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bpo-44885: Correct the ast locations of f-strings with format specs and repeated expressions (GH-27729)

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Pablo Galindo Salgado 2021-08-12 17:13:30 +01:00 • committed by GitHub
parent 789a6af29f
commit 8e832fb2a2
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6 changed files with 103 additions and 91 deletions
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68
Parser/string_parser.c
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@ -279,49 +279,48 @@ _PyPegen_parsestr(Parser *p, int *bytesmode, int *rawmode, PyObject **result,
/* 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, char *expr_str, int *p_lines, int *p_cols)
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;
}
const char *substr = strstr(parent_str, expr_str);
if (substr) {
// 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 = substr + 1;
while (start && *start != '}' && *start != '\n') {
if (*start != ' ' && *start != '\t' && *start != '\f') {
newline_after_brace = 0;
break;
}
start++;
// 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 substr.
if (!newline_after_brace) {
start = substr;
while (start > parent_str && *start != '\n') {
start--;
}
*p_cols += (int)(substr - 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--;
}
/* adjust the start based on the number of newlines encountered
before the f-string expression */
for (const char *p = parent_str; p < substr; p++) {
if (*p == '\n') {
(*p_lines)++;
}
*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)++;
}
}
}
@ -365,7 +364,7 @@ fstring_compile_expr(Parser *p, const char *expr_start, const char *expr_end,
len = expr_end - expr_start;
/* Allocate 3 extra bytes: open paren, close paren, null byte. */
str = PyMem_Malloc(len + 3);
str = PyMem_Calloc(len + 3, sizeof(char));
if (str == NULL) {
PyErr_NoMemory();
return NULL;
@ -373,17 +372,10 @@ fstring_compile_expr(Parser *p, const char *expr_start, const char *expr_end,
// 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. In order to correctly compute
// this offset, strstr gets called in fstring_find_expr_location which only succeeds
// if curly braces appear before and after the f-string expression (exactly like they do
// in the f-string itself), hence the following lines.
str[0] = '{';
// of the f-string characters before the expression starts.
memcpy(str+1, expr_start, len);
str[len+1] = '}';
str[len+2] = 0;
int lines, cols;
if (!fstring_find_expr_location(t, str, &lines, &cols)) {
if (!fstring_find_expr_location(t, expr_start-1, str+1, &lines, &cols)) {
PyMem_Free(str);
return NULL;
}