#include <stdbool.h>

#include <Python.h>

#include "tokenizer.h"

#include "pegen.h"

#include "string_parser.h"

//// STRING HANDLING FUNCTIONS ////

static int

warn_invalid_escape_sequence(Parser *p, const char *first_invalid_escape, Token *t)

{

unsigned char c = *first_invalid_escape;

int octal = ('4' <= c && c <= '7');

PyObject *msg =

octal

? PyUnicode_FromFormat("invalid octal escape sequence '\\%.3s'",

first_invalid_escape)

: PyUnicode_FromFormat("invalid escape sequence '\\%c'", c);

if (msg == NULL) {

return -1;

}

if (PyErr_WarnExplicitObject(PyExc_DeprecationWarning, msg, p->tok->filename,

t->lineno, NULL, NULL) < 0) {

if (PyErr_ExceptionMatches(PyExc_DeprecationWarning)) {

/* Replace the DeprecationWarning exception with a SyntaxError

to get a more accurate error report */

PyErr_Clear();

/* This is needed, in order for the SyntaxError to point to the token t,

since _PyPegen_raise_error uses p->tokens[p->fill - 1] for the

error location, if p->known_err_token is not set. */

p->known_err_token = t;

if (octal) {

RAISE_SYNTAX_ERROR("invalid octal escape sequence '\\%.3s'",

first_invalid_escape);

}

else {

RAISE_SYNTAX_ERROR("invalid escape sequence '\\%c'", c);

}

}

Py_DECREF(msg);

return -1;

}

Py_DECREF(msg);

return 0;

}

static PyObject *

decode_utf8(const char **sPtr, const char *end)

{

const char *s;

const char *t;

t = s = *sPtr;

while (s < end && (*s & 0x80)) {

s++;

}

*sPtr = s;

return PyUnicode_DecodeUTF8(t, s - t, NULL);

}

static PyObject *

decode_unicode_with_escapes(Parser *parser, const char *s, size_t len, Token *t)

{

PyObject *v;

PyObject *u;

char *buf;

char *p;

const char *end;

/* check for integer overflow */

if (len > SIZE_MAX / 6) {

return NULL;

}

/* "ä" (2 bytes) may become "\U000000E4" (10 bytes), or 1:5

"\ä" (3 bytes) may become "\u005c\U000000E4" (16 bytes), or ~1:6 */

u = PyBytes_FromStringAndSize((char *)NULL, len * 6);

if (u == NULL) {

return NULL;

}

p = buf = PyBytes_AsString(u);

if (p == NULL) {

return NULL;

}

end = s + len;

while (s < end) {

if (*s == '\\') {

*p++ = *s++;

if (s >= end || *s & 0x80) {

strcpy(p, "u005c");

p += 5;

if (s >= end) {

break;

}

}

}

if (*s & 0x80) {

PyObject *w;

int kind;

const void *data;

Py_ssize_t w_len;

Py_ssize_t i;

w = decode_utf8(&s, end);

if (w == NULL) {

Py_DECREF(u);

return NULL;

}

kind = PyUnicode_KIND(w);

data = PyUnicode_DATA(w);

w_len = PyUnicode_GET_LENGTH(w);

for (i = 0; i < w_len; i++) {

Py_UCS4 chr = PyUnicode_READ(kind, data, i);

sprintf(p, "\\U%08x", chr);

p += 10;

}

/* Should be impossible to overflow */

assert(p - buf <= PyBytes_GET_SIZE(u));

Py_DECREF(w);

}

else {

*p++ = *s++;

}

}

len = p - buf;

s = buf;

const char *first_invalid_escape;

v = _PyUnicode_DecodeUnicodeEscapeInternal(s, len, NULL, NULL, &first_invalid_escape);

if (v != NULL && first_invalid_escape != NULL) {

if (warn_invalid_escape_sequence(parser, first_invalid_escape, t) < 0) {

/* We have not decref u before because first_invalid_escape points

inside u. */

Py_XDECREF(u);

Py_DECREF(v);

return NULL;

}

}

Py_XDECREF(u);

return v;

}

static PyObject *

decode_bytes_with_escapes(Parser *p, const char *s, Py_ssize_t len, Token *t)

{

const char *first_invalid_escape;

PyObject *result = _PyBytes_DecodeEscape(s, len, NULL, &first_invalid_escape);

if (result == NULL) {

return NULL;

}

if (first_invalid_escape != NULL) {

if (warn_invalid_escape_sequence(p, first_invalid_escape, t) < 0) {

Py_DECREF(result);

return NULL;

}

}

return result;

}

/* s must include the bracketing quote characters, and r, b, u,

&/or f prefixes (if any), and embedded escape sequences (if any).

_PyPegen_parsestr parses it, and sets *result to decoded Python string object.

If the string is an f-string, set *fstr and *fstrlen to the unparsed

string object. Return 0 if no errors occurred. */

int

_PyPegen_parsestr(Parser *p, int *bytesmode, int *rawmode, PyObject **result,

const char **fstr, Py_ssize_t *fstrlen, Token *t)

{

const char *s = PyBytes_AsString(t->bytes);

if (s == NULL) {

return -1;

}

size_t len;

int quote = Py_CHARMASK(*s);

int fmode = 0;

*bytesmode = 0;

*rawmode = 0;

*result = NULL;

*fstr = NULL;

if (Py_ISALPHA(quote)) {

while (!*bytesmode || !*rawmode) {

if (quote == 'b' || quote == 'B') {

quote =(unsigned char)*++s;

*bytesmode = 1;

}

else if (quote == 'u' || quote == 'U') {

quote = (unsigned char)*++s;

}

else if (quote == 'r' || quote == 'R') {

quote = (unsigned char)*++s;

*rawmode = 1;

}

else if (quote == 'f' || quote == 'F') {

quote = (unsigned char)*++s;

fmode = 1;

}

else {

break;

}

}

}

/* fstrings are only allowed in Python 3.6 and greater */

if (fmode && p->feature_version < 6) {

p->error_indicator = 1;

RAISE_SYNTAX_ERROR("Format strings are only supported in Python 3.6 and greater");

return -1;

}

if (fmode && *bytesmode) {

PyErr_BadInternalCall();

return -1;

}

if (quote != '\'' && quote != '\"') {

PyErr_BadInternalCall();

return -1;

}

/* Skip the leading quote char. */

s++;

len = strlen(s);

if (len > INT_MAX) {

PyErr_SetString(PyExc_OverflowError, "string to parse is too long");

return -1;

}

if (s[--len] != quote) {

/* Last quote char must match the first. */

PyErr_BadInternalCall();

return -1;

}

if (len >= 4 && s[0] == quote && s[1] == quote) {

/* A triple quoted string. We've already skipped one quote at

the start and one at the end of the string. Now skip the

two at the start. */

s += 2;

len -= 2;

/* And check that the last two match. */

if (s[--len] != quote || s[--len] != quote) {

PyErr_BadInternalCall();

return -1;

}

}

if (fmode) {

/* Just return the bytes. The caller will parse the resulting

string. */

*fstr = s;

*fstrlen = len;

return 0;

}

/* Not an f-string. */

/* Avoid invoking escape decoding routines if possible. */

*rawmode = *rawmode || strchr(s, '\\') == NULL;

if (*bytesmode) {

/* Disallow non-ASCII characters. */

const char *ch;

for (ch = s; *ch; ch++) {

if (Py_CHARMASK(*ch) >= 0x80) {

RAISE_SYNTAX_ERROR(

"bytes can only contain ASCII "

"literal characters");

return -1;

}

}

if (*rawmode) {

*result = PyBytes_FromStringAndSize(s, len);

}

else {

*result = decode_bytes_with_escapes(p, s, len, t);

}

}

else {

if (*rawmode) {

*result = PyUnicode_DecodeUTF8Stateful(s, len, NULL, NULL);

}

else {

*result = decode_unicode_with_escapes(p, s, len, t);

}

}

return *result == NULL ? -1 : 0;

}

// FSTRING STUFF

/* Fix locations for the given node and its children.

`parent` is the enclosing node.

`expr_start` is the starting position of the expression (pointing to the open brace).

`n` is the node which locations are going to be fixed relative to parent.

`expr_str` is the child node's string representation, including braces.

*/

static bool

fstring_find_expr_location(Token *parent, const char* expr_start, char *expr_str, int *p_lines, int *p_cols)

{

*p_lines = 0;

*p_cols = 0;

assert(expr_start != NULL && *expr_start == '{');

if (parent && parent->bytes) {

const char *parent_str = PyBytes_AsString(parent->bytes);

if (!parent_str) {

return false;

}

// The following is needed, in order to correctly shift the column

// offset, in the case that (disregarding any whitespace) a newline

// immediately follows the opening curly brace of the fstring expression.

bool newline_after_brace = 1;

const char *start = expr_start + 1;

while (start && *start != '}' && *start != '\n') {

if (*start != ' ' && *start != '\t' && *start != '\f') {

newline_after_brace = 0;

break;

}

start++;

}

// Account for the characters from the last newline character to our

// left until the beginning of expr_start.

if (!newline_after_brace) {

start = expr_start;

while (start > parent_str && *start != '\n') {

start--;

}

*p_cols += (int)(expr_start - start);

}

/* adjust the start based on the number of newlines encountered

before the f-string expression */

for (const char *p = parent_str; p < expr_start; p++) {

if (*p == '\n') {

(*p_lines)++;

}

}

}

return true;

}

/* Compile this expression in to an expr_ty. Add parens around the

expression, in order to allow leading spaces in the expression. */

static expr_ty

fstring_compile_expr(Parser *p, const char *expr_start, const char *expr_end,

Token *t)

{

expr_ty expr = NULL;

char *str;

Py_ssize_t len;

const char *s;

expr_ty result = NULL;

assert(expr_end >= expr_start);

assert(*(expr_start-1) == '{');

assert(*expr_end == '}' || *expr_end == '!' || *expr_end == ':' ||

*expr_end == '=');

/* If the substring is all whitespace, it's an error. We need to catch this

here, and not when we call PyParser_SimpleParseStringFlagsFilename,

because turning the expression '' in to '()' would go from being invalid

to valid. */

for (s = expr_start; s != expr_end; s++) {

char c = *s;

/* The Python parser ignores only the following whitespace

characters (\r already is converted to \n). */

if (!(c == ' ' || c == '\t' || c == '\n' || c == '\f')) {

break;

}

}

if (s == expr_end) {

if (*expr_end == '!' || *expr_end == ':' || *expr_end == '=') {

RAISE_SYNTAX_ERROR("f-string: expression required before '%c'", *expr_end);

return NULL;

}

RAISE_SYNTAX_ERROR("f-string: empty expression not allowed");

return NULL;

}

len = expr_end - expr_start;

/* Allocate 3 extra bytes: open paren, close paren, null byte. */

str = PyMem_Calloc(len + 3, sizeof(char));

if (str == NULL) {

PyErr_NoMemory();

return NULL;

}

// The call to fstring_find_expr_location is responsible for finding the column offset

// the generated AST nodes need to be shifted to the right, which is equal to the number

// of the f-string characters before the expression starts.

memcpy(str+1, expr_start, len);

int lines, cols;

if (!fstring_find_expr_location(t, expr_start-1, str+1, &lines, &cols)) {

PyMem_Free(str);

return NULL;

}

// The parentheses are needed in order to allow for leading whitespace within

// the f-string expression. This consequently gets parsed as a group (see the

// group rule in python.gram).

str[0] = '(';

str[len+1] = ')';

struct tok_state* tok = _PyTokenizer_FromString(str, 1);

if (tok == NULL) {

PyMem_Free(str);

return NULL;

}

Py_INCREF(p->tok->filename);

tok->filename = p->tok->filename;

tok->lineno = t->lineno + lines - 1;

Parser *p2 = _PyPegen_Parser_New(tok, Py_fstring_input, p->flags, p->feature_version,

NULL, p->arena);

p2->starting_lineno = t->lineno + lines;

p2->starting_col_offset = t->col_offset + cols;

expr = _PyPegen_run_parser(p2);

if (expr == NULL) {

goto exit;

}

result = expr;

exit:

PyMem_Free(str);

_PyPegen_Parser_Free(p2);

_PyTokenizer_Free(tok);

return result;

}

/* Return -1 on error.

Return 0 if we reached the end of the literal.

Return 1 if we haven't reached the end of the literal, but we want

the caller to process the literal up to this point. Used for

doubled braces.

*/

static int

fstring_find_literal(Parser *p, const char **str, const char *end, int raw,

PyObject **literal, int recurse_lvl, Token *t)

{

/* Get any literal string. It ends when we hit an un-doubled left

brace (which isn't part of a unicode name escape such as

"\N{EULER CONSTANT}"), or the end of the string. */

const char *s = *str;

const char *literal_start = s;

int result = 0;

assert(*literal == NULL);

while (s < end) {

char ch = *s++;

if (!raw && ch == '\\' && s < end) {

ch = *s++;

if (ch == 'N') {

/* We need to look at and skip matching braces for "\N{name}"

sequences because otherwise we'll think the opening '{'

starts an expression, which is not the case with "\N".

Keep looking for either a matched '{' '}' pair, or the end

of the string. */

if (s < end && *s++ == '{') {

while (s < end && *s++ != '}') {

}

continue;

}

/* This is an invalid "\N" sequence, since it's a "\N" not

followed by a "{". Just keep parsing this literal. This

error will be caught later by

decode_unicode_with_escapes(). */

continue;

}

if (ch == '{' && warn_invalid_escape_sequence(p, s-1, t) < 0) {

return -1;

}

}

if (ch == '{' || ch == '}') {

/* Check for doubled braces, but only at the top level. If

we checked at every level, then f'{0:{3}}' would fail

with the two closing braces. */

if (recurse_lvl == 0) {

if (s < end && *s == ch) {

/* We're going to tell the caller that the literal ends

here, but that they should continue scanning. But also

skip over the second brace when we resume scanning. */

*str = s + 1;

result = 1;

goto done;

}

/* Where a single '{' is the start of a new expression, a

single '}' is not allowed. */

if (ch == '}') {

*str = s - 1;

RAISE_SYNTAX_ERROR("f-string: single '}' is not allowed");

return -1;

}

}

/* We're either at a '{', which means we're starting another

expression; or a '}', which means we're at the end of this

f-string (for a nested format_spec). */

s--;

break;

}

}

*str = s;

assert(s <= end);

assert(s == end || *s == '{' || *s == '}');

done:

if (literal_start != s) {

if (raw) {

*literal = PyUnicode_DecodeUTF8Stateful(literal_start,

s - literal_start,

NULL, NULL);

}

else {

*literal = decode_unicode_with_escapes(p, literal_start,

s - literal_start, t);

}

if (!*literal) {

return -1;

}

}

return result;

}

/* Forward declaration because parsing is recursive. */

static expr_ty

fstring_parse(Parser *p, const char **str, const char *end, int raw, int recurse_lvl,

Token *first_token, Token* t, Token *last_token);

/* Parse the f-string at *str, ending at end. We know *str starts an

expression (so it must be a '{'). Returns the FormattedValue node, which

includes the expression, conversion character, format_spec expression, and

optionally the text of the expression (if = is used).

Note that I don't do a perfect job here: I don't make sure that a

closing brace doesn't match an opening paren, for example. It

doesn't need to error on all invalid expressions, just correctly

find the end of all valid ones. Any errors inside the expression

will be caught when we parse it later.

*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. */

static int

fstring_find_expr(Parser *p, const char **str, const char *end, int raw, int recurse_lvl,

PyObject **expr_text, expr_ty *expression, Token *first_token,

Token *t, Token *last_token)

{

/* Return -1 on error, else 0. */

const char *expr_start;

const char *expr_end;

expr_ty simple_expression;

expr_ty format_spec = NULL; /* Optional format specifier. */

int conversion = -1; /* The conversion char. Use default if not

specified, or !r if using = and no format

spec. */

/* 0 if we're not in a string, else the quote char we're trying to

match (single or double quote). */

char quote_char = 0;

/* If we're inside a string, 1=normal, 3=triple-quoted. */

int string_type = 0;

/* Keep track of nesting level for braces/parens/brackets in

expressions. */

Py_ssize_t nested_depth = 0;

char parenstack[MAXLEVEL];

*expr_text = NULL;

/* Can only nest one level deep. */

if (recurse_lvl >= 2) {

RAISE_SYNTAX_ERROR("f-string: expressions nested too deeply");

goto error;

}

/* The first char must be a left brace, or we wouldn't have gotten

here. Skip over it. */

assert(**str == '{');

*str += 1;

expr_start = *str;

for (; *str < end; (*str)++) {

char ch;

/* Loop invariants. */

assert(nested_depth >= 0);

assert(*str >= expr_start && *str < end);

if (quote_char) {

assert(string_type == 1 || string_type == 3);

} else {

assert(string_type == 0);

}

ch = **str;

/* Nowhere inside an expression is a backslash allowed. */

if (ch == '\\') {

/* Error: can't include a backslash character, inside

parens or strings or not. */

RAISE_SYNTAX_ERROR(

"f-string expression part "

"cannot include a backslash");

goto error;

}

if (quote_char) {

/* We're inside a string. See if we're at the end. */

/* This code needs to implement the same non-error logic

as tok_get from tokenizer.c, at the letter_quote

label. To actually share that code would be a

nightmare. But, it's unlikely to change and is small,

so duplicate it here. Note we don't need to catch all

of the errors, since they'll be caught when parsing the

expression. We just need to match the non-error

cases. Thus we can ignore \n in single-quoted strings,

for example. Or non-terminated strings. */

if (ch == quote_char) {

/* Does this match the string_type (single or triple

quoted)? */

if (string_type == 3) {

if (*str+2 < end && *(*str+1) == ch && *(*str+2) == ch) {

/* We're at the end of a triple quoted string. */

*str += 2;

string_type = 0;

quote_char = 0;

continue;

}

} else {

/* We're at the end of a normal string. */

quote_char = 0;

string_type = 0;

continue;

}

}

} else if (ch == '\'' || ch == '"') {

/* Is this a triple quoted string? */

if (*str+2 < end && *(*str+1) == ch && *(*str+2) == ch) {

string_type = 3;

*str += 2;

} else {

/* Start of a normal string. */

string_type = 1;

}

/* Start looking for the end of the string. */

quote_char = ch;

} else if (ch == '[' || ch == '{' || ch == '(') {

if (nested_depth >= MAXLEVEL) {

RAISE_SYNTAX_ERROR("f-string: too many nested parenthesis");

goto error;

}

parenstack[nested_depth] = ch;

nested_depth++;

} else if (ch == '#') {

/* Error: can't include a comment character, inside parens

or not. */

RAISE_SYNTAX_ERROR("f-string expression part cannot include '#'");

goto error;

} else if (nested_depth == 0 &&

(ch == '!' || ch == ':' || ch == '}' ||

ch == '=' || ch == '>' || ch == '<')) {

/* See if there's a next character. */

if (*str+1 < end) {

char next = *(*str+1);

/* For "!=". since '=' is not an allowed conversion character,

nothing is lost in this test. */

if ((ch == '!' && next == '=') || /* != */

(ch == '=' && next == '=') || /* == */

(ch == '<' && next == '=') || /* <= */

(ch == '>' && next == '=') /* >= */

) {

*str += 1;

continue;

}

}

/* Don't get out of the loop for these, if they're single

chars (not part of 2-char tokens). If by themselves, they

don't end an expression (unlike say '!'). */

if (ch == '>' || ch == '<') {

continue;

}

/* Normal way out of this loop. */

break;

} else if (ch == ']' || ch == '}' || ch == ')') {

if (!nested_depth) {

RAISE_SYNTAX_ERROR("f-string: unmatched '%c'", ch);

goto error;

}

nested_depth--;

int opening = (unsigned char)parenstack[nested_depth];

if (!((opening == '(' && ch == ')') ||

(opening == '[' && ch == ']') ||

(opening == '{' && ch == '}')))

{

RAISE_SYNTAX_ERROR(

"f-string: closing parenthesis '%c' "

"does not match opening parenthesis '%c'",

ch, opening);

goto error;

}

} else {

/* Just consume this char and loop around. */

}

}

expr_end = *str;

/* If we leave the above loop in a string or with mismatched parens, we

don't really care. We'll get a syntax error when compiling the

expression. But, we can produce a better error message, so let's just

do that.*/

if (quote_char) {

RAISE_SYNTAX_ERROR("f-string: unterminated string");

goto error;

}

if (nested_depth) {

int opening = (unsigned char)parenstack[nested_depth - 1];

RAISE_SYNTAX_ERROR("f-string: unmatched '%c'", opening);

goto error;

}

if (*str >= end) {

goto unexpected_end_of_string;

}

/* Compile the expression as soon as possible, so we show errors

related to the expression before errors related to the

conversion or format_spec. */

simple_expression = fstring_compile_expr(p, expr_start, expr_end, t);

if (!simple_expression) {

goto error;

}

/* Check for =, which puts the text value of the expression in

expr_text. */

if (**str == '=') {

if (p->feature_version < 8) {

RAISE_SYNTAX_ERROR("f-string: self documenting expressions are "

"only supported in Python 3.8 and greater");

goto error;

}

*str += 1;

/* Skip over ASCII whitespace. No need to test for end of string

here, since we know there's at least a trailing quote somewhere

ahead. */

while (Py_ISSPACE(**str)) {

*str += 1;

}

if (*str >= end) {

goto unexpected_end_of_string;

}

/* Set *expr_text to the text of the expression. */

*expr_text = PyUnicode_FromStringAndSize(expr_start, *str-expr_start);

if (!*expr_text) {

goto error;

}

}

/* Check for a conversion char, if present. */

if (**str == '!') {

*str += 1;

const char *conv_start = *str;

while (1) {

if (*str >= end) {

goto unexpected_end_of_string;

}

if (**str == '}' || **str == ':') {

break;

}

*str += 1;

}

if (*str == conv_start) {

RAISE_SYNTAX_ERROR(

"f-string: missed conversion character");

goto error;

}

conversion = (unsigned char)*conv_start;

/* Validate the conversion. */

if ((*str != conv_start + 1) ||

!(conversion == 's' || conversion == 'r' || conversion == 'a'))

{

PyObject *conv_obj = PyUnicode_FromStringAndSize(conv_start,

*str-conv_start);

if (conv_obj) {

RAISE_SYNTAX_ERROR(

"f-string: invalid conversion character %R: "

"expected 's', 'r', or 'a'",

conv_obj);

Py_DECREF(conv_obj);

}

goto error;

}

}

/* Check for the format spec, if present. */

assert(*str < end);

if (**str == ':') {

*str += 1;

if (*str >= end) {

goto unexpected_end_of_string;

}

/* Parse the format spec. */

format_spec = fstring_parse(p, str, end, raw, recurse_lvl+1,

first_token, t, last_token);

if (!format_spec) {

goto error;

}

}

if (*str >= end || **str != '}') {

goto unexpected_end_of_string;

}

/* We're at a right brace. Consume it. */

assert(*str < end);

assert(**str == '}');

*str += 1;

/* If we're in = mode (detected by non-NULL expr_text), and have no format

spec and no explicit conversion, set the conversion to 'r'. */

if (*expr_text && format_spec == NULL && conversion == -1) {

conversion = 'r';

}

/* And now create the FormattedValue node that represents this

entire expression with the conversion and format spec. */

//TODO: Fix this

*expression = _PyAST_FormattedValue(simple_expression, conversion,

format_spec, first_token->lineno,

first_token->col_offset,

last_token->end_lineno,

last_token->end_col_offset, p->arena);

if (!*expression) {

goto error;

}

return 0;

unexpected_end_of_string:

RAISE_SYNTAX_ERROR("f-string: expecting '}'");

/* Falls through to error. */

error:

Py_XDECREF(*expr_text);

return -1;

}

/* Return -1 on error.

Return 0 if we have a literal (possible zero length) and an

expression (zero length if at the end of the string.

Return 1 if we have a literal, but no expression, and we want the

caller to call us again. This is used to deal with doubled

braces.

When called multiple times on the string 'a{{b{0}c', this function

will return:

1. the literal 'a{' with no expression, and a return value

of 1. Despite the fact that there's no expression, the return

value of 1 means we're not finished yet.

2. the literal 'b' and the expression '0', with a return value of

0. The fact that there's an expression means we're not finished.

3. literal 'c' with no expression and a return value of 0. The

combination of the return value of 0 with no expression means

we're finished.

*/

static int

fstring_find_literal_and_expr(Parser *p, const char **str, const char *end, int raw,

int recurse_lvl, PyObject **literal,

PyObject **expr_text, expr_ty *expression,

Token *first_token, Token *t, Token *last_token)

{

int result;

assert(*literal == NULL && *expression == NULL);

/* Get any literal string. */

result = fstring_find_literal(p, str, end, raw, literal, recurse_lvl, t);

if (result < 0) {

goto error;

}

assert(result == 0 || result == 1);

if (result == 1) {

/* We have a literal, but don't look at the expression. */

return 1;

}

if (*str >= end || **str == '}') {

/* We're at the end of the string or the end of a nested

f-string: no expression. The top-level error case where we

expect to be at the end of the string but we're at a '}' is

handled later. */

return 0;

}

/* We must now be the start of an expression, on a '{'. */

assert(**str == '{');

if (fstring_find_expr(p, str, end, raw, recurse_lvl, expr_text,

expression, first_token, t, last_token) < 0) {

goto error;

}

return 0;

error:

Py_CLEAR(*literal);

return -1;

}

#ifdef NDEBUG

#define ExprList_check_invariants(l)

#else

static void

ExprList_check_invariants(ExprList *l)

{

/* Check our invariants. Make sure this object is "live", and

hasn't been deallocated. */

assert(l->size >= 0);

assert(l->p != NULL);

if (l->size <= EXPRLIST_N_CACHED) {

assert(l->data == l->p);

}

}

#endif

static void

ExprList_Init(ExprList *l)

{

l->allocated = EXPRLIST_N_CACHED;

l->size = 0;

/* Until we start allocating dynamically, p points to data. */

l->p = l->data;

ExprList_check_invariants(l);

}

static int

ExprList_Append(ExprList *l, expr_ty exp)

{

ExprList_check_invariants(l);

if (l->size >= l->allocated) {

/* We need to alloc (or realloc) the memory. */

Py_ssize_t new_size = l->allocated * 2;

/* See if we've ever allocated anything dynamically. */

if (l->p == l->data) {

Py_ssize_t i;

/* We're still using the cached data. Switch to

alloc-ing. */

l->p = PyMem_Malloc(sizeof(expr_ty) * new_size);

if (!l->p) {

return -1;

}

/* Copy the cached data into the new buffer. */

for (i = 0; i < l->size; i++) {

l->p[i] = l->data[i];

}

} else {

/* Just realloc. */

expr_ty *tmp = PyMem_Realloc(l->p, sizeof(expr_ty) * new_size);

if (!tmp) {

PyMem_Free(l->p);

l->p = NULL;

return -1;

}

l->p = tmp;

}

l->allocated = new_size;

assert(l->allocated == 2 * l->size);

}

l->p[l->size++] = exp;

ExprList_check_invariants(l);

return 0;

}