* parse.y (arg tMATCH arg): call reg_named_capture_assign_gen if regexp

  literal is used.
  (reg_named_capture_assign_gen): assign the result of named capture
  into local variables.
  [ruby-dev:32588]

* re.c: document the assignment by named captures.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@14297 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

4 files changed, 130 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index 73001cd73a..5d166abc79 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+Tue Dec 18 20:22:44 2007  Tanaka Akira  <akr@fsij.org>
+
+	* parse.y (arg tMATCH arg): call reg_named_capture_assign_gen if regexp
+	  literal is used.
+	  (reg_named_capture_assign_gen): assign the result of named capture
+	  into local variables.
+	  [ruby-dev:32588]
+
+	* re.c: document the assignment by named captures.
+
 Tue Dec 18 18:09:15 2007  Yukihiro Matsumoto  <matz@ruby-lang.org>
 
 	* string.c (rb_str_splice): propagate encoding.
diff --git a/parse.y b/parse.y
index 85e2852659..0f09464558 100644
--- a/parse.y
+++ b/parse.y
@@ -21,6 +21,7 @@
 #include "ruby/node.h"
 #include "ruby/st.h"
 #include "ruby/encoding.h"
+#include "id.h"
 #include "regenc.h"
 #include <stdio.h>
 #include <errno.h>
@@ -442,6 +443,8 @@ static void reg_fragment_setenc_gen(struct parser_params*, VALUE, int);
 #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 +2130,9 @@ 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);
 		    %*/
@@ -8474,6 +8480,82 @@ reg_fragment_check_gen(struct parser_params* parser, VALUE str, int options)
     }
 }
 
+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);
+    if (!is_local_id(var)) {
+        compile_error(PARSER_ARG "named capture with a non local variable - %s",
+                      rb_id2name(var));
+        return ST_CONTINUE;
+    }
+    if (dvar_defined(var) || local_id(var)) {
+        rb_warningS("named capture conflicts a local variable - %s", 
+                    rb_id2name(var));
+    }
+    arg->succ_block = block_append(arg->succ_block,
+        newline_node(node_assign(assignable(var,0),
+            NEW_CALL(
+              gettable(rb_intern("$~")),
+              idAREF,
+              NEW_LIST(NEW_LIT(ID2SYM(var))))
+            )));
+    arg->fail_block = block_append(arg->fail_block,
+        newline_node(node_assign(assignable(var,0), NEW_LIT(Qnil))));
+    return ST_CONTINUE;
+}
+
+static NODE *
+reg_named_capture_assign_gen(struct parser_params* parser, VALUE regexp, NODE *match)
+{
+    reg_named_capture_assign_t arg;
+
+    arg.parser = parser;
+    arg.enc = rb_enc_get(regexp);
+    arg.succ_block = 0;
+    arg.fail_block = 0;
+    arg.num = 0;
+    onig_foreach_name(RREGEXP(regexp)->ptr, reg_named_capture_assign_iter, (void*)&arg);
+
+    if (arg.num == 0)
+        return match;
+
+    return 
+        block_append(
+            newline_node(match),
+            NEW_IF(gettable(rb_intern("$~")),
+                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)
 {
diff --git a/re.c b/re.c
index a8774237af..55037856ed 100644
--- a/re.c
+++ b/re.c
@@ -2164,6 +2164,37 @@ reg_match_pos(VALUE re, VALUE *strp, long pos)
  *
  *     /at/ =~ "input data"   #=> 7
  *     /ax/ =~ "input data"   #=> nil
+ *
+ *  If <code>=~</code> is used with a regexp literal with named captures,
+ *  captured strings (or nil) is assigned to local variables named by
+ *  the capture names.
+ *
+ *     /(?<lhs>\w+)\s*=\s*(?<rhs>\w+)/ =~ "  x = y  "
+ *     p lhs    #=> "x"
+ *     p rhs    #=> "y"
+ *
+ *  If it is not matched, nil is assigned for the variables.
+ *
+ *     /(?<lhs>\w+)\s*=\s*(?<rhs>\w+)/ =~ "  x = "   
+ *     p lhs    #=> nil
+ *     p rhs    #=> nil
+ *
+ *  This assignment is implemented in the Ruby parser.
+ *  So a regexp literal is required for the assignment. 
+ *  The assignment is not occur if the regexp is not a literal.
+ *
+ *     re = /(?<lhs>\w+)\s*=\s*(?<rhs>\w+)/
+ *     re =~ "  x = "
+ *     p lhs    # undefined local variable
+ *     p rhs    # undefined local variable
+ *
+ *  A regexp interpolation, <code>#{}</code>, also disables
+ *  the assignment.
+ *
+ *     rhs_pat = /(?<rhs>\w+)/
+ *     /(?<lhs>\w+)\s*=\s*#{rhs_pat}/ =~ "x = y"
+ *     p lhs    # undefined local variable
+ *
  */
 
 VALUE
diff --git a/test/ruby/test_regexp.rb b/test/ruby/test_regexp.rb
index 5cb6c810da..b415c03aa1 100644
--- a/test/ruby/test_regexp.rb
+++ b/test/ruby/test_regexp.rb
@@ -95,6 +95,13 @@ class TestRegexp < Test::Unit::TestCase
     assert_equal({}, /(.)(.)/.named_captures)
   end
 
+  def test_assign_named_capture
+    assert_equal("a", eval('/(?<foo>.)/ =~ "a"; foo'))
+    assert_equal("a", eval('foo = 1; /(?<foo>.)/ =~ "a"; foo'))
+    assert_equal("a", eval('1.times {|foo| /(?<foo>.)/ =~ "a"; break foo }'))
+    assert_raise(SyntaxError) { eval('/(?<Foo>.)/ =~ "a"') }
+  end
+
   def test_match_regexp
     r = /./
     m = r.match("a")