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bpo-30465: Fix lineno and col_offset in fstring AST nodes (#1800)

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For f-string ast nodes, fix the line and columns so that tools such as flake8 can identify them correctly.
This commit is contained in:
Łukasz Langa 2017-09-06 17:27:58 -07:00 • committed by ericvsmith
parent 36d644d37a
commit e7c566caf1
3 changed files with 318 additions and 5 deletions
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72
Python/ast.c
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@ -8,6 +8,7 @@
#include "node.h"
#include "ast.h"
#include "token.h"
#include "pythonrun.h"
#include <assert.h>
@ -4270,6 +4271,55 @@ decode_bytes_with_escapes(struct compiling *c, const node *n, const char *s,
return result;
}
/* Shift locations for the given node and all its children by adding `lineno`
and `col_offset` to existing locations. */
static void fstring_shift_node_locations(node *n, int lineno, int col_offset)
{
n->n_col_offset = n->n_col_offset + col_offset;
for (int i = 0; i < NCH(n); ++i) {
if (n->n_lineno && n->n_lineno < CHILD(n, i)->n_lineno) {
/* Shifting column offsets unnecessary if there's been newlines. */
col_offset = 0;
}
fstring_shift_node_locations(CHILD(n, i), lineno, col_offset);
}
n->n_lineno = n->n_lineno + lineno;
}
/* Fix locations for the given node and its children.
`parent` is the enclosing node.
`n` is the node which locations are going to be fixed relative to parent.
`expr_str` is the child node's string representation, incuding braces.
*/
static void
fstring_fix_node_location(const node *parent, node *n, char *expr_str)
{
char *substr = NULL;
char *start;
int lines = LINENO(parent) - 1;
int cols = parent->n_col_offset;
/* Find the full fstring to fix location information in `n`. */
while (parent && parent->n_type != STRING)
parent = parent->n_child;
if (parent && parent->n_str) {
substr = strstr(parent->n_str, expr_str);
if (substr) {
start = substr;
while (start > parent->n_str) {
if (start[0] == '\n')
break;
start--;
}
cols += substr - start;
/* Fix lineno in mulitline strings. */
while ((substr = strchr(substr + 1, '\n')))
lines--;
}
}
fstring_shift_node_locations(n, lines, cols);
}
/* 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
@ -4278,6 +4328,7 @@ fstring_compile_expr(const char *expr_start, const char *expr_end,
{
PyCompilerFlags cf;
node *mod_n;
mod_ty mod;
char *str;
Py_ssize_t len;
@ -4287,9 +4338,10 @@ fstring_compile_expr(const char *expr_start, const char *expr_end,
assert(*(expr_start-1) == '{');
assert(*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_ASTFromString, because turning
the expression '' in to '()' would go from being invalid to valid. */
/* 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
@ -4315,9 +4367,19 @@ fstring_compile_expr(const char *expr_start, const char *expr_end,
str[len+2] = 0;
cf.cf_flags = PyCF_ONLY_AST;
mod = PyParser_ASTFromString(str, "<fstring>",
Py_eval_input, &cf, c->c_arena);
mod_n = PyParser_SimpleParseStringFlagsFilename(str, "<fstring>",
Py_eval_input, 0);
if (!mod_n) {
PyMem_RawFree(str);
return NULL;
}
/* Reuse str to find the correct column offset. */
str[0] = '{';
str[len+1] = '}';
fstring_fix_node_location(n, mod_n, str);
mod = PyAST_FromNode(mod_n, &cf, "<fstring>", c->c_arena);
PyMem_RawFree(str);
PyNode_Free(mod_n);
if (!mod)
return NULL;
return mod->v.Expression.body;