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future.c
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137 lines (121 loc) · 4.28 KB
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#include "Python.h"
#include "Python-ast.h"
#include "node.h"
#include "token.h"
#include "graminit.h"
#include "code.h"
#include "symtable.h"
#define UNDEFINED_FUTURE_FEATURE "future feature %.100s is not defined"
#define ERR_LATE_FUTURE \
"from __future__ imports must occur at the beginning of the file"
static int
future_check_features(PyFutureFeatures *ff, stmt_ty s, const char *filename)
{
int i;
asdl_seq *names;
assert(s->kind == ImportFrom_kind);
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_AsString(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, "braces") == 0) {
PyErr_SetString(PyExc_SyntaxError,
"not a chance");
PyErr_SyntaxLocationEx(filename, s->lineno, s->col_offset);
return 0;
} else {
PyErr_Format(PyExc_SyntaxError,
UNDEFINED_FUTURE_FEATURE, feature);
PyErr_SyntaxLocationEx(filename, s->lineno, s->col_offset);
return 0;
}
}
return 1;
}
static int
future_parse(PyFutureFeatures *ff, mod_ty mod, const char *filename)
{
int i, found_docstring = 0, done = 0, prev_line = 0;
if (!(mod->kind == Module_kind || mod->kind == Interactive_kind))
return 1;
/* A subsequent pass will detect future imports that don't
appear at the beginning of the file. There's one case,
however, that is easier to handle here: A series of imports
joined by semi-colons, where the first import is a future
statement but some subsequent import has the future form
but is preceded by a regular import.
*/
for (i = 0; i < asdl_seq_LEN(mod->v.Module.body); i++) {
stmt_ty s = (stmt_ty)asdl_seq_GET(mod->v.Module.body, i);
if (done && s->lineno > prev_line)
return 1;
prev_line = s->lineno;
/* The tests below will return from this function unless it is
still possible to find a future statement. The only things
that can precede a future statement are another future
statement and a doc string.
*/
if (s->kind == ImportFrom_kind) {
identifier modname = s->v.ImportFrom.module;
if (modname &&
!PyUnicode_CompareWithASCIIString(modname, "__future__")) {
if (done) {
PyErr_SetString(PyExc_SyntaxError,
ERR_LATE_FUTURE);
PyErr_SyntaxLocationEx(filename, s->lineno, s->col_offset);
return 0;
}
if (!future_check_features(ff, s, filename))
return 0;
ff->ff_lineno = s->lineno;
}
else
done = 1;
}
else if (s->kind == Expr_kind && !found_docstring) {
expr_ty e = s->v.Expr.value;
if (e->kind != Str_kind)
done = 1;
else
found_docstring = 1;
}
else
done = 1;
}
return 1;
}
PyFutureFeatures *
PyFuture_FromAST(mod_ty mod, const char *filename)
{
PyFutureFeatures *ff;
ff = (PyFutureFeatures *)PyObject_Malloc(sizeof(PyFutureFeatures));
if (ff == NULL) {
PyErr_NoMemory();
return NULL;
}
ff->ff_features = 0;
ff->ff_lineno = -1;
if (!future_parse(ff, mod, filename)) {
PyObject_Free(ff);
return NULL;
}
return ff;
}