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#include "Python.h"
#include "node.h"
#include "token.h"
#include "graminit.h"
#include "compile.h"
#include "symtable.h"
#define UNDEFINED_FUTURE_FEATURE "future feature %.100s is not defined"
#define FUTURE_POSSIBLE(FF) ((FF)->ff_last_lineno == -1)
static int
future_check_features(PyFutureFeatures *ff, node *n)
{
int i;
char *feature;
REQ(n, import_stmt); /* must by from __future__ import ... */
for (i = 3; i < NCH(n); ++i) {
feature = STR(CHILD(CHILD(n, i), 0));
if (strcmp(feature, FUTURE_NESTED_SCOPES) == 0) {
ff->ff_nested_scopes = 1;
} else {
PyErr_Format(PyExc_SyntaxError,
UNDEFINED_FUTURE_FEATURE, feature);
return -1;
}
}
return 0;
}
static void
future_error(node *n, char *filename)
{
PyErr_SetString(PyExc_SyntaxError,
"from __future__ imports must occur at the "
"beginning of the file");
/* XXX set filename and lineno */
}
/* Relevant portions of the grammar:
single_input: NEWLINE | simple_stmt | compound_stmt NEWLINE
file_input: (NEWLINE | stmt)* ENDMARKER
stmt: simple_stmt | compound_stmt
simple_stmt: small_stmt (';' small_stmt)* [';'] NEWLINE
small_stmt: expr_stmt | print_stmt | del_stmt | pass_stmt | flow_stmt | import_stmt | global_stmt | exec_stmt | assert_stmt
import_stmt: 'import' dotted_as_name (',' dotted_as_name)* | 'from' dotted_name 'import' ('*' | import_as_name (',' import_as_name)*)
import_as_name: NAME [NAME NAME]
dotted_as_name: dotted_name [NAME NAME]
dotted_name: NAME ('.' NAME)*
*/
/* future_parse() return values:
-1 indicates an error occurred, e.g. unknown feature name
0 indicates no feature was found
1 indicates a feature was found
*/
static int
future_parse(PyFutureFeatures *ff, node *n, char *filename)
{
int i, r;
loop:
/* fprintf(stderr, "future_parse(%d, %d, %s, %d)\n",
TYPE(n), NCH(n), (n == NULL) ? "NULL" : STR(n),
n->n_lineno);
*/
switch (TYPE(n)) {
case single_input:
if (TYPE(CHILD(n, 0)) == simple_stmt) {
n = CHILD(n, 0);
goto loop;
}
return 0;
case file_input:
for (i = 0; i < NCH(n); i++) {
node *ch = CHILD(n, i);
if (TYPE(ch) == stmt) {
r = future_parse(ff, ch, filename);
if (!FUTURE_POSSIBLE(ff))
return r;
}
}
return 0;
case simple_stmt:
if (NCH(n) == 2) {
REQ(CHILD(n, 0), small_stmt);
n = CHILD(n, 0);
goto loop;
} else {
/* Deal with the special case of a series of
small statements on a single line. If a
future statement follows some other
statement, the SyntaxError is raised here.
In all other cases, the symtable pass
raises the exception.
*/
int found = 0, end_of_future = 0;
for (i = 0; i < NCH(n); i += 2) {
if (TYPE(CHILD(n, i)) == small_stmt) {
r = future_parse(ff, CHILD(n, i),
filename);
if (r < 1)
end_of_future = 1;
else {
found = 1;
if (end_of_future) {
future_error(n,
filename);
return -1;
}
}
}
}
/* If we found one and only one, then the
current lineno is legal.
*/
if (found)
ff->ff_last_lineno = n->n_lineno + 1;
else
ff->ff_last_lineno = n->n_lineno;
if (end_of_future && found)
return 1;
else
return 0;
}
case stmt:
if (TYPE(CHILD(n, 0)) == simple_stmt) {
n = CHILD(n, 0);
goto loop;
} else if (TYPE(CHILD(n, 0)) == expr_stmt) {
n = CHILD(n, 0);
goto loop;
} else {
REQ(CHILD(n, 0), compound_stmt);
ff->ff_last_lineno = n->n_lineno;
return 0;
}
case small_stmt:
n = CHILD(n, 0);
goto loop;
case import_stmt: {
node *name;
if (STR(CHILD(n, 0))[0] != 'f') { /* from */
ff->ff_last_lineno = n->n_lineno;
return 0;
}
name = CHILD(n, 1);
if (strcmp(STR(CHILD(name, 0)), "__future__") != 0)
return 0;
if (future_check_features(ff, n) < 0)
return -1;
ff->ff_last_lineno = n->n_lineno + 1;
return 1;
}
/* The cases below -- all of them! -- are necessary to find
and skip doc strings. */
case expr_stmt:
case testlist:
case test:
case and_test:
case not_test:
case comparison:
case expr:
case xor_expr:
case and_expr:
case shift_expr:
case arith_expr:
case term:
case factor:
case power:
if (NCH(n) == 1) {
n = CHILD(n, 0);
goto loop;
}
break;
case atom:
if (TYPE(CHILD(n, 0)) == STRING
&& ff->ff_found_docstring == 0) {
ff->ff_found_docstring = 1;
return 0;
}
ff->ff_last_lineno = n->n_lineno;
return 0;
default:
ff->ff_last_lineno = n->n_lineno;
return 0;
}
return 0;
}
PyFutureFeatures *
PyNode_Future(node *n, char *filename)
{
PyFutureFeatures *ff;
ff = (PyFutureFeatures *)PyMem_Malloc(sizeof(PyFutureFeatures));
if (ff == NULL)
return NULL;
ff->ff_found_docstring = 0;
ff->ff_last_lineno = -1;
ff->ff_nested_scopes = 0;
if (future_parse(ff, n, filename) < 0) {
PyMem_Free((void *)ff);
return NULL;
}
return ff;
}
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