public static AstNode CombineWithComma(Context context, JSParser parser, AstNode operand1, AstNode operand2)
{
var comma = new CommaOperator(context, parser)
{
OperatorToken = JSToken.Comma
};
// if the left is a comma-operator already....
var leftBinary = operand1 as BinaryOperator;
var rightBinary = operand2 as BinaryOperator;
if (leftBinary != null && leftBinary.OperatorToken == JSToken.Comma)
{
// the left-hand side is already a comma operator. Instead of nesting these, we're
// going to combine them
// move the old list's left-hand side to our left-hand side
comma.Operand1 = leftBinary.Operand1;
AstNodeList list;
if (rightBinary != null && rightBinary.OperatorToken == JSToken.Comma)
{
// the right is ALSO a comma operator. Create a new list, append all the rest of the operands
// and set our right-hand side to be the list
list = new AstNodeList(null, parser);
list.Append(leftBinary.Operand2).Append(rightBinary.Operand1).Append(rightBinary.Operand2);
}
else
{
// the right is not a comma operator.
// see if the left-hand side already has a list we can use
list = leftBinary.Operand2 as AstNodeList;
if (list == null)
{
// it's not a list already
// create a new list with the left's right and our right and set it to our right
list = new AstNodeList(null, parser);
list.Append(leftBinary.Operand2);
}
// and add our right-hand operand to the end of the list
list.Append(operand2);
}
// set the list on the right
comma.Operand2 = list;
}
else if (rightBinary != null && rightBinary.OperatorToken == JSToken.Comma)
{
// the left hand side is NOT a comma operator.
comma.Operand1 = operand1;
// the right-hand side is already a comma-operator, but the left is not.
// see if it already has a list we can reuse
var rightList = rightBinary.Operand2 as AstNodeList;
if (rightList != null)
{
// it does. Prepend its right-hand operand and use the list
rightList.Insert(0, rightBinary.Operand1);
}
else
{
// it's not -- create a new list containing the operands
rightList = new AstNodeList(rightBinary.Context, parser);
rightList.Append(rightBinary.Operand1);
rightList.Append(rightBinary.Operand2);
}
comma.Operand2 = rightList;
}
else
{
comma.Operand1 = operand1;
comma.Operand2 = operand2;
}
return(comma);
}
private static int RelocateVar(Block block, int insertAt, Var varStatement)
{
// 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.
var existingVar = block[insertAt] as Var;
if (existingVar != null && block[insertAt + 1] == varStatement)
{
// just append our vardecls to the insertion point, then delete our statement
existingVar.Append(varStatement);
block.RemoveAt(insertAt + 1);
}
else
{
// iterate through the decls and count how many have initializers
var initializerCount = 0;
for (var ndx = 0; ndx < varStatement.Count; ++ndx)
{
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)
{
if (varDecl.IsCCSpecialCase)
{
// create a vardecl with the same name and no initializer
var copyDecl = new VariableDeclaration(varDecl.Context, varDecl.Parser)
{
Identifier = varDecl.Identifier,
NameContext = varDecl.VariableField.OriginalContext,
VariableField = varDecl.VariableField
};
// replace the special vardecl with the copy
varStatement[ndx] = copyDecl;
// add the original vardecl to the list of "assignments"
assignments.Add(varDecl);
// add the new decl to the field's declaration list, and remove the old one
// because we're going to change that to an assignment.
varDecl.VariableField.Declarations.Add(copyDecl);
varDecl.VariableField.Declarations.Remove(varDecl);
}
else
{
// 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;
// create an assignment operator for a lookup to the name
// as the left, and the initializer as the right, and add it to the list
var lookup = new Lookup(varDecl.VariableField.OriginalContext, varDecl.Parser)
{
Name = varDecl.Identifier,
VariableField = varDecl.VariableField,
};
assignments.Add(new BinaryOperator(varDecl.Context, varDecl.Parser)
{
Operand1 = lookup,
Operand2 = initializer,
OperatorToken = JSToken.Assign,
OperatorContext = varDecl.AssignContext
});
// add the new lookup to the field's references
varDecl.VariableField.References.Add(lookup);
}
}
}
// 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(null, expression.Parser, 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.
// if the parent is a for-in statement...
var forInParent = varStatement.Parent as ForIn;
if (forInParent != null)
{
// we want to replace the var statement with a lookup for the var
// there should be only one vardecl
var varDecl = varStatement[0];
var lookup = new Lookup(varDecl.VariableField.OriginalContext, varStatement.Parser)
{
Name = varDecl.Identifier,
VariableField = varDecl.VariableField
};
varStatement.Parent.ReplaceChild(varStatement, lookup);
varDecl.VariableField.References.Add(lookup);
}
else
{
// 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);
}