// IfStatementTest
private void DefaultWalk(IfStatementTest node)
{
if (Walk(node))
{
WalkNode(node.Test);
WalkNode(node.Body);
}
PostWalk(node);
}
// IfStatementTest
private IfStatementTest Rewrite(IfStatementTest node)
{
Expression test = RewriteExpressionFreeTemps(node.Test);
Statement body = RewriteStatement(node.Body);
if (((object)test != (object)node.Test) ||
((object)body != (object)node.Body))
{
return(new IfStatementTest(node.Span, node.Header, test, body));
}
else
{
return(node);
}
}
internal static Expression BuildConditions(IList <IfStatementTest> clauses, Expression @else)
{
Expression result = @else ?? Utils.Empty();
// This should probably be using SwitchExpression to avoid stack
// overflow if we have lots of "else" clauses.
int index = clauses.Count;
while (index-- > 0)
{
IfStatementTest ist = clauses[index];
result = Expression.IfThenElse(ist.Test, ist.Body, result);
}
return(result);
}
internal static Expression BuildConditions(IList <IfStatementTest> clauses, Expression @else)
{
Expression result = @else != null?Expression.Void(@else) : Expression.Empty();
int index = clauses.Count;
while (index-- > 0)
{
IfStatementTest ist = clauses[index];
result = Expression.Condition(
ist.Test,
Expression.Void(ist.Body),
result
);
}
return(result);
}
// IfStatement
private void Dump(IfStatement node)
{
for (int i = 0; i < node.Tests.Count; i++)
{
IfStatementTest test = node.Tests[i];
Out(i == 0 ? ".if (" : "} .elif (");
WalkNode(test.Test);
Out(") {", Flow.NewLine);
Indent();
WalkNode(test.Body);
Dedent();
}
if (node.ElseStatement != null)
{
Out("} .else {", Flow.NewLine);
Indent();
WalkNode(node.ElseStatement);
Dedent();
}
Out("}", Flow.NewLine);
}
// IfStatement
private Statement Rewrite(IfStatement node)
{
ReadOnlyCollection <IfStatementTest> tests = node.Tests;
IfStatementTest[] clone = null;
for (int i = 0; i < tests.Count; i++)
{
IfStatementTest test = tests[i];
IfStatementTest rtest = Rewrite(test);
if (((object)test != (object)rtest) && (clone == null))
{
clone = Clone(tests, i);
}
if (clone != null)
{
clone[i] = rtest;
}
}
Statement @else = RewriteStatement(node.ElseStatement);
// Did we rewrite anything?
if (clone != null)
{
return(new IfStatement(node.Span, CollectionUtils.ToReadOnlyCollection(clone), @else));
}
else if ((object)@else != (object)node.ElseStatement)
{
return(new IfStatement(node.Span, CollectionUtils.ToReadOnlyCollection(tests), @else));
}
else
{
return(node);
}
}
public static Expression If(IfStatementTest[] tests, Expression @else) {
ContractUtils.RequiresNotNullItems(tests, "tests");
return IfStatementBuilder.BuildConditions(tests, @else);
}
private MSA.Expression/*!*/ TransformExceptionHandling(AstGenerator/*!*/ gen, ResultOperation resultOperation) {
Assert.NotNull(gen);
MSA.Expression exceptionThrownVariable = gen.CurrentScope.DefineHiddenVariable("#exception-thrown", typeof(bool));
MSA.ParameterExpression exceptionVariable = gen.CurrentScope.DefineHiddenVariable("#exception", typeof(Exception));
MSA.Expression exceptionRethrowVariable = gen.CurrentScope.DefineHiddenVariable("#exception-rethrow", typeof(bool));
MSA.Expression retryingVariable = gen.CurrentScope.DefineHiddenVariable("#retrying", typeof(bool));
MSA.ParameterExpression evalUnwinder = gen.CurrentScope.DefineHiddenVariable("#unwinder", typeof(EvalUnwinder));
MSA.Expression oldExceptionVariable = gen.CurrentScope.DefineHiddenVariable("#old-exception", typeof(Exception));
MSA.Expression transformedBody;
MSA.Expression transformedEnsure;
MSA.Expression transformedElse;
if (_ensureStatements != null) {
transformedEnsure = Ast.Block(
// ensure:
Ast.Assign(oldExceptionVariable, Methods.GetCurrentException.OpCall(gen.CurrentScopeVariable)),
gen.TransformStatements(_ensureStatements, ResultOperation.Ignore),
Methods.SetCurrentException.OpCall(gen.CurrentScopeVariable, oldExceptionVariable),
// rethrow:
AstUtils.IfThen(
Ast.AndAlso(
exceptionRethrowVariable,
Ast.NotEqual(oldExceptionVariable, AstUtils.Constant(null))
),
Ast.Throw(oldExceptionVariable)
),
AstUtils.Empty()
);
} else {
// rethrow:
transformedEnsure = AstUtils.IfThen(
Ast.AndAlso(
exceptionRethrowVariable,
Ast.NotEqual(
Ast.Assign(oldExceptionVariable, Methods.GetCurrentException.OpCall(gen.CurrentScopeVariable)),
AstUtils.Constant(null, typeof(Exception)))
),
Ast.Throw(oldExceptionVariable)
);
}
if (_elseStatements != null) {
transformedElse = gen.TransformStatements(_elseStatements, resultOperation);
} else {
transformedElse = AstUtils.Empty();
}
// body should do return, but else-clause is present => we cannot do return from the guarded statements:
// (the value of the last expression in the body cannot be the last executed expression statement => we can ignore it):
transformedBody = gen.TransformStatements(_statements, (_elseStatements != null) ? ResultOperation.Ignore : resultOperation);
MSA.Expression setInRescueFlag = null, clearInRescueFlag = null;
var breakLabel = Ast.Label();
var continueLabel = Ast.Label();
// make rescue clause:
MSA.Expression transformedRescue;
if (_rescueClauses != null) {
// outer-most EH blocks sets and clears runtime flag RuntimeFlowControl.InTryRescue:
if (gen.CurrentRescue == null) {
setInRescueFlag = Ast.Assign(Ast.Field(gen.CurrentRfcVariable, RuntimeFlowControl.InRescueField), AstUtils.Constant(true));
clearInRescueFlag = Ast.Assign(Ast.Field(gen.CurrentRfcVariable, RuntimeFlowControl.InRescueField), AstUtils.Constant(false));
} else {
setInRescueFlag = clearInRescueFlag = AstUtils.Empty();
}
gen.EnterRescueClause(retryingVariable, breakLabel, continueLabel);
var handlers = new IfStatementTest[_rescueClauses.Count];
for (int i = 0; i < handlers.Length; i++) {
handlers[i] = _rescueClauses[i].Transform(gen, resultOperation);
}
transformedRescue = Ast.Block(
setInRescueFlag,
AstUtils.Try(
AstUtils.If(handlers, Ast.Assign(exceptionRethrowVariable, AstUtils.Constant(true)))
).Filter(evalUnwinder, Ast.Equal(Ast.Field(evalUnwinder, EvalUnwinder.ReasonField), AstUtils.Constant(BlockReturnReason.Retry)),
Ast.Block(
Ast.Assign(retryingVariable, AstUtils.Constant(true)),
Ast.Continue(continueLabel),
AstUtils.Empty()
)
)
);
gen.LeaveRescueClause();
} else {
transformedRescue = Ast.Assign(exceptionRethrowVariable, AstUtils.Constant(true));
}
if (_elseStatements != null) {
transformedElse = AstUtils.Unless(exceptionThrownVariable, transformedElse);
}
var result = AstFactory.Infinite(breakLabel, continueLabel,
Ast.Assign(exceptionThrownVariable, AstUtils.Constant(false)),
Ast.Assign(exceptionRethrowVariable, AstUtils.Constant(false)),
Ast.Assign(retryingVariable, AstUtils.Constant(false)),
AstUtils.Try(
// save exception (old_$! is not used unless there is a rescue clause):
Ast.Block(
(_rescueClauses == null) ? (MSA.Expression)AstUtils.Empty() :
Ast.Assign(oldExceptionVariable, Methods.GetCurrentException.OpCall(gen.CurrentScopeVariable)),
AstUtils.Try(
Ast.Block(transformedBody, AstUtils.Empty())
).Filter(exceptionVariable, Methods.CanRescue.OpCall(gen.CurrentRfcVariable, exceptionVariable),
Ast.Assign(exceptionThrownVariable, AstUtils.Constant(true)),
Methods.SetCurrentExceptionAndStackTrace.OpCall(gen.CurrentScopeVariable, exceptionVariable),
transformedRescue,
AstUtils.Empty()
).FinallyIf((_rescueClauses != null),
// restore previous exception if the current one has been handled:
AstUtils.Unless(exceptionRethrowVariable,
Methods.SetCurrentException.OpCall(gen.CurrentScopeVariable, oldExceptionVariable)
),
clearInRescueFlag
),
// unless (exception_thrown) do <else-statements> end
transformedElse,
AstUtils.Empty()
)
).FilterIf((_rescueClauses != null || _elseStatements != null),
exceptionVariable, Methods.CanRescue.OpCall(gen.CurrentRfcVariable, exceptionVariable),
Ast.Block(
Methods.SetCurrentExceptionAndStackTrace.OpCall(gen.CurrentScopeVariable, exceptionVariable),
Ast.Assign(exceptionRethrowVariable, AstUtils.Constant(true)),
AstUtils.Empty()
)
).Finally(
AstUtils.Unless(retryingVariable, transformedEnsure)
),
Ast.Break(breakLabel)
);
return result;
}
public static IfStatement If(SourceSpan span, IfStatementTest[] tests, Statement @else)
{
Contract.RequiresNotNullItems(tests, "tests");
return new IfStatement(span, CollectionUtils.ToReadOnlyCollection(tests), @else);
}
public static IfStatement If(IfStatementTest[] tests, Statement @else)
{
return If(SourceSpan.None, tests, @else);
}
protected override void PostWalk(IfStatementTest node)
{
base.PostWalk(node);
if (node.Test is MethodCallExpression)
{
var mce = (MethodCallExpression)node.Test;
if (mce.Method == typeof(IronScheme.Runtime.Builtins).GetMethod("IsTrue"))
{
if (mce.Arguments[0].Type == typeof(bool))
{
node.Test = mce.Arguments[0];
}
}
}
}
// IfStatementTest
private void DefaultWalk(IfStatementTest node)
{
if (Walk(node)) {
WalkNode(node.Test);
WalkNode(node.Body);
}
PostWalk(node);
}
