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/*
* A mini C-like language scanner.
*/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
%%{
machine clang;
newline = '\n' @{curline += 1;};
any_count_line = any | newline;
# Consume a C comment.
c_comment := any_count_line* :>> '*/' @{fgoto main;};
main := |*
# Alpha numberic characters or underscore.
alnum_u = alnum | '_';
# Alpha charactres or underscore.
alpha_u = alpha | '_';
# Symbols. Upon entering clear the buffer. On all transitions
# buffer a character. Upon leaving dump the symbol.
( punct - [_'"] ) {
printf( "symbol(%i): %c\n", curline, tokstart[0] );
};
# Identifier. Upon entering clear the buffer. On all transitions
# buffer a character. Upon leaving, dump the identifier.
alpha_u alnum_u* {
printf( "ident(%i): ", curline );
fwrite( tokstart, 1, tokend-tokstart, stdout );
printf("\n");
};
# Single Quote.
sliteralChar = [^'\\] | newline | ( '\\' . any_count_line );
'\'' . sliteralChar* . '\'' {
printf( "single_lit(%i): ", curline );
fwrite( tokstart, 1, tokend-tokstart, stdout );
printf("\n");
};
# Double Quote.
dliteralChar = [^"\\] | newline | ( '\\' any_count_line );
'"' . dliteralChar* . '"' {
printf( "double_lit(%i): ", curline );
fwrite( tokstart, 1, tokend-tokstart, stdout );
printf("\n");
};
# Whitespace is standard ws, newlines and control codes.
any_count_line - 0x21..0x7e;
# Describe both c style comments and c++ style comments. The
# priority bump on tne terminator of the comments brings us
# out of the extend* which matches everything.
'//' [^\n]* newline;
'/*' { fgoto c_comment; };
# Match an integer. We don't bother clearing the buf or filling it.
# The float machine overlaps with int and it will do it.
digit+ {
printf( "int(%i): ", curline );
fwrite( tokstart, 1, tokend-tokstart, stdout );
printf("\n");
};
# Match a float. Upon entering the machine clear the buf, buffer
# characters on every trans and dump the float upon leaving.
digit+ '.' digit+ {
printf( "float(%i): ", curline );
fwrite( tokstart, 1, tokend-tokstart, stdout );
printf("\n");
};
# Match a hex. Upon entering the hex part, clear the buf, buffer characters
# on every trans and dump the hex on leaving transitions.
'0x' xdigit+ {
printf( "hex(%i): ", curline );
fwrite( tokstart, 1, tokend-tokstart, stdout );
printf("\n");
};
*|;
}%%
%% write data nofinal;
#define BUFSIZE 128
void scanner()
{
static char buf[BUFSIZE];
int cs, act, have = 0, curline = 1;
char *tokstart, *tokend = 0;
int done = 0;
%% write init;
while ( !done ) {
char *p = buf + have, *pe;
int len, space = BUFSIZE - have;
if ( space == 0 ) {
/* We've used up the entire buffer storing an already-parsed token
* prefix that must be preserved. */
fprintf(stderr, "OUT OF BUFFER SPACE\n" );
exit(1);
}
len = fread( p, 1, space, stdin );
/* If this is the last buffer, tack on an EOF. */
if ( len < space ) {
p[len++] = 0;
done = 1;
}
pe = p + len;
%% write exec;
if ( cs == clang_error ) {
fprintf(stderr, "PARSE ERROR\n" );
break;
}
if ( tokstart == 0 )
have = 0;
else {
/* There is a prefix to preserve, shift it over. */
have = pe - tokstart;
memmove( buf, tokstart, have );
tokend = buf + (tokend-tokstart);
tokstart = buf;
}
}
}
int main()
{
scanner();
return 0;
}
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