[PATCH] Parameterize the extraction of semantic values.

[Akim Demaille]

To make future changes easier, no longer rely on ".TYPE" being the
way to get a semantic value.

        * data/c.m4 (b4_symbol_value): New.
        Use it.
        * data/c++.m4, data/yacc.c: Use it.
        * data/glr.c: Use b4_symbol_value.
        (b4_rhs_data): New.
        Use it.
---
 ChangeLog   |   13 +++++++++++++
 data/c++.m4 |    5 +++--
 data/c.m4   |   17 ++++++++++++++++-
 data/glr.c  |   14 +++++++++++---
 data/yacc.c |    4 ++--
 5 files changed, 45 insertions(+), 8 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 8f7f37b..83ae569 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,18 @@
 2008-11-03  Akim Demaille  <address@hidden>
 
+       Parameterize the extraction of semantic values.
+       To make future changes easier, no longer rely on ".TYPE" being the
+       way to get a semantic value.
+       
+       * data/c.m4 (b4_symbol_value): New.
+       Use it.
+       * data/c++.m4, data/yacc.c: Use it.
+       * data/glr.c: Use b4_symbol_value.
+       (b4_rhs_data): New.
+       Use it.
+
+2008-11-03  Akim Demaille  <address@hidden>
+
        Prepare easier M4 changes.
        * data/lalr1.cc: Use escaped [] instead of literals to prepare
        future changes.
diff --git a/data/c++.m4 b/data/c++.m4
index 593390d..a896b77 100644
--- a/data/c++.m4
+++ b/data/c++.m4
@@ -102,7 +102,7 @@ m4_map_sep([     b4_token_enum], [,
 # --------------------
 # Expansion of $<TYPE>$.
 m4_define([b4_lhs_value],
-[(yyval[]m4_ifval([$1], [.$1]))])
+[b4_symbol_value([yyval], [$1])])
 
 
 # b4_rhs_value(RULE-LENGTH, NUM, [TYPE])
@@ -110,7 +110,8 @@ m4_define([b4_lhs_value],
 # Expansion of $<TYPE>NUM, where the current rule has RULE-LENGTH
 # symbols on RHS.
 m4_define([b4_rhs_value],
-[(address@hidden($1) - ($2)@}m4_ifval([$3], [.$3]))])
+[b4_symbol_value(address@hidden($1) - ($2)@}], [$3])])
+
 
 # b4_lhs_location()
 # -----------------
diff --git a/data/c.m4 b/data/c.m4
index 1fe4bc5..66d4f6d 100644
--- a/data/c.m4
+++ b/data/c.m4
@@ -205,6 +205,21 @@ m4_define([b4_token_enums_defines],
 ])
 
 
+## ----------------- ##
+## Semantic Values.  ##
+## ----------------- ##
+
+
+# b4_symbol_value(VAL, [TYPE])
+# ----------------------------
+# Given a semantic value VAL ($$, $1 etc.), extract its value of type
+# TYPE if TYPE is given, otherwise just return VAL.  The result can be
+# used safetly, it is put in parens to avoid nasty precedence issues.
+# TYPE is *not* put in braces, provide some if needed.
+m4_define([b4_symbol_value],
+[($1[]m4_ifval([$2], [.$2]))])
+
+
 
 ## --------------------------------------------- ##
 ## Defining C functions in both K&R and ANSI-C.  ##
@@ -360,7 +375,7 @@ $2
 # -------------------------------------------------
 m4_define([b4_symbol_actions],
 [m4_pushdef([b4_dollar_dollar],
-   [m4_ifval([$6], [(yyvaluep->$6)], [(*yyvaluep)])])dnl
+   [b4_symbol_value([(*yyvaluep)], [$6])])dnl
 m4_pushdef([b4_at_dollar], [(*yylocationp)])dnl
       case $4: /* $3 */
 b4_syncline([$2], [$1])
diff --git a/data/glr.c b/data/glr.c
index c6de6d8..67c2f85 100644
--- a/data/glr.c
+++ b/data/glr.c
@@ -109,7 +109,15 @@ m4_define([b4_pure_formals],
 # --------------------
 # Expansion of $<TYPE>$.
 m4_define([b4_lhs_value],
-[((*yyvalp)[]m4_ifval([$1], [.$1]))])
+[b4_symbol_value([(*yyvalp)], [$1])])
+
+
+# b4_rhs_data(RULE-LENGTH, NUM)
+# -----------------------------
+# Expand to the semantic stack place that contains value and location
+# of symbol number NUM in a rule of length RULE-LENGTH.
+m4_define([b4_rhs_data],
+[((yyGLRStackItem const *)yyvsp)@{YYFILL (($2) - ($1))@}.yystate])
 
 
 # b4_rhs_value(RULE-LENGTH, NUM, [TYPE])
@@ -117,7 +125,7 @@ m4_define([b4_lhs_value],
 # Expansion of $<TYPE>NUM, where the current rule has RULE-LENGTH
 # symbols on RHS.
 m4_define([b4_rhs_value],
-[(((yyGLRStackItem const *)yyvsp)@{YYFILL (($2) - 
($1))@}.yystate.yysemantics.yysval[]m4_ifval([$3], [.$3]))])
+[b4_symbol_value([b4_rhs_data([$1], [$2]).yysemantics.yysval], [$3])])
 
 
 
@@ -137,7 +145,7 @@ m4_define([b4_lhs_location],
 # Expansion of @NUM, where the current rule has RULE-LENGTH symbols
 # on RHS.
 m4_define([b4_rhs_location],
-[(((yyGLRStackItem const *)yyvsp)@{YYFILL (($2) - ($1))@}.yystate.yyloc)])
+[(b4_rhs_data([$1], [$2]).yyloc)])
 
 
 
diff --git a/data/yacc.c b/data/yacc.c
index 19f77a5..9f54c3a 100644
--- a/data/yacc.c
+++ b/data/yacc.c
@@ -114,7 +114,7 @@ m4_define([b4_int_type],
 # --------------------
 # Expansion of $<TYPE>$.
 m4_define([b4_lhs_value],
-[(yyval[]m4_ifval([$1], [.$1]))])
+[b4_symbol_value(yyval, [$1])])
 
 
 # b4_rhs_value(RULE-LENGTH, NUM, [TYPE])
@@ -122,7 +122,7 @@ m4_define([b4_lhs_value],
 # Expansion of $<TYPE>NUM, where the current rule has RULE-LENGTH
 # symbols on RHS.
 m4_define([b4_rhs_value],
-[(address@hidden($2) - ($1)@}m4_ifval([$3], [.$3]))])
+[b4_symbol_value(address@hidden($2) - ($1)@}], [$3])])
 
 
 
-- 
1.6.0.2.588.g3102