// Atom : Value | LParen Expression RParen
internal static INode Produce(TokenBuffer tokens)
{
var value = Value.Produce(tokens);
if (value != null)
return value;
// HACK
if (tokens.Current is LeftParenthesis)
tokens.SavePosition();
var lParen = tokens.GetTerminal<LeftParenthesis>();
if (lParen == null)
return null;
var expression = Expression.Produce(tokens);
if (expression == null)
{
tokens.RestorePosition();
return null;
}
var rParen = tokens.GetTerminal<RightParenthesis>();
if (rParen == null)
{
throw new ParseException("Missing closing parenthesis");
}
return expression;
}
// AddSubOp : AddOp | SubOp
internal static AddSubOp Produce(TokenBuffer tokens)
{
var addOp = tokens.GetTerminal<AdditionOperator>();
if (addOp != null)
return new AddSubOp(addOp);
var subOp = tokens.GetTerminal<SubtractionOperator>();
if (subOp != null)
return new AddSubOp(subOp);
return null;
}
// ExpRootOp : ExpOp | RootOp
internal static ExpRootOp Produce(TokenBuffer tokens)
{
var expOp = tokens.GetTerminal<ExponentiationOperator>();
if (expOp != null)
return new ExpRootOp(expOp);
var rootOp = tokens.GetTerminal<RootExtractionOperator>();
if (rootOp != null)
return new ExpRootOp(rootOp);
return null;
}
// MulDivOp : MulOp | DivOp
internal static MulDivOp Produce(TokenBuffer tokens)
{
var mulOp = tokens.GetTerminal<MultiplicationOperator>();
if (mulOp != null)
return new MulDivOp(mulOp);
var divOp = tokens.GetTerminal<DivisionOperator>();
if (divOp != null)
return new MulDivOp(divOp);
return null;
}
// Digits : Digit+
internal static Digits Produce(TokenBuffer tokens)
{
var digitList = new List<Digit>();
var digit = tokens.GetTerminal<Digit>();
if (digit != null)
{
while (digit != null)
{
digitList.Add(digit);
digit = tokens.GetTerminal<Digit>();
}
return new Digits(digitList);
}
return null;
}
// Identifier : Character+
internal static Identifier Produce(TokenBuffer tokens)
{
var characters = new List<Character>();
var character = tokens.GetTerminal<Character>();
if (character != null)
{
while (character != null)
{
characters.Add(character);
character = tokens.GetTerminal<Character>();
}
return new Identifier(characters);
}
return null;
}
internal static Assignment Produce(TokenBuffer tokens)
{
var assignee = Identifier.Produce(tokens);
if (assignee == null)
//throw new ParseException("Assignment must start with a identifier for the assignee.");
return null;
var assignOp = tokens.GetTerminal<AssignmentOperator>();
if (assignOp == null)
//throw new ParseException("Expected assignment operator.");
return null;
var assigner = Expression.Produce(tokens);
if (assigner == null)
throw new ParseException("Expected expression for the right side of the assignment.");
return new Assignment(assignee, assigner);
}