public Tuple <OperatorDefinition, int> GetTopOperator(IEnumerable <Token> tokens, List <OperatorDefinition> ops)
{
int pos = 0;
int winningPos = -1;
int bracketDepth = 0;
OperatorDefinition winningOpDef = null;
OperatorDefinition opDef = null;
foreach (Token t in tokens)
{
opDef = ops.FirstOrDefault(op => op.Op == t.ToString().ToLower());
if (OpenBrackets.Contains(t.ToString()))
{
bracketDepth++;
}
else if (CloseBrackets.Contains(t.ToString()))
{
bracketDepth--;
}
if (bracketDepth < 0)
{
break;
}
if (opDef != null && (winningOpDef == null || opDef.Precedence >= winningOpDef.Precedence))
{
winningOpDef = opDef;
winningPos = pos;
}
pos++;
}
return(new Tuple <OperatorDefinition, int>(winningOpDef, winningPos));
}
public List<Token> GetHead(IEnumerable<Token> tokens, List<OperatorDefinition> ops, OperatorDefinition foundOp)
{
var topOp = GetTopOperator(tokens, ops);
if (topOp.Item1 != null)
{
foundOp = topOp.Item1;
return tokens.Take(topOp.Item2 - 1).ToList();
}
else
{
foundOp = null;
return tokens.ToList();
}
}
protected Expression Parse(Dictionary<string, ParameterExpression> parameters, List<Token> tokens)
{
if (tokens == null || tokens.Count == 0)
return null;
if (tokens.Count == 1)
{
if (tokens[0] is QuotedLiteralToken)
{
return Expression.Constant(((QuotedLiteralToken)tokens[0]).Value);
}
else if (tokens[0] is WordToken)
{
return BuildReference(parameters, tokens[0].ToString().ToLower());
}
else if (tokens[0] is NumberToken)
{
return Expression.Constant((int)((NumberToken)tokens[0]).Value);
}
else
throw new ArgumentException("Unexpected token: " + tokens[0].ToString());
}
else if (tokens.MatchPattern("'guid'Q"))
return Expression.Constant(new Guid(tokens[1].ToString()));
else if (tokens.MatchPattern("'datetime'Q"))
return Expression.Constant(XmlConvert.ToDateTime(tokens[1].ToString()));
else if (tokens.MatchPattern("W'('"))
{
var funcOp = Ops.FirstOrDefault(op => op.Op == tokens[0].ToString());
if (funcOp == null)
throw new ArgumentException("Unrecognised operator " + tokens[0].ToString());
List<Expression> parms = new List<Expression>();
OperatorDefinition opFound = new OperatorDefinition();
OperatorDefinition opComma = new OperatorDefinition { Op = "," };
while (opFound != null)
{
var exp = Parse(parameters, GetHead(tokens, new List<OperatorDefinition> { opComma }, opFound));
parms.Add(exp);
}
return funcOp.Build(parms);
}
else
{
var topOp = GetTopOperator(tokens, Ops);
if (topOp.Item1 == null)
throw new Exception("Cannot find operator");
return topOp.Item1.Build(new List<Expression> {
Parse(parameters, tokens.Take(topOp.Item2).ToList()),
Parse(parameters, tokens.Skip(topOp.Item2 + 1).ToList())
});
}
}
protected Expression Parse(Dictionary <string, ParameterExpression> parameters, List <Token> tokens)
{
if (tokens == null || tokens.Count == 0)
{
return(null);
}
if (tokens.Count == 1)
{
if (tokens[0] is QuotedLiteralToken)
{
return(Expression.Constant(((QuotedLiteralToken)tokens[0]).Value));
}
else if (tokens[0] is WordToken)
{
return(BuildReference(parameters, tokens[0].ToString().ToLower()));
}
else if (tokens[0] is NumberToken)
{
return(Expression.Constant((int)((NumberToken)tokens[0]).Value));
}
else
{
throw new ArgumentException("Unexpected token: " + tokens[0].ToString());
}
}
else if (tokens.MatchPattern("'guid'Q"))
{
return(Expression.Constant(new Guid(tokens[1].ToString())));
}
else if (tokens.MatchPattern("'datetime'Q"))
{
return(Expression.Constant(XmlConvert.ToDateTime(tokens[1].ToString())));
}
else if (tokens.MatchPattern("W'('"))
{
var funcOp = Ops.FirstOrDefault(op => op.Op == tokens[0].ToString());
if (funcOp == null)
{
throw new ArgumentException("Unrecognised operator " + tokens[0].ToString());
}
List <Expression> parms = new List <Expression>();
OperatorDefinition opFound = new OperatorDefinition();
OperatorDefinition opComma = new OperatorDefinition {
Op = ","
};
while (opFound != null)
{
var exp = Parse(parameters, GetHead(tokens, new List <OperatorDefinition> {
opComma
}, opFound));
parms.Add(exp);
}
return(funcOp.Build(parms));
}
else
{
var topOp = GetTopOperator(tokens, Ops);
if (topOp.Item1 == null)
{
throw new Exception("Cannot find operator");
}
return(topOp.Item1.Build(new List <Expression> {
Parse(parameters, tokens.Take(topOp.Item2).ToList()),
Parse(parameters, tokens.Skip(topOp.Item2 + 1).ToList())
}));
}
}
public List <Token> GetHead(IEnumerable <Token> tokens, List <OperatorDefinition> ops, OperatorDefinition foundOp)
{
var topOp = GetTopOperator(tokens, ops);
if (topOp.Item1 != null)
{
foundOp = topOp.Item1;
return(tokens.Take(topOp.Item2 - 1).ToList());
}
else
{
foundOp = null;
return(tokens.ToList());
}
}
