From b3ce5dedcbcdaf6baa99de2ee9efa5a8d38e74ab Mon Sep 17 00:00:00 2001
From: "s.kamardin" <s.kamardin@corp.mail.ru>
Date: Wed, 13 Jan 2016 20:13:11 +0300
Subject: [PATCH] Optimize compilation

---
 compiler.go      | 60 ++++++++++++++++++++++++++++--------------------
 compiler_test.go |  5 ++--
 glob_test.go     |  8 +++----
 3 files changed, 41 insertions(+), 32 deletions(-)

diff --git a/compiler.go b/compiler.go
index e8aaf64..dea1839 100644
--- a/compiler.go
+++ b/compiler.go
@@ -89,11 +89,8 @@ func glueMatchers(matchers []match.Matcher) match.Matcher {
 }
 
 func glueAsRow(matchers []match.Matcher) match.Matcher {
-	switch len(matchers) {
-	case 0:
+	if len(matchers) <= 1 {
 		return nil
-	case 1:
-		return matchers[0]
 	}
 
 	row := match.Row{}
@@ -108,11 +105,8 @@ func glueAsRow(matchers []match.Matcher) match.Matcher {
 }
 
 func glueAsEvery(matchers []match.Matcher) match.Matcher {
-	switch len(matchers) {
-	case 0:
+	if len(matchers) <= 1 {
 		return nil
-	case 1:
-		return matchers[0]
 	}
 
 	var (
@@ -193,25 +187,37 @@ func glueAsEvery(matchers []match.Matcher) match.Matcher {
 	return every
 }
 
-func convertMatchers(matchers []match.Matcher, result []match.Matcher) []match.Matcher {
-	var (
-		buf  []match.Matcher
-		done match.Matcher
-	)
-	for idx, m := range matchers {
-		buf = append(buf, m)
-		if g := glueMatchers(buf); g != nil {
-			done = g
-		} else {
-			return convertMatchers(matchers[idx:], append(result, done))
+func convertMatchers(matchers []match.Matcher) []match.Matcher {
+	var done match.Matcher
+	var left, right, count int
+
+	for l := 0; l < len(matchers); l++ {
+		for r := len(matchers); r > l; r-- {
+			if glued := glueMatchers(matchers[l:r]); glued != nil {
+				if done == nil || count < r-l {
+					done = glued
+					left = l
+					right = r
+					count = r - l
+				}
+			}
 		}
 	}
 
-	if done != nil {
-		return append(result, done)
+	if done == nil {
+		return matchers
 	}
 
-	return result
+	next := append(append([]match.Matcher{}, matchers[:left]...), done)
+	if right < len(matchers) {
+		next = append(next, matchers[right:]...)
+	}
+
+	if len(next) == len(matchers) {
+		return next
+	}
+
+	return convertMatchers(next)
 }
 
 func compileMatchers(matchers []match.Matcher) (match.Matcher, error) {
@@ -219,6 +225,10 @@ func compileMatchers(matchers []match.Matcher) (match.Matcher, error) {
 		return nil, fmt.Errorf("compile error: need at least one matcher")
 	}
 
+	if len(matchers) == 1 {
+		return matchers[0], nil
+	}
+
 	if m := glueMatchers(matchers); m != nil {
 		return m, nil
 	}
@@ -285,7 +295,7 @@ func do(node node, s string) (m match.Matcher, err error) {
 		if _, ok := node.(*nodeAnyOf); ok {
 			m = match.AnyOf{matchers}
 		} else {
-			m, err = compileMatchers(convertMatchers(matchers, nil))
+			m, err = compileMatchers(convertMatchers(matchers))
 			if err != nil {
 				return nil, err
 			}
@@ -349,7 +359,7 @@ func do2(node node, s string) ([]match.Matcher, error) {
 		}
 
 		for _, matchers := range ways {
-			c, err := compileMatchers(convertMatchers(matchers, nil))
+			c, err := compileMatchers(convertMatchers(matchers))
 			if err != nil {
 				return nil, err
 			}
@@ -383,7 +393,7 @@ func do2(node node, s string) ([]match.Matcher, error) {
 		}
 
 		for _, matchers := range ways {
-			c, err := compileMatchers(convertMatchers(matchers, nil))
+			c, err := compileMatchers(convertMatchers(matchers))
 			if err != nil {
 				return nil, err
 			}
diff --git a/compiler_test.go b/compiler_test.go
index 94e8101..3b56b43 100644
--- a/compiler_test.go
+++ b/compiler_test.go
@@ -162,13 +162,12 @@ func TestConvertMatchers(t *testing.T) {
 					match.Range{'a', 'c', true},
 					match.List{"zte", false},
 					match.Raw{"c"},
-					match.Single{},
 				}},
-				match.Min{2},
+				match.Min{3},
 			},
 		},
 	} {
-		act := convertMatchers(test.in, nil)
+		act := convertMatchers(test.in)
 		if !reflect.DeepEqual(act, test.exp) {
 			t.Errorf("#%d unexpected convert matchers 2 result:\nact: %s;\nexp: %s", id, act, test.exp)
 			continue
diff --git a/glob_test.go b/glob_test.go
index 7f2cdff..be3015d 100644
--- a/glob_test.go
+++ b/glob_test.go
@@ -81,10 +81,10 @@ func TestCompilePattern(t *testing.T) {
 		sep     string
 		exp     match.Matcher
 	}{
-	//		{
-	//			pattern: "left*??B*abcd*[!b]??*abc*right",
-	//			exp:     match.Raw{"t"},
-	//		},
+	//			{
+	//				pattern: "left*??B*abcd*[!b]??*abc*right",
+	//				exp:     match.Raw{"t"},
+	//			},
 	//		{
 	//			pattern: "abc*??def",
 	//			exp:     match.Raw{"t"},