/Jurassic/Library/Function/FunctionInstance.cs

using System;

using System.Collections.Generic;



namespace Jurassic.Library

{

    /// <summary>

    /// Represents a JavaScript function.

    /// </summary>

    [Serializable]

    public abstract class FunctionInstance : ObjectInstance

    {

        // Used to speed up access to the prototype property.

        private int cachedInstancePrototypeIndex;

        private object cachedInstancePrototypeSchema;





        //     INITIALIZATION

        //_________________________________________________________________________________________



        /// <summary>

        /// Creates a new instance of a built-in function object, with the default Function

        /// prototype.

        /// </summary>

        /// <param name="engine"> The associated script engine. </param>

        protected FunctionInstance(ScriptEngine engine)

            : base(engine, engine.Function.InstancePrototype)

        {

        }



        /// <summary>

        /// Creates a new instance of a built-in function object.

        /// </summary>

        /// <param name="prototype"> The next object in the prototype chain. </param>

        protected FunctionInstance(ObjectInstance prototype)

            : base(prototype)

        {

        }



        /// <summary>

        /// Creates a new instance of a built-in function object.

        /// </summary>

        /// <param name="engine"> The associated script engine. </param>

        /// <param name="prototype"> The next object in the prototype chain.  Can be <c>null</c>. </param>

        protected FunctionInstance(ScriptEngine engine, ObjectInstance prototype)

            : base(engine, prototype)

        {

        }







        //     .NET ACCESSOR PROPERTIES

        //_________________________________________________________________________________________



        /// <summary>

        /// Gets the internal class name of the object.  Used by the default toString()

        /// implementation.

        /// </summary>

        protected override string InternalClassName

        {

            get { return "Function"; }

        }



        /// <summary>

        /// Gets the prototype of objects constructed using this function.  Equivalent to

        /// the Function.prototype property.

        /// </summary>

        public ObjectInstance InstancePrototype

        {

            get

            {

                // See 13.2.2

                

                // Retrieve the value of the prototype property.

                //var prototype = this["prototype"] as ObjectInstance;

                ObjectInstance prototype;

                if (this.cachedInstancePrototypeSchema == this.InlineCacheKey)

                    prototype = this.InlinePropertyValues[this.cachedInstancePrototypeIndex] as ObjectInstance;

                else

                    prototype = this.InlineGetPropertyValue("prototype", out this.cachedInstancePrototypeIndex, out this.cachedInstancePrototypeSchema) as ObjectInstance;



                // If the prototype property is not set to an object, use the Object prototype property instead.

                if (prototype == null && this != this.Engine.Object)

                    return this.Engine.Object.InstancePrototype;



                return prototype;

            }

        }



        /// <summary>

        /// Gets the name of the function.

        /// </summary>

        public string Name

        {

            get { return TypeConverter.ToString(this["name"]); }

        }



        /// <summary>

        /// Gets the display name of the function.  This is equal to the displayName property, if

        /// it exists, or the name property otherwise.

        /// </summary>

        public string DisplayName

        {

            get

            {

                if (this.HasProperty("displayName"))

                    return TypeConverter.ToString(this["displayName"]);

                var name = TypeConverter.ToString(this["name"]);

                if (name == string.Empty)

                    return "[Anonymous]";

                return name;

            }

        }



        /// <summary>

        /// Gets the number of arguments expected by the function.

        /// </summary>

        public int Length

        {

            get { return TypeConverter.ToInteger(this["length"]); }

            protected set { this.FastSetProperty("length", value); }

        }







        //     JAVASCRIPT INTERNAL FUNCTIONS

        //_________________________________________________________________________________________



        /// <summary>

        /// Determines whether the given object inherits from this function.  More precisely, it

        /// checks whether the prototype chain of the object contains the prototype property of

        /// this function.  Used by the "instanceof" operator.

        /// </summary>

        /// <param name="instance"> The instance to check. </param>

        /// <returns> <c>true</c> if the object inherits from this function; <c>false</c>

        /// otherwise. </returns>

        public virtual bool HasInstance(object instance)

        {

            if ((instance is ObjectInstance) == false)

                return false;

            object functionPrototype = this["prototype"];

            if ((functionPrototype is ObjectInstance) == false)

                throw new JavaScriptException(this.Engine, "TypeError", "Function has non-object prototype in instanceof check");

            var instancePrototype = ((ObjectInstance)instance).Prototype;

            while (instancePrototype != null)

            {

                if (instancePrototype == functionPrototype)

                    return true;

                instancePrototype = instancePrototype.Prototype;

            }

            return false;

        }



        /// <summary>

        /// Calls this function, passing in the given "this" value and zero or more arguments.

        /// </summary>

        /// <param name="thisObject"> The value of the "this" keyword within the function. </param>

        /// <param name="argumentValues"> An array of argument values. </param>

        /// <returns> The value that was returned from the function. </returns>

        public abstract object CallLateBound(object thisObject, params object[] argumentValues);



        /// <summary>

        /// Creates an object, using this function as the constructor.

        /// </summary>

        /// <param name="argumentValues"> An array of argument values. </param>

        /// <returns> The object that was created. </returns>

        public virtual ObjectInstance ConstructLateBound(params object[] argumentValues)

        {

            // Create a new object and set the prototype to the instance prototype of the function.

            var newObject = ObjectInstance.CreateRawObject(this.InstancePrototype);



            // Run the function, with the new object as the "this" keyword.

            var result = CallLateBound(newObject, argumentValues);



            // Return the result of the function if it is an object.

            if (result is ObjectInstance)

                return (ObjectInstance)result;



            // Otherwise, return the new object.

            return newObject;

        }







        //     JAVASCRIPT FUNCTIONS

        //_________________________________________________________________________________________



        /// <summary>

        /// Calls the function, passing in parameters from the given array.

        /// </summary>

        /// <param name="thisObj"> The value of <c>this</c> in the context of the function. </param>

        /// <param name="argumentArray"> The arguments passed to the function, as an array. </param>

        /// <returns> The result from the function call. </returns>

        [JSInternalFunction(Name = "apply")]

        public object Apply(object thisObj, object arguments)

        {

            // Convert the arguments parameter into an array.

            object[] argumentsArray;

            if (arguments == null || arguments == Undefined.Value || arguments == Null.Value)

                argumentsArray = new object[0];

            else

            {

                if ((arguments is ObjectInstance) == false)

                    throw new JavaScriptException(this.Engine, "TypeError", "The second parameter of apply() must be an array or an array-like object.");

                ObjectInstance argumentsObject = (ObjectInstance)arguments;

                object arrayLengthObj = argumentsObject["length"];

                if (arrayLengthObj == null || arrayLengthObj == Undefined.Value || arrayLengthObj == Null.Value)

                    throw new JavaScriptException(this.Engine, "TypeError", "The second parameter of apply() must be an array or an array-like object.");

                uint arrayLength = TypeConverter.ToUint32(arrayLengthObj);

                if (arrayLength != TypeConverter.ToNumber(arrayLengthObj))

                    throw new JavaScriptException(this.Engine, "TypeError", "The second parameter of apply() must be an array or an array-like object.");

                argumentsArray = new object[arrayLength];

                for (uint i = 0; i < arrayLength; i++)

                    argumentsArray[i] = argumentsObject[i];

            }



            return this.CallLateBound(thisObj, argumentsArray);

        }



        /// <summary>

        /// Calls the function.

        /// </summary>

        /// <param name="thisObj"> The value of <c>this</c> in the context of the function. </param>

        /// <param name="arguments"> Any number of arguments that will be passed to the function. </param>

        /// <returns> The result from the function call. </returns>

        [JSInternalFunction(Name = "call", Length = 1)]

        public object Call(object thisObj, params object[] arguments)

        {

            return this.CallLateBound(thisObj, arguments);

        }



        /// <summary>

        /// Creates a new function that, when called, calls this function with the given "this"

        /// value and, optionally, one or more more arguments.

        /// </summary>

        /// <param name="boundThis"> The fixed value of "this". </param>

        /// <param name="boundArguments"> Any number of fixed arguments values. </param>

        /// <returns> A new function. </returns>

        [JSInternalFunction(Name = "bind", Length = 1)]

        public FunctionInstance Bind(object boundThis, params object[] boundArguments)

        {

            return new BoundFunction(this, boundThis, boundArguments);

        }



        /// <summary>

        /// Returns a string representing this object.

        /// </summary>

        /// <returns> A string representing this object. </returns>

        [JSInternalFunction(Name = "toString")]

        public string ToStringJS()

        {

            return this.ToString();

        }

    }

}