private static Expression PredefinedAtom_Default(ParseTreeNode root, CompilerState state)
{
var funArgs = ExpressionTreeExtensions.UnwindTupleExprList(root.RequireChild("exprList", 1, 0));
funArgs.RequireChildren(1);
var arg1Node = funArgs.ChildNodes[0];
var targetType = RequireSystemType(arg1Node);
return(ExpressionTreeExtensions.GetDefaultExpression(targetType));
}
private static Expression PredefinedAtom_Cast(ParseTreeNode root, CompilerState state)
{
root.RequireChildren(2);
var arg1Node = root.RequireChild(null, 1, 0, 0);
var value = state.ParentRuntime.Analyze(arg1Node, state).RemoveNullability();
var arg2Node = root.RequireChild("string", 1, 0, 1);
var targetType = RequireSystemType(arg2Node);
if (value.IsVoid())
{
return(ExpressionTreeExtensions.GetDefaultExpression(targetType));
}
// bluntly attempt to convert the type; will throw if types are not compatible
return(ConstantHelper.TryEvalConst(root, value, ExpressionType.Convert, targetType));
}
private Expression BuildCaseStatementExpression(CompilerState state, ParseTreeNode whenThenListNode, Expression caseDefault)
{
// now start building on top of the tail, right to left,
// also making sure that types are compatible
var tail = caseDefault;
for (var i = whenThenListNode.ChildNodes.Count - 1; i >= 0; i--)
{
var caseWhenThenNode = whenThenListNode.RequireChild("caseWhenThen", i);
caseWhenThenNode.RequireChildren(4);
var whenNode = caseWhenThenNode.RequireChild(null, 1);
var thenNode = caseWhenThenNode.RequireChild(null, 3);
if (whenNode.Term.Name == "tuple")
{
throw new CompilationException("When variable for CASE is not specified, you can only have one expression in each WHEN clause", whenNode);
}
// in this flavor of CASE, we are building a sequence of IIFs
// it requires that our "WHEN" clause is of non-nullable boolean type
var when = Analyze(whenNode, state).RemoveNullability();
when.RequireBoolean(whenNode);
var then = Analyze(thenNode, state);
// try to auto-adjust types of this "THEN" and current tail expression if needed
if (tail != null)
{
Expression adjusted;
if (ExpressionTreeExtensions.TryAdjustReturnType(thenNode, then, tail.Type, out adjusted))
{
then = adjusted;
}
else if (ExpressionTreeExtensions.TryAdjustReturnType(thenNode, tail, then.Type, out adjusted))
{
tail = adjusted;
}
else
{
throw new CompilationException(
string.Format(
"Incompatible types within CASE statement. Tail is of type {0}, and then is of type {1}",
tail.Type.FullName, then.Type.FullName), thenNode);
}
}
if (when is ConstantExpression)
{
if ((bool)((ConstantExpression)when).Value)
{
tail = then;
}
}
else
{
tail = Expression.Condition(when, then, tail ?? ExpressionTreeExtensions.GetDefaultExpression(then.Type));
}
}
return(tail);
}
private Expression BuildSwitchStatementExpression(CompilerState state, ParseTreeNode caseVariableNode, ParseTreeNode whenThenListNode, Expression caseDefault)
{
var switchVariable = Analyze(caseVariableNode.ChildNodes[0], state);
switchVariable.RequireNonVoid(caseVariableNode.ChildNodes[0]);
if (switchVariable is ConstantExpression)
{
throw new CompilationException("CASE variable should not be a constant value", caseVariableNode);
}
var cases = new List <Tuple <Expression[], Expression, ParseTreeNode> >(whenThenListNode.ChildNodes.Count);
Expression firstNonVoidThen = null;
var mustReturnNullable = false;
foreach (var caseWhenThenNode in whenThenListNode.ChildNodes)
{
caseWhenThenNode.RequireChildren(4);
var whenNodesRoot = ExpressionTreeExtensions.UnwindTupleExprList(caseWhenThenNode.RequireChild(null, 1));
var thenNode = caseWhenThenNode.RequireChild(null, 3);
IList <ParseTreeNode> whenNodes;
if (whenNodesRoot.Term.Name == "exprList")
{
whenNodes = whenNodesRoot.ChildNodes;
}
else
{
whenNodes = new[] { whenNodesRoot };
}
var when = new Expression[whenNodes.Count];
for (var i = 0; i < whenNodes.Count; i++)
{
var whenNode = whenNodes[i];
when[i] = Analyze(whenNode, state);
if (!when[i].IsVoid() && !(when[i] is ConstantExpression))
{
throw new CompilationException("CASE statement with a test variable requires WHEN clauses to be constant values", whenNode);
}
Expression adjusted;
if (ExpressionTreeExtensions.TryAdjustReturnType(whenNode, when[i], switchVariable.Type, out adjusted))
{
when[i] = adjusted;
}
else
{
throw new CompilationException(
string.Format(
"Could not adjust WHEN value type {0} to CASE argument type {1}",
when[i].Type.FullName, switchVariable.Type.FullName), whenNode);
}
}
var then = Analyze(thenNode, state);
cases.Add(new Tuple <Expression[], Expression, ParseTreeNode>(when, then, thenNode));
if (then.IsVoid())
{
// if there is at least one "void" return value, resulting value must be nullable
mustReturnNullable = true;
}
else if (firstNonVoidThen == null)
{
firstNonVoidThen = then;
}
}
if (firstNonVoidThen == null && !caseDefault.IsVoid())
{
firstNonVoidThen = caseDefault;
}
var adjustedCaseDefault = caseDefault;
// now try to adjust whatever remaining VOID "then-s" to the first-met non-void then
// if all THENs are void, then just leave it as-is - type will be adjusted by caller
if (firstNonVoidThen != null)
{
if (mustReturnNullable && firstNonVoidThen.Type.IsValueType && !firstNonVoidThen.IsNullableType())
{
firstNonVoidThen = ExpressionTreeExtensions.MakeNewNullable(
typeof(UnboxableNullable <>).MakeGenericType(firstNonVoidThen.Type),
firstNonVoidThen);
}
for (var i = 0; i < cases.Count; i++)
{
var thenNode = cases[i].Item3;
var then = cases[i].Item2;
if (!ReferenceEquals(then, firstNonVoidThen) && then.IsVoid())
{
Expression adjusted;
if (ExpressionTreeExtensions.TryAdjustReturnType(thenNode, then, firstNonVoidThen.Type, out adjusted))
{
cases[i] = new Tuple <Expression[], Expression, ParseTreeNode>(cases[i].Item1, adjusted, cases[i].Item3);
}
else
{
throw new CompilationException(
string.Format(
"Could not adjust THEN value type {0} to first-met THEN value type {1}",
then.Type.FullName, firstNonVoidThen.Type.FullName), thenNode);
}
}
}
if (caseDefault != null &&
!ExpressionTreeExtensions.TryAdjustReturnType(caseVariableNode, caseDefault, firstNonVoidThen.Type, out adjustedCaseDefault))
{
throw new CompilationException(
string.Format(
"Could not adjust CASE default value's type {0} to first-met THEN value type {1}",
caseDefault.Type.FullName, firstNonVoidThen.Type.FullName), caseVariableNode);
}
}
if (adjustedCaseDefault == null)
{
adjustedCaseDefault = ExpressionTreeExtensions.GetDefaultExpression(
firstNonVoidThen == null
? typeof(UnboxableNullable <ExpressionTreeExtensions.VoidTypeMarker>)
: firstNonVoidThen.Type);
}
return(Expression.Switch(
switchVariable, adjustedCaseDefault, null,
cases.Select(x => Expression.SwitchCase(x.Item2, x.Item1))));
}