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/* ****************************************************************************
*
* Copyright (c) Microsoft Corporation.
*
* This source code is subject to terms and conditions of the Apache License, Version 2.0. A
* copy of the license can be found in the License.html file at the root of this distribution. If
* you cannot locate the Apache License, Version 2.0, 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 Apache License, Version 2.0.
*
* You must not remove this notice, or any other, from this software.
*
*
* ***************************************************************************/
#if CLR2
using Microsoft.Scripting.Ast;
using Microsoft.Scripting.Ast.Compiler;
#else
using System.Linq.Expressions;
using System.Linq.Expressions.Compiler;
#endif
#if SILVERLIGHT
using System.Core;
#else
using System.Runtime.Remoting;
#endif
using System.Collections.ObjectModel;
using System.Diagnostics;
using System.Dynamic.Utils;
using System.Runtime.CompilerServices;
namespace System.Dynamic {
/// <summary>
/// The dynamic call site binder that participates in the <see cref="DynamicMetaObject"/> binding protocol.
/// </summary>
/// <remarks>
/// The <see cref="CallSiteBinder"/> performs the binding of the dynamic operation using the runtime values
/// as input. On the other hand, the <see cref="DynamicMetaObjectBinder"/> participates in the <see cref="DynamicMetaObject"/>
/// binding protocol.
/// </remarks>
public abstract class DynamicMetaObjectBinder : CallSiteBinder {
#region Public APIs
/// <summary>
/// Initializes a new instance of the <see cref="DynamicMetaObjectBinder"/> class.
/// </summary>
protected DynamicMetaObjectBinder() {
}
/// <summary>
/// The result type of the operation.
/// </summary>
public virtual Type ReturnType {
get { return typeof(object); }
}
/// <summary>
/// Performs the runtime binding of the dynamic operation on a set of arguments.
/// </summary>
/// <param name="args">An array of arguments to the dynamic operation.</param>
/// <param name="parameters">The array of <see cref="ParameterExpression"/> instances that represent the parameters of the call site in the binding process.</param>
/// <param name="returnLabel">A LabelTarget used to return the result of the dynamic binding.</param>
/// <returns>
/// An Expression that performs tests on the dynamic operation arguments, and
/// performs the dynamic operation if the tests are valid. If the tests fail on
/// subsequent occurrences of the dynamic operation, Bind will be called again
/// to produce a new <see cref="Expression"/> for the new argument types.
/// </returns>
public sealed override Expression Bind(object[] args, ReadOnlyCollection<ParameterExpression> parameters, LabelTarget returnLabel) {
ContractUtils.RequiresNotNull(args, "args");
ContractUtils.RequiresNotNull(parameters, "parameters");
ContractUtils.RequiresNotNull(returnLabel, "returnLabel");
if (args.Length == 0) {
throw Error.OutOfRange("args.Length", 1);
}
if (parameters.Count == 0) {
throw Error.OutOfRange("parameters.Count", 1);
}
if (args.Length != parameters.Count) {
throw new ArgumentOutOfRangeException("args");
}
// Ensure that the binder's ReturnType matches CallSite's return
// type. We do this so meta objects and language binders can
// compose trees together without needing to insert converts.
Type expectedResult;
if (IsStandardBinder) {
expectedResult = ReturnType;
if (returnLabel.Type != typeof(void) &&
!TypeUtils.AreReferenceAssignable(returnLabel.Type, expectedResult)) {
throw Error.BinderNotCompatibleWithCallSite(expectedResult, this, returnLabel.Type);
}
} else {
// Even for non-standard binders, we have to at least make sure
// it works with the CallSite's type to build the return.
expectedResult = returnLabel.Type;
}
DynamicMetaObject target = DynamicMetaObject.Create(args[0], parameters[0]);
DynamicMetaObject[] metaArgs = CreateArgumentMetaObjects(args, parameters);
DynamicMetaObject binding = Bind(target, metaArgs);
if (binding == null) {
throw Error.BindingCannotBeNull();
}
Expression body = binding.Expression;
BindingRestrictions restrictions = binding.Restrictions;
// Ensure the result matches the expected result type.
if (expectedResult != typeof(void) &&
!TypeUtils.AreReferenceAssignable(expectedResult, body.Type)) {
//
// Blame the last person that handled the result: assume it's
// the dynamic object (if any), otherwise blame the language.
//
if (target.Value is IDynamicMetaObjectProvider) {
throw Error.DynamicObjectResultNotAssignable(body.Type, target.Value.GetType(), this, expectedResult);
} else {
throw Error.DynamicBinderResultNotAssignable(body.Type, this, expectedResult);
}
}
// if the target is IDO, standard binders ask it to bind the rule so we may have a target-specific binding.
// it makes sense to restrict on the target's type in such cases.
// ideally IDO metaobjects should do this, but they often miss that type of "this" is significant.
if (IsStandardBinder && args[0] as IDynamicMetaObjectProvider != null) {
if (restrictions == BindingRestrictions.Empty) {
throw Error.DynamicBindingNeedsRestrictions(target.Value.GetType(), this);
}
}
restrictions = AddRemoteObjectRestrictions(restrictions, args, parameters);
// Add the return
if (body.NodeType != ExpressionType.Goto) {
body = Expression.Return(returnLabel, body);
}
// Finally, add restrictions
if (restrictions != BindingRestrictions.Empty) {
body = Expression.IfThen(restrictions.ToExpression(), body);
}
return body;
}
private static DynamicMetaObject[] CreateArgumentMetaObjects(object[] args, ReadOnlyCollection<ParameterExpression> parameters) {
DynamicMetaObject[] mos;
if (args.Length != 1) {
mos = new DynamicMetaObject[args.Length - 1];
for (int i = 1; i < args.Length; i++) {
mos[i - 1] = DynamicMetaObject.Create(args[i], parameters[i]);
}
} else {
mos = DynamicMetaObject.EmptyMetaObjects;
}
return mos;
}
private static BindingRestrictions AddRemoteObjectRestrictions(BindingRestrictions restrictions, object[] args, ReadOnlyCollection<ParameterExpression> parameters) {
#if !SILVERLIGHT
for (int i = 0; i < parameters.Count; i++) {
var expr = parameters[i];
var value = args[i] as MarshalByRefObject;
// special case for MBR objects.
// when MBR objects are remoted they can have different conversion behavior
// so bindings created for local and remote objects should not be mixed.
if (value != null && !IsComObject(value)) {
BindingRestrictions remotedRestriction;
if (RemotingServices.IsObjectOutOfAppDomain(value)) {
remotedRestriction = BindingRestrictions.GetExpressionRestriction(
Expression.AndAlso(
Expression.NotEqual(expr, Expression.Constant(null)),
Expression.Call(
typeof(RemotingServices).GetMethod("IsObjectOutOfAppDomain"),
expr
)
)
);
} else {
remotedRestriction = BindingRestrictions.GetExpressionRestriction(
Expression.AndAlso(
Expression.NotEqual(expr, Expression.Constant(null)),
Expression.Not(
Expression.Call(
typeof(RemotingServices).GetMethod("IsObjectOutOfAppDomain"),
expr
)
)
)
);
}
restrictions = restrictions.Merge(remotedRestriction);
}
}
#endif
return restrictions;
}
/// <summary>
/// When overridden in the derived class, performs the binding of the dynamic operation.
/// </summary>
/// <param name="target">The target of the dynamic operation.</param>
/// <param name="args">An array of arguments of the dynamic operation.</param>
/// <returns>The <see cref="DynamicMetaObject"/> representing the result of the binding.</returns>
public abstract DynamicMetaObject Bind(DynamicMetaObject target, DynamicMetaObject[] args);
/// <summary>
/// Gets an expression that will cause the binding to be updated. It
/// indicates that the expression's binding is no longer valid.
/// This is typically used when the "version" of a dynamic object has
/// changed.
/// </summary>
/// <param name="type">The <see cref="Expression.Type">Type</see> property of the resulting expression; any type is allowed.</param>
/// <returns>The update expression.</returns>
[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Performance", "CA1822:MarkMembersAsStatic")]
public Expression GetUpdateExpression(Type type) {
return Expression.Goto(CallSiteBinder.UpdateLabel, type);
}
/// <summary>
/// Defers the binding of the operation until later time when the runtime values of all dynamic operation arguments have been computed.
/// </summary>
/// <param name="target">The target of the dynamic operation.</param>
/// <param name="args">An array of arguments of the dynamic operation.</param>
/// <returns>The <see cref="DynamicMetaObject"/> representing the result of the binding.</returns>
public DynamicMetaObject Defer(DynamicMetaObject target, params DynamicMetaObject[] args) {
ContractUtils.RequiresNotNull(target, "target");
if (args == null) {
return MakeDeferred(target.Restrictions, target);
} else {
return MakeDeferred(
target.Restrictions.Merge(BindingRestrictions.Combine(args)),
args.AddFirst(target)
);
}
}
/// <summary>
/// Defers the binding of the operation until later time when the runtime values of all dynamic operation arguments have been computed.
/// </summary>
/// <param name="args">An array of arguments of the dynamic operation.</param>
/// <returns>The <see cref="DynamicMetaObject"/> representing the result of the binding.</returns>
public DynamicMetaObject Defer(params DynamicMetaObject[] args) {
return MakeDeferred(BindingRestrictions.Combine(args), args);
}
private DynamicMetaObject MakeDeferred(BindingRestrictions rs, params DynamicMetaObject[] args) {
var exprs = DynamicMetaObject.GetExpressions(args);
Type delegateType = DelegateHelpers.MakeDeferredSiteDelegate(args, ReturnType);
// Because we know the arguments match the delegate type (we just created the argument types)
// we go directly to DynamicExpression.Make to avoid a bunch of unnecessary argument validation
return new DynamicMetaObject(
DynamicExpression.Make(ReturnType, delegateType, this, new TrueReadOnlyCollection<Expression>(exprs)),
rs
);
}
#endregion
// used to detect standard MetaObjectBinders.
internal virtual bool IsStandardBinder {
get {
return false;
}
}
#if !SILVERLIGHT
private static readonly Type ComObjectType = typeof(object).Assembly.GetType("System.__ComObject");
private static bool IsComObject(object obj) {
// we can't use System.Runtime.InteropServices.Marshal.IsComObject(obj) since it doesn't work in partial trust
return obj != null && ComObjectType.IsAssignableFrom(obj.GetType());
}
#endif
}
}
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