@loaders.gl/core/dist/es5/lib/select-loader.js

Framework-independent loaders for 3D graphics formats

"use strict";

var _interopRequireDefault = require("@babel/runtime/helpers/interopRequireDefault");

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.selectLoader = selectLoader;

var _typeof2 = _interopRequireDefault(require("@babel/runtime/helpers/typeof"));

var _registerLoaders = require("./register-loaders");

var _normalizeLoader = require("./loader-utils/normalize-loader");

var EXT_PATTERN = /[^.]+$/;

function selectLoader(loaders) {
  var url = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : '';
  var data = arguments.length > 2 && arguments[2] !== undefined ? arguments[2] : null;

  var _ref = arguments.length > 3 && arguments[3] !== undefined ? arguments[3] : {},
      _ref$nothrow = _ref.nothrow,
      nothrow = _ref$nothrow === void 0 ? false : _ref$nothrow;

  url = url || '';

  if (loaders && !Array.isArray(loaders)) {
    var _loader = loaders;
    (0, _normalizeLoader.normalizeLoader)(_loader);
    return _loader;
  }

  loaders = loaders || (0, _registerLoaders.getRegisteredLoaders)();
  normalizeLoaders(loaders);
  url = url.replace(/\?.*/, '');
  var loader = null;
  loader = loader || findLoaderByUrl(loaders, url);
  loader = loader || findLoaderByExamingInitialData(loaders, data);

  if (!loader) {
    if (nothrow) {
      return null;
    }

    throw new Error("No valid loader found for ".concat(url));
  }

  return loader;
}

function normalizeLoaders(loaders) {
  var _iteratorNormalCompletion = true;
  var _didIteratorError = false;
  var _iteratorError = undefined;

  try {
    for (var _iterator = loaders[Symbol.iterator](), _step; !(_iteratorNormalCompletion = (_step = _iterator.next()).done); _iteratorNormalCompletion = true) {
      var loader = _step.value;
      (0, _normalizeLoader.normalizeLoader)(loader);
    }
  } catch (err) {
    _didIteratorError = true;
    _iteratorError = err;
  } finally {
    try {
      if (!_iteratorNormalCompletion && _iterator["return"] != null) {
        _iterator["return"]();
      }
    } finally {
      if (_didIteratorError) {
        throw _iteratorError;
      }
    }
  }
}

function findLoaderByUrl(loaders, url) {
  var match = url.match(EXT_PATTERN);
  var extension = match && match[0];
  var loader = extension && findLoaderByExtension(loaders, extension);
  return loader;
}

function findLoaderByExtension(loaders, extension) {
  extension = extension.toLowerCase();
  var _iteratorNormalCompletion2 = true;
  var _didIteratorError2 = false;
  var _iteratorError2 = undefined;

  try {
    for (var _iterator2 = loaders[Symbol.iterator](), _step2; !(_iteratorNormalCompletion2 = (_step2 = _iterator2.next()).done); _iteratorNormalCompletion2 = true) {
      var loader = _step2.value;
      var _iteratorNormalCompletion3 = true;
      var _didIteratorError3 = false;
      var _iteratorError3 = undefined;

      try {
        for (var _iterator3 = loader.extensions[Symbol.iterator](), _step3; !(_iteratorNormalCompletion3 = (_step3 = _iterator3.next()).done); _iteratorNormalCompletion3 = true) {
          var loaderExtension = _step3.value;

          if (loaderExtension.toLowerCase() === extension) {
            return loader;
          }
        }
      } catch (err) {
        _didIteratorError3 = true;
        _iteratorError3 = err;
      } finally {
        try {
          if (!_iteratorNormalCompletion3 && _iterator3["return"] != null) {
            _iterator3["return"]();
          }
        } finally {
          if (_didIteratorError3) {
            throw _iteratorError3;
          }
        }
      }
    }
  } catch (err) {
    _didIteratorError2 = true;
    _iteratorError2 = err;
  } finally {
    try {
      if (!_iteratorNormalCompletion2 && _iterator2["return"] != null) {
        _iterator2["return"]();
      }
    } finally {
      if (_didIteratorError2) {
        throw _iteratorError2;
      }
    }
  }

  return null;
}

function findLoaderByExamingInitialData(loaders, data) {
  if (!data) {
    return null;
  }

  var _iteratorNormalCompletion4 = true;
  var _didIteratorError4 = false;
  var _iteratorError4 = undefined;

  try {
    for (var _iterator4 = loaders[Symbol.iterator](), _step4; !(_iteratorNormalCompletion4 = (_step4 = _iterator4.next()).done); _iteratorNormalCompletion4 = true) {
      var loader = _step4.value;

      if (typeof data === 'string') {
        if (testText(data, loader)) {
          return loader;
        }
      } else if (ArrayBuffer.isView(data)) {
        if (testBinary(data.buffer, data.byteOffset, loader)) {
          return loader;
        }
      } else if (data instanceof ArrayBuffer) {
        var byteOffset = 0;

        if (testBinary(data, byteOffset, loader)) {
          return loader;
        }
      }
    }
  } catch (err) {
    _didIteratorError4 = true;
    _iteratorError4 = err;
  } finally {
    try {
      if (!_iteratorNormalCompletion4 && _iterator4["return"] != null) {
        _iterator4["return"]();
      }
    } finally {
      if (_didIteratorError4) {
        throw _iteratorError4;
      }
    }
  }

  return null;
}

function testText(data, loader) {
  return loader.testText && loader.testText(data);
}

function testBinary(data, byteOffset, loader) {
  var type = Array.isArray(loader.test) ? 'array' : (0, _typeof2["default"])(loader.test);

  switch (type) {
    case 'function':
      return loader.test(data, loader);

    case 'string':
    case 'array':
      var tests = Array.isArray(loader.test) ? loader.test : [loader.test];
      return tests.some(function (test) {
        var magic = getMagicString(data, byteOffset, test.length);
        return test === magic;
      });

    default:
      return false;
  }
}

function getMagicString(arrayBuffer, byteOffset, length) {
  if (arrayBuffer.byteLength <= byteOffset + length) {
    return '';
  }

  var dataView = new DataView(arrayBuffer);
  var magic = '';

  for (var i = 0; i < length; i++) {
    magic += String.fromCharCode(dataView.getUint8(byteOffset + i));
  }

  return magic;
}
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