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#include "parse.h"
#include "Token.h"
#include <stdio.h>
static void *unexpected(const Token *tok, int n);
static const Token *expression(const Token *tok);
static const Token *keyword_fn(const Token *tok);
static const Token *keyword_var(const Token *tok);
static const Token *keyword_const(const Token *tok);
int parse(const Token *tok)
{
while (tok != NULL && tok->type != TOK_NONE) {
switch (tok->type) {
case TOK_KW_FN:
tok = keyword_fn(tok);
break;
case TOK_KW_VAR:
tok = keyword_var(tok);
break;
case TOK_KW_CONST:
tok = keyword_const(tok);
break;
default:
unexpected(tok, -1);
return 1;
}
if (tok == NULL)
return 1;
}
return 0;
}
/* write unexpected token error to stderr before returning NULL,
* `n` is used to mark the error in code */
static void *unexpected(const Token *tok, int n)
{
fprintf(stderr, "[%d] unexpected %s %s%s%sat %u:%u\n",
n, token_type_str(tok->type),
(tok->s != NULL) ? "(" : "",
(tok->s != NULL) ? tok->s : "",
(tok->s != NULL) ? ") " : "",
tok->line, tok->column);
return NULL;
}
/* any chain of instructions that results in a value */
static const Token *expression(const Token *tok)
{
if (tok->type == TOK_INTEGER)
return tok + 1;
if (tok->type == TOK_STRING)
return tok + 1;
if (tok->type == TOK_WORD)
return tok + 1;
return unexpected(tok, 20);
}
static const Token *keyword_fn(const Token *tok)
{
tok += 1;
if (tok->type != TOK_WORD)
return unexpected(tok, 0);
const Token *name = tok;
tok += 1;
(void)name;
if (tok->type != TOK_PAREN_OPEN)
return unexpected(tok, 1);
tok += 1;
size_t args = 0;
while (tok->type == TOK_WORD) {
tok += 1;
args += 1;
if (tok->type == TOK_COMMA)
tok += 1;
}
if (tok->type != TOK_PAREN_CLOS)
return unexpected(tok, 2);
printf("%zu args\n", args);
return tok + 1;
}
/* mutable variable declaration */
static const Token *keyword_var(const Token *tok)
{
tok += 1;
if (tok->type != TOK_WORD)
return unexpected(tok, 10);
const Token *name = tok;
(void)name;
tok += 1;
/* no initialization */
if (tok->type == TOK_SEMICOLON)
return tok + 1;
if (tok->type != TOK_ASSIGN)
return unexpected(tok, 11);
tok = expression(tok + 1);
if (tok == NULL)
return NULL;
if (tok->type != TOK_SEMICOLON)
return unexpected(tok, 12);
return tok + 1;
}
/* constant variable declaration */
static const Token *keyword_const(const Token *tok)
{
tok += 1;
if (tok->type != TOK_WORD)
return unexpected(tok, 10);
const Token *name = tok;
(void)name;
tok += 1;
if (tok->type != TOK_ASSIGN)
return unexpected(tok, 11);
tok = expression(tok + 1);
if (tok == NULL)
return NULL;
if (tok->type != TOK_SEMICOLON)
return unexpected(tok, 12);
return tok + 1;
}
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