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#include <stdio.h>
#include <ctype.h>
#define MAXLEN 80
typedef enum {
undef,
eof,
error,
identifier,
literal,
dot,
eql,
lparen,
rparen,
lbrak,
rbrak,
lbrace,
rbrace,
bar
} Sym;
typedef struct {
Sym sym;
char value[MAXLEN];
} Symbol;
typedef struct {
int line;
int col;
FILE *f;
} Scanner;
static int get_char( Scanner *scan ) {
int c = getc( scan->f );
scan->col++;
if( c == '\n' ) {
scan->line++;
scan->col = 1;
}
return c;
}
static void unget_char( Scanner *scan, int c ) {
ungetc( c, scan->f );
scan->col--;
}
static Symbol skip_blanks( Scanner *scan ) {
int c;
Symbol s;
while( ( c = get_char( scan ) ) != EOF && iscntrl( c ) || ( c == ' ' ) );
if( c == EOF ) {
s.sym = eof;
return s;
}
unget_char( scan, c );
s.sym = undef;
return s;
}
static int is_letter( char c ) {
return( ( c >= 'A' && c <= 'Z' ) || ( c >= 'a' && c <= 'z' ) );
}
static int is_digit( char c ) {
return( c >= '0' && c <= '9' );
}
static Symbol get_sym( Scanner *scan ) {
int c;
Symbol s;
int i;
s.sym = undef;
s = skip_blanks( scan );
if( s.sym == eof ) return s;
c = get_char( scan );
if( c == EOF ) {
s.sym = EOF;
return s;
}
unget_char( scan, c );
if( is_letter( c ) ) {
i = 0;
s.sym = identifier;
while( ( c = get_char( scan ) ) != EOF && is_letter( c ) ) {
s.value[i++] = c;
}
s.value[i] = '\0';
printf( "(%d:%d): ident '%s'\n", scan->line, scan->col, s.value );
} else if( c == '\"' ) {
int escaped = 0;
i = 0;
s.sym = literal;
(void)get_char( scan ); /* skip first quote */
while( ( c = get_char( scan ) ) != EOF && c != '\"' || escaped ) {
if( c == '\\' ) {
escaped = 1;
} else {
s.value[i++] = c;
escaped = 0;
}
}
s.value[i] = '\0';
/* ensure we end in a quote */
if( c != '\"' ) {
fprintf( stderr, "ERROR(%d:%d): Unbalanced quote after literal '%s'\n",
scan->line, scan->col, s.value );
s.sym = error;
return s;
}
printf( "(%d:%d): literal '%s'\n", scan->line, scan->col, s.value );
} else if( c == '=' ) {
c = get_char( scan );
s.sym = eql;
} else if( c == '(' ) {
c = get_char( scan );
s.sym = lparen;
} else if( c == ')' ) {
c = get_char( scan );
s.sym = rparen;
} else if( c == '[' ) {
c = get_char( scan );
s.sym = lbrak;
} else if( c == ']' ) {
c = get_char( scan );
s.sym = rbrak;
} else if( c == '{' ) {
c = get_char( scan );
s.sym = lbrace;
} else if( c == '}' ) {
c = get_char( scan );
s.sym = rbrace;
} else if( c == '|' ) {
c = get_char( scan );
s.sym = bar;
} else if( c == '.' ) {
c = get_char( scan );
s.sym = dot;
} else {
c = get_char( scan );
s.sym = error;
}
return s;
}
static Scanner init_scanner( FILE *f )
{
Scanner s;
s.line = 1;
s.col = 1;
s.f = f;
return s;
}
int main( void )
{
Symbol s;
Scanner scan;
scan = init_scanner( stdin );
do {
s = get_sym( &scan );
if( s.sym == eof ) continue;
} while( s.sym != eof );
return 0;
}
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