From: Tanaka Akira <akr@...>
Date: 2007-12-14T08:38:56+09:00
Subject: [ruby-dev:32588] /(?<foo>...)/ =~ str assigns foo

以下のように named capture の結果を自動的に変数に代入させた
いのですがどうでしょうか。

% ./ruby -e '
/(?<word>\w+)/ =~ "  foo   "
p word
'
"foo"

代入が起こる条件は、named capture を含み、#{} などによる動的
な展開の含まれていない正規表現が =~ の左辺にリテラルとして表
れたとき、です。

なお、マッチしなかった場合は nil を代入するようにしています。

Index: parse.y
===================================================================
--- parse.y	(revision 14215)
+++ parse.y	(working copy)
@@ -442,6 +442,8 @@ static void reg_fragment_setenc_gen(stru
 #define reg_fragment_setenc(str,options) reg_fragment_setenc_gen(parser, str, options)
 static void reg_fragment_check_gen(struct parser_params*, VALUE, int);
 #define reg_fragment_check(str,options) reg_fragment_check_gen(parser, str, options)
+static NODE *reg_named_capture_assign_gen(struct parser_params* parser, VALUE regexp, NODE *match);
+#define reg_named_capture_assign(regexp,match) reg_named_capture_assign_gen(parser,regexp,match)
 #else
 #define remove_begin(node) (node)
 #endif /* !RIPPER */
@@ -2127,6 +2129,9 @@ arg		: lhs '=' arg
 		    {
 		    /*%%%*/
 			$$ = match_op($1, $3);
+                        if (nd_type($1) == NODE_LIT && TYPE($1->nd_lit) == T_REGEXP) {
+                            $$ = reg_named_capture_assign($1->nd_lit, $$);
+                        }
 		    /*%
 			$$ = dispatch3(binary, $1, ripper_intern("=~"), $3);
 		    %*/
@@ -8450,6 +8455,73 @@ reg_fragment_check_gen(struct parser_par
     }
 }
 
+typedef struct {
+    struct parser_params* parser;
+    rb_encoding *enc;
+    NODE *succ_block;
+    NODE *fail_block;
+    int num;
+} reg_named_capture_assign_t;
+
+static int
+reg_named_capture_assign_iter(const OnigUChar *name, const OnigUChar *name_end,
+          int back_num, int *back_refs, OnigRegex regex, void *arg0)
+{
+    reg_named_capture_assign_t *arg = (reg_named_capture_assign_t*)arg0;
+    struct parser_params* parser = arg->parser;
+
+    arg->num++;
+
+    if (arg->succ_block == 0) {
+        arg->succ_block = NEW_BEGIN(0);
+        arg->fail_block = NEW_BEGIN(0);
+    }
+
+    ID var = rb_intern3((const char *)name, name_end-name, arg->enc);
+    arg->succ_block = block_append(arg->succ_block,
+        newline_node(node_assign(assignable(var,0),
+            NEW_CALL(
+              gettable(rb_intern("$~")),
+              rb_intern("[]"),
+              NEW_LIST(NEW_LIT(ID2SYM(var))))
+            )));
+    arg->fail_block = block_append(arg->fail_block,
+        newline_node(node_assign(assignable(var,0), NEW_LIT(Qnil))));
+    return 0;
+}
+
+static NODE *
+reg_named_capture_assign_gen(struct parser_params* parser, VALUE regexp, NODE *match)
+{
+    reg_named_capture_assign_t arg;
+
+    arg.parser = parser;
+    arg.enc = rb_enc_get(regexp);
+    arg.succ_block = 0;
+    arg.fail_block = 0;
+    arg.num = 0;
+    onig_foreach_name(RREGEXP(regexp)->ptr, reg_named_capture_assign_iter, (void*)&arg);
+
+    if (arg.num == 0)
+        return match;
+
+    return 
+        block_append(
+            newline_node(match),
+            NEW_IF(gettable(rb_intern("$~")),
+                block_append(
+                    newline_node(arg.succ_block),
+                    newline_node(
+                        NEW_CALL(
+                          gettable(rb_intern("$~")),
+                          rb_intern("begin"),
+                          NEW_LIST(NEW_LIT(INT2FIX(0)))))),
+                block_append(
+                    newline_node(arg.fail_block),
+                    newline_node(
+                        NEW_LIT(Qnil)))));
+}
+
 static VALUE
 reg_compile_gen(struct parser_params* parser, VALUE str, int options)
 {
-- 
[田中 哲][たなか あきら][Tanaka Akira]