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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.
*
*
* ***************************************************************************/
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Diagnostics;
using System.Dynamic.Utils;
using System.Runtime.CompilerServices;
#if !FEATURE_CORE_DLR
namespace Microsoft.Scripting.Ast {
#else
namespace System.Linq.Expressions {
#endif
/// <summary>
/// An expression that provides runtime read/write access to variables.
/// Needed to implement "eval" in some dynamic languages.
/// Evaluates to an instance of <see cref="IList{IStrongBox}" /> when executed.
/// </summary>
[DebuggerTypeProxy(typeof(Expression.RuntimeVariablesExpressionProxy))]
public sealed class RuntimeVariablesExpression : Expression {
private readonly ReadOnlyCollection<ParameterExpression> _variables;
internal RuntimeVariablesExpression(ReadOnlyCollection<ParameterExpression> variables) {
_variables = variables;
}
/// <summary>
/// Gets the static type of the expression that this <see cref="Expression" /> represents.
/// </summary>
/// <returns>The <see cref="Type"/> that represents the static type of the expression.</returns>
public sealed override Type Type {
get { return typeof(IRuntimeVariables); }
}
/// <summary>
/// Returns the node type of this Expression. Extension nodes should return
/// ExpressionType.Extension when overriding this method.
/// </summary>
/// <returns>The <see cref="ExpressionType"/> of the expression.</returns>
public sealed override ExpressionType NodeType {
get { return ExpressionType.RuntimeVariables; }
}
/// <summary>
/// The variables or parameters to which to provide runtime access.
/// </summary>
public ReadOnlyCollection<ParameterExpression> Variables {
get { return _variables; }
}
/// <summary>
/// Dispatches to the specific visit method for this node type.
/// </summary>
protected internal override Expression Accept(ExpressionVisitor visitor) {
return visitor.VisitRuntimeVariables(this);
}
/// <summary>
/// Creates a new expression that is like this one, but using the
/// supplied children. If all of the children are the same, it will
/// return this expression.
/// </summary>
/// <param name="variables">The <see cref="Variables" /> property of the result.</param>
/// <returns>This expression if no children changed, or an expression with the updated children.</returns>
public RuntimeVariablesExpression Update(IEnumerable<ParameterExpression> variables) {
if (variables == Variables) {
return this;
}
return Expression.RuntimeVariables(variables);
}
}
public partial class Expression {
/// <summary>
/// Creates an instance of <see cref="T:System.Linq.Expressions.RuntimeVariablesExpression" />.
/// </summary>
/// <param name="variables">An array of <see cref="T:System.Linq.Expressions.ParameterExpression" /> objects to use to populate the <see cref="P:System.Linq.Expressions.RuntimeVariablesExpression.Variables" /> collection.</param>
/// <returns>An instance of <see cref="T:System.Linq.Expressions.RuntimeVariablesExpression" /> that has the <see cref="P:System.Linq.Expressions.Expression.NodeType" /> property equal to <see cref="F:System.Linq.Expressions.ExpressionType.RuntimeVariables" /> and the <see cref="P:System.Linq.Expressions.RuntimeVariablesExpression.Variables" /> property set to the specified value.</returns>
public static RuntimeVariablesExpression RuntimeVariables(params ParameterExpression[] variables) {
return RuntimeVariables((IEnumerable<ParameterExpression>)variables);
}
/// <summary>
/// Creates an instance of <see cref="T:System.Linq.Expressions.RuntimeVariablesExpression" />.
/// </summary>
/// <param name="variables">A collection of <see cref="T:System.Linq.Expressions.ParameterExpression" /> objects to use to populate the <see cref="P:System.Linq.Expressions.RuntimeVariablesExpression.Variables" /> collection.</param>
/// <returns>An instance of <see cref="T:System.Linq.Expressions.RuntimeVariablesExpression" /> that has the <see cref="P:System.Linq.Expressions.Expression.NodeType" /> property equal to <see cref="F:System.Linq.Expressions.ExpressionType.RuntimeVariables" /> and the <see cref="P:System.Linq.Expressions.RuntimeVariablesExpression.Variables" /> property set to the specified value.</returns>
public static RuntimeVariablesExpression RuntimeVariables(IEnumerable<ParameterExpression> variables) {
ContractUtils.RequiresNotNull(variables, "variables");
var vars = variables.ToReadOnly();
for (int i = 0; i < vars.Count; i++) {
Expression v = vars[i];
if (v == null) {
throw new ArgumentNullException("variables[" + i + "]");
}
}
return new RuntimeVariablesExpression(vars);
}
}
}
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