%}"
     {
-      code_props plain_code;
-      code_props_plain_init (&plain_code, $1, @1);
-      code_props_translate_code (&plain_code);
-      gram_scanner_last_string_free ();
       muscle_code_grow (union_seen ? "post_prologue" : "pre_prologue",
-                        plain_code.code, @1);
+                        translate_code ($1, @1, true), @1);
       code_scanner_last_string_free ();
     }
 | "%<flag>"
@@ -305,11 +308,7 @@ prologue_declaration:
     }
 | "%initial-action" "{...}"
     {
-      code_props action;
-      code_props_symbol_action_init (&action, $2, @2);
-      code_props_translate_code (&action);
-      gram_scanner_last_string_free ();
-      muscle_code_grow ("initial_action", action.code, @2);
+      muscle_code_grow ("initial_action", translate_code ($2, @2, false), @2);
       code_scanner_last_string_free ();
     }
 | "%language" STRING            { language_argmatch ($2, grammar_prio, @1); }
@@ -386,16 +385,17 @@ grammar_declaration:
     {
       default_prec = false;
     }
-| "%code" braceless
+| "%code" "{...}"
     {
       /* Do not invoke muscle_percent_code_grow here since it invokes
          muscle_user_name_list_grow.  */
-      muscle_code_grow ("percent_code()", $2, @2);
+      muscle_code_grow ("percent_code()",
+                        translate_code_braceless ($2, @2), @2);
       code_scanner_last_string_free ();
     }
-| "%code" ID braceless
+| "%code" ID "{...}"
     {
-      muscle_percent_code_grow ($2, @2, $3, @3);
+      muscle_percent_code_grow ($2, @2, translate_code_braceless ($3, @3), @3);
       code_scanner_last_string_free ();
     }
 ;
@@ -420,10 +420,10 @@ union_name:
 ;
 
 grammar_declaration:
-  "%union" union_name braceless
+  "%union" union_name "{...}"
     {
       union_seen = true;
-      muscle_code_grow ("union_members", $3, @3);
+      muscle_code_grow ("union_members", translate_code_braceless ($3, @3), 
@3);
       code_scanner_last_string_free ();
     }
 ;
@@ -658,27 +658,11 @@ variable:
 } <value>;
 
 value:
-  %empty    { $$.kind = muscle_keyword; $$.chars = ""; }
-| ID        { $$.kind = muscle_keyword; $$.chars = $1; }
-| STRING    { $$.kind = muscle_string;  $$.chars = $1; }
-| braceless { $$.kind = muscle_code;    $$.chars = $1; }
-;
-
-
-/*------------.
-| braceless.  |
-`------------*/
-
-braceless:
-  "{...}"
-    {
-      code_props plain_code;
-      $1[strlen ($1) - 1] = '\0';
-      code_props_plain_init (&plain_code, $1+1, @1);
-      code_props_translate_code (&plain_code);
-      gram_scanner_last_string_free ();
-      $$ = plain_code.code;
-    }
+  %empty  { $$.kind = muscle_keyword; $$.chars = ""; }
+| ID      { $$.kind = muscle_keyword; $$.chars = $1; }
+| STRING  { $$.kind = muscle_string;  $$.chars = $1; }
+| "{...}" { $$.kind = muscle_code;
+            $$.chars = translate_code_braceless ($1, @1); }
 ;
 
 
@@ -723,11 +707,7 @@ epilogue.opt:
   %empty
 | "%%" EPILOGUE
     {
-      code_props plain_code;
-      code_props_plain_init (&plain_code, $2, @2);
-      code_props_translate_code (&plain_code);
-      gram_scanner_last_string_free ();
-      muscle_code_grow ("epilogue", plain_code.code, @2);
+      muscle_code_grow ("epilogue", translate_code ($2, @2, true), @2);
       code_scanner_last_string_free ();
     }
 ;
@@ -763,6 +743,33 @@ lloc_default (YYLTYPE const *rhs, int n)
   return loc;
 }
 
+static
+char *strip_braces (char *code)
+{
+  code[strlen(code) - 1] = 0;
+  return code + 1;
+}
+
+static
+char const *
+translate_code (char *code, location loc, bool plain)
+{
+  code_props plain_code;
+  if (plain)
+    code_props_plain_init (&plain_code, code, loc);
+  else
+    code_props_symbol_action_init (&plain_code, code, loc);
+  code_props_translate_code (&plain_code);
+  gram_scanner_last_string_free ();
+  return plain_code.code;
+}
+
+static
+char const *
+translate_code_braceless (char *code, location loc)
+{
+  return translate_code (strip_braces (code), loc, true);
+}
 
 static void
 add_param (param_type type, char *decl, location loc)
diff --git a/src/scan-gram.l b/src/scan-gram.l
index cf8b220..665e80d 100644
--- a/src/scan-gram.l
+++ b/src/scan-gram.l
@@ -512,7 +512,7 @@ eqopt    ([[:space:]]*=)?
   "\"" {
     STRING_FINISH;
     loc->start = token_start;
-    val->chars = last_string;
+    val->code = last_string;
     BEGIN INITIAL;
     return STRING;
   }
@@ -751,7 +751,7 @@ eqopt    ([[:space:]]*=)?
   "%}" {
     STRING_FINISH;
     loc->start = code_start;
-    val->chars = last_string;
+    val->code = last_string;
     BEGIN INITIAL;
     return PROLOGUE;
   }
@@ -770,7 +770,7 @@ eqopt    ([[:space:]]*=)?
   <<EOF>> {
     STRING_FINISH;
     loc->start = code_start;
-    val->chars = last_string;
+    val->code = last_string;
     BEGIN INITIAL;
     return EPILOGUE;
   }
-- 
1.8.2.1