void match(Token ter, Error err)
{
if (next.t == ter.t)
move();
else
throw new ProgramError(err, ter.ToString(), next.line, next.col);
}
public Token Scan()
{
if (pushed.Count != 0) return pushed.Pop();
skipwhite:
while (char.IsWhiteSpace(peek))
{
peek = readch();
}
if (peek == eof) return Token.Eof;
tokencol = col;
// [A-Za-z_][A-Za-z0-9_]*
if (char.IsLetter(peek) || peek == '_')
{
System.Text.StringBuilder sb = new System.Text.StringBuilder();
do
{
sb.Append(peek);
peek = readch();
} while (char.IsLetterOrDigit(peek) || peek == '_');
string s = sb.ToString();
// reserve keywords and constants. Return their values literally as tokens
if (Words.ContainsKey(s)) return Words[s];
var t = new Token(TokenKind.Identifier, s, line, tokencol);
Words.Add(s, t);
return t;
}
else if (peek == '\"')
{
var sb = new StringBuilder();
do
{
peek = readch();
switch (peek)
{
case eof:
case '\"':
break;
default:
sb.Append(peek);
break;
}
} while (peek != '\"' && peek != eof);
peek = ' ';
return new StringLiteral(sb.ToString(), line, tokencol);
}
else if (peek == '\'')
{
var sb = new StringBuilder();
do
{
peek = readch();
switch (peek)
{
case eof:
case '\'':
break;
default:
sb.Append(peek);
break;
}
} while (peek != '\'' && peek != eof);
peek = ' ';
return new StringLiteral(sb.ToString(), line, tokencol);
}
else if (peek == '.' || char.IsDigit(peek))
{
// returns: a dot or a real. real = .d[.d]*|d[.d]*
double d = 0;
if (peek == '.')
{
peek = readch();
if (!char.IsDigit(peek))
{
return new Token(TokenKind.Dot, line, tokencol);
}
// Fall through to the fractional part: peek holds the first digit
}
else
{
// integral part (lexeme begins with a digit)
do
{
d = d * 10 + double.Parse(peek.ToString());
peek = readch();
} while (char.IsDigit(peek));
}
double p = 10;
// fractional part
while (char.IsDigit(peek) || peek == '.')
{
if (peek != '.')
{
d += double.Parse(peek.ToString()) / p;
p *= 10;
}
peek = readch();
}
return new Real(d, line, tokencol);
}
else if (peek == '$')
{
peek = readch();
double d = 0;
while (char.IsDigit(peek) || (peek >= 'a' && peek <= 'f') || (peek >= 'A' && peek <= 'F'))
{
d = d * 16 + (double)int.Parse(peek.ToString(), System.Globalization.NumberStyles.AllowHexSpecifier);
peek = readch();
}
return new Real(d, line, tokencol);
}
else if (peek == '/')
{
peek = readch();
switch (peek)
{
case '=':
peek = readch(); return new Token(TokenKind.DivideAssignment, line, tokencol);
case '/':
do peek = readch(); while (peek != '\n' && peek != '\r' && peek != eof);
goto skipwhite;
case '*':
do
{
peek = readch();
if (peek == '*')
{
peek = readch();
if (peek == '/')
{
peek = readch();
goto skipwhite;
}
}
} while (peek != eof);
//error(Token.None, "End-of-file found, '*/' expected");
goto skipwhite;
default:
return new Token(TokenKind.Divide, line, tokencol);
}
}
else
{
switch (peek)
{
case '~': peek = readch(); return new Token(TokenKind.BitwiseComplement, line, tokencol);
case '(': peek = readch(); return new Token(TokenKind.OpeningParenthesis, line, tokencol);
case ')': peek = readch(); return new Token(TokenKind.ClosingParenthesis, line, tokencol);
case '{': peek = readch(); return new Token(TokenKind.OpeningCurlyBrace, line, tokencol);
case '}': peek = readch(); return new Token(TokenKind.ClosingCurlyBrace, line, tokencol);
case '[': peek = readch(); return new Token(TokenKind.OpeningSquareBracket, line, tokencol);
case ']': peek = readch(); return new Token(TokenKind.ClosingSquareBracket, line, tokencol);
case ';': peek = readch(); return new Token(TokenKind.Semicolon, line, tokencol);
case ',': peek = readch(); return new Token(TokenKind.Comma, line, tokencol);
case ':': peek = readch(); if (peek == '=') { peek = readch(); return new Token(TokenKind.Assignment, ":=", line, tokencol); } return new Token(TokenKind.Colon, line, tokencol);
case '=': peek = readch(); if (peek == '=') { peek = readch(); return new Token(TokenKind.Equality, line, tokencol); } return new Token(TokenKind.Assignment, line, tokencol);
case '!': peek = readch(); if (peek == '=') { peek = readch(); return new Token(TokenKind.Inequality, line, tokencol); } return new Token(TokenKind.Not, line, tokencol);
case '*': peek = readch(); if (peek == '=') { peek = readch(); return new Token(TokenKind.MultiplyAssignment, line, tokencol); } return new Token(TokenKind.Multiply, line, tokencol);
case '+': peek = readch(); if (peek == '=') { peek = readch(); return new Token(TokenKind.AdditionAssignment, line, tokencol); } return new Token(TokenKind.Plus, line, tokencol);
case '-': peek = readch(); if (peek == '=') { peek = readch(); return new Token(TokenKind.SubtractionAssignment, line, tokencol); } return new Token(TokenKind.Minus, line, tokencol);
case '&': peek = readch(); if (peek == '=') { peek = readch(); return new Token(TokenKind.AndAssignment, line, tokencol); }
else
if (peek == '&') { peek = readch(); return new Token(TokenKind.LogicalAnd, line, tokencol); } return new Token(TokenKind.BitwiseAnd, line, tokencol);
case '|': peek = readch(); if (peek == '=') { peek = readch(); return new Token(TokenKind.OrAssignment, line, tokencol); }
else
if (peek == '|') { peek = readch(); return new Token(TokenKind.LogicalOr, line, tokencol); } return new Token(TokenKind.BitwiseOr, line, tokencol);
case '^': peek = readch(); if (peek == '=') { peek = readch(); return new Token(TokenKind.XorAssignment, line, tokencol); }
else
if (peek == '^') { peek = readch(); return new Token(TokenKind.LogicalXor, line, tokencol); } return new Token(TokenKind.BitwiseXor, line, tokencol);
case '<':
peek = readch();
if (peek == '=')
{
peek = readch();
return new Token(TokenKind.LessThanOrEqual, line, tokencol);
}
else if (peek == '<')
{
peek = readch();
return new Token(TokenKind.ShiftLeft, line, tokencol);
}
else if (peek == '>')
{
peek = readch();
return new Token(TokenKind.Inequality, "<>", line, tokencol);
}
else return new Token(TokenKind.LessThan, line, tokencol);
case '>':
peek = readch();
if (peek == '=')
{
peek = readch();
return new Token(TokenKind.GreaterThanOrEqual, line, tokencol);
}
else if (peek == '>')
{
peek = readch();
return new Token(TokenKind.ShiftRight, line, tokencol);
}
else return new Token(TokenKind.GreaterThan, line, tokencol);
default:
throw new ProgramError(Error.UnexpectedSymbol, line, tokencol);
}
}
}
// useful for lookahead or: >>, interpreted as > >, as in Array<Array<int> > so PutBack(Token.GreaterThan);
public void PutBack(Token t)
{
pushed.Push(t);
}
static void reserve(Token t) { Words.Add(t.lexeme, t); }
void match(Token tok)
{
match(tok, Error.SymbolExpected);
}
void move()
{
next = l.Scan();
t = next.t;
}