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 * Copyright (c) Microsoft Corporation. 
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 * copy of the license can be found in the License.html file at the root of this distribution. If 
 * you cannot locate the  Microsoft Public License, please send an email to 
 * dlr@microsoft.com. By using this source code in any fashion, you are agreeing to be bound 
 * by the terms of the Microsoft Public License.
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 * You must not remove this notice, or any other, from this software.
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using System.Dynamic.Utils;

namespace System.Dynamic {

    /// <summary>
    /// Represents the dynamic get index operation at the call site, providing the binding semantic and the details about the operation.
    /// </summary>
    public abstract class GetIndexBinder : DynamicMetaObjectBinder {
        private readonly CallInfo _callInfo;

        /// <summary>
        /// Initializes a new instance of the <see cref="GetIndexBinder" />.
        /// </summary>
        /// <param name="callInfo">The signature of the arguments at the call site.</param>
        protected GetIndexBinder(CallInfo callInfo) {
            ContractUtils.RequiresNotNull(callInfo, "callInfo");
            _callInfo = callInfo;
        }

        /// <summary>
        /// The result type of the operation.
        /// </summary>
        public override sealed Type ReturnType {
            get { return typeof(object); }
        }

        /// <summary>
        /// Gets the signature of the arguments at the call site.
        /// </summary>
        public CallInfo CallInfo {
            get { return _callInfo; }
        }

        /// <summary>
        /// Performs the binding of the dynamic get index operation.
        /// </summary>
        /// <param name="target">The target of the dynamic get index operation.</param>
        /// <param name="args">An array of arguments of the dynamic get index operation.</param>
        /// <returns>The <see cref="DynamicMetaObject"/> representing the result of the binding.</returns>
        public sealed override DynamicMetaObject Bind(DynamicMetaObject target, DynamicMetaObject[] args) {
            ContractUtils.RequiresNotNull(target, "target");
            ContractUtils.RequiresNotNullItems(args, "args");

            return target.BindGetIndex(this, args);
        }
        
        // this is a standard DynamicMetaObjectBinder
        internal override sealed bool IsStandardBinder {
            get {
                return true;
            }
        }

        /// <summary>
        /// Performs the binding of the dynamic get index operation if the target dynamic object cannot bind.
        /// </summary>
        /// <param name="target">The target of the dynamic get index operation.</param>
        /// <param name="indexes">The arguments of the dynamic get index operation.</param>
        /// <returns>The <see cref="DynamicMetaObject"/> representing the result of the binding.</returns>
        public DynamicMetaObject FallbackGetIndex(DynamicMetaObject target, DynamicMetaObject[] indexes) {
            return FallbackGetIndex(target, indexes, null);
        }

        /// <summary>
        /// When overridden in the derived class, performs the binding of the dynamic get index operation if the target dynamic object cannot bind.
        /// </summary>
        /// <param name="target">The target of the dynamic get index operation.</param>
        /// <param name="indexes">The arguments of the dynamic get index operation.</param>
        /// <param name="errorSuggestion">The binding result to use if binding fails, or null.</param>
        /// <returns>The <see cref="DynamicMetaObject"/> representing the result of the binding.</returns>
        public abstract DynamicMetaObject FallbackGetIndex(DynamicMetaObject target, DynamicMetaObject[] indexes, DynamicMetaObject errorSuggestion);
    }
}