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fix bug in bytes.Map and add test cases for Map in both strings and bytes packages.

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thanks to ulrik.sverdrup for the test case.

Fixes #191.

R=rsc
CC=golang-dev
https://golang.org/cl/155056
This commit is contained in:
Rob Pike 2009-11-15 12:07:27 -08:00
parent 13ad5d40c4
commit 27779dd6cb
3 changed files with 56 additions and 3 deletions
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4
src/pkg/bytes/bytes.go
View File

@ -220,9 +220,7 @@ func Map(mapping func(rune int) int, s []byte) []byte {
for i := 0; i < len(s); {
wid := 1;
rune := int(s[i]);
if rune < utf8.RuneSelf {
rune = mapping(rune)
} else {
if rune >= utf8.RuneSelf {
rune, wid = utf8.DecodeRune(s[i:len(s)])
}
rune = mapping(rune);

28
src/pkg/bytes/bytes_test.go
View File

@ -268,9 +268,22 @@ func tenRunes(rune int) string {
return string(r);
}
// User-defined self-inverse mapping function
func rot13(rune int) int {
step := 13;
if rune >= 'a' && rune <= 'z' {
return ((rune - 'a' + step) % 26) + 'a'
}
if rune >= 'A' && rune <= 'Z' {
return ((rune - 'A' + step) % 26) + 'A'
}
return rune;
}
func TestMap(t *testing.T) {
// Run a couple of awful growth/shrinkage tests
a := tenRunes('a');
// 1. Grow. This triggers two reallocations in Map.
maxRune := func(rune int) int { return unicode.MaxRune };
m := Map(maxRune, Bytes(a));
@ -278,6 +291,7 @@ func TestMap(t *testing.T) {
if string(m) != expect {
t.Errorf("growing: expected %q got %q", expect, m)
}
// 2. Shrink
minRune := func(rune int) int { return 'a' };
m = Map(minRune, Bytes(tenRunes(unicode.MaxRune)));
@ -285,6 +299,20 @@ func TestMap(t *testing.T) {
if string(m) != expect {
t.Errorf("shrinking: expected %q got %q", expect, m)
}
// 3. Rot13
m = Map(rot13, Bytes("a to zed"));
expect = "n gb mrq";
if string(m) != expect {
t.Errorf("rot13: expected %q got %q", expect, m)
}
// 4. Rot13^2
m = Map(rot13, Map(rot13, Bytes("a to zed")));
expect = "a to zed";
if string(m) != expect {
t.Errorf("rot13: expected %q got %q", expect, m)
}
}
func TestToUpper(t *testing.T) { runStringTests(t, ToUpper, "ToUpper", upperTests) }

27
src/pkg/strings/strings_test.go
View File

@ -226,6 +226,18 @@ func tenRunes(rune int) string {
return string(r);
}
// User-defined self-inverse mapping function
func rot13(rune int) int {
step := 13;
if rune >= 'a' && rune <= 'z' {
return ((rune - 'a' + step) % 26) + 'a'
}
if rune >= 'A' && rune <= 'Z' {
return ((rune - 'A' + step) % 26) + 'A'
}
return rune;
}
func TestMap(t *testing.T) {
// Run a couple of awful growth/shrinkage tests
a := tenRunes('a');
@ -236,6 +248,7 @@ func TestMap(t *testing.T) {
if m != expect {
t.Errorf("growing: expected %q got %q", expect, m)
}
// 2. Shrink
minRune := func(rune int) int { return 'a' };
m = Map(minRune, tenRunes(unicode.MaxRune));
@ -243,6 +256,20 @@ func TestMap(t *testing.T) {
if m != expect {
t.Errorf("shrinking: expected %q got %q", expect, m)
}
// 3. Rot13
m = Map(rot13, "a to zed");
expect = "n gb mrq";
if m != expect {
t.Errorf("rot13: expected %q got %q", expect, m)
}
// 4. Rot13^2
m = Map(rot13, Map(rot13, "a to zed"));
expect = "a to zed";
if m != expect {
t.Errorf("rot13: expected %q got %q", expect, m)
}
}
func TestToUpper(t *testing.T) { runStringTests(t, ToUpper, "ToUpper", upperTests) }