public override Expression Scan(ParseEngine engine)
{
var index = engine.Pointer;
var chars = engine.Characters;
if (ParseEngine.IsIdentifierStart(chars[index]))
{
index++;
while (index < chars.Length && ParseEngine.IsIdentifierPart(chars[index]))
{
index++;
}
var name = new String(chars, engine.Pointer, index - engine.Pointer);
if (engine.UseKeywords)
{
var keyword = engine.Elements.FindKeywordExpression(name, engine);
if (keyword != null)
{
return(keyword);
}
}
var exp = new SymbolExpression(engine, name);
engine.SetPointer(index);
return(exp);
}
return(null);
}
Value Assign(SymbolExpression left, Value value, IDictionary <String, Value> symbols)
{
if (symbols.ContainsKey(left.SymbolName))
{
symbols[left.SymbolName] = value.Copy();
}
else
{
Context.AssignVariable(left.SymbolName, value.Copy());
}
return(value);
}
public static Boolean IsAssigned(this ContainerExpression container, SymbolExpression symbol)
{
var expressions = container.Expressions;
if (expressions.Length > 0)
{
var leftExpression = expressions[0];
container = leftExpression as ContainerExpression;
if (container != null)
{
return(container.IsAssigned(symbol));
}
return(Object.ReferenceEquals(leftExpression, symbol));
}
return(false);
}