public ExprParser()
{
this.Tokenizer = new Tokenizer();
_prefixHandlers = new Dictionary <TokenKind, Func <ParsingContext, int, Expr> >()
{
{ TokenKind.Number, (ctx, bp) => double.Parse(ctx.CurrentToken.Content) },
{ TokenKind.Symbol, (ctx, bp) => KnownNames.Symbol(ctx.CurrentToken.Content) },
{ TokenKind.String, (ctx, bp) => R.Regex.Replace(ctx.CurrentToken.Content.Substring(1, ctx.CurrentToken.Content.Length - 2), @"\\(.)", "$1") },
{ TokenKind.OpenGroup, (ctx, bp) => {
var inner = this.ParseInternal(ctx);
ctx.ExpectToken(TokenKind.CloseGroup);
return(inner);
} },
{ TokenKind.OpChar, (ctx, bp) => {
var opToken = ctx.CurrentToken;
var arg = this.ParseInternal(ctx, bp);
return(opToken.TokenInfo.UnaryHandler(arg));
} },
};
_infixHandlers = new Dictionary <TokenKind, Func <ParsingContext, int, Expr, Expr> >()
{
{ TokenKind.OpenBracket, (ctx, bp, left) => {
var args = new List <Expr>();
if (ctx.Peek().Kind != TokenKind.CloseBracket)
{
args.Add(this.ParseInternal(ctx));
while (ctx.Peek().Kind == TokenKind.Comma)
{
ctx.Advance();
args.Add(this.ParseInternal(ctx));
}
}
ctx.ExpectToken(TokenKind.CloseBracket);
return(new Apply(left, args.ToArray()));
} },
{ TokenKind.OpChar, (ctx, bp, left) => {
var opToken = ctx.CurrentToken;
var right = this.ParseInternal(ctx, bp);
return(opToken.TokenInfo.BinaryHandler(left, right));
} },
};
}
public static Expr Apply(this string head, params Expr[] args)
{
return(new Apply(KnownNames.Symbol(head), args));
}
