/// <summary>
/// Parses a label
/// </summary>
public static Label ParseLabel(Scanner scanner)
{
Token t = scanner.nextToken();
if (t.Type != TokenType.Identifier)
{
throw new Exception("Identifier expected: " + t);
}
String name = t.StringValue;
StringBuilder str = new StringBuilder();
t = scanner.peekToken();
if (t.Type == TokenType.LParen)
{
// (
scanner.nextToken();
t = scanner.peekToken();
if (t.Type != TokenType.RParen)
{
while (true)
{
t = scanner.nextToken();
if (t.Type != TokenType.Identifier && t.Type != TokenType.Integer)
{
throw new Exception("Identifier or integer expected: " + t);
}
str.Append(t.StringValue);
// ) or ,
t = scanner.nextToken();
if (t.Type == TokenType.RParen)
{
break;
}
if (t.Type != TokenType.Comma)
{
throw new Exception(", expected: " + t);
}
str.Append(',');
}
}
else
{
// )
scanner.nextToken();
}
}
return(new Label(name, str.ToString()));
}
// Loads definitions for variables
private void LoadVariables(Scanner s)
{
variables = new Dictionary <string, Definition>();
while (true)
{
Token t = s.peekToken();
if (t.Type == TokenType.EOF)
{
break;
}
if (t.Type == TokenType.Identifier && t.StringValue == "end")
{
// end
s.nextToken();
break;
}
Definition def = ReadDefinition(s);
if (def.set == null)
{
def.set = defaultSets[def.domain];
}
variables.Add(def.name, def);
}
}
/// <summary>
/// Parses a bound of a variable
/// </summary>
/// <param name="scanner"></param>
/// <param name="lp"></param>
private static void ParseBound(Scanner scanner, LP lp)
{
Label varName;
// TODO: wrong way of dealing with free variables
// because the name of a variable could be more complicated
// than just one identifier
Token t = scanner.peekToken(1);
if (t.Type == TokenType.Identifier && t.StringValue == "free")
{
// name
varName = Label.ParseLabel(scanner);
lp.vars.AddVariable(varName);
// free
t = scanner.nextToken();
return;
}
// Lower bound
t = scanner.nextToken();
if (t.Type != TokenType.Integer && t.Type != TokenType.Double)
{
throw new Exception("A number is expected: " + t);
}
decimal low = decimal.Parse(t.StringValue);
// <=
t = scanner.nextToken();
if (t.Type != TokenType.Le)
{
throw new Exception("<= expected: " + t);
}
// Variable
varName = Label.ParseLabel(scanner);
// <=
t = scanner.nextToken();
if (t.Type != TokenType.Le)
{
throw new Exception("<= expected: " + t);
}
// Upper bound
t = scanner.nextToken();
if (t.Type != TokenType.Integer && t.Type != TokenType.Double)
{
throw new Exception("A number is expected: " + t);
}
decimal high = decimal.Parse(t.StringValue);
lp.vars.AddVariable(varName);
lp.vars[varName].LBound = low;
lp.vars[varName].UBound = high;
}
private Definition ReadDefinition(Scanner s)
{
// name
Token t = s.nextToken();
if (t.Type != TokenType.Identifier)
{
throw new Exception("Identifier expected: " + t);
}
string name = t.StringValue;
// :
t = s.nextToken();
if (t.Type != TokenType.Colon)
{
throw new Exception(": expected: " + t);
}
// domain
t = s.nextToken();
if (t.Type != TokenType.Identifier)
{
throw new Exception("Identifier expected: " + t);
}
string domain = t.StringValue;
string set = null;
t = s.peekToken();
if (t.Type == TokenType.Comma)
{
// ,
t = s.nextToken();
// set
t = s.nextToken();
if (t.Type != TokenType.Identifier)
{
throw new Exception("Identifier expected: " + t);
}
set = t.StringValue;
}
return(new Definition(name, domain, set));
}
/// <summary>
/// Parses a linear function
/// </summary>
/// <param name="scanner"></param>
/// <returns></returns>
public static LinearFunction ParseFunction(Scanner scanner)
{
LinearFunction f = new LinearFunction();
Token t;
while (true)
{
t = scanner.peekToken();
if (t.Type != TokenType.Plus && t.Type != TokenType.Minus)
{
break;
}
Term term = Term.ParseTerm(scanner);
f.terms.Add(term);
}
return(f);
}
/// <summary>
/// Parses a term
/// </summary>
/// <param name="scanner"></param>
/// <returns></returns>
public static Term ParseTerm(Scanner scanner)
{
Token t = scanner.nextToken();
bool negative = false;
decimal c;
Label varName;
// Sign
if (t.Type == TokenType.Minus)
{
negative = true;
}
else if (t.Type != TokenType.Plus)
{
throw new Exception("+ or - expected: " + t);
}
t = scanner.peekToken();
// Coefficient
if (t.Type == TokenType.Integer || t.Type == TokenType.Double)
{
// number
scanner.nextToken();
c = decimal.Parse(t.StringValue);
}
else
{
c = 1;
}
if (negative)
{
c = -c;
}
// Variable
varName = Label.ParseLabel(scanner);
return(new Term(new LpNumber(c), varName));
}
// Loads default sets
private void LoadDefaultSets(Scanner s)
{
defaultSets = new Dictionary <string, string>();
while (true)
{
Token t = s.peekToken();
if (t.Type == TokenType.EOF)
{
break;
}
if (t.Type == TokenType.Identifier && t.StringValue == "end")
{
// end
s.nextToken();
break;
}
Definition def = ReadDefinition(s);
defaultSets.Add(def.name, def.domain);
}
}
/// <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);
}
// Reads one definition
private Definition ReadDefinition(Scanner s)
{
// name
Token t = s.nextToken();
if (t.Type != TokenType.Identifier)
throw new Exception("Identifier expected: " + t);
string name = t.StringValue;
// :
t = s.nextToken();
if (t.Type != TokenType.Colon)
throw new Exception(": expected: " + t);
// domain
t = s.nextToken();
if (t.Type != TokenType.Identifier)
throw new Exception("Identifier expected: " + t);
string domain = t.StringValue;
string set = null;
t = s.peekToken();
if (t.Type == TokenType.Comma)
{
// ,
t = s.nextToken();
// set
t = s.nextToken();
if (t.Type != TokenType.Identifier)
throw new Exception("Identifier expected: " + t);
set = t.StringValue;
}
return new Definition(name, domain, set);
}
// Loads definitions for variables
private void LoadVariables(Scanner s)
{
variables = new Dictionary<string, Definition>();
while (true)
{
Token t = s.peekToken();
if (t.Type == TokenType.EOF)
break;
if (t.Type == TokenType.Identifier && t.StringValue == "end")
{
// end
s.nextToken();
break;
}
Definition def = ReadDefinition(s);
if (def.set == null)
def.set = defaultSets[def.domain];
variables.Add(def.name, def);
}
}
// Loads default sets
private void LoadDefaultSets(Scanner s)
{
defaultSets = new Dictionary<string, string>();
while (true)
{
Token t = s.peekToken();
if (t.Type == TokenType.EOF)
break;
if (t.Type == TokenType.Identifier && t.StringValue == "end")
{
// end
s.nextToken();
break;
}
Definition def = ReadDefinition(s);
defaultSets.Add(def.name, def.domain);
}
}
/// <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;
}
/// <summary>
/// Parses a bound of a variable
/// </summary>
/// <param name="scanner"></param>
/// <param name="lp"></param>
private static void ParseBound(Scanner scanner, LP lp)
{
Label varName;
// TODO: wrong way of dealing with free variables
// because the name of a variable could be more complicated
// than just one identifier
Token t = scanner.peekToken(1);
if (t.Type == TokenType.Identifier && t.StringValue == "free")
{
// name
varName = Label.ParseLabel(scanner);
lp.vars.AddVariable(varName);
// free
t = scanner.nextToken();
return;
}
// Lower bound
t = scanner.nextToken();
if (t.Type != TokenType.Integer && t.Type != TokenType.Double)
throw new Exception("A number is expected: " + t);
decimal low = decimal.Parse(t.StringValue);
// <=
t = scanner.nextToken();
if (t.Type != TokenType.Le)
throw new Exception("<= expected: " + t);
// Variable
varName = Label.ParseLabel(scanner);
// <=
t = scanner.nextToken();
if (t.Type != TokenType.Le)
throw new Exception("<= expected: " + t);
// Upper bound
t = scanner.nextToken();
if (t.Type != TokenType.Integer && t.Type != TokenType.Double)
throw new Exception("A number is expected: " + t);
decimal high = decimal.Parse(t.StringValue);
lp.vars.AddVariable(varName);
lp.vars[varName].LBound = low;
lp.vars[varName].UBound = high;
}
