private Expression ParseLambdaHelperEnd(FunctionDefinition func, Expression expr) {
// Pep 342 in Python 2.5 allows Yield Expressions, which can occur inside a Lambda body.
// In this case, the lambda is a generator and will yield it's final result instead of just return it.
Statement body;
if (func.IsGenerator) {
YieldExpression y = new YieldExpression(expr);
y.SetLoc(_globalParent, expr.IndexSpan);
body = new ExpressionStatement(y);
} else {
body = new ReturnStatement(expr);
}
body.SetLoc(_globalParent, expr.StartIndex, expr.EndIndex);
FunctionDefinition func2 = PopFunction();
System.Diagnostics.Debug.Assert(func == func2);
func.Body = body;
func.EndIndex = GetEnd();
LambdaExpression ret = new LambdaExpression(func);
func.SetLoc(_globalParent, func.IndexSpan);
ret.SetLoc(_globalParent, func.IndexSpan);
return ret;
}
/// <summary>
/// Peek if the next token is a 'yield' and parse a yield expression. Else return null.
///
/// Called w/ yield already eaten.
/// </summary>
/// <returns>A yield expression if present, else null. </returns>
// yield_expression: "yield" [expression_list]
private Expression ParseYieldExpression() {
// Mark that this function is actually a generator.
// If we're in a generator expression, then we don't have a function yet.
// g=((yield i) for i in range(5))
// In that acse, the genexp will mark IsGenerator.
FunctionDefinition current = CurrentFunction;
if (current != null) {
current.IsGenerator = true;
}
var start = GetStart();
// Parse expression list after yield. This can be:
// 1) empty, in which case it becomes 'yield None'
// 2) a single expression
// 3) multiple expression, in which case it's wrapped in a tuple.
Expression yieldResult;
bool trailingComma;
List<Expression> l = ParseExpressionList(out trailingComma);
if (l.Count == 0) {
// Check empty expression and convert to 'none'
yieldResult = new ConstantExpression(null);
} else if (l.Count != 1) {
// make a tuple
yieldResult = MakeTupleOrExpr(l, trailingComma);
} else {
// just take the single expression
yieldResult = l[0];
}
Expression yieldExpression = new YieldExpression(yieldResult);
yieldExpression.SetLoc(_globalParent, start, GetEnd());
return yieldExpression;
}
/// <summary>
/// Peek if the next token is a 'yield' and parse a yield expression. Else return null.
///
/// Called w/ yield already eaten.
/// </summary>
/// <returns>A yield expression if present, else null. </returns>
// yield_expression: "yield" [expression_list]
private Expression ParseYieldExpression() {
// Mark that this function is actually a generator.
// If we're in a generator expression, then we don't have a function yet.
// g=((yield i) for i in range(5))
// In that acse, the genexp will mark IsGenerator.
FunctionDefinition current = CurrentFunction;
if (current != null) {
current.IsGenerator = true;
}
SourceLocation start = GetStart();
// Parse expression list after yield. This can be:
// 1) empty, in which case it becomes 'yield None'
// 2) a single expression
// 3) multiple expression, in which case it's wrapped in a tuple.
const bool allowEmptyExpr = true;
Expression yieldResult = ParseTestListAsExpr(allowEmptyExpr);
// Check empty expression and convert to 'none'
TupleExpression t = yieldResult as TupleExpression;
if (t != null) {
if (t.Items.Length == 0) {
yieldResult = new ConstantExpression(null);
}
}
Expression yieldExpression = new YieldExpression(yieldResult);
yieldExpression.SetLoc(start, GetEnd());
return yieldExpression;
}
