int parseexpression() {
int invert = 0;
switch (token) {
case TOK_ADD:
token = tokeniser_next();
break;
case TOK_SUB:
token = tokeniser_next();
invert = 1;
break;
}
int lhs = parseterm();
if (invert) {
lhs = -lhs;
}
if (token == TOK_ADD) {
token = tokeniser_next();
int rhs = parseterm();
if (token == TOK_ERR) {
return 0;
}
return lhs + rhs;
}
if (token == TOK_SUB) {
token = tokeniser_next();
int rhs = parseterm();
if (token == TOK_ERR) {
return 0;
}
return lhs - rhs;
}
return lhs;
}
int parsefactor() {
if (token == TOK_NUM) {
int lhs = tokeniser_number();
token = tokeniser_next();
return lhs;
} else if (token == TOK_VAR) {
char* varName = tokeniser_string();
token = tokeniser_next();
return getvariable(varName);
} else {
printf("invalid expression\n");
token = TOK_ERR;
return 0;
}
}
int main(int argc, char *argv[])
{
int ecode;
bfcc_options bfopts = {0};
if (parse_arguments(argc, argv, &bfopts) != 0)
{
return -2;
}
FILE *f = stdin;
if (bfopts.input_file != 0)
{
f = fopen(bfopts.input_file, "r");
if (!f)
{
fprintf(stderr, "Unknown file.\n");
return ERROR_FILE_NOT_FOUND;
}
}
c99_options opts;
c99_options_default(&opts);
backend back = create_c99_backend(&opts);
ecode = back.begin(&back, stdout);
FATAL_IF_ERROR(ecode, "Backend preamble generation");
tokeniser *t = tokeniser_setup(f);
CHECK_ALLOCATION(t, "Tokeniser setup");
while (1)
{
token tok;
int error = tokeniser_next(t, &tok);
if (IS_ERROR(error))
{
fprintf(stderr, "Tokenisation error detected: %d.\n", error);
return ERROR_TOKENISATION;
}
if (tok == token_eof)
break;
if (IS_ERROR(back.emit(&back, stdout, (token) tok)))
{
fprintf(stderr, "Failure encountered when translating token: %s\n", token_name((token) tok));
}
}
ecode = back.end(&back, stdout);
FATAL_IF_ERROR(ecode, "Backend could not finish")
return 0;
}
static Pointer readForm(Tokeniser* t)
{
if (tokeniser_eof(t)) {
return nil_make();
}
Pointer ret = tokeniser_token(t);
// If ret is a string, it's ready to return
if (ret.type == Type_symbol) {
const char* token = symbol_get(ret);
int intValue;
if (util_streq(token, "(")) {
tokeniser_next(t); // consume the '(', read the list and
return readList(t); // return immediately to avoid hitting the
// tokeniser_next() below
}
else if (util_streq(token, "nil")) {
ret = nil_make();
}
else if (util_streq(token, "true")) {
ret = boolean_make(1);
}
else if (util_streq(token, "false")) {
ret = boolean_make(0);
}
else if (readInteger(token, &intValue)) {
ret = integer_make(intValue);
}
else {
// Insert the symbol into the symbol table. We may or may not get
// the same symbol back.
ret = symtab_insert(ret);
}
}
PUSH(ret);
tokeniser_next(t);
return POP();
}
int parseterm() {
int lhs = parsefactor();
if (token == TOK_ERR) {
return 0;
}
if (token == TOK_MUL) {
token = tokeniser_next();
int rhs = parsefactor();
if (token == TOK_ERR) {
return 0;
}
return lhs * rhs;
}
if (token == TOK_DIV) {
token = tokeniser_next();
int rhs = parsefactor();
if (token == TOK_ERR) {
return 0;
}
return lhs / rhs;
}
return lhs;
}
static Pointer readList(Tokeniser* t)
{
if (tokeniser_eof(t)) {
THROW("Expected ), got EOF");
}
Pointer token = tokeniser_token(t);
if ((token.type == Type_symbol) && util_streq(symbol_get(token), ")")) {
tokeniser_next(t);
return nil_make();
}
StackIndex carIndex = PUSH(readForm(t));
StackIndex cdrIndex = PUSH(readList(t));
Pointer ret = pair_make(carIndex, cdrIndex);
DROP(2);
return ret;
}
int runline(char* line, int* pc) {
tokeniser_setup(line);
token = tokeniser_next();
switch (token) {
case TOK_PRINT:// STRING|EXPR (, STRING|EXPR)
do {
token = tokeniser_next();
if (token == TOK_EOL || token == TOK_ERR) {
break;
}
if (token == TOK_STRING) {
printf("%s ", tokeniser_string());
token = tokeniser_next();
} else {
printf("%d ", parseexpression());
}
if (token != TOK_COMMA && token != TOK_EOL) {
printf("expected ','\n");
return 0;
}
}
while (token != TOK_EOL && token != TOK_ERR);
printf("\n");
break;
case TOK_LET:// VAR = EXPR
token = tokeniser_next();
if (token != TOK_VAR) {
printf("expected variable name\n");
return 0;
}
char* varName = tokeniser_string();
token = tokeniser_next();
if (token != TOK_EQ) {
printf("expected = after variable name\n");
return 0;
}
token = tokeniser_next();
int val = parseexpression();
if (token == TOK_ERR) {
return 0;
}
setvariable(varName, token);
break;
}
(*pc)++;
return 1;
}
