static private Token ExpandString(CharReader reader, StringBuilder literal)
{
bool expandEscapeChar = false;
char c;
while (reader.Next())
{
c = reader.Read();
if (expandEscapeChar)
{
literal.Append(c);
}
else if (c == '\\')
{
expandEscapeChar = true;
}
else if (c == '\'')
{
break;
}
else
{
literal.Append(c);
}
}
return(literal.ToString());
}
static private Token[] ExpandParameters(CharReader reader, StringBuilder literal, IResolver resolver)
{
List <Token> tokens = new List <Token>();
while (reader.Next())
{
char c = reader.Current;
switch (c)
{
case ',':
if (literal.Length == 0)
{
throw ThrowSyntaxError(reader.Position);
}
literal.Length = 0;
break;
case ')':
literal.Length = 0;
return(tokens.ToArray());
case '\'':
reader.Read(); //skip the char
tokens.Add(ExpandString(reader, literal));
continue;
default:
if (char.IsLetter(c))
{
tokens.Add(ExpandVariable(reader, literal, resolver));
continue;
}
else if (char.IsDigit(c))
{
tokens.Add(ExpandNumber(reader, literal));
continue;
}
else
{
// it is whitespace or newline, to do nothing...
}
break;
}
literal.Length = 0;
reader.Read();
}
throw ThrowSyntaxError(reader.Position);
}
static private Token ExpandVariable(CharReader reader, StringBuilder literal, IResolver resolver)
{
char c;
while (reader.Next())
{
c = reader.Current;
if (char.IsLetterOrDigit(c))
{
literal.Append(c);
}
else
{
if (literal.ToString() == "true")
{
return(true);
}
else if (literal.ToString() == "false")
{
return(false);
}
else if (char.IsWhiteSpace(c))
{
continue;
}
else if (c == '(')
{
string name = literal.ToString();
literal.Length = 0;
reader.Read(); // skip the char
Token[] args = ExpandParameters(reader, literal, resolver);
Token result = resolver.HandleFunction(name, args);
return(result);
}
else
{
Token result = resolver.HandleVariable(literal.ToString());
return(result);
}
}
reader.Read();
}
return(Token.Null);
}
static private Token ExpandNumber(CharReader reader, StringBuilder literal)
{
char c;
while (reader.Next())
{
c = reader.Current;
if (char.IsDigit(c))
{
literal.Append(c);
}
else
{
break;
}
reader.Read();
}
return(int.Parse(literal.ToString()));
}
static private ParseTree Parse(string expression, IResolver resolver)
{
if (expression == null)
{
throw new ArgumentNullException("expression");
}
ParseTree tokenTree = new ParseTree();
StringBuilder literal = new StringBuilder();
CharReader reader = new CharReader(expression);
Token last = Token.Null;
while (reader.Next())
{
Debug.Assert(literal.Length == 0);
char c = reader.Read();
switch (c)
{
case '(':
{
switch (last.Type)
{
case TokenType.Prefix:
case TokenType.Operation:
case TokenType.Expression:
case TokenType.None:
last = Token.Create(TokenType.Expression, null);
tokenTree.Append(last);
break;
default:
throw ThrowSyntaxError(reader.Position);
}
}
break;
case ')':
{
switch (last.Type)
{
case TokenType.Boolean:
case TokenType.Number:
case TokenType.String:
case TokenType.Variable:
case TokenType.Function:
case TokenType.EndExpression:
last = Token.Create(TokenType.EndExpression, null);
tokenTree.Append(last);
break;
default:
throw ThrowSyntaxError(reader.Position);
}
}
break;
case '?':
switch (last.Type)
{
case TokenType.Boolean:
case TokenType.Number:
case TokenType.String:
case TokenType.Variable:
case TokenType.Function:
case TokenType.EndExpression:
last = Token.CreateOperator(c.ToString());
tokenTree.Append(last);
break;
default:
throw ThrowSyntaxError(reader.Position);
}
break;
case '|':
case '&':
switch (last.Type)
{
case TokenType.Boolean:
case TokenType.Number:
case TokenType.String:
case TokenType.Variable:
case TokenType.Function:
case TokenType.Expression:
literal.Append(c);
if (!reader.Next())
{
throw ThrowSyntaxError(reader.Position);
}
if (reader.Current != c)
{
throw ThrowSyntaxError(reader.Position);
}
literal.Append(reader.Read());
last = Token.CreateOperator(literal.ToString());
tokenTree.Append(last);
literal.Length = 0;
break;
default:
throw ThrowSyntaxError(reader.Position);
}
break;
case '!':
switch (last.Type)
{
case TokenType.Operation:
case TokenType.Expression:
case TokenType.None:
// prefix
last = Token.CreatePrefix(c.ToString());
tokenTree.Append(last);
break;
case TokenType.Boolean:
case TokenType.Number:
case TokenType.String:
case TokenType.Variable:
case TokenType.Function:
case TokenType.EndExpression:
// operator
literal.Append(c);
if (!reader.Next())
{
throw ThrowSyntaxError(reader.Position);
}
if (reader.Current != '=')
{
throw ThrowSyntaxError(reader.Position);
}
literal.Append(reader.Read());
last = Token.CreateOperator(literal.ToString());
tokenTree.Append(last);
literal.Length = 0;
break;
default:
throw ThrowSyntaxError(reader.Position);
}
break;
case '-':
switch (last.Type)
{
case TokenType.Operation:
case TokenType.Expression:
case TokenType.None:
// prefix
last = Token.CreatePrefix(c.ToString());
tokenTree.Append(last);
break;
case TokenType.Boolean:
case TokenType.Number:
case TokenType.String:
case TokenType.Variable:
case TokenType.Function:
case TokenType.EndExpression:
// operator
last = Token.CreateOperator(c.ToString());
tokenTree.Append(last);
break;
default:
throw ThrowSyntaxError(reader.Position);
}
break;
case '+':
case '*':
case '/':
case '%':
switch (last.Type)
{
case TokenType.Boolean:
case TokenType.Number:
case TokenType.String:
case TokenType.Variable:
case TokenType.Function:
case TokenType.EndExpression:
last = Token.CreateOperator(c.ToString());
tokenTree.Append(last);
break;
default:
throw ThrowSyntaxError(reader.Position);
}
break;
case '>':
case '<':
switch (last.Type)
{
case TokenType.Boolean:
case TokenType.Number:
case TokenType.String:
case TokenType.Variable:
case TokenType.Function:
case TokenType.EndExpression:
literal.Append(c);
if (!reader.Next())
{
throw ThrowSyntaxError(reader.Position);
}
if (reader.Current == '=')
{
literal.Append(reader.Read());
}
last = Token.CreateOperator(literal.ToString());
tokenTree.Append(last);
literal.Length = 0;
break;
default:
throw ThrowSyntaxError(reader.Position);
}
break;
case '=':
switch (last.Type)
{
case TokenType.Boolean:
case TokenType.Number:
case TokenType.String:
case TokenType.Variable:
case TokenType.Function:
case TokenType.EndExpression:
literal.Append(c);
if (!reader.Next())
{
throw ThrowSyntaxError(reader.Position);
}
if (reader.Current != '=')
{
throw ThrowSyntaxError(reader.Position);
}
literal.Append(reader.Read());
last = Token.CreateOperator(literal.ToString());
tokenTree.Append(last);
literal.Length = 0;
break;
default:
throw ThrowSyntaxError(reader.Position);
}
break;
case '\'':
switch (last.Type)
{
case TokenType.Operation:
case TokenType.Expression:
case TokenType.None:
last = ExpandString(reader, literal);
tokenTree.Append(last);
literal.Length = 0;
break;
default:
throw ThrowSyntaxError(reader.Position);
}
break;
default:
if (char.IsLetter(c))
{
switch (last.Type)
{
case TokenType.Prefix:
case TokenType.Operation:
case TokenType.Expression:
case TokenType.None:
literal.Append(c);
last = ExpandVariable(reader, literal, resolver);
tokenTree.Append(last);
literal.Length = 0;
break;
default:
throw ThrowSyntaxError(reader.Position);
}
}
else if (char.IsDigit(c))
{
switch (last.Type)
{
case TokenType.Prefix:
case TokenType.Operation:
case TokenType.Expression:
case TokenType.None:
literal.Append(c);
last = ExpandNumber(reader, literal);
tokenTree.Append(last);
literal.Length = 0;
break;
default:
throw ThrowSyntaxError(reader.Position);
}
}
else
{
// it is whitespace or newline, to do nothing...
}
break;
}
}
return(tokenTree);
}
