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#include "parser.h"
#include "darray.h"
Token
peek_token(const Parser *parser) {
return parser->tokens[parser->current];
}
Token
next_token(Parser *parser) {
return parser->tokens[parser->current++];
}
Token
previous_token(Parser *parser) {
return parser->tokens[parser->current - 1];
}
Token
rewind_token(Parser *parser) {
return parser->tokens[--parser->current];
}
bool
has_next_token(const Parser *parser) {
return parser->current < array_size(parser->tokens)
&& peek_token(parser).type != TOKEN_EOF;
}
Object *
parse_fixnum(Token tok) {
ssize_t num = 0;
ssize_t sign = 1;
for (size_t i = 0; i < tok.value.n; i++) {
char c = tok.value.start[i];
if (c == '-') {
sign = -1;
continue;
}
num = num * 10 + (c - '0');
}
Object *ret = object_alloc(tok, OBJ_TYPE_FIXNUM);
ret->fixnum = num * sign;
return ret;
}
Object *
parse_bool(Token tok) {
ObjectType type = tok.type == TOKEN_TRUE ? OBJ_TYPE_TRUE : OBJ_TYPE_FALSE;
Object *ret = object_alloc(tok, type);
return ret;
}
Object *
parse_string(Token tok) {
Object *ret = object_alloc(tok, OBJ_TYPE_STRING);
array_init(ret->text, tok.value.n);
array_insert(ret->text, tok.value.start, tok.value.n);
return ret;
}
Object *
parse_symbol(Token tok) {
Object *ret = object_alloc(tok, OBJ_TYPE_SYMBOL);
array_init(ret->text, tok.value.n);
array_insert(ret->text, tok.value.start, tok.value.n);
return ret;
}
Object *
parse_list(Parser *parser, Errors *errors) {
if (errors->n != 0) {
return NULL;
}
Token start = previous_token(parser);
Object *root = object_alloc(start, OBJ_TYPE_PAIR);
root->car = NULL;
root->cdr = NULL;
Object *current = root;
while (has_next_token(parser)) {
current->car = parse_tree(parser, errors);
if (errors->n != 0 || current->car == NULL) {
object_free(root);
return NULL;
}
Token tok = peek_token(parser);
if (tok.type == TOKEN_RPAREN) {
next_token(parser);
return root;
}
Object *next = object_alloc(start, OBJ_TYPE_PAIR);
next->car = NULL;
next->cdr = NULL;
current->cdr = next;
current = current->cdr;
}
object_free(root);
error_push(errors, (Error){
.type = ERR_TYPE_PARSER,
.value = ERR_UNBALANCED_PAREN,
.line = start.line,
.col = start.col,
});
return NULL;
}
Object *
parse_tree(Parser *parser, Errors *errors) {
Token tok = next_token(parser);
if (errors->n != 0) {
return NULL;
}
switch (tok.type) {
case TOKEN_FIXNUM: {
return parse_fixnum(tok);
} break;
case TOKEN_TRUE:
case TOKEN_FALSE: {
return parse_bool(tok);
} break;
case TOKEN_RPAREN: {
error_push(errors, (Error){
.type = ERR_TYPE_PARSER,
.value = ERR_UNBALANCED_PAREN,
.line = tok.line,
.col = tok.col,
});
return NULL;
} break;
case TOKEN_LPAREN: {
return parse_list(parser, errors);
} break;
case TOKEN_STRING: {
return parse_string(tok);
} break;
case TOKEN_SYMBOL: {
return parse_symbol(tok);
} break;
case TOKEN_NIL: {
return object_alloc(tok, OBJ_TYPE_NIL);
} break;
default: {
break;
} break;
}
error_push(errors, (Error){
.type = ERR_TYPE_PARSER,
.value = ERR_EOF_REACHED,
.line = tok.line,
.col = tok.col,
});
return NULL;
}
Root *
parse(Token *tokens, Errors *errors) {
Root *roots = NULL;
array_init(roots, 0);
Parser parser = {
.tokens = tokens,
.current = 0,
};
while (has_next_token(&parser)) {
Object *root = parse_tree(&parser, errors);
OBJ_PRINT(root);
if (errors->n != 0) {
break;
}
array_push(roots, root);
}
return roots;
}
Object *
object_alloc(Token tok, ObjectType type) {
Object *node = malloc(sizeof(Object));
node->line = tok.line;
node->col = tok.col;
node->type = type;
return node;
}
void
object_free(Object *node) {
if (node == NULL) {
return;
}
if (IS_STRING(node) || IS_SYMBOL(node)) {
array_free(node->text);
}
if (IS_PAIR(node)) {
object_free(node->car);
object_free(node->cdr);
}
free(node);
}
void
free_roots(Root *roots) {
if (roots != NULL) {
for (size_t i = 0; i < array_size(roots); i++) {
object_free(roots[i]);
}
array_free(roots);
}
}
void
display_pair(Object *obj) {
object_display(obj->car);
if (obj->cdr == NULL) {
return;
}
if (IS_PAIR(obj->cdr)) {
printf(" ");
display_pair(obj->cdr);
} else {
printf(" . ");
object_display(obj->cdr);
}
}
void
object_display(Object *obj) {
if (obj == NULL) {
printf("#{error}");
return;
}
switch (obj->type) {
case OBJ_TYPE_FIXNUM: {
printf("%zd", obj->fixnum);
} break;
case OBJ_TYPE_TRUE: {
printf("true");
} break;
case OBJ_TYPE_FALSE: {
printf("false");
} break;
case OBJ_TYPE_NIL: {
printf("()");
} break;
case OBJ_TYPE_STRING: {
printf("\"%.*s\"", (int)array_size(obj->text), obj->text);
} break;
case OBJ_TYPE_SYMBOL: {
printf(":%.*s", (int)array_size(obj->text), obj->text);
} break;
case OBJ_TYPE_PAIR: {
printf("(");
display_pair(obj);
printf(")");
} break;
}
return;
}
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