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reader: add position restoration for read_vec and read_list

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Same as read_str really, using a label to push control flow.
This commit is contained in:
Aryadev Chavali
2026-03-05 20:27:13 +00:00
parent c65ec319f5
commit 775d9f51bf
1 changed files with 16 additions and 4 deletions
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20
src/reader.c
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@@ -128,6 +128,7 @@ read_err_t read_negative(sys_t *sys, stream_t *stream, lisp_t **ret)
read_err_t read_list(sys_t *sys, stream_t *stream, lisp_t **ret) read_err_t read_list(sys_t *sys, stream_t *stream, lisp_t **ret)
{ {
u64 old_pos = stream->position;
// skip past the open parentheses '(' // skip past the open parentheses '('
(void)stream_next(stream); (void)stream_next(stream);
@@ -139,7 +140,7 @@ read_err_t read_list(sys_t *sys, stream_t *stream, lisp_t **ret)
read_err_t err = read(sys, stream, &item); read_err_t err = read(sys, stream, &item);
if (err == READ_ERR_EOF) if (err == READ_ERR_EOF)
{ {
return READ_ERR_EXPECTED_CLOSED_BRACE; goto no_close_brace;
} }
else if (err) else if (err)
{ {
@@ -158,16 +159,23 @@ read_err_t read_list(sys_t *sys, stream_t *stream, lisp_t **ret)
} }
if (stream_peek(stream) != ')') if (stream_peek(stream) != ')')
return READ_ERR_EXPECTED_CLOSED_BRACE; {
goto no_close_brace;
}
stream_next(stream); stream_next(stream);
*ret = top; *ret = top;
return READ_ERR_OK; return READ_ERR_OK;
no_close_brace:
stream->position = old_pos;
return READ_ERR_EXPECTED_CLOSED_BRACE;
} }
read_err_t read_vec(sys_t *sys, stream_t *stream, lisp_t **ret) read_err_t read_vec(sys_t *sys, stream_t *stream, lisp_t **ret)
{ {
u64 old_pos = stream->position;
(void)stream_next(stream); (void)stream_next(stream);
lisp_t *container = make_vec(sys, 0); lisp_t *container = make_vec(sys, 0);
while (!stream_eoc(stream) && stream_peek(stream) != ']') while (!stream_eoc(stream) && stream_peek(stream) != ']')
{ {
@@ -175,7 +183,7 @@ read_err_t read_vec(sys_t *sys, stream_t *stream, lisp_t **ret)
read_err_t err = read(sys, stream, &item); read_err_t err = read(sys, stream, &item);
if (err == READ_ERR_EOF) if (err == READ_ERR_EOF)
{ {
return READ_ERR_EXPECTED_CLOSED_BRACE; goto no_close_square_bracket;
} }
else if (err) else if (err)
{ {
@@ -188,10 +196,14 @@ read_err_t read_vec(sys_t *sys, stream_t *stream, lisp_t **ret)
} }
if (stream_peek(stream) != ']') if (stream_peek(stream) != ']')
return READ_ERR_EXPECTED_CLOSED_SQUARE_BRACKET; goto no_close_square_bracket;
stream_next(stream); stream_next(stream);
*ret = container; *ret = container;
return READ_ERR_OK; return READ_ERR_OK;
no_close_square_bracket:
stream->position = old_pos;
return READ_ERR_EXPECTED_CLOSED_SQUARE_BRACKET;
} }
read_err_t read_str(sys_t *sys, stream_t *stream, lisp_t **ret) read_err_t read_str(sys_t *sys, stream_t *stream, lisp_t **ret)