private JSForLoop ReplaceWhileLoopAndEnumerator(JSWhileLoop wl, JSExpression backingStore, JSExpression enumerator, TypeInfo enumeratorType, string arrayMember, string lengthMember)
{
var loopId = _NextLoopId++;
var arrayVariableName = String.Format("a${0:x}", loopId);
var indexVariableName = String.Format("i${0:x}", loopId);
var lengthVariableName = String.Format("l${0:x}", loopId);
var currentPropertyReference = enumeratorType.Definition.Properties.First((p) => p.Name == "Current");
var currentPropertyInfo = enumeratorType.Source.GetProperty(currentPropertyReference);
var itemType = currentPropertyInfo.ReturnType;
var arrayType = new ArrayType(itemType);
var arrayVariable = new JSVariable(
arrayVariableName, arrayType, Function.Method.Reference,
JSDotExpression.New(backingStore, new JSStringIdentifier(arrayMember, arrayType))
);
var indexVariable = new JSVariable(
indexVariableName, TypeSystem.Int32, Function.Method.Reference,
JSLiteral.New(0)
);
var lengthVariable = new JSVariable(
lengthVariableName, TypeSystem.Int32, Function.Method.Reference,
JSDotExpression.New(backingStore, new JSStringIdentifier(lengthMember, TypeSystem.Int32))
);
var initializer = new JSVariableDeclarationStatement(
new JSBinaryOperatorExpression(
JSOperator.Assignment, arrayVariable, arrayVariable.DefaultValue, arrayVariable.IdentifierType
),
new JSBinaryOperatorExpression(
JSOperator.Assignment, indexVariable, indexVariable.DefaultValue, indexVariable.IdentifierType
),
new JSBinaryOperatorExpression(
JSOperator.Assignment, lengthVariable, lengthVariable.DefaultValue, lengthVariable.IdentifierType
)
);
var condition = new JSBinaryOperatorExpression(
JSOperator.LessThan,
indexVariable, lengthVariable, TypeSystem.Boolean
);
var increment = new JSUnaryOperatorExpression(
JSOperator.PostIncrement,
indexVariable, TypeSystem.Int32
);
var result = new JSForLoop(
initializer, condition, new JSExpressionStatement(increment),
wl.Statements.ToArray()
);
result.Index = wl.Index;
new PropertyAccessReplacer(
enumerator, new JSProperty(currentPropertyReference, currentPropertyInfo),
new JSIndexerExpression(
arrayVariable, indexVariable,
itemType
)
).Visit(result);
return(result);
}
protected void TransformVariableIntoReference(JSVariable variable, JSVariableDeclarationStatement statement, int declarationIndex, JSBlockStatement enclosingBlock)
{
var oldDeclaration = statement.Declarations[declarationIndex];
var valueType = oldDeclaration.Right.GetActualType(JSIL.TypeSystem);
var newVariable = variable.Reference();
var enclosingFunction = Stack.OfType <JSFunctionExpression>().First();
JSExpression initialValue;
// If the declaration was in function scope originally we can hoist the initial value
// into our new variable declaration. If not, we need to initialize the ref variable
// to the default value for its type. It will get the correct value assigned later.
if (enclosingBlock == enclosingFunction.Body)
{
initialValue = oldDeclaration.Right;
}
else
{
initialValue = new JSDefaultValueLiteral(valueType);
}
var newDeclaration = new JSVariableDeclarationStatement(new JSBinaryOperatorExpression(
JSOperator.Assignment,
// We have to use a constructed ref to the variable here, otherwise
// the declaration will look like 'var x.value = foo'
new JSVariable(variable.Identifier, variable.IdentifierType, variable.Function),
JSIL.NewReference(initialValue),
newVariable.IdentifierType
));
if (Tracing)
{
Console.WriteLine(String.Format("Transformed {0} into {1} in {2}", variable, newVariable, statement));
}
// Insert the new declaration directly before the top-level block containing the original
// declaration. This ensures that if its initial value has a dependency on external state,
// the declaration will not precede the values it depends on.
// Note that for declarations that were hoisted out of inner blocks (conditionals, loops)
// it doesn't actually matter where the insert occurs, since we initialize with a default
// value in that case.
enclosingFunction.Body.InsertNearChildRecursive(
statement, newDeclaration, 0
);
// If the reference is being declared in function scope, it doesn't need a separate assignment
// for its initialization. Otherwise, we need to insert an assignment after the original variable
// declaration statement to ensure that the reference variable is initialized to the right value
// at the exact right point in the function's execution.
if (enclosingBlock != enclosingFunction.Body)
{
var newAssignment = new JSExpressionStatement(
new JSBinaryOperatorExpression(
JSOperator.Assignment, newVariable, oldDeclaration.Right, valueType
)
);
var insertLocation = enclosingBlock.Statements.IndexOf(statement) + 1;
enclosingBlock.Statements.Insert(insertLocation, newAssignment);
}
Variables[variable.Identifier] = newVariable;
statement.Declarations.RemoveAt(declarationIndex);
TransformedVariables.Add(variable.Identifier);
}
