parcel-bundler/lib/Resolver.js

Blazing fast, zero configuration web application bundler

'use strict';

function _asyncToGenerator(fn) { return function () { var gen = fn.apply(this, arguments); return new Promise(function (resolve, reject) { function step(key, arg) { try { var info = gen[key](arg); var value = info.value; } catch (error) { reject(error); return; } if (info.done) { resolve(value); } else { return Promise.resolve(value).then(function (value) { step("next", value); }, function (err) { step("throw", err); }); } } return step("next"); }); }; }

const builtins = require('./builtins');
const path = require('path');
const glob = require('glob');
const fs = require('./utils/fs');

const EMPTY_SHIM = require.resolve('./builtins/_empty');

/**
 * This resolver implements a modified version of the node_modules resolution algorithm:
 * https://nodejs.org/api/modules.html#modules_all_together
 *
 * In addition to the standard algorithm, Parcel supports:
 *   - All file extensions supported by Parcel.
 *   - Glob file paths
 *   - Absolute paths (e.g. /foo) resolved relative to the project root.
 *   - Tilde paths (e.g. ~/foo) resolved relative to the nearest module root in node_modules.
 *   - The package.json module, jsnext:main, and browser field as replacements for package.main.
 *   - The package.json browser and alias fields as an alias map within a local module.
 *   - The package.json alias field in the root package for global aliases across all modules.
 */
class Resolver {
  constructor(options = {}) {
    this.options = options;
    this.cache = new Map();
    this.packageCache = new Map();
    this.rootPackage = null;
  }

  resolve(input, parent) {
    var _this = this;

    return _asyncToGenerator(function* () {
      let filename = input;

      // Check the cache first
      let key = _this.getCacheKey(filename, parent);
      if (_this.cache.has(key)) {
        return _this.cache.get(key);
      }

      // Check if this is a glob
      if (/[*+{}]/.test(filename) && glob.hasMagic(filename)) {
        return { path: path.resolve(path.dirname(parent), filename) };
      }

      // Get file extensions to search
      let extensions = Array.isArray(_this.options.extensions) ? _this.options.extensions.slice() : Object.keys(_this.options.extensions);

      if (parent) {
        // parent's extension given high priority
        const parentExt = path.extname(parent);
        extensions = [parentExt, ...extensions.filter(function (ext) {
          return ext !== parentExt;
        })];
      }

      extensions.unshift('');

      let dir = parent ? path.dirname(parent) : process.cwd();

      // If this isn't the entrypoint, resolve the input file to an absolute path
      if (parent) {
        filename = _this.resolveFilename(filename, dir);
      }

      // Resolve aliases in the parent module for this file.
      filename = yield _this.loadAlias(filename, dir);

      let resolved;
      if (path.isAbsolute(filename)) {
        // load as file
        resolved = yield _this.loadRelative(filename, extensions);
      } else {
        // load node_modules
        resolved = yield _this.loadNodeModules(filename, dir, extensions);
      }

      if (!resolved) {
        let err = new Error("Cannot find module '" + input + "' from '" + dir + "'");
        err.code = 'MODULE_NOT_FOUND';
        throw err;
      }

      _this.cache.set(key, resolved);
      return resolved;
    })();
  }

  getCacheKey(filename, parent) {
    return (parent ? path.dirname(parent) : '') + ':' + filename;
  }

  resolveFilename(filename, dir) {
    switch (filename[0]) {
      case '/':
        // Absolute path. Resolve relative to project root.
        return path.resolve(this.options.rootDir, filename.slice(1));

      case '~':
        // Tilde path. Resolve relative to nearest node_modules directory,
        // or the project root - whichever comes first.
        while (dir !== this.options.rootDir && path.basename(path.dirname(dir)) !== 'node_modules') {
          dir = path.dirname(dir);
        }

        return path.join(dir, filename.slice(1));

      case '.':
        // Relative path.
        return path.resolve(dir, filename);

      default:
        // Module
        return path.normalize(filename);
    }
  }

  loadRelative(filename, extensions) {
    var _this2 = this;

    return _asyncToGenerator(function* () {
      // Find a package.json file in the current package.
      let pkg = yield _this2.findPackage(path.dirname(filename));

      // First try as a file, then as a directory.
      return (yield _this2.loadAsFile(filename, extensions, pkg)) || (yield _this2.loadDirectory(filename, extensions, pkg));
    })();
  }

  loadNodeModules(filename, dir, extensions) {
    var _this3 = this;

    return _asyncToGenerator(function* () {
      // Check if this is a builtin module
      if (builtins[filename]) {
        return { path: builtins[filename] };
      }

      let parts = _this3.getModuleParts(filename);
      let root = path.parse(dir).root;

      while (dir !== root) {
        // Skip node_modules directories
        if (path.basename(dir) === 'node_modules') {
          dir = path.dirname(dir);
        }

        try {
          // First, check if the module directory exists. This prevents a lot of unnecessary checks later.
          let moduleDir = path.join(dir, 'node_modules', parts[0]);
          let stats = yield fs.stat(moduleDir);
          if (stats.isDirectory()) {
            let f = path.join(dir, 'node_modules', filename);

            // If a module was specified as a module sub-path (e.g. some-module/some/path),
            // it is likely a file. Try loading it as a file first.
            if (parts.length > 1) {
              let pkg = yield _this3.readPackage(moduleDir);
              let res = yield _this3.loadAsFile(f, extensions, pkg);
              if (res) {
                return res;
              }
            }

            // Otherwise, load as a directory.
            return yield _this3.loadDirectory(f, extensions);
          }
        } catch (err) {}
        // ignore


        // Move up a directory
        dir = path.dirname(dir);
      }
    })();
  }

  isFile(file) {
    return _asyncToGenerator(function* () {
      try {
        let stat = yield fs.stat(file);
        return stat.isFile() || stat.isFIFO();
      } catch (err) {
        return false;
      }
    })();
  }

  loadDirectory(dir, extensions, pkg) {
    var _this4 = this;

    return _asyncToGenerator(function* () {
      try {
        pkg = yield _this4.readPackage(dir);

        // First try loading package.main as a file, then try as a directory.
        let main = _this4.getPackageMain(pkg);
        let res = (yield _this4.loadAsFile(main, extensions, pkg)) || (yield _this4.loadDirectory(main, extensions, pkg));

        if (res) {
          return res;
        }
      } catch (err) {}
      // ignore


      // Fall back to an index file inside the directory.
      return yield _this4.loadAsFile(path.join(dir, 'index'), extensions, pkg);
    })();
  }

  readPackage(dir) {
    var _this5 = this;

    return _asyncToGenerator(function* () {
      let file = path.join(dir, 'package.json');
      if (_this5.packageCache.has(file)) {
        return _this5.packageCache.get(file);
      }

      let json = yield fs.readFile(file, 'utf8');
      let pkg = JSON.parse(json);

      pkg.pkgfile = file;
      pkg.pkgdir = dir;

      _this5.packageCache.set(file, pkg);
      return pkg;
    })();
  }

  getPackageMain(pkg) {
    // libraries like d3.js specifies node.js specific files in the "main" which breaks the build
    // we use the "module" or "jsnext:main" field to get the full dependency tree if available
    let main = [pkg.module, pkg['jsnext:main'], pkg.browser, pkg.main].find(entry => typeof entry === 'string');

    // Default to index file if no main field find
    if (!main || main === '.' || main === './') {
      main = 'index';
    }

    return path.resolve(pkg.pkgdir, main);
  }

  loadAsFile(file, extensions, pkg) {
    var _this6 = this;

    return _asyncToGenerator(function* () {
      // Try all supported extensions
      var _iteratorNormalCompletion = true;
      var _didIteratorError = false;
      var _iteratorError = undefined;

      try {
        for (var _iterator = _this6.expandFile(file, extensions, pkg)[Symbol.iterator](), _step; !(_iteratorNormalCompletion = (_step = _iterator.next()).done); _iteratorNormalCompletion = true) {
          let f = _step.value;

          if (yield _this6.isFile(f)) {
            return { path: f, pkg };
          }
        }
      } catch (err) {
        _didIteratorError = true;
        _iteratorError = err;
      } finally {
        try {
          if (!_iteratorNormalCompletion && _iterator.return) {
            _iterator.return();
          }
        } finally {
          if (_didIteratorError) {
            throw _iteratorError;
          }
        }
      }
    })();
  }

  expandFile(file, extensions, pkg, expandAliases = true) {
    // Expand extensions and aliases
    let res = [];
    var _iteratorNormalCompletion2 = true;
    var _didIteratorError2 = false;
    var _iteratorError2 = undefined;

    try {
      for (var _iterator2 = extensions[Symbol.iterator](), _step2; !(_iteratorNormalCompletion2 = (_step2 = _iterator2.next()).done); _iteratorNormalCompletion2 = true) {
        let ext = _step2.value;

        let f = file + ext;

        if (expandAliases) {
          let alias = this.resolveAliases(file + ext, pkg);
          if (alias !== f) {
            res = res.concat(this.expandFile(alias, extensions, pkg, false));
          }
        }

        res.push(f);
      }
    } catch (err) {
      _didIteratorError2 = true;
      _iteratorError2 = err;
    } finally {
      try {
        if (!_iteratorNormalCompletion2 && _iterator2.return) {
          _iterator2.return();
        }
      } finally {
        if (_didIteratorError2) {
          throw _iteratorError2;
        }
      }
    }

    return res;
  }

  resolveAliases(filename, pkg) {
    // First resolve local package aliases, then project global ones.
    return this.resolvePackageAliases(this.resolvePackageAliases(filename, pkg), this.rootPackage);
  }

  resolvePackageAliases(filename, pkg) {
    // Resolve aliases in the package.alias and package.browser fields.
    if (pkg) {
      return this.getAlias(filename, pkg.pkgdir, pkg.alias) || this.getAlias(filename, pkg.pkgdir, pkg.browser) || filename;
    }

    return filename;
  }

  getAlias(filename, dir, aliases) {
    if (!filename || !aliases || typeof aliases !== 'object') {
      return null;
    }

    let alias;

    // If filename is an absolute path, get one relative to the package.json directory.
    if (path.isAbsolute(filename)) {
      filename = path.relative(dir, filename);
      if (filename[0] !== '.') {
        filename = './' + filename;
      }

      alias = aliases[filename];
    } else {
      // It is a node_module. First try the entire filename as a key.
      alias = aliases[filename];
      if (alias == null) {
        // If it didn't match, try only the module name.
        let parts = this.getModuleParts(filename);
        alias = aliases[parts[0]];
        if (typeof alias === 'string') {
          // Append the filename back onto the aliased module.
          alias = path.join(alias, ...parts.slice(1));
        }
      }
    }

    // If the alias is set to `false`, return an empty file.
    if (alias === false) {
      return EMPTY_SHIM;
    }

    // If the alias is a relative path, then resolve
    // relative to the package.json directory.
    if (alias && alias[0] === '.') {
      return path.resolve(dir, alias);
    }

    // Otherwise, assume the alias is a module
    return alias;
  }

  findPackage(dir) {
    var _this7 = this;

    return _asyncToGenerator(function* () {
      // Find the nearest package.json file within the current node_modules folder
      let root = path.parse(dir).root;
      while (dir !== root && path.basename(dir) !== 'node_modules') {
        try {
          return yield _this7.readPackage(dir);
        } catch (err) {
          // ignore
        }

        dir = path.dirname(dir);
      }
    })();
  }

  loadAlias(filename, dir) {
    var _this8 = this;

    return _asyncToGenerator(function* () {
      // Load the root project's package.json file if we haven't already
      if (!_this8.rootPackage) {
        _this8.rootPackage = yield _this8.findPackage(_this8.options.rootDir);
      }

      // Load the local package, and resolve aliases
      let pkg = yield _this8.findPackage(dir);
      return _this8.resolveAliases(filename, pkg);
    })();
  }

  getModuleParts(name) {
    let parts = path.normalize(name).split(path.sep);
    if (parts[0].charAt(0) === '@') {
      // Scoped module (e.g. @scope/module). Merge the first two parts back together.
      parts.splice(0, 2, `${parts[0]}/${parts[1]}`);
    }

    return parts;
  }
}

module.exports = Resolver;