From 457c2c4a55b5896b30510ff8b39256b61b46cdf4 Mon Sep 17 00:00:00 2001
From: mame <mame@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Wed, 17 Feb 2010 12:36:41 +0000
Subject: [PATCH] * regcomp.c (setup_tree, onig_compile): optimize .* at last
 by   converting into (?>.*), which does not backtrack.  [ruby-core:27791]

* test/ruby/test_regexp.rb: add a test for above.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@26701 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 ChangeLog                |  7 +++++++
 regcomp.c                | 20 ++++++++++++++++++--
 test/ruby/test_regexp.rb |  7 +++++++
 3 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index d7efba55dd..932976b16a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+Wed Feb 17 21:34:01 2010  Yusuke Endoh  <mame@tsg.ne.jp>
+
+	* regcomp.c (setup_tree, onig_compile): optimize .* at last by
+	  converting into (?>.*), which does not backtrack.  [ruby-core:27791]
+
+	* test/ruby/test_regexp.rb: add a test for above.
+
 Wed Feb 17 21:26:53 2010  Tanaka Akira  <akr@fsij.org>
 
 	* bootstraptest/runner.rb (assert_normal_exit): add :timeout option.
diff --git a/regcomp.c b/regcomp.c
index e1ac7ee85c..16c816b1f7 100644
--- a/regcomp.c
+++ b/regcomp.c
@@ -3643,6 +3643,7 @@ setup_comb_exp_check(Node* node, int state, ScanEnv* env)
 #define IN_NOT        (1<<1)
 #define IN_REPEAT     (1<<2)
 #define IN_VAR_REPEAT (1<<3)
+#define IN_LAST	      (1<<4)
 
 /* setup_tree does the following work.
  1. check empty loop. (set qn->target_empty_info)
@@ -3664,7 +3665,8 @@ setup_tree(Node* node, regex_t* reg, int state, ScanEnv* env)
     {
       Node* prev = NULL_NODE;
       do {
-	r = setup_tree(NCAR(node), reg, state, env);
+	int s = IS_NOT_NULL(NCDR(node)) ? (state & ~IN_LAST) : state;
+	r = setup_tree(NCAR(node), reg, s, env);
 	if (IS_NOT_NULL(prev) && r == 0) {
 	  r = next_setup(prev, NCAR(node), reg);
 	}
@@ -3795,6 +3797,20 @@ setup_tree(Node* node, regex_t* reg, int state, ScanEnv* env)
 	}
       }
 #endif
+
+      if ((state & IN_LAST) != 0 && qn->greedy && IS_REPEAT_INFINITE(qn->upper)) {
+	/* automatic posseivation a* (at last) ==> (?>a*) */
+	if (qn->lower <= 1) {
+	  int ttype = NTYPE(qn->target);
+	  if (IS_NODE_TYPE_SIMPLE(ttype)) {
+	    Node* en = onig_node_new_enclose(ENCLOSE_STOP_BACKTRACK);
+	    CHECK_NULL_RETURN_MEMERR(en);
+	    SET_ENCLOSE_STATUS(en, NST_STOP_BT_SIMPLE_REPEAT);
+	    swap_node(node, en);
+	    NENCLOSE(node)->target = en;
+	  }
+	}
+      }
     }
     break;
 
@@ -5423,7 +5439,7 @@ onig_compile(regex_t* reg, const UChar* pattern, const UChar* pattern_end,
     reg->num_call = 0;
 #endif
 
-  r = setup_tree(root, reg, 0, &scan_env);
+  r = setup_tree(root, reg, IN_LAST, &scan_env);
   if (r != 0) goto err_unset;
 
 #ifdef ONIG_DEBUG_PARSE_TREE
diff --git a/test/ruby/test_regexp.rb b/test/ruby/test_regexp.rb
index 4cd35d5248..06c6d1c633 100644
--- a/test/ruby/test_regexp.rb
+++ b/test/ruby/test_regexp.rb
@@ -800,4 +800,11 @@ class TestRegexp < Test::Unit::TestCase
     assert_nothing_raised { eval("a = 1; /\#{ a }/; a") }
     assert_nothing_raised { eval("a = 1; /\#{ a }/o; a") }
   end
+
+  def test_optimize_last_anycharstar
+    s = "1" + " " * 5000000
+    assert_nothing_raised { s.match(/(\d) (.*)/) }
+    assert_equal("1", $1)
+    assert_equal(" " * 4999999, $2)
+  end
 end