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/* ****************************************************************************
*
* Copyright (c) Microsoft Corporation.
*
* This source code is subject to terms and conditions of the Microsoft Public License. A
* 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.
*
* You must not remove this notice, or any other, from this software.
*
*
* ***************************************************************************/
using System;
using System.Diagnostics;
using System.Dynamic.Utils;
#if SILVERLIGHT
using System.Core;
#endif
#if CLR2
namespace Microsoft.Scripting.Ast {
#else
namespace System.Linq.Expressions {
#endif
/// <summary>
/// Represents a catch statement in a try block.
/// This must have the same return type (i.e., the type of <see cref="P:CatchBlock.Body"/>) as the try block it is associated with.
/// </summary>
#if !SILVERLIGHT
[DebuggerTypeProxy(typeof(Expression.CatchBlockProxy))]
#endif
public sealed class CatchBlock {
private readonly Type _test;
private readonly ParameterExpression _var;
private readonly Expression _body;
private readonly Expression _filter;
internal CatchBlock(Type test, ParameterExpression variable, Expression body, Expression filter) {
_test = test;
_var = variable;
_body = body;
_filter = filter;
}
/// <summary>
/// Gets a reference to the <see cref="Exception"/> object caught by this handler.
/// </summary>
public ParameterExpression Variable {
get { return _var; }
}
/// <summary>
/// Gets the type of <see cref="Exception"/> this handler catches.
/// </summary>
public Type Test {
get { return _test; }
}
/// <summary>
/// Gets the body of the catch block.
/// </summary>
public Expression Body {
get { return _body; }
}
/// <summary>
/// Gets the body of the <see cref="CatchBlock"/>'s filter.
/// </summary>
public Expression Filter {
get {
return _filter;
}
}
/// <summary>
/// Returns a <see cref="String"/> that represents the current <see cref="Object"/>.
/// </summary>
/// <returns>A <see cref="String"/> that represents the current <see cref="Object"/>. </returns>
public override string ToString() {
return ExpressionStringBuilder.CatchBlockToString(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="variable">The <see cref="Variable" /> property of the result.</param>
/// <param name="filter">The <see cref="Filter" /> property of the result.</param>
/// <param name="body">The <see cref="Body" /> property of the result.</param>
/// <returns>This expression if no children changed, or an expression with the updated children.</returns>
public CatchBlock Update(ParameterExpression variable, Expression filter, Expression body) {
if (variable == Variable && filter == Filter && body == Body) {
return this;
}
return Expression.MakeCatchBlock(Test, variable, body, filter);
}
}
public partial class Expression {
/// <summary>
/// Creates a <see cref="CatchBlock"/> representing a catch statement.
/// The <see cref="Type"/> of object to be caught can be specified but no reference to the object
/// will be available for use in the <see cref="CatchBlock"/>.
/// </summary>
/// <param name="type">The <see cref="Type"/> of <see cref="Exception"/> this <see cref="CatchBlock"/> will handle.</param>
/// <param name="body">The body of the catch statement.</param>
/// <returns>The created <see cref="CatchBlock"/>.</returns>
public static CatchBlock Catch(Type type, Expression body) {
return MakeCatchBlock(type, null, body, null);
}
/// <summary>
/// Creates a <see cref="CatchBlock"/> representing a catch statement with a reference to the caught object for use in the handler body.
/// </summary>
/// <param name="variable">A <see cref="ParameterExpression"/> representing a reference to the <see cref="Exception"/> object caught by this handler.</param>
/// <param name="body">The body of the catch statement.</param>
/// <returns>The created <see cref="CatchBlock"/>.</returns>
public static CatchBlock Catch(ParameterExpression variable, Expression body) {
ContractUtils.RequiresNotNull(variable, "variable");
return MakeCatchBlock(variable.Type, variable, body, null);
}
/// <summary>
/// Creates a <see cref="CatchBlock"/> representing a catch statement with
/// an <see cref="Exception"/> filter but no reference to the caught <see cref="Exception"/> object.
/// </summary>
/// <param name="type">The <see cref="Type"/> of <see cref="Exception"/> this <see cref="CatchBlock"/> will handle.</param>
/// <param name="body">The body of the catch statement.</param>
/// <param name="filter">The body of the <see cref="Exception"/> filter.</param>
/// <returns>The created <see cref="CatchBlock"/>.</returns>
public static CatchBlock Catch(Type type, Expression body, Expression filter) {
return MakeCatchBlock(type, null, body, filter);
}
/// <summary>
/// Creates a <see cref="CatchBlock"/> representing a catch statement with
/// an <see cref="Exception"/> filter and a reference to the caught <see cref="Exception"/> object.
/// </summary>
/// <param name="variable">A <see cref="ParameterExpression"/> representing a reference to the <see cref="Exception"/> object caught by this handler.</param>
/// <param name="body">The body of the catch statement.</param>
/// <param name="filter">The body of the <see cref="Exception"/> filter.</param>
/// <returns>The created <see cref="CatchBlock"/>.</returns>
public static CatchBlock Catch(ParameterExpression variable, Expression body, Expression filter) {
ContractUtils.RequiresNotNull(variable, "variable");
return MakeCatchBlock(variable.Type, variable, body, filter);
}
/// <summary>
/// Creates a <see cref="CatchBlock"/> representing a catch statement with the specified elements.
/// </summary>
/// <param name="type">The <see cref="Type"/> of <see cref="Exception"/> this <see cref="CatchBlock"/> will handle.</param>
/// <param name="variable">A <see cref="ParameterExpression"/> representing a reference to the <see cref="Exception"/> object caught by this handler.</param>
/// <param name="body">The body of the catch statement.</param>
/// <param name="filter">The body of the <see cref="Exception"/> filter.</param>
/// <returns>The created <see cref="CatchBlock"/>.</returns>
/// <remarks><paramref name="type"/> must be non-null and match the type of <paramref name="variable"/> (if it is supplied).</remarks>
public static CatchBlock MakeCatchBlock(Type type, ParameterExpression variable, Expression body, Expression filter) {
ContractUtils.RequiresNotNull(type, "type");
ContractUtils.Requires(variable == null || TypeUtils.AreEquivalent(variable.Type, type), "variable");
if (variable != null && variable.IsByRef) {
throw Error.VariableMustNotBeByRef(variable, variable.Type);
}
RequiresCanRead(body, "body");
if (filter != null) {
RequiresCanRead(filter, "filter");
if (filter.Type != typeof(bool)) throw Error.ArgumentMustBeBoolean();
}
return new CatchBlock(type, variable, body, filter);
}
}
}
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