From f9e4f398b67995d9c7ed6dc4f21a5a5879a4ba5b Mon Sep 17 00:00:00 2001
From: Rob Pike <r@golang.org>
Date: Mon, 31 Aug 2009 18:12:40 -0700
Subject: [PATCH] IsSpace

R=rsc
DELTA=39  (39 added, 0 deleted, 0 changed)
OCL=34153
CL=34167
---
 src/pkg/unicode/letter.go      | 12 ++++++++++++
 src/pkg/unicode/letter_test.go | 27 +++++++++++++++++++++++++++
 2 files changed, 39 insertions(+)

diff --git a/src/pkg/unicode/letter.go b/src/pkg/unicode/letter.go
index f67b7e5cf0..45b68f485d 100644
--- a/src/pkg/unicode/letter.go
+++ b/src/pkg/unicode/letter.go
@@ -117,6 +117,18 @@ func IsLetter(rune int) bool {
 	return Is(Letter, rune);
 }
 
+// IsSpace reports whether the rune is a white space character.
+func IsSpace(rune int) bool {
+	if rune <= 0xFF {	// quick Latin-1 check
+		switch rune {
+		case '\t', '\n', '\v', '\f', '\r', ' ', 0x85, 0xA0:
+			return true;
+		}
+		return false;
+	}
+	return Is(White_Space, rune);
+}
+
 // To maps the rune to the specified case: UpperCase, LowerCase, or TitleCase
 func To(_case int, rune int) int {
 	if _case < 0 || MaxCase <= _case {
diff --git a/src/pkg/unicode/letter_test.go b/src/pkg/unicode/letter_test.go
index 0ccb29f0a2..f5cb72f7f8 100644
--- a/src/pkg/unicode/letter_test.go
+++ b/src/pkg/unicode/letter_test.go
@@ -92,6 +92,20 @@ var notletterTest = []int{
 	0x10ffff,
 }
 
+// Contains all the special cased Latin-1 chars.
+var spaceTest = []int{
+	0x09,
+	0x0a,
+	0x0b,
+	0x0c,
+	0x0d,
+	0x20,
+	0x85,
+	0xA0,
+	0x2000,
+	0x3000,
+}
+
 type caseT struct {
 	cas, in, out int
 }
@@ -291,3 +305,16 @@ func TestToTitleCase(t *testing.T) {
 		}
 	}
 }
+
+func TestIsSpace(t *testing.T) {
+	for _, c := range spaceTest {
+		if !IsSpace(c) {
+			t.Errorf("IsSpace(U+%04X) = false; want true", c);
+		}
+	}
+	for _, c := range letterTest {
+		if IsSpace(c) {
+			t.Errorf("IsSpace(U+%04X) = true; want false", c);
+		}
+	}
+}
-- 
2.48.1