Add Patch and PatchList for making textual changes

Patch and PatchList provide an API for making changes to substrings
of a Blueprint file by parsing the AST and using the token positions
to perform text replacements.

Test: modify_test.go
Change-Id: Ibb8993221982b54602ba5a05486198fab8d35a67

1 files changed, 65 insertions, 0 deletions

diff --git a/parser/modify_test.go b/parser/modify_test.go
new file mode 100644
index 0000000..95fc293
--- /dev/null
+++ b/parser/modify_test.go
@@ -0,0 +1,65 @@
+// Copyright 2018 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package parser
+
+import (
+	"bytes"
+	"testing"
+)
+
+func TestPatchList(t *testing.T) {
+	expectOverlap := func(err error) {
+		t.Helper()
+		if _, ok := err.(PatchOverlapError); !ok {
+			t.Error("missing PatchOverlapError")
+		}
+	}
+
+	expectOk := func(err error) {
+		t.Helper()
+		if err != nil {
+			t.Error(err)
+		}
+	}
+
+	in := []byte("abcdefghijklmnopqrstuvwxyz")
+
+	patchlist := PatchList{}
+	expectOk(patchlist.Add(0, 3, "ABC"))
+	expectOk(patchlist.Add(12, 15, "MNO"))
+	expectOk(patchlist.Add(24, 26, "Z"))
+	expectOk(patchlist.Add(15, 15, "_"))
+
+	expectOverlap(patchlist.Add(0, 3, "x"))
+	expectOverlap(patchlist.Add(12, 13, "x"))
+	expectOverlap(patchlist.Add(13, 14, "x"))
+	expectOverlap(patchlist.Add(14, 15, "x"))
+	expectOverlap(patchlist.Add(11, 13, "x"))
+	expectOverlap(patchlist.Add(12, 15, "x"))
+	expectOverlap(patchlist.Add(11, 15, "x"))
+	expectOverlap(patchlist.Add(15, 15, "x"))
+
+	if t.Failed() {
+		return
+	}
+
+	buf := new(bytes.Buffer)
+	patchlist.Apply(bytes.NewReader(in), buf)
+	expected := "ABCdefghijklMNO_pqrstuvwxZ"
+	got := buf.String()
+	if got != expected {
+		t.Errorf("expected %q, got %q", expected, got)
+	}
+}