fix: change vlq encoding to encode only positive ints (#389)

removes the 3rd party libary for vlq.

__snapshots__/PuppeteerReplayStringifyExtension.test.ts.js

@@ -48,6 +48,6 @@ export async function run(extension) {
 if (process && import.meta.url === url.pathToFileURL(process.argv[1]).href) {
   run()
 }
-//# recorderSourceMap=CQc
+//# recorderSourceMap=BIO
 
 `;

__snapshots__/lighthouse.test.ts.js

@@ -258,6 +258,6 @@ const puppeteer = require('puppeteer'); // v13.0.0 or later
   console.error(err);
   process.exit(1);
 });
-//# recorderSourceMap=CaIiBMuBaoCYgDiB
+//# recorderSourceMap=BNERGXNkBMwBR
 
 `;

__snapshots__/stringify.test.ts.js

@@ -201,7 +201,7 @@ const puppeteer = require('puppeteer'); // v13.0.0 or later
   console.error(err);
   process.exit(1);
 });
-//# recorderSourceMap=CQI
+//# recorderSourceMap=BIE
 
 `;
 
@@ -415,7 +415,7 @@ const puppeteer = require('puppeteer'); // v13.0.0 or later
   console.error(err);
   process.exit(1);
 });
-//# recorderSourceMap=CQS
+//# recorderSourceMap=BIJ
 
 `;
 
@@ -633,7 +633,7 @@ const puppeteer = require('puppeteer'); // v13.0.0 or later
   console.error(err);
   process.exit(1);
 });
-//# recorderSourceMap=CQa
+//# recorderSourceMap=BIN
 
 `;
 
@@ -850,7 +850,7 @@ const puppeteer = require('puppeteer'); // v13.0.0 or later
   console.error(err);
   process.exit(1);
 });
-//# recorderSourceMap=CQc
+//# recorderSourceMap=BIO
 
 `;
 
@@ -1069,7 +1069,7 @@ const puppeteer = require('puppeteer'); // v13.0.0 or later
   console.error(err);
   process.exit(1);
 });
-//# recorderSourceMap=CQc
+//# recorderSourceMap=BIO
 
 `;
 
@@ -1276,7 +1276,7 @@ const puppeteer = require('puppeteer'); // v13.0.0 or later
   console.error(err);
   process.exit(1);
 });
-//# recorderSourceMap=CQI
+//# recorderSourceMap=BIE
 
 `;
 
@@ -1483,7 +1483,7 @@ const puppeteer = require('puppeteer'); // v13.0.0 or later
   console.error(err);
   process.exit(1);
 });
-//# recorderSourceMap=CQI
+//# recorderSourceMap=BIE
 
 `;
 
@@ -1696,7 +1696,7 @@ const puppeteer = require('puppeteer'); // v13.0.0 or later
   console.error(err);
   process.exit(1);
 });
-//# recorderSourceMap=CQMcI
+//# recorderSourceMap=BIGOE
 
 `;
 
@@ -1905,7 +1905,7 @@ const puppeteer = require('puppeteer'); // v13.0.0 or later
   console.error(err);
   process.exit(1);
 });
-//# recorderSourceMap=CQI
+//# recorderSourceMap=BIE
 
 `;
 
@@ -2114,7 +2114,7 @@ const puppeteer = require('puppeteer'); // v13.0.0 or later
   console.error(err);
   process.exit(1);
 });
-//# recorderSourceMap=CQI
+//# recorderSourceMap=BIE
 
 `;
 

package.json

@@ -87,7 +87,6 @@
   "dependencies": {
     "cli-table3": "0.6.3",
     "colorette": "2.0.19",
-    "vlq": "2.0.4",
     "yargs": "17.6.1"
   }
 }

src/stringify.ts

@@ -19,7 +19,7 @@ import { LineWriter } from './LineWriter.js';
 import { PuppeteerStringifyExtension } from './PuppeteerStringifyExtension.js';
 import type { Step, UserFlow } from './Schema.js';
 import { StringifyExtension } from './StringifyExtension.js';
-import * as vlq from 'vlq';
+import { decode, encode } from './vlq.js';
 
 export interface StringifyOptions {
   extension?: StringifyExtension;
@@ -54,7 +54,7 @@ export async function stringify(
 
   await ext.beforeAllSteps?.(out, flow);
 
-  const sourceMap: Array<number> = [1];
+  const sourceMap: Array<number> = [1]; // The first int indicates the version.
   for (const step of flow.steps) {
     const firstLine = out.getSize();
     await ext.beforeEachStep?.(out, step, flow);
@@ -65,7 +65,7 @@ export async function stringify(
   }
   await ext.afterAllSteps?.(out, flow);
 
-  out.appendLine(SOURCE_MAP_PREFIX + vlq.encode(sourceMap));
+  out.appendLine(SOURCE_MAP_PREFIX + encode(sourceMap));
 
   return out.toString();
 }
@@ -107,7 +107,7 @@ export function parseSourceMap(text: string): SourceMap | undefined {
   for (let i = lines.length - 1; i >= 0; i--) {
     const line = lines[i] as string;
     if (line.trim().startsWith(SOURCE_MAP_PREFIX)) {
-      return vlq.decode(line.trim().substring(SOURCE_MAP_PREFIX.length));
+      return decode(line.trim().substring(SOURCE_MAP_PREFIX.length));
     }
   }
   return;

src/vlq.ts

@@ -0,0 +1,82 @@
+/**
+    Copyright 2022 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.
+ */
+
+const alpha =
+  'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
+
+const charToIdx = alpha.split('').reduce((acc, char, idx) => {
+  acc.set(char, idx);
+  return acc;
+}, new Map());
+
+const LEAST_5_BIT_MASK = 0b011111;
+const CONTINUATION_BIT_MASK = 0b100000;
+const MAX_INT = 2147483647;
+
+/**
+ * Encoding variable length integer into base64 (6-bit):
+ *
+ * 1 N N N N N | 0 N N N N N
+ *
+ * The first bit indicates if there is more data for the int.
+ */
+export function encodeInt(num: number) {
+  if (num < 0) {
+    throw new Error('Only postive integers and zero are supported');
+  }
+  if (num > MAX_INT) {
+    throw new Error(
+      'Only integers between 0 and ' + MAX_INT + ' are supported'
+    );
+  }
+  const result = [];
+  do {
+    let payload = num & LEAST_5_BIT_MASK;
+    num >>>= 5;
+    if (num > 0) payload |= CONTINUATION_BIT_MASK;
+    result.push(alpha[payload]);
+  } while (num !== 0);
+  return result.join('');
+}
+
+export function encode(nums: number[]): string {
+  const parts = [];
+  for (const num of nums) {
+    parts.push(encodeInt(num));
+  }
+  return parts.join('');
+}
+
+export function decode(str: string) {
+  const results = [];
+  const chrs = str.split('');
+
+  let result = 0;
+  let shift = 0;
+  for (const ch of chrs) {
+    const num = charToIdx.get(ch);
+    result |= (num & LEAST_5_BIT_MASK) << shift;
+    shift += 5;
+    const hasMore = num & CONTINUATION_BIT_MASK;
+    if (!hasMore) {
+      results.push(result);
+      result = 0;
+      shift = 0;
+    }
+  }
+
+  return results;
+}

test/stringify.test.ts

@@ -20,7 +20,7 @@ import { StringifyExtension } from '../src/StringifyExtension.js';
 import { Step, StepType, UserFlow } from '../src/Schema.js';
 import { LineWriter } from '../src/LineWriter.js';
 import snapshot from 'snap-shot-it';
-import * as vlq from 'vlq';
+import { decode } from '../src/vlq.js';
 
 describe('stringify', () => {
   it('should print the correct script for a navigate step', async () => {
@@ -250,7 +250,7 @@ describe('stringify', () => {
         'stringifyStep0',
         'afterStep0',
         'afterAll',
-        '//# recorderSourceMap=CCG',
+        '//# recorderSourceMap=BBD',
         '',
       ].join('\n')
     );
@@ -272,7 +272,7 @@ describe('stringify', () => {
       .reverse()
       .find((line) => line.trim() !== '');
     snapshot(
-      vlq.decode(sourceMapLine?.split('//# recorderSourceMap=').pop() as string)
+      decode(sourceMapLine?.split('//# recorderSourceMap=').pop() as string)
     );
   });
 
@@ -281,7 +281,7 @@ describe('stringify', () => {
       test
       test
       test
-      //# recorderSourceMap=CCG
+      //# recorderSourceMap=BBD
     `);
     assert.deepStrictEqual(sourceMap, [1, 1, 3]);
   });

test/vlq.test.ts

@@ -0,0 +1,41 @@
+/**
+    Copyright 2022 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 { encodeInt, decode, encode } from '../src/vlq.js';
+import { assert } from 'chai';
+
+describe('vlq', () => {
+  it('should encode', () => {
+    assert.strictEqual(encodeInt(0), 'A');
+    assert.strictEqual(encodeInt(1), 'B');
+    assert.strictEqual(encodeInt(123), '7D');
+    assert.strictEqual(encodeInt(123) + encodeInt(123456789), '7D1oz31D');
+    assert.strictEqual(encodeInt(123456789), '1oz31D');
+    assert.strictEqual(encodeInt(2147483647), '//////B');
+  });
+  it('should decode', () => {
+    assert.deepStrictEqual(decode('A'), [0]);
+    assert.deepStrictEqual(decode('C'), [2]);
+    assert.deepStrictEqual(decode('D'), [3]);
+    assert.deepStrictEqual(decode('7D'), [123]);
+    assert.deepStrictEqual(decode('1oz31D'), [123456789]);
+    assert.deepStrictEqual(decode('7D1oz31D'), [123, 123456789]);
+    assert.deepStrictEqual(decode('//////B'), [2147483647]);
+  });
+  it('should encode array', () => {
+    assert.strictEqual(encode([0, 1, 123]), 'AB7D');
+  });
+});

tsconfig.base.json

@@ -24,7 +24,6 @@
     "strictNullChecks": true,
     "strictPropertyInitialization": true,
     "target": "ES2019",
-    "useUnknownInCatchVariables": true,
-    "typeRoots": ["./node_modules/@types", "./src/@types"]
+    "useUnknownInCatchVariables": true
   }
 }