go/doc: Fix URL linking in ToHTML.

Fixes issue: 2832

R=rsc, gri
CC=golang-dev
https://golang.org/cl/5616060

src/pkg/go/doc/comment.go

@@ -56,7 +56,7 @@ const (
 		filePart + `([:.,]` + filePart + `)*`
 )
 
-var matchRx = regexp.MustCompile(`(` + identRx + `)|(` + urlRx + `)`)
+var matchRx = regexp.MustCompile(`(` + urlRx + `)|(` + identRx + `)`)
 
 var (
 	html_a      = []byte(`<a href="`)
@@ -87,7 +87,7 @@ func emphasize(w io.Writer, line string, words map[string]string, nice bool) {
 		if m == nil {
 			break
 		}
-		// m >= 6 (two parenthesized sub-regexps in matchRx, 1st one is identRx)
+		// m >= 6 (two parenthesized sub-regexps in matchRx, 1st one is urlRx)
 
 		// write text before match
 		commentEscape(w, line[0:m[0]], nice)
@@ -99,8 +99,8 @@ func emphasize(w io.Writer, line string, words map[string]string, nice bool) {
 		if words != nil {
 			url, italics = words[string(match)]
 		}
-		if m[2] < 0 {
-			// didn't match against first parenthesized sub-regexp; must be match against urlRx
+		if m[2] >= 0 {
+			// match against first parenthesized sub-regexp; must be match against urlRx
 			if !italics {
 				// no alternative URL in words list, use match instead
 				url = string(match)

src/pkg/go/doc/comment_test.go

@@ -5,6 +5,7 @@
 package doc
 
 import (
+	"bytes"
 	"reflect"
 	"testing"
 )
@@ -81,3 +82,28 @@ func TestBlocks(t *testing.T) {
 		}
 	}
 }
+
+var emphasizeTests = []struct {
+	in  string
+	out string
+}{
+	{"http://www.google.com/", `<a href="http://www.google.com/">http://www.google.com/</a>`},
+	{"https://www.google.com/", `<a href="https://www.google.com/">https://www.google.com/</a>`},
+	{"http://www.google.com/path.", `<a href="http://www.google.com/path">http://www.google.com/path</a>.`},
+	{"(http://www.google.com/)", `(<a href="http://www.google.com/">http://www.google.com/</a>)`},
+	{"Foo bar http://example.com/ quux!", `Foo bar <a href="http://example.com/">http://example.com/</a> quux!`},
+	{"Hello http://example.com/%2f/ /world.", `Hello <a href="http://example.com/%2f/">http://example.com/%2f/</a> /world.`},
+	{"Lorem http: ipsum //host/path", "Lorem http: ipsum //host/path"},
+	{"javascript://is/not/linked", "javascript://is/not/linked"},
+}
+
+func TestEmphasize(t *testing.T) {
+	for i, tt := range emphasizeTests {
+		var buf bytes.Buffer
+		emphasize(&buf, tt.in, nil, true)
+		out := buf.String()
+		if out != tt.out {
+			t.Errorf("#%d: mismatch\nhave: %v\nwant: %v", i, out, tt.out)
+		}
+	}
+}