Add support for ES2025 RegExp Modifiers

FEATURE: Support ES2025 RegExp modifiers.

Closes #1323

Author: ota-meshi

acorn/src/regexp.js

@@ -378,12 +378,41 @@ pp.regexp_eatReverseSolidusAtomEscape = function(state) {
 pp.regexp_eatUncapturingGroup = function(state) {
   const start = state.pos
   if (state.eat(0x28 /* ( */)) {
-    if (state.eat(0x3F /* ? */) && state.eat(0x3A /* : */)) {
-      this.regexp_disjunction(state)
-      if (state.eat(0x29 /* ) */)) {
-        return true
+    if (state.eat(0x3F /* ? */)) {
+      if (this.options.ecmaVersion >= 16) {
+        const addModifiers = this.regexp_eatModifiers(state)
+        const hasHyphen = state.eat(0x2D /* - */)
+        if (addModifiers || hasHyphen) {
+          for (let i = 0; i < addModifiers.length; i++) {
+            const modifier = addModifiers.charAt(i)
+            if (addModifiers.indexOf(modifier, i + 1) > -1) {
+              state.raise("Duplicate regular expression modifiers")
+            }
+          }
+          if (hasHyphen) {
+            const removeModifiers = this.regexp_eatModifiers(state)
+            if (!addModifiers && !removeModifiers && state.current() === 0x3A /* : */) {
+              state.raise("Invalid regular expression modifiers")
+            }
+            for (let i = 0; i < removeModifiers.length; i++) {
+              const modifier = removeModifiers.charAt(i)
+              if (
+                removeModifiers.indexOf(modifier, i + 1) > -1 ||
+                addModifiers.indexOf(modifier) > -1
+              ) {
+                state.raise("Duplicate regular expression modifiers")
+              }
+            }
+          }
+        }
+      }
+      if (state.eat(0x3A /* : */)) {
+        this.regexp_disjunction(state)
+        if (state.eat(0x29 /* ) */)) {
+          return true
+        }
+        state.raise("Unterminated group")
       }
-      state.raise("Unterminated group")
     }
     state.pos = start
   }
@@ -405,6 +434,23 @@ pp.regexp_eatCapturingGroup = function(state) {
   }
   return false
 }
+// RegularExpressionModifiers ::
+//   [empty]
+//   RegularExpressionModifiers RegularExpressionModifier
+pp.regexp_eatModifiers = function(state) {
+  let modifiers = ""
+  let ch = 0
+  while ((ch = state.current()) !== -1 && isRegularExpressionModifier(ch)) {
+    modifiers += codePointToString(ch)
+    state.advance()
+  }
+  return modifiers
+}
+// RegularExpressionModifier :: one of
+//   `i` `m` `s`
+function isRegularExpressionModifier(ch) {
+  return ch === 0x69 /* i */ || ch === 0x6d /* m */ || ch === 0x73 /* s */
+}
 
 // https://www.ecma-international.org/ecma-262/8.0/#prod-annexB-ExtendedAtom
 pp.regexp_eatExtendedAtom = function(state) {

bin/test262.unsupported-features

@@ -1,4 +1,3 @@
 decorators
 explicit-resource-management
-regexp-modifiers
 source-phase-imports

test/tests-regexp-2025.js

@@ -3,6 +3,7 @@ if (typeof exports !== "undefined") {
   var testFail = require("./driver.js").testFail
 }
 
+// Duplicate named capture groups
 test("/(?<x>a)|(?<x>b)/", {}, {ecmaVersion: 2025})
 testFail("/(?<x>a)|(?<x>b)/", "Invalid regular expression: /(?<x>a)|(?<x>b)/: Duplicate capture group name (1:1)", {ecmaVersion: 2024 })
 testFail("/(?<x>a)(?<x>b)/", "Invalid regular expression: /(?<x>a)(?<x>b)/: Duplicate capture group name (1:1)", {ecmaVersion: 2025})
@@ -16,3 +17,31 @@ testFail("/(?<x>a)|(?<x>b)(?<x>c)/", "Invalid regular expression: /(?<x>a)|(?<x>
 testFail("/(?:(?<x>a)|(?<x>b))(?<x>c)/", "Invalid regular expression: /(?:(?<x>a)|(?<x>b))(?<x>c)/: Duplicate capture group name (1:1)", {ecmaVersion: 2025})
 testFail("/(?<x>a)(?:(?<x>b)|(?<x>c))/", "Invalid regular expression: /(?<x>a)(?:(?<x>b)|(?<x>c))/: Duplicate capture group name (1:1)", {ecmaVersion: 2025})
 testFail("/(?:(?:(?<x>a)|(?<x>b))|(?:))(?<x>c)/", "Invalid regular expression: /(?:(?:(?<x>a)|(?<x>b))|(?:))(?<x>c)/: Duplicate capture group name (1:1)", {ecmaVersion: 2025})
+
+// Modifiers
+test("/(?i-m:p)?/", {}, {ecmaVersion: 2025})
+test("/(?i-m:p)?/u", {}, {ecmaVersion: 2025})
+test("/(?ims:p)?/", {}, {ecmaVersion: 2025})
+test("/(?ims-:p)?/", {}, {ecmaVersion: 2025})
+test("/(?-ims:p)?/", {}, {ecmaVersion: 2025})
+test("/(?:no modifiers)?/", {}, {ecmaVersion: 2025})
+// In ES2024
+testFail("/(?i-m:p)?/", "Invalid regular expression: /(?i-m:p)?/: Invalid group (1:1)", {ecmaVersion: 2024})
+testFail("/(?ims:p)?/", "Invalid regular expression: /(?ims:p)?/: Invalid group (1:1)", {ecmaVersion: 2024})
+testFail("/(?ims-:p)?/", "Invalid regular expression: /(?ims-:p)?/: Invalid group (1:1)", {ecmaVersion: 2024})
+testFail("/(?-ims:p)?/", "Invalid regular expression: /(?-ims:p)?/: Invalid group (1:1)", {ecmaVersion: 2024})
+// It is a Syntax Error if the first modifiers and the second modifiers are both empty.
+testFail("/(?-:p)?/", "Invalid regular expression: /(?-:p)?/: Invalid regular expression modifiers (1:1)", {ecmaVersion: 2025})
+// It is a Syntax Error if the first modifiers contains the same code point more than once.
+testFail("/(?ii:p)?/", "Invalid regular expression: /(?ii:p)?/: Duplicate regular expression modifiers (1:1)", {ecmaVersion: 2025})
+// It is a Syntax Error if the second modifiers contains the same code point more than once.
+testFail("/(?-ii:p)?/", "Invalid regular expression: /(?-ii:p)?/: Duplicate regular expression modifiers (1:1)", {ecmaVersion: 2025})
+testFail("/(?i-mm:p)?/", "Invalid regular expression: /(?i-mm:p)?/: Duplicate regular expression modifiers (1:1)", {ecmaVersion: 2025})
+// It is a Syntax Error if any code point in the first modifiers is also contained in the second modifiers.
+testFail("/(?i-i:p)?/", "Invalid regular expression: /(?i-i:p)?/: Duplicate regular expression modifiers (1:1)", {ecmaVersion: 2025})
+// Not modifiers
+testFail("/(?u:p)?/", "Invalid regular expression: /(?u:p)?/: Invalid group (1:1)", {ecmaVersion: 2025})
+testFail("/(?u-:p)?/", "Invalid regular expression: /(?u-:p)?/: Invalid group (1:1)", {ecmaVersion: 2025})
+testFail("/(?u-i:p)?/", "Invalid regular expression: /(?u-i:p)?/: Invalid group (1:1)", {ecmaVersion: 2025})
+testFail("/(?-u:p)?/", "Invalid regular expression: /(?-u:p)?/: Invalid group (1:1)", {ecmaVersion: 2025})
+testFail("/(?i-u:p)?/", "Invalid regular expression: /(?i-u:p)?/: Invalid group (1:1)", {ecmaVersion: 2025})