bytes: add function get all indexes of token in string

5 files changed, 68 insertions, 1 deletions

diff --git a/CHANGELOG.adoc b/CHANGELOG.adoc
index b1f284f7..a7711c3b 100644
--- a/CHANGELOG.adoc
+++ b/CHANGELOG.adoc
@@ -9,6 +9,8 @@ This library is released each month, usually at the first week of month.
 
 ===  New Features
 
+*  bytes: add function to get all indexes of token in string
+
 *  memfs: add method to Search content of files
 
 *  sanitize: new package to sanitize markup document into plain text
diff --git a/CHANGELOG.html b/CHANGELOG.html
index a1d7b8d2..102d9824 100644
--- a/CHANGELOG.html
+++ b/CHANGELOG.html
@@ -115,6 +115,9 @@
 <div class="ulist">
 <ul>
 <li>
+<p>bytes: add function to get all indexes of token in string</p>
+</li>
+<li>
 <p>memfs: add method to Search content of files</p>
 </li>
 <li>
diff --git a/lib/bytes/bytes.go b/lib/bytes/bytes.go
index 62e7d307..ae7aae12 100644
--- a/lib/bytes/bytes.go
+++ b/lib/bytes/bytes.go
@@ -6,6 +6,7 @@
 package bytes
 
 import (
+	"bytes"
 	"fmt"
 	"reflect"
 )
@@ -363,6 +364,29 @@ func InReplace(in, allowed []byte, c byte) (out []byte) {
 }
 
 //
+// Indexes returns the index of the all instance of token in s, or nil if
+// token is not present in s.
+//
+func Indexes(s []byte, token []byte) (idxs []int) {
+	if len(s) == 0 || len(token) == 0 {
+		return nil
+	}
+
+	offset := 0
+	for {
+		idx := bytes.Index(s, token)
+		if idx == -1 {
+			break
+		}
+		idxs = append(idxs, offset+idx)
+		skip := idx + len(token)
+		offset += skip
+		s = s[skip:]
+	}
+	return idxs
+}
+
+//
 // SkipAfterToken skip all bytes until matched token is found and return the
 // index after the token and boolean true.
 //
diff --git a/lib/bytes/bytes_example_test.go b/lib/bytes/bytes_example_test.go
index 141d7f17..bd6b41ea 100644
--- a/lib/bytes/bytes_example_test.go
+++ b/lib/bytes/bytes_example_test.go
@@ -54,6 +54,16 @@ func ExampleEncloseToken() {
 	// '// Copyright 2016-2018 \"_Shulhan <ms@kilabit.info>\"_. All rights reserved.' true
 }
 
+func ExampleIndexes() {
+	s := []byte("moo moomoo")
+	token := []byte("moo")
+
+	idxs := Indexes(s, token)
+	fmt.Println(idxs)
+	// Output:
+	// [0 4 7]
+}
+
 func ExampleIsTokenAt() {
 	line := []byte("Hello, world")
 	token := []byte("world")
diff --git a/lib/bytes/bytes_test.go b/lib/bytes/bytes_test.go
index 938f4ca1..66b04e6a 100644
--- a/lib/bytes/bytes_test.go
+++ b/lib/bytes/bytes_test.go
@@ -171,7 +171,7 @@ func TestIsTokenAt(t *testing.T) {
 		p     int
 		exp   bool
 	}{{
-		// empty
+	// empty
 	}, {
 		token: []byte("world"),
 		p:     -1,
@@ -332,3 +332,31 @@ func TestInReplace(t *testing.T) {
 		test.Assert(t, "InReplace", c.exp, string(got), true)
 	}
 }
+
+func TestIndexes(t *testing.T) {
+	cases := []struct {
+		desc  string
+		s     []byte
+		token []byte
+		exp   []int
+	}{{
+		desc:  "With empty string",
+		token: []byte("moo"),
+	}, {
+		desc: "With empty token",
+		s:    []byte("moo moo"),
+	}, {
+		desc:  "With non empty string and token",
+		s:     []byte("moo moomoo"),
+		token: []byte("moo"),
+		exp:   []int{0, 4, 7},
+	}}
+
+	for _, c := range cases {
+		t.Log(c.desc)
+
+		got := Indexes(c.s, c.token)
+
+		test.Assert(t, "Indexes", c.exp, got, true)
+	}
+}