public Expression Parse(PrattParser parser, Expression left, Token token)
{
var right = parser.ParseExpression(
_precedence - (_isRight ? 1 : 0));
return(new BinaryOpExpression(left, token, right));
}
public Expression Parse(PrattParser parser, Token token)
{
var expression = parser.ParseExpression();
parser.ConsumeNext(TokenType.RPAREN);
return(expression);
}
/// <summary>
/// Execute the left denotation function of this token.
/// </summary>
/// <param name="parser">The parser state.</param>
/// <param name="left">The value to the left of this token.</param>
/// <returns>The left denotation of this token.</returns>
public T Led(PrattParser <T> parser, T left)
{
if (LeftDenotation == null)
{
throw new ParseException(Line, Column, "Unknown symbol: '" + Id + "'.");
}
return(LeftDenotation(parser, left));
}
/// <summary>
/// Execute the null denotation function of this token.
/// </summary>
/// <returns>The value for the null denotation of this token.</returns>
public T Nud(PrattParser <T> parser)
{
if (NullDenotation == null)
{
throw new ParseException(Line, Column, "Syntax error: '" + Id + "'.");
}
return(NullDenotation(parser));
}
public Expression Parse(PrattParser parser, Token token)
{
parser.ConsumeNext(TokenType.LPAREN);
var operand = parser.ParseExpression(PrecedenceTable.FUNCTION);
parser.ConsumeNext(TokenType.RPAREN);
return(new AbsExpression(token.Location, operand));
}
private bool Accept <TInput, TOutput>(PrattParser <TInput, TOutput> p, BnfStringifyVisitor state)
{
var children = p.GetChildren().ToArray();
if (children.Length == 0)
{
state.Append("PRATT()");
return(true);
}
state.Append("PRATT(", children[0]);
for (int i = 1; i < children.Length; i++)
{
state.Append(", ", children[i]);
}
state.Append(')');
return(true);
}
/// <summary>
/// Parse the given text and return the corresponding value, or throw a parse error.
/// </summary>
/// <param name="text">The text to parse.</param>
/// <returns>The value parsed from the text.</returns>
/// <exception cref="ParseException">Thrown when the text has an invalid structure.</exception>
public T Parse(string text)
{
var p = new PrattParser <T>(text, symbols);
try
{
var x = p.Parse(0);
p.EnsureInputConsumed();
return(x);
}
catch (ParseException)
{
throw;
}
catch (Exception e)
{
p.Fail(text, e.Message);
return(default(T)); // unreachable
}
}
public Expression Parse(PrattParser parser, Token token)
{
var operand = parser.ParseExpression(_precedence);
return(new PrefixExpression(token.TokenType, token.Location, operand));
}
public Expression Parse(PrattParser parser, Token token)
{
return(new RealExpression(token.Text, token.Location));
}
/// <summary> /// Creates a Pratt parser, which is especially useful for mathematical expression parsing. /// </summary> /// <typeparam name="TOutput"></typeparam> /// <param name="setup"></param> /// <returns></returns> public static IParser <TInput, TOutput> Pratt <TOutput>(Action <IConfiguration <TInput, TOutput> > setup) => PrattParser <TInput, TOutput> .Configure(setup);
