Merge commit '6e92d2345e8231a44556ce7d416451f5f3e6c398' as 'engine262'

engine262/src/static-semantics/CharacterValue.mts

@@ -0,0 +1,112 @@
+import { OutOfRange, unreachable } from '../helpers.mts';
+import type { ParseNode } from '../parser/ParseNode.mts';
+import { UTF16SurrogatePairToCodePoint } from './all.mts';
+import { Unicode, type CodePoint } from '#self';
+
+export type CharacterValueAcceptNode =
+  | ParseNode.RegExp.CharacterEscape
+  | ParseNode.RegExp.RegExpUnicodeEscapeSequence
+  | ParseNode.RegExp.ClassAtom
+  | ParseNode.RegExp.ClassEscape
+  | ParseNode.RegExp.ClassSetCharacter;
+
+/** https://tc39.es/ecma262/#sec-patterns-static-semantics-character-value */
+export function CharacterValue(node: CharacterValueAcceptNode): CodePoint {
+  switch (node.type) {
+    case 'CharacterEscape':
+      switch (node.production) {
+        case 'ControlEscape':
+          switch (node.ControlEscape) {
+            case 't':
+              return 0x0009 as CodePoint;
+            case 'n':
+              return 0x000A as CodePoint;
+            case 'v':
+              return 0x000B as CodePoint;
+            case 'f':
+              return 0x000C as CodePoint;
+            case 'r':
+              return 0x000D as CodePoint;
+            default:
+              unreachable(node.ControlEscape);
+          }
+        case 'AsciiLetter': {
+          // 1. Let ch be the code point matched by ControlLetter.
+          const ch = node.AsciiLetter;
+          // 2. Let i be ch's code point value.
+          const i = ch.codePointAt(0)!;
+          // 3. Return the remainder of dividing i by 32.
+          return i % 32 as CodePoint;
+        }
+        case 'HexEscapeSequence':
+          // 1. Return the numeric value of the code unit that is the SV of HexEscapeSequence.
+          return Number.parseInt(`${node.HexEscapeSequence.HexDigit_a}${node.HexEscapeSequence.HexDigit_b}`, 16) as CodePoint;
+        case 'RegExpUnicodeEscapeSequence':
+          return CharacterValue(node.RegExpUnicodeEscapeSequence);
+        case '0':
+          // 1. Return the code point value of U+0000 (NULL).
+          return 0x0000 as CodePoint;
+        case 'IdentityEscape': {
+          // 1. Let ch be the code point matched by IdentityEscape.
+          const ch = node.IdentityEscape.codePointAt(0)!;
+          // 2. Return the code point value of ch.
+          return ch as CodePoint;
+        }
+        default:
+          unreachable(node);
+      }
+    case 'RegExpUnicodeEscapeSequence':
+      switch (true) {
+        case 'Hex4Digits' in node:
+          return node.Hex4Digits as CodePoint;
+        case 'CodePoint' in node:
+          return node.CodePoint as CodePoint;
+        case 'HexTrailSurrogate' in node:
+          return UTF16SurrogatePairToCodePoint(node.HexLeadSurrogate!, node.HexTrailSurrogate!);
+        case 'HexLeadSurrogate' in node:
+          return node.HexLeadSurrogate as CodePoint;
+        default:
+          throw new OutOfRange('CharacterValue', node);
+      }
+    case 'ClassAtom':
+      switch (node.production) {
+        case '-':
+          // 1. Return the code point value of U+002D (HYPHEN-MINUS).
+          return 0x002D as CodePoint;
+        case 'SourceCharacter': {
+          // 1. Let ch be the code point matched by SourceCharacter.
+          const ch = node.SourceCharacter.codePointAt(0)!;
+          // 2. Return ch.
+          return ch as CodePoint;
+        }
+        case 'ClassEscape':
+          return CharacterValue(node.ClassEscape);
+        default:
+          unreachable(node);
+      }
+    case 'ClassEscape':
+      switch (node.production) {
+        case 'b':
+          // 1. Return the code point value of U+0008 (BACKSPACE).
+          return 0x0008 as CodePoint;
+        case '-':
+          // 1. Return the code point value of U+002D (HYPHEN-MINUS).
+          return 0x002D as CodePoint;
+        case 'CharacterEscape':
+          return CharacterValue(node.CharacterEscape);
+        case 'CharacterClassEscape':
+          throw new OutOfRange('CharacterValue', node);
+        default:
+          unreachable(node);
+      }
+    case 'ClassSetCharacter': {
+      if (node.production === 'CharacterEscape') {
+        return CharacterValue(node.CharacterEscape);
+      } else {
+        return Unicode.toCodePoint(node.UnicodeCharacter);
+      }
+    }
+    default:
+      unreachable(node);
+  }
+}