public override void AfterVisit(ForStatement node)
{
Expression whereCondition = null, between = null;
var currentLoopContext = _loopContextStack.Pop();
if (node.Where != null)
whereCondition = _expressionStack.Pop();
if (node.Between != null)
between = _expressionStack.Pop();
var loopBody = _expressionStack.Pop();
Expression enumerable = _expressionStack.Pop();
ParameterExpression loopVariable = node.GetExtension<ForExtension>().LoopVariableSymbol.GetGetExpression() as ParameterExpression;
Expression getEnumerator = whereCondition == null
? Expression.Call(Expression.Convert(enumerable, typeof(IEnumerable)), typeof(IEnumerable).GetMethod("GetEnumerator"))
: getWhereEnumerator(node, enumerable, whereCondition);
ParameterExpression enumerator = Expression.Parameter(typeof(IEnumerator), EnumeratorParameterExpressionName);
List<Expression> loop = new List<Expression> { Expression.Assign(enumerator, getEnumerator) };
//The loop "wrapper", which wraps the actual loop body
//It's purpose is to assign the loopVariable after each iteration and
//to write the between clause to the current output
var iteratorAdvancerAndLoopExiter =
Expression.IfThenElse(
Expression.Call(enumerator, typeof(IEnumerator).GetMethod("MoveNext")),
between == null ? Expression.Empty() : SafeWriteToTopWriter(between),
Expression.Goto(currentLoopContext.BreakLabel));
BlockExpression loopWrapper = Expression.Block(
// ReSharper disable AssignNullToNotNullAttribute
Expression.Assign(loopVariable, Expression.Property(enumerator, typeof(IEnumerator).GetProperty("Current"))),
// ReSharper restore AssignNullToNotNullAttribute
loopBody,
Expression.Label(currentLoopContext.ContinueLabel),
iteratorAdvancerAndLoopExiter);
//Primes the loop
ConditionalExpression outerIf = Expression.IfThen(
Expression.Call(enumerator, typeof(IEnumerator).GetMethod("MoveNext")),
Expression.Loop(loopWrapper, currentLoopContext.BreakLabel));
loop.Add(outerIf);
var parameters = node.LoopBody.GetExtension<ScopeExtension>().SymbolTable.GetParameterExpressions().Union(new[] { enumerator }).ToArray();
_expressionStack.Push(node, MaybeBlock(parameters, loop));
base.AfterVisit(node);
}
public override void AfterVisit(ForStatement node)
{
base.AfterVisit(node);
if(node.LoopBody.GetExtension<ScopeExtension>().SymbolTable.FindInCurrentScope(node.LoopVariable.Text) != null)
_errorCollector.VariableOfSameNameDefinedInForLoopScope(node.LoopVariable);
else
node.GetExtension<ForExtension>().LoopVariableSymbol = node.LoopBody.GetExtension<ScopeExtension>().SymbolTable.Add(node.LoopVariable.Text);
}