Code:
/ 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / Core / Microsoft / Scripting / Ast / SwitchExpression.cs / 1305376 / SwitchExpression.cs
/* **************************************************************************** * * 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.Collections.Generic; using System.Collections.ObjectModel; using System.Diagnostics; using System.Dynamic.Utils; using System.Reflection; #if SILVERLIGHT using System.Core; #endif namespace System.Linq.Expressions { ////// Represents a control expression that handles multiple selections by passing control to a #if !SILVERLIGHT [DebuggerTypeProxy(typeof(Expression.SwitchExpressionProxy))] #endif public sealed class SwitchExpression : Expression { private readonly Type _type; private readonly Expression _switchValue; private readonly ReadOnlyCollection. /// _cases; private readonly Expression _defaultBody; private readonly MethodInfo _comparison; internal SwitchExpression(Type type, Expression switchValue, Expression defaultBody, MethodInfo comparison, ReadOnlyCollection cases) { _type = type; _switchValue = switchValue; _defaultBody = defaultBody; _comparison = comparison; _cases = cases; } /// /// Gets the static type of the expression that this ///represents. /// The public sealed override Type Type { get { return _type; } } ///that represents the static type of the expression. /// Returns the node type of this Expression. Extension nodes should return /// ExpressionType.Extension when overriding this method. /// ///The public sealed override ExpressionType NodeType { get { return ExpressionType.Switch; } } ///of the expression. /// Gets the test for the switch. /// public Expression SwitchValue { get { return _switchValue; } } ////// Gets the collection of public ReadOnlyCollectionobjects for the switch. /// Cases { get { return _cases; } } /// /// Gets the test for the switch. /// public Expression DefaultBody { get { return _defaultBody; } } ////// Gets the equality comparison method, if any. /// public MethodInfo Comparison { get { return _comparison; } } ////// Dispatches to the specific visit method for this node type. /// protected internal override Expression Accept(ExpressionVisitor visitor) { return visitor.VisitSwitch(this); } internal bool IsLifted { get { if (_switchValue.Type.IsNullableType()) { return (_comparison == null) || !TypeUtils.AreEquivalent(_switchValue.Type, _comparison.GetParametersCached()[0].ParameterType.GetNonRefType()); } return false; } } ////// 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. /// /// Theproperty of the result. /// The property of the result. /// The property of the result. /// This expression if no children changed, or an expression with the updated children. public SwitchExpression Update(Expression switchValue, IEnumerablecases, Expression defaultBody) { if (switchValue == SwitchValue && cases == Cases && defaultBody == DefaultBody) { return this; } return Expression.Switch(Type, switchValue, defaultBody, Comparison, cases); } } public partial class Expression { /// /// Creates a /// The value to be tested against each case. /// The valid cases for this switch. ///. /// The created public static SwitchExpression Switch(Expression switchValue, params SwitchCase[] cases) { return Switch(switchValue, null, null, (IEnumerable. )cases); } /// /// Creates a /// The value to be tested against each case. /// The result of the switch if no cases are matched. /// The valid cases for this switch. ///. /// The created public static SwitchExpression Switch(Expression switchValue, Expression defaultBody, params SwitchCase[] cases) { return Switch(switchValue, defaultBody, null, (IEnumerable. )cases); } /// /// Creates a /// The value to be tested against each case. /// The result of the switch if no cases are matched. /// The equality comparison method to use. /// The valid cases for this switch. ///. /// The created public static SwitchExpression Switch(Expression switchValue, Expression defaultBody, MethodInfo comparison, params SwitchCase[] cases) { return Switch(switchValue, defaultBody, comparison, (IEnumerable. )cases); } /// /// Creates a /// The result type of the switch. /// The value to be tested against each case. /// The result of the switch if no cases are matched. /// The equality comparison method to use. /// The valid cases for this switch. ///. /// The created public static SwitchExpression Switch(Type type, Expression switchValue, Expression defaultBody, MethodInfo comparison, params SwitchCase[] cases) { return Switch(type, switchValue, defaultBody, comparison, (IEnumerable. )cases); } /// /// Creates a /// The value to be tested against each case. /// The result of the switch if no cases are matched. /// The equality comparison method to use. /// The valid cases for this switch. ///. /// The created public static SwitchExpression Switch(Expression switchValue, Expression defaultBody, MethodInfo comparison, IEnumerable. cases) { return Switch(null, switchValue, defaultBody, comparison, cases); } /// /// Creates a /// The result type of the switch. /// The value to be tested against each case. /// The result of the switch if no cases are matched. /// The equality comparison method to use. /// The valid cases for this switch. ///. /// The created public static SwitchExpression Switch(Type type, Expression switchValue, Expression defaultBody, MethodInfo comparison, IEnumerable. cases) { RequiresCanRead(switchValue, "switchValue"); if (switchValue.Type == typeof(void)) throw Error.ArgumentCannotBeOfTypeVoid(); var caseList = cases.ToReadOnly(); ContractUtils.RequiresNotEmpty(caseList, "cases"); ContractUtils.RequiresNotNullItems(caseList, "cases"); // Type of the result. Either provided, or it is type of the branches. Type resultType = type ?? caseList[0].Body.Type; bool customType = type != null; if (comparison != null) { var pms = comparison.GetParametersCached(); if (pms.Length != 2) { throw Error.IncorrectNumberOfMethodCallArguments(comparison); } // Validate that the switch value's type matches the comparison method's // left hand side parameter type. var leftParam = pms[0]; bool liftedCall = false; if (!ParameterIsAssignable(leftParam, switchValue.Type)) { liftedCall = ParameterIsAssignable(leftParam, switchValue.Type.GetNonNullableType()); if (!liftedCall) { throw Error.SwitchValueTypeDoesNotMatchComparisonMethodParameter(switchValue.Type, leftParam.ParameterType); } } var rightParam = pms[1]; foreach (var c in caseList) { ContractUtils.RequiresNotNull(c, "cases"); ValidateSwitchCaseType(c.Body, customType, resultType, "cases"); for (int i = 0; i < c.TestValues.Count; i++) { // When a comparison method is provided, test values can have different type but have to // be reference assignable to the right hand side parameter of the method. Type rightOperandType = c.TestValues[i].Type; if (liftedCall) { if (!rightOperandType.IsNullableType()) { throw Error.TestValueTypeDoesNotMatchComparisonMethodParameter(rightOperandType, rightParam.ParameterType); } rightOperandType = rightOperandType.GetNonNullableType(); } if (!ParameterIsAssignable(rightParam, rightOperandType)) { throw Error.TestValueTypeDoesNotMatchComparisonMethodParameter(rightOperandType, rightParam.ParameterType); } } } } else { // When comparison method is not present, all the test values must have // the same type. Use the first test value's type as the baseline. var firstTestValue = caseList[0].TestValues[0]; foreach (var c in caseList) { ContractUtils.RequiresNotNull(c, "cases"); ValidateSwitchCaseType(c.Body, customType, resultType, "cases"); // When no comparison method is provided, require all test values to have the same type. for (int i = 0; i < c.TestValues.Count; i++) { if (!TypeUtils.AreEquivalent(firstTestValue.Type, c.TestValues[i].Type)) { throw new ArgumentException(Strings.AllTestValuesMustHaveSameType, "cases"); } } } // Now we need to validate that switchValue.Type and testValueType // make sense in an Equal node. Fortunately, Equal throws a // reasonable error, so just call it. var equal = Equal(switchValue, firstTestValue, false, comparison); // Get the comparison function from equals node. comparison = equal.Method; } if (defaultBody == null) { if (resultType != typeof(void)) throw Error.DefaultBodyMustBeSupplied(); } else { ValidateSwitchCaseType(defaultBody, customType, resultType, "defaultBody"); } // if we have a non-boolean userdefined equals, we don't want it. if (comparison != null && comparison.ReturnType != typeof(bool)) { throw Error.EqualityMustReturnBoolean(comparison); } return new SwitchExpression(resultType, switchValue, defaultBody, comparison, caseList); } /// /// If custom type is provided, all branches must be reference assignable to the result type. /// If no custom type is provided, all branches must have the same type - resultType. /// private static void ValidateSwitchCaseType(Expression @case, bool customType, Type resultType, string parameterName) { if (customType) { if (resultType != typeof(void)) { if (!TypeUtils.AreReferenceAssignable(resultType, @case.Type)) { throw new ArgumentException(Strings.ArgumentTypesMustMatch, parameterName); } } } else { if (!TypeUtils.AreEquivalent(resultType, @case.Type)) { throw new ArgumentException(Strings.AllCaseBodiesMustHaveSameType, parameterName); } } } } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007. // Copyright (c) Microsoft Corporation. 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