feat(patch text to hunk bounds): support regex for patch texts

src/github-handler/comment-handler/github-patch-format-handler.ts

@@ -0,0 +1,113 @@
+// Copyright 2020 Google LLC
+//
+// 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
+//
+//     https://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.
+
+import {Range} from '../../types';
+
+const REGEX_INDEX_OF_UPDATED_HUNK = 2;
+
+/**
+ * @@ -<start line original>,<offset> +<start line updated>,<offset> @@
+ * i.e. @@ -132,7 +132,7 @@
+ */
+const REGEX_MULTILINE_RANGE = /@@ -([0-9]+,[0-9]+) \+([0-9]+,[0-9]+) @@/g;
+
+/**
+ * @@ -<start line original> +<start line updated>,<offset> @@
+ * i.e. a deletion @@ -1 +0,0 @@
+ */
+const REGEX_ONELINE_TO_MULTILINE_RANGE = /@@ -([0-9]+) \+([0-9]+,[0-9]+) @@/g;
+/**
+ * @@ -<line original> +<line updated> @@
+ * i.e. @@ -1 +1 @@
+ */
+const REGEX_ONELINE_RANGE = /@@ -([0-9]+) \+([0-9]+) @@/g;
+/**
+ * @@ -<start line original>,<offset> +<line updated> @@
+ * i.e. file creation @@ -0,0 +1 @@
+ */
+const REGEX_MULTILINE_TO_ONELINE_RANGE = /@@ -([0-9]+,[0-9]+) \+([0-9]+) @@/g;
+
+/**
+ * Parses the GitHub line-based patch text
+ * Example output of one output of one regex exec
+ *
+ * '@@ -0,0 +1,12 @@\n', // original text
+ * '0,0', // original hunk
+ * '1,12', // new hunk
+ * index: 0,
+ * input: '@@ -0,0 +1,12 @@\n+Hello world%0A',
+ * groups: undefined
+ * @param {string} patchText
+ * @returns patch ranges
+ */
+export function getGitHubPatchRanges(patchText: string): Range[] {
+  const ranges: Range[] = [];
+  // CASE I: multiline patch ranges
+  // includes non-first single-line patches
+  // i.e. @@ -3,4 +3,4 @@
+  // which only edits line 3, but is still a multiline patch range
+  for (
+    let patch = REGEX_MULTILINE_RANGE.exec(patchText);
+    patch !== null;
+    patch = REGEX_MULTILINE_RANGE.exec(patchText)
+  ) {
+    // stricly interested in the updated/current github file content
+    const patchData = patch[REGEX_INDEX_OF_UPDATED_HUNK].split(',');
+    // the line number ranges of the updated text
+    const start = parseInt(patchData[0]);
+    const offset = parseInt(patchData[1]);
+    const range: Range = {start, end: start + offset};
+    ranges.push(range);
+  }
+  // CASE II: oneline text becomes multiline text
+  for (
+    let patch = REGEX_ONELINE_TO_MULTILINE_RANGE.exec(patchText);
+    patch !== null;
+    patch = REGEX_ONELINE_TO_MULTILINE_RANGE.exec(patchText)
+  ) {
+    // stricly interested in the updated/current github file content
+    const patchData = patch[REGEX_INDEX_OF_UPDATED_HUNK].split(',');
+    // the line number ranges of the updated text
+    const start = parseInt(patchData[0]);
+    const offset = parseInt(patchData[1]);
+    const range: Range = {start, end: start + offset};
+    ranges.push(range);
+  }
+  // CASE III: first line of text updated
+  for (
+    let patch = REGEX_ONELINE_RANGE.exec(patchText);
+    patch !== null;
+    patch = REGEX_ONELINE_RANGE.exec(patchText)
+  ) {
+    // stricly interested in the updated/current github file content
+    // the line number ranges of the updated text
+    const start = parseInt(patch[REGEX_INDEX_OF_UPDATED_HUNK]);
+    const range: Range = {start, end: start + 1};
+    ranges.push(range);
+  }
+  // CASE IV: Multiline range is reduced to one line
+  // 0,0 constitutes a multi-line range
+  for (
+    let patch = REGEX_MULTILINE_TO_ONELINE_RANGE.exec(patchText);
+    patch !== null;
+    patch = REGEX_MULTILINE_TO_ONELINE_RANGE.exec(patchText)
+  ) {
+    // stricly interested in the updated/current github file content
+    // the line number ranges of the updated text
+    const start = parseInt(patch[REGEX_INDEX_OF_UPDATED_HUNK]);
+    const range: Range = {start, end: start + 1};
+    ranges.push(range);
+  }
+  return ranges;
+}

src/types/index.ts

@@ -116,3 +116,31 @@ export interface CreatePullRequest {
   // Whether or not maintainers can modify the PR.
   maintainersCanModify: boolean;
 }
+
+/**
+ * The file content of the original content and the patched content
+ */
+export interface RawContent {
+  readonly old_content: string;
+  readonly new_content: string;
+}
+
+/**
+ * A range object defined by lower boundary as 'start' and upper boundary as 'end'
+ */
+export interface Range {
+  readonly start: number;
+  readonly end: number;
+}
+
+/**
+ * The range of a patch along with the raw file content
+ */
+export interface Patch extends Range {
+  readonly raw_content: string;
+}
+
+export type FilePatches = Map<string, Patch[]>;
+export type RawChanges = Map<string, RawContent>;
+export type PatchText = Map<string, string>;
+export type FileRanges = Map<string, Range[]>;

test/github-regex-patch.ts

@@ -0,0 +1,59 @@
+// Copyright 2020 Google LLC
+//
+// 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.
+
+import {expect} from 'chai';
+import {describe, it} from 'mocha';
+import {getGitHubPatchRanges} from '../src/github-handler/comment-handler/github-patch-format-handler';
+
+describe('Getting patch range from GitHub patch text', async () => {
+  it('parses original text for multiline modifies', () => {
+    const multiline_patch =
+      '@@ -1,2 +1,5 @@\n Hello world\n-!\n+Goodbye World\n+gOodBYE world\n+\n+Goodbye World';
+    const ranges = getGitHubPatchRanges(multiline_patch);
+    expect(ranges[0].start).equals(1);
+    expect(ranges[0].end).equals(6);
+    expect(ranges.length).equals(1);
+  });
+  it('parses original text for single line modifies at the start of the file', () => {
+    const first_line_patch = '@@ -1 +1 @@\n-Hello foo\n+';
+    const ranges = getGitHubPatchRanges(first_line_patch);
+    expect(ranges[0].start).equals(1);
+    expect(ranges[0].end).equals(2);
+    expect(ranges.length).equals(1);
+  });
+  it('parses original text for single line deletes', () => {
+    const single_line_to_multiline_format = '@@ -1 +0,0 @@\n-hello world';
+    const ranges = getGitHubPatchRanges(single_line_to_multiline_format);
+    expect(ranges[0].start).equals(0);
+    expect(ranges[0].end).equals(0);
+    expect(ranges.length).equals(1);
+  });
+  it('parses original text for single line file creations', () => {
+    const first_line_patch = "@@ -0,0 +1 @@\n+console.log('Hello World!');";
+    const ranges = getGitHubPatchRanges(first_line_patch);
+    expect(ranges[0].start).equals(1);
+    expect(ranges[0].end).equals(2);
+    expect(ranges.length).equals(1);
+  });
+  it('parses patch text with multiple patches', () => {
+    const first_line_patch =
+      '@@ -356,6 +356,7 @@ Hello\n Hello\n Hello\n Hello\n+Bye\n Hello\n Hello\n Hello\n@@ -6576,8 +6577,7 @@ Hello\n Hello\n Hello\n Hello\n-Hello\n-Hello\n+Bye\n Hello\n Hello\n Hello';
+    const ranges = getGitHubPatchRanges(first_line_patch);
+    expect(ranges[0].start).equals(356);
+    expect(ranges[0].end).equals(363);
+    expect(ranges[1].start).equals(6577);
+    expect(ranges[1].end).equals(6584);
+    expect(ranges.length).equals(2);
+  });
+});