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#include "scan.h"
#include "io.h"
#include "minilib.h"
#include "const.h"
#include "stdlib.h"
#include "string.h"
#include "ctype.h"
void scanner_init( Scanner *s, char *src )
{
s->src = src;
scanner_reset( s );
}
void scanner_reset( Scanner *s )
{
s->peek = ' ';
s->row = 1;
s->col = 0;
s->pos = s->src;
}
void scanner_done( Scanner *s )
{
}
static char get_char( Scanner *s )
{
char c;
c = *s->pos;
s->pos++;
s->peek = c;
s->col++;
if( c == '\n' ) {
s->col = 1;
s->row++;
}
return c;
}
static char peek_char( Scanner *s, int seek )
{
char *pos = s->pos;
char c = *pos;
while( c != '\0' && seek > 0 ) {
c = *pos;
pos++;
seek--;
}
return c;
}
static void skip_char( Scanner *s, int seek )
{
while( seek > 0 ) {
get_char( s );
seek--;
}
}
static void skip_whitespace( Scanner *s )
{
for( ; ; get_char( s ) ) {
if( s->peek == ' ' || s->peek == '\t' || s->peek == '\n' ) {
continue;
} else if( s->peek == '\0' ) {
return;
} else {
break;
}
}
}
static void error( Scanner *s, char *msg )
{
char buf[MAX_TMP_LEN];
char buf2[12];
buf[0] = '\0';
itoa( s->row, buf2, 10 );
strcat( buf, "ERROR in row " );
strcat( buf, buf2 );
itoa( s->col, buf2, 10 );
strcat( buf, ", col " );
strcat( buf, buf2 );
strcat( buf, ": " );
strcat( buf, msg );
print( buf );
halt( );
}
static void unexpected_char( Scanner *s, int c )
{
char msg[MAX_TMP_LEN];
msg[0] = '\0';
strcat( msg, "unexpected character '" );
strcat_c( msg, c );
strcat( msg, "'" );
error( s, msg );
}
static void skip_comment( Scanner *s )
{
get_char( s );
get_char( s );
while( s->peek != '*' ) {
get_char( s );
}
get_char( s );
if( s->peek != '/' ) {
error( s, "unclosed comment" );
}
get_char( s );
}
static scanner_Symbol parse_ident( Scanner *s )
{
scanner_Symbol sym;
int len = 0;
sym.sym = S_IDENT;
sym.data.s[0] = '\0';
while( len < MAX_IDENT_LEN && ( isalnum( s->peek ) || s->peek == '_' ) ) {
strcat_c( sym.data.s, s->peek );
len++;
get_char( s );
}
return sym;
}
static scanner_Symbol parse_number( Scanner *s )
{
scanner_Symbol sym;
int len = 0;
sym.sym = S_INT_CONST;
sym.data.i = 0;
/* TODO: unsigned, signed, overflow handling */
while( len < MAX_NUMBER_LEN && isdigit( s->peek ) ) {
int digit = s->peek - '0';
sym.data.i = sym.data.i * 10 + digit;
len++;
get_char( s );
}
return sym;
}
scanner_Symbol scanner_scan( Scanner *s )
{
scanner_Symbol sym;
int c;
for( ;; ) {
skip_whitespace( s );
switch( s->peek ) {
case '\0':
sym.sym = S_eof;
if( s->debug ) {
print( "SCANNER(EOF)" );
}
return sym;
case '/':
c = peek_char( s, 1 );
if( c == '*' ) {
if( s->debug ) {
print( "SCANNER(COMMENT_START)" );
}
skip_comment( s );
if( s->debug ) {
print( "SCANNER(COMMENT_END)" );
}
continue;
} else {
get_char( s );
sym.sym = S_DIV;
return sym;
}
break;
case 'i':
switch( peek_char( s, 1 ) ) {
case 'n':
switch( peek_char( s, 2 ) ) {
case 't':
skip_char( s, 3 );
sym.sym = S_INT;
return sym;
}
}
goto id;
case 'v':
switch( peek_char( s, 1 ) ) {
case 'o':
switch( peek_char( s, 2 ) ) {
case 'i':
switch( peek_char( s, 3 ) ) {
case 'd':
skip_char( s, 4 );
sym.sym = S_VOID;
return sym;
}
}
}
goto id;
case 'r':
switch( peek_char( s, 1 ) ) {
case 'e':
switch( peek_char( s, 2 ) ) {
case 't':
switch( peek_char( s, 3 ) ) {
case 'u':
switch( peek_char( s, 4 ) ) {
case 'r':
switch( peek_char( s, 5 ) ) {
case 'n':
skip_char( s, 6 );
sym.sym = S_RETURN;
return sym;
}
}
}
}
}
goto id;
case '0': case '1': case '2': case '3': case '4':
case '5': case '6': case '7': case '8': case '9':
sym = parse_number( s );
return sym;
id:
case 'm': case 'a': case 'n':
sym = parse_ident( s );
return sym;
case ';':
get_char( s );
sym.sym = S_SEMICOLON;
return sym;
case '(':
get_char( s );
sym.sym = S_LPARENT;
return sym;
case ')':
get_char( s );
sym.sym = S_RPARENT;
return sym;
case '{':
get_char( s );
sym.sym = S_LCURL;
return sym;
case '}':
get_char( s );
sym.sym = S_RCURL;
return sym;
default:
unexpected_char( s, s->peek );
sym.sym = S_eof;
return sym;
}
}
}
void scanner_debug( Scanner *s, int enable )
{
s->debug = enable;
if( s->debug ) {
print( "SCANNER DEBUGGING ENABLED" );
}
}
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