Update ANSI processor to handle more VT-100 escape sequences

The updated regular expression should include not all but most of the
frequently used ANSI sequences. Close #735.

src/ansi.go

@@ -35,7 +35,16 @@ func (s *ansiState) equals(t *ansiState) bool {
 var ansiRegex *regexp.Regexp
 
 func init() {
-	ansiRegex = regexp.MustCompile("\x1b\\[[0-9;]*.|[\x0e\x0f]")
+	/*
+		References:
+		- https://github.com/gnachman/iTerm2
+		- http://ascii-table.com/ansi-escape-sequences.php
+		- http://ascii-table.com/ansi-escape-sequences-vt-100.php
+		- http://tldp.org/HOWTO/Bash-Prompt-HOWTO/x405.html
+	*/
+	// The following regular expression will include not all but most of the
+	// frequently used ANSI sequences
+	ansiRegex = regexp.MustCompile("\x1b[\\[()][0-9;]*[a-zA-Z@]|\x1b.|[\x08\x0e\x0f]")
 }
 
 func extractColor(str string, state *ansiState, proc func(string, *ansiState) bool) (string, *[]ansiOffset, *ansiState) {
@@ -100,7 +109,7 @@ func interpretCode(ansiCode string, prevState *ansiState) *ansiState {
 	} else {
 		state = &ansiState{prevState.fg, prevState.bg, prevState.attr}
 	}
-	if ansiCode[0] != '\x1b' || ansiCode[len(ansiCode)-1] != 'm' {
+	if ansiCode[0] != '\x1b' || ansiCode[1] != '[' || ansiCode[len(ansiCode)-1] != 'm' {
 		return state
 	}
 

src/ansi_test.go

@@ -26,7 +26,7 @@ func TestExtractColor(t *testing.T) {
 		output, ansiOffsets, newState := extractColor(src, state, nil)
 		state = newState
 		if output != "hello world" {
-			t.Errorf("Invalid output: {}", output)
+			t.Errorf("Invalid output: %s %s", output, []rune(output))
 		}
 		fmt.Println(src, ansiOffsets, clean)
 		assertion(ansiOffsets, state)
@@ -56,7 +56,7 @@ func TestExtractColor(t *testing.T) {
 	})
 
 	state = nil
-	src = "\x1b[1mhello \x1b[mworld"
+	src = "\x1b[1mhello \x1b[mw\x1b7o\x1b8r\x1b(Bl\x1b[2@d"
 	check(func(offsets *[]ansiOffset, state *ansiState) {
 		if len(*offsets) != 1 {
 			t.Fail()