cpython/Python/future.c

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#include "Python.h"
#include "pycore_ast.h" // _PyAST_GetDocString()
#include "pycore_symtable.h" // _PyFutureFeatures
#include "pycore_unicodeobject.h" // _PyUnicode_EqualToASCIIString()
#define UNDEFINED_FUTURE_FEATURE "future feature %.100s is not defined"
static int
future_check_features(_PyFutureFeatures *ff, stmt_ty s, PyObject *filename)
{
Py_ssize_t i;
assert(s->kind == ImportFrom_kind);
asdl_alias_seq *names = s->v.ImportFrom.names;
for (i = 0; i < asdl_seq_LEN(names); i++) {
alias_ty name = (alias_ty)asdl_seq_GET(names, i);
const char *feature = PyUnicode_AsUTF8(name->name);
if (!feature)
return 0;
if (strcmp(feature, FUTURE_NESTED_SCOPES) == 0) {
continue;
} else if (strcmp(feature, FUTURE_GENERATORS) == 0) {
continue;
} else if (strcmp(feature, FUTURE_DIVISION) == 0) {
continue;
} else if (strcmp(feature, FUTURE_ABSOLUTE_IMPORT) == 0) {
continue;
} else if (strcmp(feature, FUTURE_WITH_STATEMENT) == 0) {
continue;
} else if (strcmp(feature, FUTURE_PRINT_FUNCTION) == 0) {
continue;
} else if (strcmp(feature, FUTURE_UNICODE_LITERALS) == 0) {
continue;
} else if (strcmp(feature, FUTURE_BARRY_AS_BDFL) == 0) {
ff->ff_features |= CO_FUTURE_BARRY_AS_BDFL;
} else if (strcmp(feature, FUTURE_GENERATOR_STOP) == 0) {
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continue;
} else if (strcmp(feature, FUTURE_ANNOTATIONS) == 0) {
ff->ff_features |= CO_FUTURE_ANNOTATIONS;
} else if (strcmp(feature, "braces") == 0) {
PyErr_SetString(PyExc_SyntaxError,
"not a chance");
PyErr_SyntaxLocationObject(filename, s->lineno, s->col_offset + 1);
return 0;
} else {
PyErr_Format(PyExc_SyntaxError,
UNDEFINED_FUTURE_FEATURE, feature);
PyErr_SyntaxLocationObject(filename, s->lineno, s->col_offset + 1);
return 0;
}
}
return 1;
}
static int
future_parse(_PyFutureFeatures *ff, mod_ty mod, PyObject *filename)
{
if (!(mod->kind == Module_kind || mod->kind == Interactive_kind)) {
return 1;
}
Py_ssize_t n = asdl_seq_LEN(mod->v.Module.body);
if (n == 0) {
return 1;
}
Py_ssize_t i = 0;
if (_PyAST_GetDocString(mod->v.Module.body) != NULL) {
i++;
}
for (; i < n; i++) {
stmt_ty s = (stmt_ty)asdl_seq_GET(mod->v.Module.body, i);
/* The only things that can precede a future statement
* are another future statement and a doc string.
*/
if (s->kind == ImportFrom_kind && s->v.ImportFrom.level == 0) {
identifier modname = s->v.ImportFrom.module;
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if (modname &&
_PyUnicode_EqualToASCIIString(modname, "__future__")) {
if (!future_check_features(ff, s, filename)) {
return 0;
}
ff->ff_location = SRC_LOCATION_FROM_AST(s);
}
else {
return 1;
}
}
else {
return 1;
}
}
return 1;
}
int
_PyFuture_FromAST(mod_ty mod, PyObject *filename, _PyFutureFeatures *ff)
{
ff->ff_features = 0;
ff->ff_location = (_Py_SourceLocation){-1, -1, -1, -1};
if (!future_parse(ff, mod, filename)) {
return 0;
}
return 1;
}