/* ****************************************************************************
*
* 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.
*
*
* ***************************************************************************/
#if !CLR2
using System.Linq.Expressions;
#else
using Microsoft.Scripting.Ast;
#endif
using System;
using System.Collections.Generic;
using System.Dynamic;
using System.Collections.ObjectModel;
using Microsoft.Scripting.Utils;
namespace Microsoft.Scripting.Ast{
public static partial class Utils {
// Helper to add a variable to a block
internal static Expression AddScopedVariable(Expression body, ParameterExpression variable, Expression variableInit) {
List<ParameterExpression> vars = new List<ParameterExpression>();
List<Expression> newBody = new List<Expression>();
var exprs = new ReadOnlyCollection<Expression>(new [] { body });
var parent = body;
//Merge blocks if the current block has only one child that is another block,
//the blocks to merge must have the same type.
while (exprs.Count == 1 && exprs[0].NodeType == ExpressionType.Block && parent.Type == exprs[0].Type) {
BlockExpression scope = (BlockExpression)(exprs[0]);
vars.AddRange(scope.Variables);
parent = scope;
exprs = scope.Expressions;
}
newBody.Add(Expression.Assign(variable, variableInit));
newBody.AddRange(exprs);
vars.Add(variable);
return Expression.Block(
vars,
newBody.ToArray()
);
}
internal static BlockExpression BlockVoid(Expression[] expressions) {
if (expressions.Length == 0 || expressions[expressions.Length - 1].Type != typeof(void)) {
expressions = expressions.AddLast(Utils.Empty());
}
return Expression.Block(expressions);
}
internal static BlockExpression Block(Expression[] expressions) {
if (expressions.Length == 0) {
expressions = expressions.AddLast(Utils.Empty());
}
return Expression.Block(expressions);
}
}
}
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