/// <summary>
/// Parses an inequality
/// </summary>
/// <param name="scanner"></param>
/// <returns></returns>
public static Inequality ParseInequality(Scanner scanner)
{
Token t;
// Identifier
Label id = Label.ParseLabel(scanner);
// :
t = scanner.nextToken();
if (t.Type != TokenType.Colon)
{
throw new Exception(": expected: " + t);
}
// lhs
LinearFunction lhs = LinearFunction.ParseFunction(scanner);
// type
t = scanner.nextToken();
IneqType type;
switch (t.Type)
{
case TokenType.Le:
type = IneqType.Le;
break;
case TokenType.Ge:
type = IneqType.Ge;
break;
case TokenType.Eq:
type = IneqType.Eq;
break;
default:
throw new Exception("<=, =>, or = expected: " + t);
}
// rhs
t = scanner.nextToken();
if (t.Type != TokenType.Integer && t.Type != TokenType.Double)
{
throw new Exception("A number is expected: " + t);
}
LpNumber rhs = new LpNumber(decimal.Parse(t.StringValue));
return(new Inequality(id, type, lhs, rhs, false));
}
/// <summary>
/// Parses a LP
/// </summary>
/// <param name="scanner"></param>
/// <returns></returns>
public static LP ParseLP(Scanner scanner)
{
LP lp = new LP();
// Maximize
Token t = scanner.nextToken();
if (t.Type != TokenType.Identifier && t.StringValue != "Maximize")
{
throw new Exception("Maximize expected: " + t);
}
// objective
t = scanner.nextToken();
if (t.Type != TokenType.Identifier)
{
throw new Exception("Identifier expected: " + t);
}
// :
t = scanner.nextToken();
if (t.Type != TokenType.Colon)
{
throw new Exception(": expected: " + t);
}
// objective function
lp.objective = LinearFunction.ParseFunction(scanner);
// Subject To
t = scanner.nextToken();
if (t.Type != TokenType.Identifier && t.StringValue != "Subject")
{
throw new Exception("Subject To expected: " + t);
}
t = scanner.nextToken();
if (t.Type != TokenType.Identifier && t.StringValue != "To")
{
throw new Exception("Subject To expected: " + t);
}
// Constraints
while (true)
{
t = scanner.peekToken();
if (t.Type == TokenType.Identifier && t.StringValue == "Bounds")
{
break;
}
if (t.Type == TokenType.EOF)
{
break;
}
Inequality ineq = Inequality.ParseInequality(scanner);
lp.originalIneqs.Add(ineq);
}
// Bounds
t = scanner.nextToken();
if (t.Type != TokenType.Identifier && t.StringValue != "Bounds")
{
throw new Exception("Bounds expected: " + t);
}
// Bounds
while (true)
{
t = scanner.peekToken();
if (t.Type == TokenType.Identifier && t.StringValue == "End")
{
break;
}
if (t.Type == TokenType.EOF)
{
break;
}
ParseBound(scanner, lp);
}
return(lp);
}