regexp: add Split
As discussed in issue 2672 and on golang-nuts, this CL adds a Split() method
to regexp. It is based on returning the "opposite" of FindAllString() so that
the returned substrings are everything not matched by the expression.
See: https://groups.google.com/forum/?fromgroups=#!topic/golang-nuts/xodBZh9Lh2E
Fixes #2762.
R=remyoudompheng, r, rsc
CC=golang-dev
https://golang.org/cl/6846048
diff --git a/src/pkg/regexp/all_test.go b/src/pkg/regexp/all_test.go
index f7b41a6..dd2ed04 100644
--- a/src/pkg/regexp/all_test.go
+++ b/src/pkg/regexp/all_test.go
@@ -5,6 +5,7 @@
package regexp
import (
+ "reflect"
"strings"
"testing"
)
@@ -416,6 +417,59 @@
}
}
+var splitTests = []struct {
+ s string
+ r string
+ n int
+ out []string
+}{
+ {"foo:and:bar", ":", -1, []string{"foo", "and", "bar"}},
+ {"foo:and:bar", ":", 1, []string{"foo:and:bar"}},
+ {"foo:and:bar", ":", 2, []string{"foo", "and:bar"}},
+ {"foo:and:bar", "foo", -1, []string{"", ":and:bar"}},
+ {"foo:and:bar", "bar", -1, []string{"foo:and:", ""}},
+ {"foo:and:bar", "baz", -1, []string{"foo:and:bar"}},
+ {"baabaab", "a", -1, []string{"b", "", "b", "", "b"}},
+ {"baabaab", "a*", -1, []string{"b", "b", "b"}},
+ {"baabaab", "ba*", -1, []string{"", "", "", ""}},
+ {"foobar", "f*b*", -1, []string{"", "o", "o", "a", "r"}},
+ {"foobar", "f+.*b+", -1, []string{"", "ar"}},
+ {"foobooboar", "o{2}", -1, []string{"f", "b", "boar"}},
+ {"a,b,c,d,e,f", ",", 3, []string{"a", "b", "c,d,e,f"}},
+ {"a,b,c,d,e,f", ",", 0, nil},
+ {",", ",", -1, []string{"", ""}},
+ {",,,", ",", -1, []string{"", "", "", ""}},
+ {"", ",", -1, []string{""}},
+ {"", ".*", -1, []string{""}},
+ {"", ".+", -1, []string{""}},
+ {"", "", -1, []string{}},
+ {"foobar", "", -1, []string{"f", "o", "o", "b", "a", "r"}},
+ {"abaabaccadaaae", "a*", 5, []string{"", "b", "b", "c", "cadaaae"}},
+ {":x:y:z:", ":", -1, []string{"", "x", "y", "z", ""}},
+}
+
+func TestSplit(t *testing.T) {
+ for i, test := range splitTests {
+ re, err := Compile(test.r)
+ if err != nil {
+ t.Errorf("#%d: %q: compile error: %s", i, test.r, err.Error())
+ continue
+ }
+
+ split := re.Split(test.s, test.n)
+ if !reflect.DeepEqual(split, test.out) {
+ t.Errorf("#%d: %q: got %q; want %q", i, test.r, split, test.out)
+ }
+
+ if QuoteMeta(test.r) == test.r {
+ strsplit := strings.SplitN(test.s, test.r, test.n)
+ if !reflect.DeepEqual(split, strsplit) {
+ t.Errorf("#%d: Split(%q, %q, %d): regexp vs strings mismatch\nregexp=%q\nstrings=%q", i, test.s, test.r, test.n, split, strsplit)
+ }
+ }
+ }
+}
+
func BenchmarkLiteral(b *testing.B) {
x := strings.Repeat("x", 50) + "y"
b.StopTimer()
diff --git a/src/pkg/regexp/regexp.go b/src/pkg/regexp/regexp.go
index 2a1ae56..bcf354b 100644
--- a/src/pkg/regexp/regexp.go
+++ b/src/pkg/regexp/regexp.go
@@ -1048,3 +1048,52 @@
}
return result
}
+
+// Split slices s into substrings separated by the expression and returns a slice of
+// the substrings between those expression matches.
+//
+// The slice returned by this method consists of all the substrings of s
+// not contained in the slice returned by FindAllString. When called on an expression
+// that contains no metacharacters, it is equivalent to strings.SplitN.
+//
+// Example:
+// s := regexp.MustCompile("a*").Split("abaabaccadaaae", 5)
+// // s: ["", "b", "b", "c", "cadaaae"]
+//
+// The count determines the number of substrings to return:
+// n > 0: at most n substrings; the last substring will be the unsplit remainder.
+// n == 0: the result is nil (zero substrings)
+// n < 0: all substrings
+func (re *Regexp) Split(s string, n int) []string {
+
+ if n == 0 {
+ return nil
+ }
+
+ if len(re.expr) > 0 && len(s) == 0 {
+ return []string{""}
+ }
+
+ matches := re.FindAllStringIndex(s, n)
+ strings := make([]string, 0, len(matches))
+
+ beg := 0
+ end := 0
+ for _, match := range matches {
+ if n > 0 && len(strings) >= n-1 {
+ break
+ }
+
+ end = match[0]
+ if match[1] != 0 {
+ strings = append(strings, s[beg:end])
+ }
+ beg = match[1]
+ }
+
+ if end != len(s) {
+ strings = append(strings, s[beg:])
+ }
+
+ return strings
+}
