Gather some string slice utils.

api/internal/utils/stringslice.go

@@ -0,0 +1,44 @@
+// Copyright 2020 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+package utils
+
+// StringSliceIndex returns the index of the str, else -1.
+func StringSliceIndex(slice []string, str string) int {
+	for i := range slice {
+		if slice[i] == str {
+			return i
+		}
+	}
+	return -1
+}
+
+// StringSliceContains returns true if the slice has the string.
+func StringSliceContains(slice []string, str string) bool {
+	for _, s := range slice {
+		if s == str {
+			return true
+		}
+	}
+	return false
+}
+
+// SameEndingSubSlice returns true if the slices end the same way, e.g.
+// {"a", "b", "c"}, {"b", "c"} => true
+// {"a", "b", "c"}, {"a", "b"} => false
+// If one slice is empty and the other is not, return false.
+func SameEndingSubSlice(shortest, longest []string) bool {
+	if len(shortest) > len(longest) {
+		longest, shortest = shortest, longest
+	}
+	diff := len(longest) - len(shortest)
+	if len(shortest) == 0 {
+		return diff == 0
+	}
+	for i := len(shortest) - 1; i >= 0; i-- {
+		if longest[i+diff] != shortest[i] {
+			return false
+		}
+	}
+	return true
+}

api/internal/utils/stringslice_test.go

@@ -0,0 +1,37 @@
+// Copyright 2020 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+package utils_test
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	. "sigs.k8s.io/kustomize/api/internal/utils"
+)
+
+func TestStringSliceIndex(t *testing.T) {
+	assert.Equal(t, 0, StringSliceIndex([]string{"a", "b"}, "a"))
+	assert.Equal(t, 1, StringSliceIndex([]string{"a", "b"}, "b"))
+	assert.Equal(t, -1, StringSliceIndex([]string{"a", "b"}, "c"))
+	assert.Equal(t, -1, StringSliceIndex([]string{}, "c"))
+}
+
+func TestStringSliceContains(t *testing.T) {
+	assert.True(t, StringSliceContains([]string{"a", "b"}, "a"))
+	assert.True(t, StringSliceContains([]string{"a", "b"}, "b"))
+	assert.False(t, StringSliceContains([]string{"a", "b"}, "c"))
+	assert.False(t, StringSliceContains([]string{}, "c"))
+}
+
+func TestSameEndingSubarray(t *testing.T) {
+	assert.True(t, SameEndingSubSlice([]string{"", "a", "b"}, []string{"a", "b"}))
+	assert.True(t, SameEndingSubSlice([]string{"a", "b", ""}, []string{"b", ""}))
+	assert.True(t, SameEndingSubSlice([]string{"a", "b"}, []string{"a", "b"}))
+	assert.True(t, SameEndingSubSlice([]string{"a", "b"}, []string{"b"}))
+	assert.True(t, SameEndingSubSlice([]string{"b"}, []string{"a", "b"}))
+	assert.True(t, SameEndingSubSlice([]string{}, []string{}))
+	assert.False(t, SameEndingSubSlice([]string{"a", "b"}, []string{"b", "a"}))
+	assert.False(t, SameEndingSubSlice([]string{"a", "b"}, []string{}))
+	assert.False(t, SameEndingSubSlice([]string{"a", "b"}, []string{""}))
+}