Add a built-in RE2 implementation based on re2js

package.json

@@ -10,7 +10,12 @@
     "license-header": "license-header --ignore 'packages/**'",
     "lint": "biome lint --error-on-warnings"
   },
-  "workspaces": ["packages/cel-spec", "packages/cel", "packages/example"],
+  "workspaces": [
+    "packages/cel-spec",
+    "packages/cel",
+    "packages/example",
+    "packages/re2"
+  ],
   "type": "module",
   "packageManager": "npm@10.9.0",
   "licenseHeader": {

packages/cel/package.json

@@ -51,11 +51,12 @@
     "@bufbuild/protobuf": "^2.6.2"
   },
   "dependencies": {
-    "@bufbuild/cel-spec": "0.4.0"
+    "@bufbuild/cel-spec": "0.4.0",
+    "@bufbuild/re2": "0.4.0"
   },
   "devDependencies": {
+    "expect-type": "^1.3.0",
     "peggy": "^5.0.6",
-    "peggy-ts": "github:hudlow/peggy-ts#v0.0.9",
-    "expect-type": "^1.3.0"
+    "peggy-ts": "github:hudlow/peggy-ts#v0.0.9"
   }
 }

packages/cel/src/std/logic.ts

@@ -26,63 +26,10 @@ import { equals } from "../equals.js";
 import { celMethod, celFunc } from "../func.js";
 import type { CelList } from "../list.js";
 import type { CelMap } from "../map.js";
-
-/**
- * Patterns that are supported in ECMAScript RE and not in
- * RE2.
- *
- * ECMAScript Ref: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_expressions/Cheatsheet
- * RE2: https://github.com/google/re2/wiki/syntax
- */
-const invalidPatterns = [
-  /\\[1-9]/, // backreference eg: \1
-  /\\k<.>/, // backreference eg: \k<name>
-  /\(\?\=/, // lookahead eg: Jack(?=Sprat)
-  /\(\?\!/, // negative lookahead eg: Jack(?!Sprat)
-  /\(\?\<\=/, // lookbehind eg: (?<=Sprat)Jack
-  /\(\?\<\!/, // negative lookbehind eg: (?<!Sprat)Jack,
-  /\\c[A-Z]/, // control character eg: /\cM\cJ/
-  /\\u[0-9a-fA-F]{4}/, // UTF-16 code-unit
-  /\\0(?!\d)/, // NUL
-  /\[\\b.*\]/, // Backspace eg: [\b]
-];
-
-const flagPattern = new RegExp(/^\(\?(?<flags>[ims\-]+)\)/);
+import { RE2JS } from "@bufbuild/re2";
 
 export function matches(this: string, pattern: string): boolean {
-  for (const invalidPattern of invalidPatterns) {
-    if (invalidPattern.test(pattern)) {
-      throw new Error(
-        `Error evaluating pattern ${pattern}, invalid RE2 syntax`,
-      );
-    }
-  }
-  // CEL use RE2 syntax which is a subset of Ecmascript RE except for
-  // the flags and the ability to change the flags mid-sequence.
-  //
-  // The conformance tests use flags at the very beginning of the sequence, which
-  // is likely the most common place where this rare feature will be used.
-  //
-  // Instead of importing an RE2 engine to be able to support this niche, we
-  // can instead just check for the flags at the very beginning and apply them.
-  //
-  // Unsupported flags and flags mid-sequence will fail with to compile the regex.
-  //
-  // Users can choose to override this function and provide an RE2 engine if they really
-  // need to.
-  let flags = "";
-  const flagMatches = pattern.match(flagPattern);
-  if (flagMatches) {
-    for (let flag of flagMatches?.groups?.flags ?? "") {
-      if (flag == "-") {
-        break;
-      }
-      flags += flag;
-    }
-    pattern = pattern.substring(flagMatches[0].length);
-  }
-  const re = new RegExp(pattern, flags);
-  return re.test(this);
+  return RE2JS.compile(pattern).test(this);
 }
 
 function compareDuration(