processing-js/src/Helpers/defaultScope.js

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/**
 * Processing.js default scope
 */
module.exports = function(options) {

  // Building defaultScope. Changing of the prototype protects
  // internal Processing code from the changes in defaultScope
  function DefaultScope() {}
  DefaultScope.prototype = options.PConstants;

  var defaultScope = new DefaultScope();

  // copy over all known Object types and helper objects
  Object.keys(options).forEach(function(prop) {
    defaultScope[prop] = options[prop];
  });

  ////////////////////////////////////////////////////////////////////////////
  // Class inheritance helper methods
  ////////////////////////////////////////////////////////////////////////////

  defaultScope.defineProperty = function(obj, name, desc) {
    if("defineProperty" in Object) {
      Object.defineProperty(obj, name, desc);
    } else {
      if (desc.hasOwnProperty("get")) {
        obj.__defineGetter__(name, desc.get);
      }
      if (desc.hasOwnProperty("set")) {
        obj.__defineSetter__(name, desc.set);
      }
    }
  };

  /**
   * class overloading, part 1
   */
  function overloadBaseClassFunction(object, name, basefn) {
    if (!object.hasOwnProperty(name) || typeof object[name] !== 'function') {
      // object method is not a function or just inherited from Object.prototype
      object[name] = basefn;
      return;
    }
    var fn = object[name];
    if ("$overloads" in fn) {
      // the object method already overloaded (see defaultScope.addMethod)
      // let's just change a fallback method
      fn.$defaultOverload = basefn;
      return;
    }
    if (!("$overloads" in basefn) && fn.length === basefn.length) {
      // special case when we just overriding the method
      return;
    }
    var overloads, defaultOverload;
    if ("$overloads" in basefn) {
      // let's inherit base class overloads to speed up things
      overloads = basefn.$overloads.slice(0);
      overloads[fn.length] = fn;
      defaultOverload = basefn.$defaultOverload;
    } else {
      overloads = [];
      overloads[basefn.length] = basefn;
      overloads[fn.length] = fn;
      defaultOverload = fn;
    }
    var hubfn = function() {
      var fn = hubfn.$overloads[arguments.length] ||
               ("$methodArgsIndex" in hubfn && arguments.length > hubfn.$methodArgsIndex ?
               hubfn.$overloads[hubfn.$methodArgsIndex] : null) ||
               hubfn.$defaultOverload;
      return fn.apply(this, arguments);
    };
    hubfn.$overloads = overloads;
    if ("$methodArgsIndex" in basefn) {
      hubfn.$methodArgsIndex = basefn.$methodArgsIndex;
    }
    hubfn.$defaultOverload = defaultOverload;
    hubfn.name = name;
    object[name] = hubfn;
  }

  /**
   * class overloading, part 2
   */

  function extendClass(subClass, baseClass) {
    function extendGetterSetter(propertyName) {
      defaultScope.defineProperty(subClass, propertyName, {
        get: function() {
          return baseClass[propertyName];
        },
        set: function(v) {
          baseClass[propertyName]=v;
        },
        enumerable: true
      });
    }

    var properties = [];
    for (var propertyName in baseClass) {
      if (typeof baseClass[propertyName] === 'function') {
        overloadBaseClassFunction(subClass, propertyName, baseClass[propertyName]);
      } else if(propertyName.charAt(0) !== "$" && !(propertyName in subClass)) {
        // Delaying the properties extension due to the IE9 bug (see #918).
        properties.push(propertyName);
      }
    }
    while (properties.length > 0) {
      extendGetterSetter(properties.shift());
    }

    subClass.$super = baseClass;
  }

  /**
   * class overloading, part 3
   */
  defaultScope.extendClassChain = function(base) {
    var path = [base];
    for (var self = base.$upcast; self; self = self.$upcast) {
      extendClass(self, base);
      path.push(self);
      base = self;
    }
    while (path.length > 0) {
      path.pop().$self=base;
    }
  };

  // static
  defaultScope.extendStaticMembers = function(derived, base) {
    extendClass(derived, base);
  };

  // interface
  defaultScope.extendInterfaceMembers = function(derived, base) {
    extendClass(derived, base);
  };

  /**
   * Java methods and JavaScript functions differ enough that
   * we need a special function to make sure it all links up
   * as classical hierarchical class chains.
   */
  defaultScope.addMethod = function(object, name, fn, hasMethodArgs) {
    var existingfn = object[name];
    if (existingfn || hasMethodArgs) {
      var args = fn.length;
      // builds the overload methods table
      if ("$overloads" in existingfn) {
        existingfn.$overloads[args] = fn;
      } else {
        var hubfn = function() {
          var fn = hubfn.$overloads[arguments.length] ||
                   ("$methodArgsIndex" in hubfn && arguments.length > hubfn.$methodArgsIndex ?
                   hubfn.$overloads[hubfn.$methodArgsIndex] : null) ||
                   hubfn.$defaultOverload;
          return fn.apply(this, arguments);
        };
        var overloads = [];
        if (existingfn) {
          overloads[existingfn.length] = existingfn;
        }
        overloads[args] = fn;
        hubfn.$overloads = overloads;
        hubfn.$defaultOverload = existingfn || fn;
        if (hasMethodArgs) {
          hubfn.$methodArgsIndex = args;
        }
        hubfn.name = name;
        object[name] = hubfn;
      }
    } else {
      object[name] = fn;
    }
  };

  // internal helper function
  function isNumericalJavaType(type) {
    if (typeof type !== "string") {
      return false;
    }
    return ["byte", "int", "char", "color", "float", "long", "double"].indexOf(type) !== -1;
  }

  /**
   * Java's arrays are pre-filled when declared with
   * an initial size, but no content. JS arrays are not.
   */
  defaultScope.createJavaArray = function(type, bounds) {
    var result = null,
        defaultValue = null;
    if (typeof type === "string") {
      if (type === "boolean") {
        defaultValue = false;
      } else if (isNumericalJavaType(type)) {
        defaultValue = 0;
      }
    }
    if (typeof bounds[0] === 'number') {
      var itemsCount = 0 | bounds[0];
      if (bounds.length <= 1) {
        result = [];
        result.length = itemsCount;
        for (var i = 0; i < itemsCount; ++i) {
          result[i] = defaultValue;
        }
      } else {
        result = [];
        var newBounds = bounds.slice(1);
        for (var j = 0; j < itemsCount; ++j) {
          result.push(defaultScope.createJavaArray(type, newBounds));
        }
      }
    }
    return result;
  };

  // screenWidth and screenHeight are shared by all instances.
  // and return the width/height of the browser's viewport.
  defaultScope.defineProperty(defaultScope, 'screenWidth',
    { get: function() { return window.innerWidth; } });

  defaultScope.defineProperty(defaultScope, 'screenHeight',
    { get: function() { return window.innerHeight; } });

  return defaultScope;
};