public static void Apply(BlockStatement block, JSParser parser)
{
if (parser == null)
{
throw new ArgumentNullException("parser");
}
if (block != null)
{
// create a new instance of the visitor and apply it to the block
var visitor = new ReorderScopeVisitor(parser);
block.Accept(visitor);
// if there were any module directive prologues we need to promote, do them first
var insertAt = 0;
if (visitor.m_moduleDirectives != null)
{
foreach (var directivePrologue in visitor.m_moduleDirectives)
{
insertAt = RelocateDirectivePrologue(block, insertAt, directivePrologue);
}
}
// Make sure that we skip over any remaining comments and directive prologues.
// we do NOT want to insert anything between the start of the scope and any directive prologues.
while (insertAt < block.Count &&
(block[insertAt] is DirectivePrologue || block[insertAt] is ImportantComment))
{
++insertAt;
}
// first, we want to move all function declarations to the top of this block
if (visitor.m_functionDeclarations != null)
{
foreach (var funcDecl in visitor.m_functionDeclarations)
{
insertAt = RelocateFunction(block, insertAt, funcDecl);
}
}
// special case: if there is only one var statement in the entire scope,
// then just leave it alone because we will only add bytes by moving it around,
// or be byte-neutral at best (no initializers and not in a for-statement).
if (visitor.m_varStatements != null && visitor.m_varStatements.Count > 1)
{
// then we want to move all variable declarations after to the top (after the functions)
foreach (var varStatement in visitor.m_varStatements)
{
insertAt = RelocateVar(block, insertAt, varStatement);
}
}
// then we want to do the same thing for all child functions (declarations AND other)
if (visitor.m_functionDeclarations != null)
{
foreach (var funcDecl in visitor.m_functionDeclarations)
{
Apply(funcDecl.Body, parser);
}
}
if (visitor.m_functionExpressions != null)
{
foreach (var funcExpr in visitor.m_functionExpressions)
{
Apply(funcExpr.Body, parser);
}
}
// and then recurse the modules
if (visitor.m_moduleDeclarations != null)
{
foreach (var moduleDecl in visitor.m_moduleDeclarations)
{
Apply(moduleDecl.Body, parser);
}
}
}
}
private static int RelocateVar(BlockStatement block, int insertAt, VarDeclaration varStatement)
{
var forInParent = varStatement.Parent as ForInStatement;
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.
ForStatement forStatement;
var existingVar = block[insertAt] as VarDeclaration;
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 &&
(forStatement = varStatement.Parent as ForStatement) != null &&
forStatement.Initializer == varStatement &&
forStatement == 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 BinaryExpression(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 = CommaExpression.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);
}