// Precondition: sr is a valid streamreader which has been initialized
// Postcondition: cch, cpos, and prevch are updated for sr accordingly.
void inc_char ( )
{
sr.prevch = sr.cch;
sr.cch = getc(sr.fp); //get next character
//update cpos
if (sr.prevch == '\n')
{
inc_line(sr.cpos);
}
else
{
inc_col(sr.cpos);
}
}
static int lex(lexer_state *ls, token_info *info)
{
buffer_reset(ls->buf);
if(setjmp(ls->error.buf))
return TK_ERROR;
for(;;) {
switch(ls->current) {
case '\n': case '\r': { // newline
inc_line(ls);
break;
}
case ' ': case '\t': { // whitespace
next(ls);
break;
}
case '-': { // comment or minus
// minus
if(next(ls) != '-') return '-';
// comment, skip line
while(next(ls) != EOS && !isnewline(ls));
break;
}
case '=': { // EQ
next(ls);
return '=';
}
case '<': { // LT, LTE, ASSIGN
next(ls);
if(ls->current == '=') {
next(ls);
return TK_LTE;
}
else if(ls->current == '-'){
next(ls);
return TK_ASSIGN;
}
else return '<';
}
case '>': { // GT, GTE
next(ls);
if(ls->current == '=') {
next(ls);
return TK_GTE;
}
else return '>';
}
case '/': { // NEQ, DIV
next(ls);
if(ls->current == '=') {
next(ls);
return TK_NEQ;
}
else return '/';
}
case '"': { // STRING
read_string(ls, info);
return TK_STRING;
}
case EOS: { // EOS
return TK_EOS;
}
default: {
if(lisdigit(ls->current)) { // NUMERIC
read_numeric(ls, info);
return TK_REAL;
}
if(lisalpha(ls->current)) { // ID or RESERVED
return read_id_or_reserved(ls, info);
}
int c = ls->current;
// valid operators, single character tokens, etc.
switch(ls->current) {
case '+': case '-': case '*': case '/':
case '!': case '>': case '<': case '=':
case '(': case ')': case '[': case ']':
case '{': case '}': case ':': case '.':
case ',':
next(ls);
return c;
default:
lexer_error(ls, "unrecognized symbol %c", c);
next(ls);
}
}
}
}
}
