From 67c574736912003c377218153f9d3b9c0c96a17b Mon Sep 17 00:00:00 2001
From: nobu <nobu@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Mon, 31 Dec 2018 15:00:37 +0000
Subject: Method reference operator

Introduce the new operator for method reference, `.:`.
[Feature #12125] [Feature #13581]
[EXPERIMENTAL]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66667 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 parse.y | 28 +++++++++++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

(limited to 'parse.y')

diff --git a/parse.y b/parse.y
index 09afa6bedd..cf00b60b72 100644
--- a/parse.y
+++ b/parse.y
@@ -886,6 +886,7 @@ static void token_info_warn(struct parser_params *p, const char *token, token_in
 %token tRSHFT		RUBY_TOKEN(RSHFT)  ">>"
 %token <id> tANDDOT	RUBY_TOKEN(ANDDOT) "&."
 %token <id> tCOLON2	RUBY_TOKEN(COLON2) "::"
+%token <id> tMETHREF	RUBY_TOKEN(METHREF) ".:"
 %token tCOLON3		":: at EXPR_BEG"
 %token <id> tOP_ASGN	/* +=, -=  etc. */
 %token tASSOC		"=>"
@@ -2710,6 +2711,13 @@ primary		: literal
 		    /*% %*/
 		    /*% ripper: retry! %*/
 		    }
+		| primary_value tMETHREF operation2
+		    {
+		    /*%%%*/
+			$$ = NEW_METHREF($1, $3, &@$);
+		    /*% %*/
+		    /*% ripper: methref!($1, $3) %*/
+		    }
 		;
 
 primary_value	: primary
@@ -8060,12 +8068,30 @@ parser_yylex(struct parser_params *p)
 
       case '.':
 	SET_LEX_STATE(EXPR_BEG);
-	if ((c = nextc(p)) == '.') {
+	switch (c = nextc(p)) {
+	  case '.':
 	    if ((c = nextc(p)) == '.') {
 		return tDOT3;
 	    }
 	    pushback(p, c);
 	    return tDOT2;
+	  case ':':
+	    switch (c = nextc(p)) {
+	      default:
+		if (!parser_is_identchar(p)) break;
+		/* fallthru */
+	      case '!': case '%': case '&': case '*': case '+':
+	      case '-': case '/': case '<': case '=': case '>':
+	      case '[': case '^': case '`': case '|': case '~':
+		pushback(p, c);
+		SET_LEX_STATE(EXPR_DOT);
+		return tMETHREF;
+	      case -1:
+		break;
+	    }
+	    pushback(p, c);
+	    c = ':';
+	    break;
 	}
 	pushback(p, c);
 	if (c != -1 && ISDIGIT(c)) {
-- 
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