internal void AddGeneratedVar(string name, AstNode initializer, bool isLiteral)
{
// if the body is empty, create one now
if (Body == null)
{
Body = new Block(null, Parser);
}
// see if the first statement in the body (if any) is a var already
Var var = null;
if (Body.Count > 0)
{
var = Body[0] as Var;
}
VariableDeclaration varDecl = new VariableDeclaration(
null,
Parser,
name,
new Context(Parser),
initializer,
(isLiteral ? FieldAttributes.Literal : 0)
);
varDecl.IsGenerated = true;
// make sure we set the crunchability of this field to TRUE. Doesn't matter
// whether it's a global or within a with-scope or what-have-you. It didn't
// exist in the sources (we are generating it now) so we can rename it whatever
// the heck we want.
varDecl.Field.CanCrunch = true;
if (var != null)
{
// the first statement is a var; just add a new declaration to the front
var.InsertAt(0, varDecl);
}
else
{
// not a var; create a new one
var = new Var(null, Parser);
var.Append(varDecl);
Body.Insert(0, var);
}
}
private static int RelocateVar(Block block, int insertAt, Var varStatement)
{
var forInParent = varStatement.Parent as ForIn;
if (forInParent != null)
{
insertAt = ReorderScopeVisitor.RelocateForInVar(block, insertAt, varStatement, forInParent);
}
else
{
// if the var statement is at the next position to insert, then we don't need
// to do anything.
if (block[insertAt] != varStatement)
{
// check to see if the current position is a var and we are the NEXT statement.
// if that's the case, we don't need to break out the initializer, just append all the
// vardecls as-is to the current position.
ForNode forNode;
var existingVar = block[insertAt] as Var;
if (existingVar != null && block[insertAt + 1] == varStatement)
{
// two var-s one right after the other.
// just append our vardecls to the insertion point, then delete our statement
existingVar.Append(varStatement);
block.RemoveAt(insertAt + 1);
}
else if (existingVar != null &&
(forNode = varStatement.Parent as ForNode) != null &&
forNode.Initializer == varStatement &&
forNode == block[insertAt + 1])
{
// this var statement is the initializer of a for-statement, which is
// immediately after the var we would insert our vardecls into.
// rather than moving our vardecls into the outside var-statement, let's
// move the outside var-statement into our for-statement.
varStatement.InsertAt(0, existingVar);
block.RemoveAt(insertAt);
}
else
{
// iterate through the decls and count how many have initializers
var initializerCount = 0;
for (var ndx = 0; ndx < varStatement.Count; ++ndx)
{
// count the number of vardecls with initializers
if (varStatement[ndx].Initializer != null)
{
++initializerCount;
}
}
// if there are more than two decls with initializers, then we won't actually
// be gaining anything by moving the var to the top. We'll get rid of the four
// bytes for the "var ", but we'll be adding two bytes for the name and comma
// because name=init will still need to remain behind.
if (initializerCount <= 2)
{
// first iterate through all the declarations in the var statement,
// constructing an expression statement that is made up of assignment
// operators for each of the declarations that have initializers (if any)
// and removing all the initializers
var assignments = new List <AstNode>();
for (var ndx = 0; ndx < varStatement.Count; ++ndx)
{
var varDecl = varStatement[ndx];
if (varDecl.Initializer != null)
{
// hold on to the object so we don't lose it to the GC
var initializer = varDecl.Initializer;
// remove it from the vardecl
varDecl.Initializer = null;
var reference = BindingTransform.FromBinding(varDecl.Binding);
if (varDecl.IsCCSpecialCase)
{
// we don't want to add the special-case to the binary operator class,
// so just create a copy of the vardecl for this location, using a reference
// for the "binding"
assignments.Add(new VariableDeclaration(varDecl.Context)
{
Binding = reference,
AssignContext = varDecl.AssignContext,
Initializer = initializer,
IsCCSpecialCase = true,
UseCCOn = varDecl.UseCCOn,
TerminatingContext = varDecl.TerminatingContext
});
}
else
{
assignments.Add(new BinaryOperator(varDecl.Context)
{
Operand1 = reference,
Operand2 = initializer,
OperatorToken = JSToken.Assign,
OperatorContext = varDecl.AssignContext
});
}
}
// if the vardecl we are moving isn't a binding pattern, we need to
// break it down into a simple list of names.
if (!(varDecl.Binding is BindingIdentifier))
{
// place the original vardecl with the first one
var first = true;
foreach (var declName in BindingsVisitor.Bindings(varDecl.Binding))
{
if (first)
{
varStatement[ndx] = new VariableDeclaration(declName.Context)
{
Binding = new BindingIdentifier(declName.Context)
{
Name = declName.Name,
VariableField = declName.VariableField
}
};
first = false;
}
else
{
// otherwise we want to insert a new one at the current position + 1
varStatement.InsertAt(++ndx, new VariableDeclaration(declName.Context)
{
Binding = new BindingIdentifier(declName.Context)
{
Name = declName.Name,
VariableField = declName.VariableField
}
});
}
}
}
}
// now if there were any initializers...
if (assignments.Count > 0)
{
// we want to create one big expression from all the assignments and replace the
// var statement with the assignment(s) expression. Start at position n=1 and create
// a binary operator of n-1 as the left, n as the right, and using a comma operator.
var expression = assignments[0];
for (var ndx = 1; ndx < assignments.Count; ++ndx)
{
expression = CommaOperator.CombineWithComma(expression.Context.FlattenToStart(), expression, assignments[ndx]);
}
// replace the var with the expression.
// we still have a pointer to the var, so we can insert it back into the proper
// place next.
varStatement.Parent.ReplaceChild(varStatement, expression);
}
else
{
// no initializers.
// just remove the var statement altogether
varStatement.Parent.ReplaceChild(varStatement, null);
}
// if the statement at the insertion point is a var-statement already,
// then we just need to append our vardecls to it. Otherwise we'll insert our
// var statement at the right point
if (existingVar != null)
{
// append the varstatement we want to move to the existing var, which will
// transfer all the vardecls to it.
existingVar.Append(varStatement);
}
else
{
// move the var to the insert point, incrementing the position or next time
block.Insert(insertAt, varStatement);
}
}
}
}
}
return(insertAt);
}
internal override void AnalyzeNode()
{
// javascript doesn't have block scope, so there really is no point
// in nesting blocks. Unnest any now, before we start combining var statements
UnnestBlocks();
// if we want to remove debug statements...
if (Parser.Settings.StripDebugStatements && Parser.Settings.IsModificationAllowed(TreeModifications.StripDebugStatements))
{
// do it now before we try doing other things
StripDebugStatements();
}
// these variables are used to check for combining a particular type of
// for-statement with preceding var-statements.
ForNode targetForNode = null;
string targetName = null;
// check to see if we want to combine adjacent var statements
bool combineVarStatements = Parser.Settings.IsModificationAllowed(TreeModifications.CombineVarStatements);
// check to see if we want to combine a preceding var with a for-statement
bool moveVarIntoFor = Parser.Settings.IsModificationAllowed(TreeModifications.MoveVarIntoFor);
// look at the statements in the block.
// if there are multiple var statements adjacent to each other, combine them.
// walk BACKWARDS down the list because we'll be removing items when we encounter
// multiple vars.
// we also don't need to check the first one, since there is nothing before it.
for (int ndx = m_list.Count - 1; ndx > 0; --ndx)
{
// if the previous node is not a Var, then we don't need to try and combine
// it withthe current node
Var previousVar = m_list[ndx - 1] as Var;
if (previousVar != null)
{
// see if THIS item is also a Var...
if (m_list[ndx] is Var && combineVarStatements)
{
// add the items in this VAR to the end of the previous
previousVar.Append(m_list[ndx]);
// delete this item from the block
m_list.RemoveAt(ndx);
// if we have a target for-node waiting for another comparison....
if (targetForNode != null)
{
// check to see if the variable we are looking for is in the new list
if (previousVar.Contains(targetName))
{
// IT DOES! we can combine the var statement with the initializer in the for-statement
// we already know it's a binaryop, or it wouldn't be a target for-statement
BinaryOperator binaryOp = targetForNode.Initializer as BinaryOperator;
// create a vardecl that matches our assignment initializer
// ignore duplicates because this scope will already have the variable defined.
VariableDeclaration varDecl = new VariableDeclaration(
binaryOp.Context.Clone(),
Parser,
targetName,
binaryOp.Operand1.Context.Clone(),
binaryOp.Operand2,
0,
true
);
// append it to the preceding var-statement
previousVar.Append(varDecl);
// move the previous vardecl to our initializer
targetForNode.ReplaceChild(targetForNode.Initializer, previousVar);
// and remove the previous var from the list.
m_list.RemoveAt(ndx - 1);
// this will bump the for node up one position in the list, so the next iteration
// will be right back on this node, but the initializer will not be null
// but now we no longer need the target mechanism -- the for-statement is
// not the current node again
targetForNode = null;
}
}
}
else if (moveVarIntoFor)
{
// see if this item is a ForNode
ForNode forNode = m_list[ndx] as ForNode;
if (forNode != null)
{
// and see if the forNode's initializer is empty
if (forNode.Initializer != null)
{
// not empty -- see if it is a Var node
Var varInitializer = forNode.Initializer as Var;
if (varInitializer != null)
{
// we want to PREPEND the initializers in the previous var statement
// to our for-statement's initializer list
varInitializer.InsertAt(0, previousVar);
// then remove the previous var statement
m_list.RemoveAt(ndx - 1);
// this will bump the for node up one position in the list, so the next iteration
// will be right back on this node in case there are other var statements we need
// to combine
}
else
{
// see if the initializer is a simple assignment
BinaryOperator binaryOp = forNode.Initializer as BinaryOperator;
if (binaryOp != null && binaryOp.OperatorToken == JSToken.Assign)
{
// it is. See if it's a simple lookup
Lookup lookup = binaryOp.Operand1 as Lookup;
if (lookup != null)
{
// it is. see if that variable is in the previous var statement
if (previousVar.Contains(lookup.Name))
{
// create a vardecl that matches our assignment initializer
// ignore duplicates because this scope will already have the variable defined.
VariableDeclaration varDecl = new VariableDeclaration(
binaryOp.Context.Clone(),
Parser,
lookup.Name,
lookup.Context.Clone(),
binaryOp.Operand2,
0,
true
);
// append it to the var statement before us
previousVar.Append(varDecl);
// move the previous vardecl to our initializer
forNode.ReplaceChild(forNode.Initializer, previousVar);
// and remove the previous var from the list.
m_list.RemoveAt(ndx - 1);
// this will bump the for node up one position in the list, so the next iteration
// will be right back on this node, but the initializer will not be null
}
else
{
// it's not in the immediately preceding var-statement, but that doesn't mean it won't be in
// a var-statement immediately preceding that one -- in which case they'll get combined and
// then it WILL be in the immediately preceding var-statement. So hold on to this
// for statement and we'll check after we do a combine.
targetForNode = forNode;
targetName = lookup.Name;
}
}
}
}
}
else
{
// if it's empty, then we're free to add the previous var statement
// to this for statement's initializer. remove it from it's current
// position and add it as the initializer
m_list.RemoveAt(ndx - 1);
forNode.ReplaceChild(forNode.Initializer, previousVar);
// this will bump the for node up one position in the list, so the next iteration
// will be right back on this node, but the initializer will not be null
}
}
}
}
else
{
// not a var statement. make sure the target for-node is cleared.
targetForNode = null;
ConditionalCompilationComment previousComment = m_list[ndx - 1] as ConditionalCompilationComment;
if (previousComment != null)
{
ConditionalCompilationComment thisComment = m_list[ndx] as ConditionalCompilationComment;
if (thisComment != null)
{
// two adjacent conditional comments -- combine them into the first.
// this will actually make the second block a nested block within the first block,
// but they'll be flattened when the comment's block gets recursed.
previousComment.Statements.Append(thisComment.Statements);
// and remove the second one (which is now a duplicate)
m_list.RemoveAt(ndx);
}
}
}
}
if (m_blockScope != null)
{
ScopeStack.Push(m_blockScope);
}
try
{
// call the base class to recurse
base.AnalyzeNode();
}
finally
{
if (m_blockScope != null)
{
ScopeStack.Pop();
}
}
// NOW that we've recursively analyzed all the child nodes in this block, let's see
// if we can further reduce the statements by checking for a couple good opportunities
if (Parser.Settings.RemoveUnneededCode)
{
// Transform: {var foo=expression;return foo;} to: {return expression;}
if (m_list.Count == 2 && Parser.Settings.IsModificationAllowed(TreeModifications.VarInitializeReturnToReturnInitializer))
{
Var varStatement = m_list[0] as Var;
ReturnNode returnStatement = m_list[1] as ReturnNode;
// see if we have two statements in our block: a var with a single declaration, and a return
if (returnStatement != null && varStatement != null &&
varStatement.Count == 1 && varStatement[0].Initializer != null)
{
// now see if the return is returning a lookup for the same var we are declaring in the
// previous statement
Lookup lookup = returnStatement.Operand as Lookup;
if (lookup != null &&
string.Compare(lookup.Name, varStatement[0].Identifier, StringComparison.Ordinal) == 0)
{
// it's a match!
// create a combined context starting with the var and adding in the return
Context context = varStatement.Context.Clone();
context.UpdateWith(returnStatement.Context);
// create a new return statement
ReturnNode newReturn = new ReturnNode(context, Parser, varStatement[0].Initializer);
// clear out the existing statements
m_list.Clear();
// and add our new one
Append(newReturn);
}
}
}
// we do things differently if these statements are the last in a function
// because we can assume the implicit return
bool isFunctionLevel = (Parent is FunctionObject);
// see if we want to change if-statement that forces a return to a return conditional
if (Parser.Settings.IsModificationAllowed(TreeModifications.IfElseReturnToReturnConditional))
{
// transform: {...; if(cond1)return;} to {...;cond;}
// transform: {...; if(cond1)return exp1;else return exp2;} to {...;return cond1?exp1:exp2;}
if (m_list.Count >= 1)
{
// see if the last statement is an if-statement with a true-block containing only one statement
IfNode ifStatement = m_list[m_list.Count - 1] as IfNode;
if (ifStatement != null &&
ifStatement.TrueBlock != null)
{
// see if this if-statement is structured such that we can convert it to a
// Conditional node that is the operand of a return statement
Conditional returnOperand = ifStatement.CanBeReturnOperand(null, isFunctionLevel);
if (returnOperand != null)
{
// it can! change it.
ReturnNode returnNode = new ReturnNode(
(Context == null ? null : Context.Clone()),
Parser,
returnOperand);
// replace the if-statement with the return statement
ReplaceChild(ifStatement, returnNode);
}
}
// else last statement is not an if-statement, or true block is not a single statement
}
// transform: {...; if(cond1)return exp1;return exp2;} to {...; return cond1?exp1:exp2;}
// my cascade! changing the two statements to a return may cause us to run this again if the
// third statement up becomes the penultimate and is an if-statement
while (m_list.Count > 1)
{
int lastIndex = m_list.Count - 1;
// end in a return statement?
ReturnNode finalReturn = m_list[lastIndex] as ReturnNode;
if (finalReturn != null)
{
// it does -- see if the penultimate statement is an if-block
IfNode ifNode = m_list[lastIndex - 1] as IfNode;
if (ifNode != null)
{
// if followed by return. See if the if statement can be changed to a
// return of a conditional, using the operand of the following return
// as the ultimate expression
Conditional returnConditional = ifNode.CanBeReturnOperand(finalReturn.Operand, isFunctionLevel);
if (returnConditional != null)
{
// it can! so create the new return statement.
// the context of this new return statement should start with a clone of
// the if-statement and updated with the return statement
Context context = ifNode.Context.Clone();
context.UpdateWith(finalReturn.Context);
// create the new return node
ReturnNode newReturn = new ReturnNode(
context,
Parser,
returnConditional);
// remove the last node (the old return)
m_list.RemoveAt(lastIndex--);
// and replace the if-statement with the new return
m_list[lastIndex] = newReturn;
newReturn.Parent = this;
// we collapsed the last two statements, and we KNOW the last one is a
// return -- go back up to the top of the loop to see if we can keep going.
continue;
}
}
}
// if we get here, then something went wrong, we didn't collapse the last
// two statements, so break out of the loop
break;
}
// now we may have converted the last functional statement
// from if(cond)return expr to return cond?expr:void 0, which is four
// extra bytes. So let's check to see if the last statement in the function
// now fits this pattern, and if so, change it back.
// We didn't just NOT change it in the first place because changing it could've
// enabled even more changes that would save a lot more space. But apparently
// those subsequent changes didn't pan out.
if (m_list.Count >= 1)
{
int lastIndex = m_list.Count - 1;
ReturnNode returnNode = m_list[lastIndex] as ReturnNode;
if (returnNode != null)
{
Conditional conditional = returnNode.Operand as Conditional;
if (conditional != null)
{
VoidNode falseVoid = conditional.FalseExpression as VoidNode;
if (falseVoid != null && falseVoid.Operand is ConstantWrapper)
{
// we have the required pattern: "return cond?expr:void 0"
// (well, the object of the void is a constant, at least).
// undo it back to "if(cond)return expr" because that takes fewer bytes.
// by default, the operand of the return operator will be the
// true branch of the conditional
AstNode returnOperand = conditional.TrueExpression;
VoidNode trueVoid = conditional.TrueExpression as VoidNode;
if (trueVoid != null && trueVoid.Operand is ConstantWrapper)
{
// the true branch of the conditional is a void operator acting
// on a constant! So really, there is no operand to the return statement
returnOperand = null;
if (Parser.Settings.IsModificationAllowed(TreeModifications.IfConditionReturnToCondition))
{
// actually, we have return cond?void 0:void 0,
// which would get changed back to function{...;if(cond)return}
// BUT we can just shorten it to function{...;cond}
m_list[lastIndex] = conditional.Condition;
conditional.Condition.Parent = this;
return;
}
}
IfNode ifNode = new IfNode(
returnNode.Context.Clone(),
Parser,
conditional.Condition,
new ReturnNode(returnNode.Context.Clone(), Parser, returnOperand),
null);
m_list[lastIndex] = ifNode;
ifNode.Parent = this;
}
}
}
}
}
}
}