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Tidy lexer.

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This commit is contained in:
Graydon Hoare 2010-08-24 08:50:56 -07:00
parent 2745a5ebb2
commit df3ea680ea
1 changed files with 23 additions and 15 deletions
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38
src/comp/fe/lexer.rs
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@ -56,6 +56,14 @@ fn next_token(stdio_reader rdr) -> token.token {
auto accum_str = "";
auto accum_int = 0;
fn next(stdio_reader rdr) -> char {
ret rdr.getc() as char;
}
fn forget(stdio_reader rdr, char c) {
rdr.ungetc(c as int);
}
c = consume_any_whitespace(rdr, c);
if (c == eof) { ret token.EOF(); }
@ -63,9 +71,9 @@ fn next_token(stdio_reader rdr) -> token.token {
if (is_alpha(c)) {
while (is_alpha(c)) {
accum_str += (c as u8);
c = rdr.getc() as char;
c = next(rdr);
}
rdr.ungetc(c as int);
forget(rdr, c);
ret token.IDENT(accum_str);
}
@ -75,9 +83,9 @@ fn next_token(stdio_reader rdr) -> token.token {
while (is_dec_digit(c)) {
accum_int *= 10;
accum_int += (c as int) - ('0' as int);
c = rdr.getc() as char;
c = next(rdr);
}
rdr.ungetc(c as int);
forget(rdr, c);
ret token.LIT_INT(accum_int);
}
}
@ -88,7 +96,7 @@ fn next_token(stdio_reader rdr) -> token.token {
if (c2 == '=') {
ret token.OPEQ(op);
} else {
rdr.ungetc(c2 as int);
forget(rdr, c2);
ret token.OP(op);
}
}
@ -109,17 +117,17 @@ fn next_token(stdio_reader rdr) -> token.token {
// Multi-byte tokens.
case ('=') {
auto c2 = rdr.getc() as char;
auto c2 = next(rdr);
if (c2 == '=') {
ret token.OP(token.EQEQ());
} else {
rdr.ungetc(c2 as int);
forget(rdr, c2);
ret token.OP(token.EQ());
}
}
case ('-') {
auto c2 = rdr.getc() as char;
auto c2 = next(rdr);
if (c2 == '>') {
ret token.RARROW();
} else {
@ -128,7 +136,7 @@ fn next_token(stdio_reader rdr) -> token.token {
}
case ('&') {
auto c2 = rdr.getc() as char;
auto c2 = next(rdr);
if (c2 == '&') {
ret token.OP(token.ANDAND());
} else {
@ -137,27 +145,27 @@ fn next_token(stdio_reader rdr) -> token.token {
}
case ('+') {
ret op_or_opeq(rdr, rdr.getc() as char, token.PLUS());
ret op_or_opeq(rdr, next(rdr), token.PLUS());
}
case ('*') {
ret op_or_opeq(rdr, rdr.getc() as char, token.STAR());
ret op_or_opeq(rdr, next(rdr), token.STAR());
}
case ('/') {
ret op_or_opeq(rdr, rdr.getc() as char, token.STAR());
ret op_or_opeq(rdr, next(rdr), token.STAR());
}
case ('!') {
ret op_or_opeq(rdr, rdr.getc() as char, token.NOT());
ret op_or_opeq(rdr, next(rdr), token.NOT());
}
case ('^') {
ret op_or_opeq(rdr, rdr.getc() as char, token.CARET());
ret op_or_opeq(rdr, next(rdr), token.CARET());
}
case ('%') {
ret op_or_opeq(rdr, rdr.getc() as char, token.PERCENT());
ret op_or_opeq(rdr, next(rdr), token.PERCENT());
}
}