fix: enclose regexp when using PCRE (#566)

node/declaration.test.ts

@@ -163,23 +163,23 @@ test('netlify.toml-defined excludedPath are respected', () => {
 test('Does not escape front slashes in a regex pattern if they are already escaped', () => {
   const regexPattern = '^(?:\\/(_next\\/data\\/[^/]{1,}))?(?:\\/([^/.]{1,}))\\/shows(?:\\/(.*))(.json)?[\\/#\\?]?$'
   const expected = '^(?:\\/(_next\\/data\\/[^/]{1,}))?(?:\\/([^/.]{1,}))\\/shows(?:\\/(.*))(.json)?[\\/#\\?]?$'
-  const actual = parsePattern(regexPattern)
 
-  expect(actual).toEqual(expected)
+  expect(parsePattern(regexPattern, false)).toEqual(expected)
+  expect(parsePattern(regexPattern, true)).toEqual(expected)
 })
 
 test('Escapes front slashes in a regex pattern', () => {
   const regexPattern = '^(?:/(_next/data/[^/]{1,}))?(?:/([^/.]{1,}))/shows(?:/(.*))(.json)?[/#\\?]?$'
   const expected = '^(?:\\/(_next\\/data\\/[^/]{1,}))?(?:\\/([^/.]{1,}))\\/shows(?:\\/(.*))(.json)?[/#\\?]?$'
-  const actual = parsePattern(regexPattern)
 
-  expect(actual).toEqual(expected)
+  expect(parsePattern(regexPattern, false)).toEqual(expected)
+  expect(parsePattern(regexPattern, true)).toEqual(expected)
 })
 
 test('Ensures pattern match on the whole path', () => {
   const regexPattern = '/foo/.*/bar'
   const expected = '^\\/foo\\/.*\\/bar$'
-  const actual = parsePattern(regexPattern)
 
-  expect(actual).toEqual(expected)
+  expect(parsePattern(regexPattern, false)).toEqual(expected)
+  expect(parsePattern(regexPattern, true)).toEqual(expected)
 })

node/declaration.ts

@@ -116,14 +116,34 @@ const createDeclarationsFromFunctionConfigs = (
   return declarations
 }
 
-// Validates and normalizes a pattern so that it's a valid regular expression
-// in Go, which is the engine used by our edge nodes.
-export const parsePattern = (pattern: string) => {
+/**
+ * Normalizes a regular expression, ensuring it has a leading `^` and trailing
+ * `$` characters. It also converts the regular expression from PCRE to RE2 if
+ * needed.
+ */
+export const parsePattern = (pattern: string, pcreRegexpEngine: boolean) => {
   let enclosedPattern = pattern
-  if (!pattern.startsWith('^')) enclosedPattern = `^${enclosedPattern}`
-  if (!pattern.endsWith('$')) enclosedPattern = `${enclosedPattern}$`
+
+  if (!pattern.startsWith('^')) {
+    enclosedPattern = `^${enclosedPattern}`
+  }
+
+  if (!pattern.endsWith('$')) {
+    enclosedPattern = `${enclosedPattern}$`
+  }
 
   const regexp = new RegExp(enclosedPattern)
+  const regexpString = pcreRegexpEngine ? regexp.toString() : transformPCRERegexp(regexp)
+
+  // Strip leading and forward slashes.
+  return regexpString.slice(1, -1)
+}
+
+/**
+ * Transforms a PCRE regular expression into a RE2 expression, compatible
+ * with the Go engine used in our edge nodes.
+ */
+const transformPCRERegexp = (regexp: RegExp) => {
   const newRegexp = regexpAST.transform(regexp, {
     Assertion(path) {
       // Lookaheads are not supported. If we find one, throw an error.
@@ -146,6 +166,5 @@ export const parsePattern = (pattern: string) => {
     },
   })
 
-  // Strip leading and forward slashes.
-  return newRegexp.toString().slice(1, -1)
+  return newRegexp.toString()
 }

node/manifest.ts

@@ -228,12 +228,8 @@ const pathToRegularExpression = (path: string) => {
 
 const getRegularExpression = (declaration: Declaration, pcreRegexpEngine: boolean) => {
   if ('pattern' in declaration) {
-    if (pcreRegexpEngine) {
-      return declaration.pattern
-    }
-
     try {
-      return parsePattern(declaration.pattern)
+      return parsePattern(declaration.pattern, pcreRegexpEngine)
     } catch (error: unknown) {
       throw wrapBundleError(
         new Error(
@@ -252,13 +248,9 @@ const getExcludedRegularExpressions = (declaration: Declaration, pcreRegexpEngin
       ? declaration.excludedPattern
       : [declaration.excludedPattern]
 
-    if (pcreRegexpEngine) {
-      return excludedPatterns
-    }
-
     return excludedPatterns.map((excludedPattern) => {
       try {
-        return parsePattern(excludedPattern)
+        return parsePattern(excludedPattern, pcreRegexpEngine)
       } catch (error: unknown) {
         throw wrapBundleError(
           new Error(