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// $Id$
using System;
using System.IO;
namespace Lisp
{
public class Parser {
public enum LispType {
START_LIST,
END_LIST,
SYMBOL,
INTEGER,
STRING,
REAL,
BOOLEAN
};
private Lexer lexer;
private Lexer.TokenType token;
public Parser(StreamReader stream) {
lexer = new Lexer(stream);
}
public bool Parse() {
token = lexer.GetNextToken();
if(delayinc) {
depth++;
delayinc = false;
}
if(token == Lexer.TokenType.EOF) {
depth = 0;
return false;
}
/*
Console.WriteLine("Token: " + token.ToString() + " - " +
lexer.TokenString);
*/
switch(token) {
case Lexer.TokenType.CLOSE_PAREN:
if(depth == 0)
throw new Exception("Parse Error: unexpected )");
depth--;
type = LispType.END_LIST;
break;
case Lexer.TokenType.OPEN_PAREN:
type = LispType.START_LIST;
delayinc = true;
break;
case Lexer.TokenType.SYMBOL:
type = LispType.SYMBOL;
break;
case Lexer.TokenType.STRING:
type = LispType.STRING;
break;
case Lexer.TokenType.TRUE:
type = LispType.BOOLEAN;
break;
case Lexer.TokenType.INTEGER:
type = LispType.INTEGER;
break;
}
return true;
}
public static void ParseIntList(Parser parser, System.Collections.Generic.List<int> intList) {
int d = parser.Depth;
while(parser.Depth >= d) {
intList.Add(parser.IntegerValue);
parser.Parse();
}
}
private LispType type;
public LispType Type {
get { return type; }
}
private bool delayinc;
private int depth;
public int Depth {
get { return depth; }
}
//public int IntValue
public string SymbolValue {
get { return lexer.TokenString; }
}
public string StringValue {
get { return lexer.TokenString; }
}
public int IntegerValue {
get { return Int32.Parse(lexer.TokenString); }
}
public bool BoolValue {
get { return StringValue == "t"; }
}
public float FloatValue {
get { return Single.Parse(lexer.TokenString); }
}
}
}
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