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bpo-37070: Cleanup fstring debug handling (GH-13607) 

* Clean up some comments, fix potential memory leaks, clarify literal and expr_text.
This commit is contained in:
Eric V. Smith 2019-05-29 03:55:44 -04:00 committed by GitHub
parent 0ae022c6a4
commit f83d1dbd3b
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2 changed files with 19 additions and 27 deletions
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1
Lib/test/test_future.py
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@ -284,6 +284,7 @@ class AnnotationsFutureTestCase(unittest.TestCase):
eq("(x:=10)")
eq("f'{(x:=10):=10}'")
def test_fstring_debug_annotations(self):
# f-strings with '=' don't round trip very well, so set the expected
# result explicitely.
self.assertAnnotationEqual("f'{x=!r}'", expected="f'x={x!r}'")

45
Python/ast.c
View File

@ -5010,8 +5010,8 @@ fstring_parse(const char **str, const char *end, int raw, int recurse_lvl,
*expression is set to the expression. For an '=' "debug" expression,
*expr_text is set to the debug text (the original text of the expression,
*including the '=' and any whitespace around it, as a string object). If
*not a debug expression, *expr_text set to NULL. */
including the '=' and any whitespace around it, as a string object). If
not a debug expression, *expr_text set to NULL. */
static int
fstring_find_expr(const char **str, const char *end, int raw, int recurse_lvl,
PyObject **expr_text, expr_ty *expression,
@ -5039,6 +5039,8 @@ fstring_find_expr(const char **str, const char *end, int raw, int recurse_lvl,
Py_ssize_t nested_depth = 0;
char parenstack[MAXLEVEL];
*expr_text = NULL;
/* Can only nest one level deep. */
if (recurse_lvl >= 2) {
ast_error(c, n, "f-string: expressions nested too deeply");
@ -5214,8 +5216,6 @@ fstring_find_expr(const char **str, const char *end, int raw, int recurse_lvl,
if (!*expr_text) {
goto error;
}
} else {
*expr_text = NULL;
}
/* Check for a conversion char, if present. */
@ -5281,6 +5281,7 @@ unexpected_end_of_string:
/* Falls through to error. */
error:
Py_XDECREF(*expr_text);
return -1;
}
@ -5603,7 +5604,8 @@ FstringParser_ConcatFstring(FstringParser *state, const char **str,
/* Parse the f-string. */
while (1) {
PyObject *literal[2] = {NULL, NULL};
PyObject *literal = NULL;
PyObject *expr_text = NULL;
expr_ty expression = NULL;
/* If there's a zero length literal in front of the
@ -5611,34 +5613,23 @@ FstringParser_ConcatFstring(FstringParser *state, const char **str,
the f-string, expression will be NULL (unless result == 1,
see below). */
int result = fstring_find_literal_and_expr(str, end, raw, recurse_lvl,
&literal[0], &literal[1],
&literal, &expr_text,
&expression, c, n);
if (result < 0)
return -1;
/* Add the literals, if any. */
for (int i = 0; i < 2; i++) {
if (!literal[i]) {
/* Do nothing. Just leave last_str alone (and possibly
NULL). */
} else if (!state->last_str) {
/* Note that the literal can be zero length, if the
input string is "\\\n" or "\\\r", among others. */
state->last_str = literal[i];
literal[i] = NULL;
} else {
/* We have a literal, concatenate it. */
assert(PyUnicode_GET_LENGTH(literal[i]) != 0);
if (FstringParser_ConcatAndDel(state, literal[i]) < 0)
return -1;
literal[i] = NULL;
}
/* Add the literal, if any. */
if (literal && FstringParser_ConcatAndDel(state, literal) < 0) {
Py_XDECREF(expr_text);
return -1;
}
/* Add the expr_text, if any. */
if (expr_text && FstringParser_ConcatAndDel(state, expr_text) < 0) {
return -1;
}
/* We've dealt with the literals now. They can't be leaked on further
errors. */
assert(literal[0] == NULL);
assert(literal[1] == NULL);
/* We've dealt with the literal and expr_text, their ownership has
been transferred to the state object. Don't look at them again. */
/* See if we should just loop around to get the next literal
and expression, while ignoring the expression this