strings.utflen -> utf8.RuneCount, RuneCountInString

R=r
DELTA=94  (52 added, 33 deleted, 9 changed)
OCL=20547
CL=20552

src/lib/Makefile

@@ -88,6 +88,7 @@ bignum.6: fmt.dirinstall
 bufio.6: io.dirinstall os.dirinstall
 flag.6: fmt.dirinstall
 testing.6: flag.install fmt.dirinstall
+strings.6: utf8.install
 
 fmt.dirinstall: io.dirinstall reflect.dirinstall strconv.dirinstall
 hash.dirinstall: os.dirinstall

src/lib/strings.go

@@ -4,30 +4,17 @@
 
 package strings
 
-// Count UTF-8 sequences in s.
-// Assumes s is well-formed.
-export func utflen(s string) int {
-	n := 0;
-	for i := 0; i < len(s); i++ {
-		if s[i]&0xC0 != 0x80 {
-			n++
-		}
-	}
-	return n
-}
+import "utf8"
 
 // Split string into array of UTF-8 sequences (still strings)
 export func explode(s string) *[]string {
-	a := new([]string, utflen(s));
+	a := new([]string, utf8.RuneCountInString(s, 0, len(s)));
 	j := 0;
+	var size, rune int;
 	for i := 0; i < len(a); i++ {
-		ej := j;
-		ej++;
-		for ej < len(s) && (s[ej]&0xC0) == 0x80 {
-			ej++
-		}
-		a[i] = s[j:ej];
-		j = ej
+		rune, size = utf8.DecodeRuneInString(s, j);
+		a[i] = string(rune);
+		j += size;
 	}
 	return a
 }
@@ -35,7 +22,7 @@ export func explode(s string) *[]string {
 // Count non-overlapping instances of sep in s.
 export func count(s, sep string) int {
 	if sep == "" {
-		return utflen(s)+1
+		return utf8.RuneCountInString(s, 0, len(s))+1
 	}
 	c := sep[0];
 	n := 0;

src/lib/strings_test.go

@@ -79,21 +79,3 @@ export func TestSplit(t *testing.T) {
 	}
 }
 
-// TODO: utflen shouldn't even be in strings.
-type UtflenTest struct {
-	in string;
-	out int;
-}
-var utflentests = []UtflenTest {
-	UtflenTest{ abcd, 4 },
-	UtflenTest{ faces, 3 },
-	UtflenTest{ commas, 7 },
-}
-export func TestUtflen(t *testing.T) {
-	for i := 0; i < len(utflentests); i++ {
-		tt := utflentests[i];
-		if out := strings.utflen(tt.in); out != tt.out {
-			t.Errorf("utflen(%q) = %d, want %d", tt.in, out, tt.out);
-		}
-	}
-}

src/lib/utf8.go

@@ -107,8 +107,7 @@ func DecodeRuneInternal(p *[]byte) (rune, size int, short bool) {
 	return RuneError, 1, false
 }
 
-func DecodeRuneInStringInternal(s string, i int) (rune, size int, short bool) {
-	n := len(s) - i;
+func DecodeRuneInStringInternal(s string, i int, n int) (rune, size int, short bool) {
 	if n < 1 {
 		return RuneError, 0, true;
 	}
@@ -188,7 +187,7 @@ export func FullRune(p *[]byte) bool {
 }
 
 export func FullRuneInString(s string, i int) bool {
-	rune, size, short := DecodeRuneInStringInternal(s, i);
+	rune, size, short := DecodeRuneInStringInternal(s, i, len(s) - i);
 	return !short
 }
 
@@ -200,7 +199,7 @@ export func DecodeRune(p *[]byte) (rune, size int) {
 
 export func DecodeRuneInString(s string, i int) (rune, size int) {
 	var short bool;
-	rune, size, short = DecodeRuneInStringInternal(s, i);
+	rune, size, short = DecodeRuneInStringInternal(s, i, len(s) - i);
 	return;
 }
 
@@ -248,3 +247,31 @@ export func EncodeRune(rune int, p *[]byte) int {
 	return 4;
 }
 
+export func RuneCount(p *[]byte) int {
+	i := 0;
+	var n int;
+	for n = 0; i < len(p); n++ {
+		if p[i] < RuneSelf {
+			i++;
+		} else {
+			rune, size := DecodeRune(p[i:len(p)]);
+			i += size;
+		}
+	}
+	return n;
+}
+
+export func RuneCountInString(s string, i int, l int) int {
+	ei := i + l;
+	n := 0;
+	for n = 0; i < ei; n++ {
+		if s[i] < RuneSelf {
+			i++;
+		} else {
+			rune, size, short := DecodeRuneInStringInternal(s, i, ei - i);
+			i += size;
+		}
+	}
+	return n;
+}
+

src/lib/utf8_test.go

@@ -156,3 +156,25 @@ export func TestDecodeRune(t *testing.T) {
 		}
 	}
 }
+
+type RuneCountTest struct {
+	in string;
+	out int;
+}
+var runecounttests = []RuneCountTest {
+	RuneCountTest{ "abcd", 4 },
+	RuneCountTest{ "☺☻☹", 3 },
+	RuneCountTest{ "1,2,3,4", 7 },
+	RuneCountTest{ "\xe2\x00", 2 },
+}
+export func TestRuneCount(t *testing.T) {
+	for i := 0; i < len(runecounttests); i++ {
+		tt := runecounttests[i];
+		if out := utf8.RuneCountInString(tt.in, 0, len(tt.in)); out != tt.out {
+			t.Errorf("RuneCountInString(%q) = %d, want %d", tt.in, out, tt.out);
+		}
+		if out := utf8.RuneCount(Bytes(tt.in)); out != tt.out {
+			t.Errorf("RuneCount(%q) = %d, want %d", tt.in, out, tt.out);
+		}
+	}
+}