lexer.js

let source, pos, end;
let openTokenDepth,
  templateDepth,
  lastTokenPos,
  lastSlashWasDivision,
  templateStack,
  templateStackDepth,
  openTokenPosStack,
  openClassPosStack,
  nextBraceIsClass,
  starExportMap,
  lastStarExportSpecifier,
  _exports,
  reexports;

function resetState () {
  openTokenDepth = 0;
  templateDepth = -1;
  lastTokenPos = -1;
  lastSlashWasDivision = false;
  templateStack = new Array(1024);
  templateStackDepth = 0;
  openTokenPosStack = new Array(1024);
  openClassPosStack = new Array(1024);
  nextBraceIsClass = false;
  starExportMap = Object.create(null);
  lastStarExportSpecifier = null;

  _exports = new Set();
  reexports = new Set();
}

const strictReserved = new Set(['implements', 'interface', 'let', 'package', 'private', 'protected', 'public', 'static', 'yield', 'enum']);

module.exports = function parseCJS (source, name = '@') {
  resetState();
  try {
    parseSource(source);
  }
  catch (e) {
    e.message += `\n  at ${name}:${source.slice(0, pos).split('\n').length}:${pos - source.lastIndexOf('\n', pos - 1)}`;
    e.loc = pos;
    throw e;
  }
  const result = { exports: [..._exports], reexports: [...reexports] };
  resetState();
  return result;
}

function addExport (name) {
  if (!strictReserved.has(name))
    _exports.add(name);
}

function parseSource (cjsSource) {
  source = cjsSource;
  pos = -1;
  end = source.length - 1;
  let ch = 0;

  // Handle #!
  if (source.charCodeAt(0) === 35/*#*/ && source.charCodeAt(1) === 33/*!*/) {
    if (source.length === 2)
      return true;
    pos += 2;
    while (pos++ < end) {
      ch = source.charCodeAt(pos);
      if (ch === 10/*\n*/ || ch === 13/*\r*/)
        break;
    }
  }

  while (pos++ < end) {
    ch = source.charCodeAt(pos);

    if (ch === 32 || ch < 14 && ch > 8)
      continue;

    if (openTokenDepth === 0) {
      switch (ch) {
        case 105/*i*/:
          if (source.startsWith('mport', pos + 1) && keywordStart(pos))
            throwIfImportStatement();
          lastTokenPos = pos;
          continue;
        case 114/*r*/:
          const startPos = pos;
          if (tryParseRequire(false) && keywordStart(startPos))
            tryBacktrackAddStarExportBinding(startPos - 1);
          lastTokenPos = pos;
          continue;
        case 95/*_*/:
          if (source.startsWith('_export', pos + 1) && (keywordStart(pos) || source.charCodeAt(pos - 1) === 46/*.*/)) {
            pos += 8;
            if (source.startsWith('Star', pos))
              pos += 4;
            if (source.charCodeAt(pos) === 40/*(*/) {
              openTokenPosStack[openTokenDepth++] = lastTokenPos;
              if (source.charCodeAt(++pos) === 114/*r*/)
                tryParseRequire(true);
            }
          }
          lastTokenPos = pos;
          continue;
      }
    }

    switch (ch) {
      case 101/*e*/:
        if (source.startsWith('xport', pos + 1) && keywordStart(pos)) {
          if (source.charCodeAt(pos + 6) === 115/*s*/)
            tryParseExportsDotAssign(false);
          else if (openTokenDepth === 0)
            throwIfExportStatement();
        }
        break;
      case 99/*c*/:
        if (keywordStart(pos) && source.startsWith('lass', pos + 1) && isBrOrWs(source.charCodeAt(pos + 5)))
          nextBraceIsClass = true;
        break;
      case 109/*m*/:
        if (source.startsWith('odule', pos + 1) && keywordStart(pos))
          tryParseModuleExportsDotAssign();
        break;
      case 79/*O*/:
        if (source.startsWith('bject', pos + 1) && keywordStart(pos))
          tryParseObjectDefineOrKeys(openTokenDepth === 0);
        break;
      case 40/*(*/:
        openTokenPosStack[openTokenDepth++] = lastTokenPos;
        break;
      case 41/*)*/:
        if (openTokenDepth === 0)
          throw new Error('Unexpected closing bracket.');
        openTokenDepth--;
        break;
      case 123/*{*/:
        openClassPosStack[openTokenDepth] = nextBraceIsClass;
        nextBraceIsClass = false;
        openTokenPosStack[openTokenDepth++] = lastTokenPos;
        break;
      case 125/*}*/:
        if (openTokenDepth === 0)
          throw new Error('Unexpected closing brace.');
        if (openTokenDepth-- === templateDepth) {
          templateDepth = templateStack[--templateStackDepth];
          templateString();
        }
        else {
          if (templateDepth !== -1 && openTokenDepth < templateDepth)
            throw new Error('Unexpected closing brace.');
        }
        break;
      case 60/*>*/:
        // TODO: <!-- XML comment support
        break;
      case 39/*'*/:
        singleQuoteString();
        break;
      case 34/*"*/:
        doubleQuoteString();
        break;
      case 47/*/*/: {
        const next_ch = source.charCodeAt(pos + 1);
        if (next_ch === 47/*/*/) {
          lineComment();
          // dont update lastToken
          continue;
        }
        else if (next_ch === 42/***/) {
          blockComment();
          // dont update lastToken
          continue;
        }
        else {
          // Division / regex ambiguity handling based on checking backtrack analysis of:
          // - what token came previously (lastToken)
          // - if a closing brace or paren, what token came before the corresponding
          //   opening brace or paren (lastOpenTokenIndex)
          const lastToken = source.charCodeAt(lastTokenPos);
          if (isExpressionPunctuator(lastToken) &&
              !(lastToken === 46/*.*/ && (source.charCodeAt(lastTokenPos - 1) >= 48/*0*/ && source.charCodeAt(lastTokenPos - 1) <= 57/*9*/)) &&
              !(lastToken === 43/*+*/ && source.charCodeAt(lastTokenPos - 1) === 43/*+*/) && !(lastToken === 45/*-*/ && source.charCodeAt(lastTokenPos - 1) === 45/*-*/) ||
              lastToken === 41/*)*/ && isParenKeyword(openTokenPosStack[openTokenDepth]) ||
              lastToken === 125/*}*/ && (isExpressionTerminator(openTokenPosStack[openTokenDepth]) || openClassPosStack[openTokenDepth]) ||
              lastToken === 47/*/*/ && lastSlashWasDivision ||
              isExpressionKeyword(lastTokenPos) ||
              !lastToken) {
            regularExpression();
            lastSlashWasDivision = false;
          }
          else {
            lastSlashWasDivision = true;
          }
        }
        break;
      }
      case 96/*`*/:
        templateString();
        break;
    }
    lastTokenPos = pos;
  }

  if (templateDepth !== -1)
    throw new Error('Unterminated template.');

  if (openTokenDepth)
    throw new Error('Unterminated braces.');
}

function tryBacktrackAddStarExportBinding (bPos) {
  while (source.charCodeAt(bPos) === 32/* */ && bPos >= 0)
    bPos--;
  if (source.charCodeAt(bPos) === 61/*=*/) {
    bPos--;
    while (source.charCodeAt(bPos) === 32/* */ && bPos >= 0)
      bPos--;
    let codePoint;
    const id_end = bPos;
    let identifierStart = false;
    while ((codePoint = codePointAtLast(bPos)) && bPos >= 0) {
      if (codePoint === 92/*\*/)
        return;
      if (!isIdentifierChar(codePoint, true))
        break;
      identifierStart = isIdentifierStart(codePoint, true);
      bPos -= codePointLen(codePoint);
    }
    if (identifierStart && source.charCodeAt(bPos) === 32/* */) {
      const starExportId = source.slice(bPos + 1, id_end + 1);
      while (source.charCodeAt(bPos) === 32/* */ && bPos >= 0)
        bPos--;
      switch (source.charCodeAt(bPos)) {
        case 114/*r*/:
          if (!source.startsWith('va', bPos - 2))
            return;
          break;
        case 116/*t*/:
          if (!source.startsWith('le', bPos - 2) && !source.startsWith('cons', bPos - 4))
            return;
          break;
        default: return;
      }
      starExportMap[starExportId] = lastStarExportSpecifier;
    }
  }
}

function tryParseObjectDefineOrKeys (keys) {
  pos += 6;
  let revertPos = pos - 1;
  let ch = commentWhitespace();
  if (ch === 46/*.*/) {
    pos++;
    ch = commentWhitespace();
    if (ch === 100/*d*/ && source.startsWith('efineProperty', pos + 1)) {
      pos += 14;
      revertPos = pos - 1;
      ch = commentWhitespace();
      if (ch !== 40/*(*/) {
        pos = revertPos;
        return;
      }
      pos++;
      ch = commentWhitespace();
      if (readExportsOrModuleDotExports(ch)) {
        ch = commentWhitespace();
        if (ch === 44/*,*/) {
          pos++;
          ch = commentWhitespace();
          if (ch === 39/*'*/ || ch === 34/*"*/) {
            const exportPos = ++pos;
            if (identifier() && source.charCodeAt(pos) === ch) {
              // revert for "("
              addExport(source.slice(exportPos, pos));
            }
          }
        }
      }
    }
    else if (keys && ch === 107/*k*/ && source.startsWith('eys', pos + 1)) {
      while (true) {
        pos += 4;
        revertPos = pos - 1;
        ch = commentWhitespace();
        if (ch !== 40/*(*/) break;
        pos++;
        ch = commentWhitespace();
        const id_start = pos;
        if (!identifier()) break;
        const id = source.slice(id_start, pos);
        ch = commentWhitespace();
        if (ch !== 41/*)*/) break;

        revertPos = pos++;
        ch = commentWhitespace();
        if (ch !== 46/*.*/) break;
        pos++;
        ch = commentWhitespace();
        if (ch !== 102/*f*/ || !source.startsWith('orEach', pos + 1)) break;
        pos += 7;
        ch = commentWhitespace();
        revertPos = pos - 1;
        if (ch !== 40/*(*/) break;
        pos++;
        ch = commentWhitespace();
        if (ch !== 102/*f*/ || !source.startsWith('unction', pos + 1)) break;
        pos += 8;
        ch = commentWhitespace();
        if (ch !== 40/*(*/) break;
        pos++;
        ch = commentWhitespace();
        const it_id_start = pos;
        if (!identifier()) break;
        const it_id = source.slice(it_id_start, pos);
        ch = commentWhitespace();
        if (ch !== 41/*)*/) break;
        pos++;
        ch = commentWhitespace();
        if (ch !== 123/*{*/) break;
        pos++;
        ch = commentWhitespace();
        if (ch !== 105/*i*/ || !source.startsWith('f ', pos + 1)) break;
        pos += 3;
        ch = commentWhitespace();
        if (ch !== 40/*(*/) break;
        pos++;
        ch = commentWhitespace();
        if (!source.startsWith(it_id, pos)) break;
        pos += it_id.length;
        ch = commentWhitespace();
        // `if (` IDENTIFIER$2 `===` ( `'default'` | `"default"` ) `||` IDENTIFIER$2 `===` ( '__esModule' | `"__esModule"` ) `) return` `;`? |
        if (ch === 61/*=*/) {
          if (!source.startsWith('==', pos + 1)) break;
          pos += 3;
          ch = commentWhitespace();
          if (ch !== 34/*"*/ && ch !== 39/*'*/) break;
          let quot = ch;
          if (!source.startsWith('default', pos + 1)) break;
          pos += 8;
          ch = commentWhitespace();
          if (ch !== quot) break;
          pos += 1;
          ch = commentWhitespace();
          if (ch !== 124/*|*/ || source.charCodeAt(pos + 1) !== 124/*|*/) break;
          pos += 2;
          ch = commentWhitespace();
          if (source.slice(pos, pos + it_id.length) !== it_id) break;
          pos += it_id.length;
          ch = commentWhitespace();
          if (ch !== 61/*=*/ || source.slice(pos + 1, pos + 3) !== '==') break;
          pos += 3;
          ch = commentWhitespace();
          if (ch !== 34/*"*/ && ch !== 39/*'*/) break;
          quot = ch;
          if (!source.startsWith('__esModule', pos + 1)) break;
          pos += 11;
          ch = commentWhitespace();
          if (ch !== quot) break;
          pos += 1;
          ch = commentWhitespace();
          if (ch !== 41/*)*/) break;
          pos += 1;
          ch = commentWhitespace();
          if (ch !== 114/*r*/ || !source.startsWith('eturn', pos + 1)) break;
          pos += 6;
          ch = commentWhitespace();
          if (ch === 59/*;*/)
            pos++;
          ch = commentWhitespace();
        }
        // `if (` IDENTIFIER$2 `!==` ( `'default'` | `"default"` ) `)`
        else if (ch === 33/*!*/) {
          if (!source.startsWith('==', pos + 1)) break;
          pos += 3;
          ch = commentWhitespace();
          if (ch !== 34/*"*/ && ch !== 39/*'*/) break;
          const quot = ch;
          if (!source.startsWith('default', pos + 1)) break;
          pos += 8;
          ch = commentWhitespace();
          if (ch !== quot) break;
          pos += 1;
          ch = commentWhitespace();
          if (ch !== 41/*)*/) break;
          pos += 1;
          ch = commentWhitespace();
        }
        else break;

        // EXPORTS_IDENTIFIER `[` IDENTIFIER$2 `] =` IDENTIFIER$1 `[` IDENTIFIER$2 `]`
        if (readExportsOrModuleDotExports(ch)) {
          ch = commentWhitespace();
          if (ch !== 91/*[*/) break;
          pos++;
          ch = commentWhitespace();
          if (source.slice(pos, pos + it_id.length) !== it_id) break;
          pos += it_id.length;
          ch = commentWhitespace();
          if (ch !== 93/*]*/) break;
          pos++;
          ch = commentWhitespace();
          if (ch !== 61/*=*/) break;
          pos++;
          ch = commentWhitespace();
          if (source.slice(pos, pos + id.length) !== id) break;
          pos += id.length;
          ch = commentWhitespace();
          if (ch !== 91/*[*/) break;
          pos++;
          ch = commentWhitespace();
          if (source.slice(pos, pos + it_id.length) !== it_id) break;
          pos += it_id.length;
          ch = commentWhitespace();
          if (ch !== 93/*]*/) break;
          pos++;
          ch = commentWhitespace();
          if (ch === 59/*;*/) {
            pos++;
            ch = commentWhitespace();
          }
        }
        // `Object.defineProperty(` EXPORTS_IDENTIFIER `, ` IDENTIFIER$2 `, { enumerable: true, get: function () { return ` IDENTIFIER$1 `[` IDENTIFIER$2 `]; } })`
        else if (ch === 79/*O*/) {
          if (source.slice(pos + 1, pos + 6) !== 'bject') break;
          pos += 6;
          ch = commentWhitespace();
          if (ch !== 46/*.*/) break;
          pos++;
          ch = commentWhitespace();
          if (ch !== 100/*d*/ || !source.startsWith('efineProperty', pos + 1)) break;
          pos += 14;
          ch = commentWhitespace();
          if (ch !== 40/*(*/) break;
          pos++;
          ch = commentWhitespace();
          if (!readExportsOrModuleDotExports(ch)) break;
          ch = commentWhitespace();
          if (ch !== 44/*,*/) break;
          pos++;
          ch = commentWhitespace();
          if (!source.startsWith(it_id, pos)) break;
          pos += it_id.length;
          ch = commentWhitespace();
          if (ch !== 44/*,*/) break;
          pos++;
          ch = commentWhitespace();
          if (ch !== 123/*{*/) break;
          pos++;
          ch = commentWhitespace();
          if (ch !== 101/*e*/ || !source.startsWith('numerable', pos + 1)) break;
          pos += 10;
          ch = commentWhitespace();
          if (ch !== 58/*:*/) break;
          pos++;
          ch = commentWhitespace();
          if (ch !== 116/*t*/ && !source.startsWith('rue', pos + 1)) break;
          pos += 4;
          ch = commentWhitespace();
          if (ch !== 44/*,*/) break;
          pos++;
          ch = commentWhitespace();
          if (ch !== 103/*g*/ || !source.startsWith('et', pos + 1)) break;
          pos += 3;
          ch = commentWhitespace();
          if (ch !== 58/*:*/) break;
          pos++;
          ch = commentWhitespace();
          if (ch !== 102/*f*/ || !source.startsWith('unction', pos + 1)) break;
          pos += 8;
          ch = commentWhitespace();
          if (ch !== 40/*(*/) break;
          pos++;
          ch = commentWhitespace();
          if (ch !== 41/*)*/) break;
          pos++;
          ch = commentWhitespace();
          if (ch !== 123/*{*/) break;
          pos++;
          ch = commentWhitespace();
          if (ch !== 114/*r*/ || !source.startsWith('eturn', pos + 1)) break;
          pos += 6;
          ch = commentWhitespace();
          if (!source.startsWith(id, pos)) break;
          pos += id.length;
          ch = commentWhitespace();
          if (ch !== 91/*[*/) break;
          pos++;
          ch = commentWhitespace();
          if (!source.startsWith(it_id, pos)) break;
          pos += it_id.length;
          ch = commentWhitespace();
          if (ch !== 93/*]*/) break;
          pos++;
          ch = commentWhitespace();
          if (ch === 59/*;*/) {
            pos++;
            ch = commentWhitespace();
          }
          if (ch !== 125/*}*/) break;
          pos++;
          ch = commentWhitespace();
          if (ch !== 125/*}*/) break;
          pos++;
          ch = commentWhitespace();
          if (ch !== 41/*)*/) break;
          pos++;
          ch = commentWhitespace();
          if (ch === 59/*;*/) {
            pos++;
            ch = commentWhitespace();
          }
        }
        else break;

        if (ch !== 125/*}*/) break;
        pos++;
        ch = commentWhitespace();
        if (ch !== 41/*)*/) break;

        const starExportSpecifier = starExportMap[id];
        if (starExportSpecifier) {
          reexports.add(starExportSpecifier);
          pos = revertPos;
          return;
        }
        return;
      }
    }
  }
  pos = revertPos;
}

function readExportsOrModuleDotExports (ch) {
  const revertPos = pos;
  if (ch === 109/*m*/ && source.startsWith('odule', pos + 1)) {
    pos += 6;
    ch = commentWhitespace();
    if (ch !== 46/*.*/) {
      pos = revertPos;
      return false;
    }
    pos++;
    ch = commentWhitespace();
  }
  if (ch === 101/*e*/ && source.startsWith('xports', pos + 1)) {
    pos += 7;
    return true;
  }
  else {
    pos = revertPos;
    return false;
  }
}

function tryParseModuleExportsDotAssign () {
  pos += 6;
  const revertPos = pos - 1;
  let ch = commentWhitespace();
  if (ch === 46/*.*/) {
    pos++;
    ch = commentWhitespace();
    if (ch === 101/*e*/ && source.startsWith('xports', pos + 1)) {
      tryParseExportsDotAssign(true);
      return;
    }
  }
  pos = revertPos;
}

function tryParseExportsDotAssign (assign) {
  pos += 7;
  const revertPos = pos - 1;
  let ch = commentWhitespace();
  switch (ch) {
    // exports.asdf
    case 46/*.*/: {
      pos++;
      ch = commentWhitespace();
      const startPos = pos;
      if (identifier()) {
        const endPos = pos;
        ch = commentWhitespace();
        if (ch === 61/*=*/) {
          addExport(source.slice(startPos, endPos));
          return;
        }
      }
      break;
    }
    // exports['asdf']
    case 91/*[*/: {
      pos++;
      ch = commentWhitespace();
      if (ch === 39/*'*/ || ch === 34/*"*/) {
        pos++;
        const startPos = pos;
        if (identifier() && source.charCodeAt(pos) === ch) {
          const endPos = pos++;
          ch = commentWhitespace();
          if (ch !== 93/*]*/)
            break;
          pos++;
          ch = commentWhitespace();
          if (ch !== 61/*=*/)
            break;
          addExport(source.slice(startPos, endPos));
        }
      }
      break;
    }
    // module.exports =
    case 61/*=*/: {
      if (assign) {
        pos++;
        ch = commentWhitespace();
        // { ... }
        if (ch === 123/*{*/) {
          tryParseLiteralExports();
          return;
        }

        // require('...')
        if (ch === 114/*r*/)
          tryParseRequire(true);
      }
    }
  }
  pos = revertPos;
}

function tryParseRequire (directStarExport) {
  // require('...')
  if (source.startsWith('equire', pos + 1)) {
    pos += 7;
    const revertPos = pos - 1;
    let ch = commentWhitespace();
    if (ch === 40/*(*/) {
      pos++;
      ch = commentWhitespace();
      const reexportStart = pos + 1;
      if (ch === 39/*'*/) {
        singleQuoteString();
        const reexportEnd = pos++;
        ch = commentWhitespace();
        if (ch === 41/*)*/) {
          if (directStarExport) {
            reexports.add(source.slice(reexportStart, reexportEnd));
          }
          else {
            lastStarExportSpecifier = source.slice(reexportStart, reexportEnd);
          }
          return true;
        }
      }
      else if (ch === 34/*"*/) {
        doubleQuoteString();
        const reexportEnd = pos++;
        ch = commentWhitespace();
        if (ch === 41/*)*/) {
          if (directStarExport) {
            reexports.add(source.slice(reexportStart, reexportEnd));
          }
          else {
            lastStarExportSpecifier = source.slice(reexportStart, reexportEnd);
          }
          return true;
        }
      }
    }
    pos = revertPos;
  }
  return false;
}

function tryParseLiteralExports () {
  const revertPos = pos - 1;
  while (pos++ < end) {
    let ch = commentWhitespace();
    const startPos = pos;
    if (identifier()) {
      const endPos = pos;
      ch = commentWhitespace();
      if (ch === 58/*:*/) {
        pos++;
        ch = commentWhitespace();
        // nothing more complex than identifier expressions for now
        if (!identifier()) {
          pos = revertPos;
          return;
        }
        ch = source.charCodeAt(pos);
      }
      addExport(source.slice(startPos, endPos));
    }
    else if (ch === 39/*'*/ || ch === 34/*"*/) {
      const startPos = ++pos;
      if (identifier() && source.charCodeAt(pos) === ch) {
        const endPos = pos++;
        ch = commentWhitespace();
        if (ch === 58/*:*/) {
          pos++;
          ch = commentWhitespace();
          // nothing more complex than identifier expressions for now
          if (!identifier()) {
            pos = revertPos;
            return;
          }
          ch = source.charCodeAt(pos);
          addExport(source.slice(startPos, endPos));
        }
      }
    }
    else {
      pos = revertPos;
      return;
    }

    if (ch === 125/*}*/)
      return;

    if (ch !== 44/*,*/) {
      pos = revertPos;
      return;
    }
  }
}

// --- Extracted from AcornJS ---
//(https://github.com/acornjs/acorn/blob/master/acorn/src/identifier.js#L23
// 
// MIT License

// Copyright (C) 2012-2018 by various contributors (see AUTHORS)

// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:

// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

// ## Character categories

// Big ugly regular expressions that match characters in the
// whitespace, identifier, and identifier-start categories. These
// are only applied when a character is found to actually have a
// code point above 128.
// Generated by `bin/generate-identifier-regex.js`.
let nonASCIIidentifierStartChars = "\xaa\xb5\xba\xc0-\xd6\xd8-\xf6\xf8-\u02c1\u02c6-\u02d1\u02e0-\u02e4\u02ec\u02ee\u0370-\u0374\u0376\u0377\u037a-\u037d\u037f\u0386\u0388-\u038a\u038c\u038e-\u03a1\u03a3-\u03f5\u03f7-\u0481\u048a-\u052f\u0531-\u0556\u0559\u0560-\u0588\u05d0-\u05ea\u05ef-\u05f2\u0620-\u064a\u066e\u066f\u0671-\u06d3\u06d5\u06e5\u06e6\u06ee\u06ef\u06fa-\u06fc\u06ff\u0710\u0712-\u072f\u074d-\u07a5\u07b1\u07ca-\u07ea\u07f4\u07f5\u07fa\u0800-\u0815\u081a\u0824\u0828\u0840-\u0858\u0860-\u086a\u08a0-\u08b4\u08b6-\u08c7\u0904-\u0939\u093d\u0950\u0958-\u0961\u0971-\u0980\u0985-\u098c\u098f\u0990\u0993-\u09a8\u09aa-\u09b0\u09b2\u09b6-\u09b9\u09bd\u09ce\u09dc\u09dd\u09df-\u09e1\u09f0\u09f1\u09fc\u0a05-\u0a0a\u0a0f\u0a10\u0a13-\u0a28\u0a2a-\u0a30\u0a32\u0a33\u0a35\u0a36\u0a38\u0a39\u0a59-\u0a5c\u0a5e\u0a72-\u0a74\u0a85-\u0a8d\u0a8f-\u0a91\u0a93-\u0aa8\u0aaa-\u0ab0\u0ab2\u0ab3\u0ab5-\u0ab9\u0abd\u0ad0\u0ae0\u0ae1\u0af9\u0b05-\u0b0c\u0b0f\u0b10\u0b13-\u0b28\u0b2a-\u0b30\u0b32\u0b33\u0b35-\u0b39\u0b3d\u0b5c\u0b5d\u0b5f-\u0b61\u0b71\u0b83\u0b85-\u0b8a\u0b8e-\u0b90\u0b92-\u0b95\u0b99\u0b9a\u0b9c\u0b9e\u0b9f\u0ba3\u0ba4\u0ba8-\u0baa\u0bae-\u0bb9\u0bd0\u0c05-\u0c0c\u0c0e-\u0c10\u0c12-\u0c28\u0c2a-\u0c39\u0c3d\u0c58-\u0c5a\u0c60\u0c61\u0c80\u0c85-\u0c8c\u0c8e-\u0c90\u0c92-\u0ca8\u0caa-\u0cb3\u0cb5-\u0cb9\u0cbd\u0cde\u0ce0\u0ce1\u0cf1\u0cf2\u0d04-\u0d0c\u0d0e-\u0d10\u0d12-\u0d3a\u0d3d\u0d4e\u0d54-\u0d56\u0d5f-\u0d61\u0d7a-\u0d7f\u0d85-\u0d96\u0d9a-\u0db1\u0db3-\u0dbb\u0dbd\u0dc0-\u0dc6\u0e01-\u0e30\u0e32\u0e33\u0e40-\u0e46\u0e81\u0e82\u0e84\u0e86-\u0e8a\u0e8c-\u0ea3\u0ea5\u0ea7-\u0eb0\u0eb2\u0eb3\u0ebd\u0ec0-\u0ec4\u0ec6\u0edc-\u0edf\u0f00\u0f40-\u0f47\u0f49-\u0f6c\u0f88-\u0f8c\u1000-\u102a\u103f\u1050-\u1055\u105a-\u105d\u1061\u1065\u1066\u106e-\u1070\u1075-\u1081\u108e\u10a0-\u10c5\u10c7\u10cd\u10d0-\u10fa\u10fc-\u1248\u124a-\u124d\u1250-\u1256\u1258\u125a-\u125d\u1260-\u1288\u128a-\u128d\u1290-\u12b0\u12b2-\u12b5\u12b8-\u12be\u12c0\u12c2-\u12c5\u12c8-\u12d6\u12d8-\u1310\u1312-\u1315\u1318-\u135a\u1380-\u138f\u13a0-\u13f5\u13f8-\u13fd\u1401-\u166c\u166f-\u167f\u1681-\u169a\u16a0-\u16ea\u16ee-\u16f8\u1700-\u170c\u170e-\u1711\u1720-\u1731\u1740-\u1751\u1760-\u176c\u176e-\u1770\u1780-\u17b3\u17d7\u17dc\u1820-\u1878\u1880-\u18a8\u18aa\u18b0-\u18f5\u1900-\u191e\u1950-\u196d\u1970-\u1974\u1980-\u19ab\u19b0-\u19c9\u1a00-\u1a16\u1a20-\u1a54\u1aa7\u1b05-\u1b33\u1b45-\u1b4b\u1b83-\u1ba0\u1bae\u1baf\u1bba-\u1be5\u1c00-\u1c23\u1c4d-\u1c4f\u1c5a-\u1c7d\u1c80-\u1c88\u1c90-\u1cba\u1cbd-\u1cbf\u1ce9-\u1cec\u1cee-\u1cf3\u1cf5\u1cf6\u1cfa\u1d00-\u1dbf\u1e00-\u1f15\u1f18-\u1f1d\u1f20-\u1f45\u1f48-\u1f4d\u1f50-\u1f57\u1f59\u1f5b\u1f5d\u1f5f-\u1f7d\u1f80-\u1fb4\u1fb6-\u1fbc\u1fbe\u1fc2-\u1fc4\u1fc6-\u1fcc\u1fd0-\u1fd3\u1fd6-\u1fdb\u1fe0-\u1fec\u1ff2-\u1ff4\u1ff6-\u1ffc\u2071\u207f\u2090-\u209c\u2102\u2107\u210a-\u2113\u2115\u2118-\u211d\u2124\u2126\u2128\u212a-\u2139\u213c-\u213f\u2145-\u2149\u214e\u2160-\u2188\u2c00-\u2c2e\u2c30-\u2c5e\u2c60-\u2ce4\u2ceb-\u2cee\u2cf2\u2cf3\u2d00-\u2d25\u2d27\u2d2d\u2d30-\u2d67\u2d6f\u2d80-\u2d96\u2da0-\u2da6\u2da8-\u2dae\u2db0-\u2db6\u2db8-\u2dbe\u2dc0-\u2dc6\u2dc8-\u2dce\u2dd0-\u2dd6\u2dd8-\u2dde\u3005-\u3007\u3021-\u3029\u3031-\u3035\u3038-\u303c\u3041-\u3096\u309b-\u309f\u30a1-\u30fa\u30fc-\u30ff\u3105-\u312f\u3131-\u318e\u31a0-\u31bf\u31f0-\u31ff\u3400-\u4dbf\u4e00-\u9ffc\ua000-\ua48c\ua4d0-\ua4fd\ua500-\ua60c\ua610-\ua61f\ua62a\ua62b\ua640-\ua66e\ua67f-\ua69d\ua6a0-\ua6ef\ua717-\ua71f\ua722-\ua788\ua78b-\ua7bf\ua7c2-\ua7ca\ua7f5-\ua801\ua803-\ua805\ua807-\ua80a\ua80c-\ua822\ua840-\ua873\ua882-\ua8b3\ua8f2-\ua8f7\ua8fb\ua8fd\ua8fe\ua90a-\ua925\ua930-\ua946\ua960-\ua97c\ua984-\ua9b2\ua9cf\ua9e0-\ua9e4\ua9e6-\ua9ef\ua9fa-\ua9fe\uaa00-\uaa28\uaa40-\uaa42\uaa44-\uaa4b\uaa60-\uaa76\uaa7a\uaa7e-\uaaaf\uaab1\uaab5\uaab6\uaab9-\uaabd\uaac0\uaac2\uaadb-\uaadd\uaae0-\uaaea\uaaf2-\uaaf4\uab01-\uab06\uab09-\uab0e\uab11-\uab16\uab20-\uab26\uab28-\uab2e\uab30-\uab5a\uab5c-\uab69\uab70-\uabe2\uac00-\ud7a3\ud7b0-\ud7c6\ud7cb-\ud7fb\uf900-\ufa6d\ufa70-\ufad9\ufb00-\ufb06\ufb13-\ufb17\ufb1d\ufb1f-\ufb28\ufb2a-\ufb36\ufb38-\ufb3c\ufb3e\ufb40\ufb41\ufb43\ufb44\ufb46-\ufbb1\ufbd3-\ufd3d\ufd50-\ufd8f\ufd92-\ufdc7\ufdf0-\ufdfb\ufe70-\ufe74\ufe76-\ufefc\uff21-\uff3a\uff41-\uff5a\uff66-\uffbe\uffc2-\uffc7\uffca-\uffcf\uffd2-\uffd7\uffda-\uffdc"
let nonASCIIidentifierChars = "\u200c\u200d\xb7\u0300-\u036f\u0387\u0483-\u0487\u0591-\u05bd\u05bf\u05c1\u05c2\u05c4\u05c5\u05c7\u0610-\u061a\u064b-\u0669\u0670\u06d6-\u06dc\u06df-\u06e4\u06e7\u06e8\u06ea-\u06ed\u06f0-\u06f9\u0711\u0730-\u074a\u07a6-\u07b0\u07c0-\u07c9\u07eb-\u07f3\u07fd\u0816-\u0819\u081b-\u0823\u0825-\u0827\u0829-\u082d\u0859-\u085b\u08d3-\u08e1\u08e3-\u0903\u093a-\u093c\u093e-\u094f\u0951-\u0957\u0962\u0963\u0966-\u096f\u0981-\u0983\u09bc\u09be-\u09c4\u09c7\u09c8\u09cb-\u09cd\u09d7\u09e2\u09e3\u09e6-\u09ef\u09fe\u0a01-\u0a03\u0a3c\u0a3e-\u0a42\u0a47\u0a48\u0a4b-\u0a4d\u0a51\u0a66-\u0a71\u0a75\u0a81-\u0a83\u0abc\u0abe-\u0ac5\u0ac7-\u0ac9\u0acb-\u0acd\u0ae2\u0ae3\u0ae6-\u0aef\u0afa-\u0aff\u0b01-\u0b03\u0b3c\u0b3e-\u0b44\u0b47\u0b48\u0b4b-\u0b4d\u0b55-\u0b57\u0b62\u0b63\u0b66-\u0b6f\u0b82\u0bbe-\u0bc2\u0bc6-\u0bc8\u0bca-\u0bcd\u0bd7\u0be6-\u0bef\u0c00-\u0c04\u0c3e-\u0c44\u0c46-\u0c48\u0c4a-\u0c4d\u0c55\u0c56\u0c62\u0c63\u0c66-\u0c6f\u0c81-\u0c83\u0cbc\u0cbe-\u0cc4\u0cc6-\u0cc8\u0cca-\u0ccd\u0cd5\u0cd6\u0ce2\u0ce3\u0ce6-\u0cef\u0d00-\u0d03\u0d3b\u0d3c\u0d3e-\u0d44\u0d46-\u0d48\u0d4a-\u0d4d\u0d57\u0d62\u0d63\u0d66-\u0d6f\u0d81-\u0d83\u0dca\u0dcf-\u0dd4\u0dd6\u0dd8-\u0ddf\u0de6-\u0def\u0df2\u0df3\u0e31\u0e34-\u0e3a\u0e47-\u0e4e\u0e50-\u0e59\u0eb1\u0eb4-\u0ebc\u0ec8-\u0ecd\u0ed0-\u0ed9\u0f18\u0f19\u0f20-\u0f29\u0f35\u0f37\u0f39\u0f3e\u0f3f\u0f71-\u0f84\u0f86\u0f87\u0f8d-\u0f97\u0f99-\u0fbc\u0fc6\u102b-\u103e\u1040-\u1049\u1056-\u1059\u105e-\u1060\u1062-\u1064\u1067-\u106d\u1071-\u1074\u1082-\u108d\u108f-\u109d\u135d-\u135f\u1369-\u1371\u1712-\u1714\u1732-\u1734\u1752\u1753\u1772\u1773\u17b4-\u17d3\u17dd\u17e0-\u17e9\u180b-\u180d\u1810-\u1819\u18a9\u1920-\u192b\u1930-\u193b\u1946-\u194f\u19d0-\u19da\u1a17-\u1a1b\u1a55-\u1a5e\u1a60-\u1a7c\u1a7f-\u1a89\u1a90-\u1a99\u1ab0-\u1abd\u1abf\u1ac0\u1b00-\u1b04\u1b34-\u1b44\u1b50-\u1b59\u1b6b-\u1b73\u1b80-\u1b82\u1ba1-\u1bad\u1bb0-\u1bb9\u1be6-\u1bf3\u1c24-\u1c37\u1c40-\u1c49\u1c50-\u1c59\u1cd0-\u1cd2\u1cd4-\u1ce8\u1ced\u1cf4\u1cf7-\u1cf9\u1dc0-\u1df9\u1dfb-\u1dff\u203f\u2040\u2054\u20d0-\u20dc\u20e1\u20e5-\u20f0\u2cef-\u2cf1\u2d7f\u2de0-\u2dff\u302a-\u302f\u3099\u309a\ua620-\ua629\ua66f\ua674-\ua67d\ua69e\ua69f\ua6f0\ua6f1\ua802\ua806\ua80b\ua823-\ua827\ua82c\ua880\ua881\ua8b4-\ua8c5\ua8d0-\ua8d9\ua8e0-\ua8f1\ua8ff-\ua909\ua926-\ua92d\ua947-\ua953\ua980-\ua983\ua9b3-\ua9c0\ua9d0-\ua9d9\ua9e5\ua9f0-\ua9f9\uaa29-\uaa36\uaa43\uaa4c\uaa4d\uaa50-\uaa59\uaa7b-\uaa7d\uaab0\uaab2-\uaab4\uaab7\uaab8\uaabe\uaabf\uaac1\uaaeb-\uaaef\uaaf5\uaaf6\uabe3-\uabea\uabec\uabed\uabf0-\uabf9\ufb1e\ufe00-\ufe0f\ufe20-\ufe2f\ufe33\ufe34\ufe4d-\ufe4f\uff10-\uff19\uff3f"

const nonASCIIidentifierStart = new RegExp("[" + nonASCIIidentifierStartChars + "]")
const nonASCIIidentifier = new RegExp("[" + nonASCIIidentifierStartChars + nonASCIIidentifierChars + "]")

nonASCIIidentifierStartChars = nonASCIIidentifierChars = null

// These are a run-length and offset encoded representation of the
// >0xffff code points that are a valid part of identifiers. The
// offset starts at 0x10000, and each pair of numbers represents an
// offset to the next range, and then a size of the range. They were
// generated by bin/generate-identifier-regex.js

// eslint-disable-next-line comma-spacing
const astralIdentifierStartCodes = [0,11,2,25,2,18,2,1,2,14,3,13,35,122,70,52,268,28,4,48,48,31,14,29,6,37,11,29,3,35,5,7,2,4,43,157,19,35,5,35,5,39,9,51,157,310,10,21,11,7,153,5,3,0,2,43,2,1,4,0,3,22,11,22,10,30,66,18,2,1,11,21,11,25,71,55,7,1,65,0,16,3,2,2,2,28,43,28,4,28,36,7,2,27,28,53,11,21,11,18,14,17,111,72,56,50,14,50,14,35,349,41,7,1,79,28,11,0,9,21,107,20,28,22,13,52,76,44,33,24,27,35,30,0,3,0,9,34,4,0,13,47,15,3,22,0,2,0,36,17,2,24,85,6,2,0,2,3,2,14,2,9,8,46,39,7,3,1,3,21,2,6,2,1,2,4,4,0,19,0,13,4,159,52,19,3,21,2,31,47,21,1,2,0,185,46,42,3,37,47,21,0,60,42,14,0,72,26,230,43,117,63,32,7,3,0,3,7,2,1,2,23,16,0,2,0,95,7,3,38,17,0,2,0,29,0,11,39,8,0,22,0,12,45,20,0,35,56,264,8,2,36,18,0,50,29,113,6,2,1,2,37,22,0,26,5,2,1,2,31,15,0,328,18,190,0,80,921,103,110,18,195,2749,1070,4050,582,8634,568,8,30,114,29,19,47,17,3,32,20,6,18,689,63,129,74,6,0,67,12,65,1,2,0,29,6135,9,1237,43,8,8952,286,50,2,18,3,9,395,2309,106,6,12,4,8,8,9,5991,84,2,70,2,1,3,0,3,1,3,3,2,11,2,0,2,6,2,64,2,3,3,7,2,6,2,27,2,3,2,4,2,0,4,6,2,339,3,24,2,24,2,30,2,24,2,30,2,24,2,30,2,24,2,30,2,24,2,7,2357,44,11,6,17,0,370,43,1301,196,60,67,8,0,1205,3,2,26,2,1,2,0,3,0,2,9,2,3,2,0,2,0,7,0,5,0,2,0,2,0,2,2,2,1,2,0,3,0,2,0,2,0,2,0,2,0,2,1,2,0,3,3,2,6,2,3,2,3,2,0,2,9,2,16,6,2,2,4,2,16,4421,42717,35,4148,12,221,3,5761,15,7472,3104,541,1507,4938]

// eslint-disable-next-line comma-spacing
const astralIdentifierCodes = [509,0,227,0,150,4,294,9,1368,2,2,1,6,3,41,2,5,0,166,1,574,3,9,9,370,1,154,10,176,2,54,14,32,9,16,3,46,10,54,9,7,2,37,13,2,9,6,1,45,0,13,2,49,13,9,3,2,11,83,11,7,0,161,11,6,9,7,3,56,1,2,6,3,1,3,2,10,0,11,1,3,6,4,4,193,17,10,9,5,0,82,19,13,9,214,6,3,8,28,1,83,16,16,9,82,12,9,9,84,14,5,9,243,14,166,9,71,5,2,1,3,3,2,0,2,1,13,9,120,6,3,6,4,0,29,9,41,6,2,3,9,0,10,10,47,15,406,7,2,7,17,9,57,21,2,13,123,5,4,0,2,1,2,6,2,0,9,9,49,4,2,1,2,4,9,9,330,3,19306,9,135,4,60,6,26,9,1014,0,2,54,8,3,82,0,12,1,19628,1,5319,4,4,5,9,7,3,6,31,3,149,2,1418,49,513,54,5,49,9,0,15,0,23,4,2,14,1361,6,2,16,3,6,2,1,2,4,262,6,10,9,419,13,1495,6,110,6,6,9,4759,9,787719,239]

// This has a complexity linear to the value of the code. The
// assumption is that looking up astral identifier characters is
// rare.
function isInAstralSet(code, set) {
  let pos = 0x10000
  for (let i = 0; i < set.length; i += 2) {
    pos += set[i]
    if (pos > code) return false
    pos += set[i + 1]
    if (pos >= code) return true
  }
}

// Test whether a given character code starts an identifier.

function isIdentifierStart(code, astral) {
  if (code < 65) return code === 36
  if (code < 91) return true
  if (code < 97) return code === 95
  if (code < 123) return true
  if (code <= 0xffff) return code >= 0xaa && nonASCIIidentifierStart.test(String.fromCharCode(code))
  if (astral === false) return false
  return isInAstralSet(code, astralIdentifierStartCodes)
}

// Test whether a given character is part of an identifier.

function isIdentifierChar(code, astral) {
  if (code < 48) return code === 36
  if (code < 58) return true
  if (code < 65) return false
  if (code < 91) return true
  if (code < 97) return code === 95
  if (code < 123) return true
  if (code <= 0xffff) return code >= 0xaa && nonASCIIidentifier.test(String.fromCharCode(code))
  if (astral === false) return false
  return isInAstralSet(code, astralIdentifierStartCodes) || isInAstralSet(code, astralIdentifierCodes)
}

function identifier () {
  let ch = source.codePointAt(pos);
  if (!isIdentifierStart(ch, true) || ch === '\\')
    return false;
  pos += codePointLen(ch);
  while (ch = source.codePointAt(pos)) {
    if (isIdentifierChar(ch, true)) {
      pos += codePointLen(ch);
    }
    else if (ch === '\\') {
      // no identifier escapes support for now
      return false;
    }
    else {
      break;
    }
  }
  return true;
}

function codePointLen (ch) {
  if (ch < 0x10000) return 1;
  return 2;
}

function codePointAtLast (bPos) {
  // Gives the UTF char for backtracking surrogates
  const ch = source.charCodeAt(bPos);
  if ((ch & 0xFC00) === 0xDC00)
    return (((source.charCodeAt(bPos - 1) & 0x3FF) << 10) | (ch & 0x3FF)) + 0x10000;
  return ch;
}

function throwIfImportStatement () {
  const startPos = pos;
  pos += 6;
  const ch = commentWhitespace();
  switch (ch) {
    // dynamic import
    case 40/*(*/:
      openTokenPosStack[openTokenDepth++] = startPos;
      return;
    // import.meta
    case 46/*.*/:
      throw new Error('Unexpected import.meta in CJS module.');
      return;
    
    default:
      // no space after "import" -> not an import keyword
      if (pos === startPos + 6)
        break;
    case 34/*"*/:
    case 39/*'*/:
    case 123/*{*/:
    case 42/***/:
      // import statement only permitted at base-level
      if (openTokenDepth !== 0) {
        pos--;
        return;
      }
      // import statements are a syntax error in CommonJS
      throw new Error('Unexpected import statement in CJS module.');
  }
}

function throwIfExportStatement () {
  pos += 6;
  const curPos = pos;
  const ch = commentWhitespace();
  if (pos === curPos && !isPunctuator(ch))
    return;
  throw new Error('Unexpected export statement in CJS module.');
}

function commentWhitespace () {
  let ch;
  do {
    ch = source.charCodeAt(pos);
    if (ch === 47/*/*/) {
      const next_ch = source.charCodeAt(pos + 1);
      if (next_ch === 47/*/*/)
        lineComment();
      else if (next_ch === 42/***/)
        blockComment();
      else
        return ch;
    }
    else if (!isBrOrWs(ch)) {
      return ch;
    }
  } while (pos++ < end);
  return ch;
}

function templateString () {
  while (pos++ < end) {
    const ch = source.charCodeAt(pos);
    if (ch === 36/*$*/ && source.charCodeAt(pos + 1) === 123/*{*/) {
      pos++;
      templateStack[templateStackDepth++] = templateDepth;
      templateDepth = ++openTokenDepth;
      return;
    }
    if (ch === 96/*`*/)
      return;
    if (ch === 92/*\*/)
      pos++;
  }
  syntaxError();
}

function blockComment () {
  pos++;
  while (pos++ < end) {
    const ch = source.charCodeAt(pos);
    if (ch === 42/***/ && source.charCodeAt(pos + 1) === 47/*/*/) {
      pos++;
      return;
    }
  }
}

function lineComment () {
  while (pos++ < end) {
    const ch = source.charCodeAt(pos);
    if (ch === 10/*\n*/ || ch === 13/*\r*/)
      return;
  }
}

function singleQuoteString () {
  while (pos++ < end) {
    let ch = source.charCodeAt(pos);
    if (ch === 39/*'*/)
      return;
    if (ch === 92/*\*/) {
      ch = source.charCodeAt(++pos);
      if (ch === 13/*\r*/ && source.charCodeAt(pos + 1) === 10/*\n*/)
        pos++;
    }
    else if (isBr(ch))
      break;
  }
  throw new Error('Unterminated string.');
}

function doubleQuoteString () {
  while (pos++ < end) {
    let ch = source.charCodeAt(pos);
    if (ch === 34/*"*/)
      return;
    if (ch === 92/*\*/) {
      ch = source.charCodeAt(++pos);
      if (ch === 13/*\r*/ && source.charCodeAt(pos + 1) === 10/*\n*/)
        pos++;
    }
    else if (isBr(ch))
      break;
  }
  throw new Error('Unterminated string.');
}

function regexCharacterClass () {
  while (pos++ < end) {
    let ch = source.charCodeAt(pos);
    if (ch === 93/*]*/)
      return ch;
    if (ch === 92/*\*/)
      pos++;
    else if (ch === 10/*\n*/ || ch === 13/*\r*/)
      break;
  }
  throw new Error('Syntax error reading regular expression class.');
}

function regularExpression () {
  while (pos++ < end) {
    let ch = source.charCodeAt(pos);
    if (ch === 47/*/*/)
      return;
    if (ch === 91/*[*/)
      ch = regexCharacterClass();
    else if (ch === 92/*\*/)
      pos++;
    else if (ch === 10/*\n*/ || ch === 13/*\r*/)
      break;
  }
  throw new Error('Syntax error reading regular expression.');
}

// Note: non-asii BR and whitespace checks omitted for perf / footprint
// if there is a significant user need this can be reconsidered
function isBr (c) {
  return c === 13/*\r*/ || c === 10/*\n*/;
}

function isBrOrWs (c) {
  return c > 8 && c < 14 || c === 32 || c === 160;
}

function isBrOrWsOrPunctuatorNotDot (c) {
  return c > 8 && c < 14 || c === 32 || c === 160 || isPunctuator(c) && c !== 46/*.*/;
}

function keywordStart (pos) {
  return pos === 0 || isBrOrWsOrPunctuatorNotDot(source.charCodeAt(pos - 1));
}

function readPrecedingKeyword (pos, match) {
  if (pos < match.length - 1)
    return false;
  return source.startsWith(match, pos - match.length + 1) && (pos === 0 || isBrOrWsOrPunctuatorNotDot(source.charCodeAt(pos - match.length)));
}

function readPrecedingKeyword1 (pos, ch) {
  return source.charCodeAt(pos) === ch && (pos === 0 || isBrOrWsOrPunctuatorNotDot(source.charCodeAt(pos - 1)));  
}

// Detects one of case, debugger, delete, do, else, in, instanceof, new,
//   return, throw, typeof, void, yield, await
function isExpressionKeyword (pos) {
  switch (source.charCodeAt(pos)) {
    case 100/*d*/:
      switch (source.charCodeAt(pos - 1)) {
        case 105/*i*/:
          // void
          return readPrecedingKeyword(pos - 2, 'vo');
        case 108/*l*/:
          // yield
          return readPrecedingKeyword(pos - 2, 'yie');
        default:
          return false;
      }
    case 101/*e*/:
      switch (source.charCodeAt(pos - 1)) {
        case 115/*s*/:
          switch (source.charCodeAt(pos - 2)) {
            case 108/*l*/:
              // else
              return readPrecedingKeyword1(pos - 3, 101/*e*/);
            case 97/*a*/:
              // case
              return readPrecedingKeyword1(pos - 3, 99/*c*/);
            default:
              return false;
          }
        case 116/*t*/:
          // delete
          return readPrecedingKeyword(pos - 2, 'dele');
        default:
          return false;
      }
    case 102/*f*/:
      if (source.charCodeAt(pos - 1) !== 111/*o*/ || source.charCodeAt(pos - 2) !== 101/*e*/)
        return false;
      switch (source.charCodeAt(pos - 3)) {
        case 99/*c*/:
          // instanceof
          return readPrecedingKeyword(pos - 4, 'instan');
        case 112/*p*/:
          // typeof
          return readPrecedingKeyword(pos - 4, 'ty');
        default:
          return false;
      }
    case 110/*n*/:
      // in, return
      return readPrecedingKeyword1(pos - 1, 105/*i*/) || readPrecedingKeyword(pos - 1, 'retur');
    case 111/*o*/:
      // do
      return readPrecedingKeyword1(pos - 1, 100/*d*/);
    case 114/*r*/:
      // debugger
      return readPrecedingKeyword(pos - 1, 'debugge');
    case 116/*t*/:
      // await
      return readPrecedingKeyword(pos - 1, 'awai');
    case 119/*w*/:
      switch (source.charCodeAt(pos - 1)) {
        case 101/*e*/:
          // new
          return readPrecedingKeyword1(pos - 2, 110/*n*/);
        case 111/*o*/:
          // throw
          return readPrecedingKeyword(pos - 2, 'thr');
        default:
          return false; 
      }
  }
  return false;
}

function isParenKeyword (curPos) {
  return source.charCodeAt(curPos) === 101/*e*/ && source.startsWith('whil', curPos - 4) ||
      source.charCodeAt(curPos) === 114/*r*/ && source.startsWith('fo', curPos - 2) ||
      source.charCodeAt(curPos - 1) === 105/*i*/ && source.charCodeAt(curPos) === 102/*f*/;
}

function isPunctuator (ch) {
  // 23 possible punctuator endings: !%&()*+,-./:;<=>?[]^{}|~
  return ch === 33/*!*/ || ch === 37/*%*/ || ch === 38/*&*/ ||
    ch > 39 && ch < 48 || ch > 57 && ch < 64 ||
    ch === 91/*[*/ || ch === 93/*]*/ || ch === 94/*^*/ ||
    ch > 122 && ch < 127;
}

function isExpressionPunctuator (ch) {
  // 20 possible expression endings: !%&(*+,-.:;<=>?[^{|~
  return ch === 33/*!*/ || ch === 37/*%*/ || ch === 38/*&*/ ||
    ch > 39 && ch < 47 && ch !== 41 || ch > 57 && ch < 64 ||
    ch === 91/*[*/ || ch === 94/*^*/ || ch > 122 && ch < 127 && ch !== 125/*}*/;
}

function isExpressionTerminator (curPos) {
  // detects:
  // => ; ) finally catch else
  // as all of these followed by a { will indicate a statement brace
  switch (source.charCodeAt(curPos)) {
    case 62/*>*/:
      return source.charCodeAt(curPos - 1) === 61/*=*/;
    case 59/*;*/:
    case 41/*)*/:
      return true;
    case 104/*h*/:
      return source.startsWith('catc', curPos - 4);
    case 121/*y*/:
      return source.startsWith('finall', curPos - 6);
    case 101/*e*/:
      return source.startsWith('els', curPos - 3);
  }
  return false;
}