1 #include "Python.h"
2 #include "pycore_ast.h" // _PyAST_GetDocString()
3
4 #define UNDEFINED_FUTURE_FEATURE "future feature %.100s is not defined"
5 #define ERR_LATE_FUTURE \
6 "from __future__ imports must occur at the beginning of the file"
7
8 static int
future_check_features(PyFutureFeatures * ff,stmt_ty s,PyObject * filename)9 future_check_features(PyFutureFeatures *ff, stmt_ty s, PyObject *filename)
10 {
11 int i;
12
13 assert(s->kind == ImportFrom_kind);
14
15 asdl_alias_seq *names = s->v.ImportFrom.names;
16 for (i = 0; i < asdl_seq_LEN(names); i++) {
17 alias_ty name = (alias_ty)asdl_seq_GET(names, i);
18 const char *feature = PyUnicode_AsUTF8(name->name);
19 if (!feature)
20 return 0;
21 if (strcmp(feature, FUTURE_NESTED_SCOPES) == 0) {
22 continue;
23 } else if (strcmp(feature, FUTURE_GENERATORS) == 0) {
24 continue;
25 } else if (strcmp(feature, FUTURE_DIVISION) == 0) {
26 continue;
27 } else if (strcmp(feature, FUTURE_ABSOLUTE_IMPORT) == 0) {
28 continue;
29 } else if (strcmp(feature, FUTURE_WITH_STATEMENT) == 0) {
30 continue;
31 } else if (strcmp(feature, FUTURE_PRINT_FUNCTION) == 0) {
32 continue;
33 } else if (strcmp(feature, FUTURE_UNICODE_LITERALS) == 0) {
34 continue;
35 } else if (strcmp(feature, FUTURE_BARRY_AS_BDFL) == 0) {
36 ff->ff_features |= CO_FUTURE_BARRY_AS_BDFL;
37 } else if (strcmp(feature, FUTURE_GENERATOR_STOP) == 0) {
38 continue;
39 } else if (strcmp(feature, FUTURE_ANNOTATIONS) == 0) {
40 ff->ff_features |= CO_FUTURE_ANNOTATIONS;
41 } else if (strcmp(feature, "braces") == 0) {
42 PyErr_SetString(PyExc_SyntaxError,
43 "not a chance");
44 PyErr_SyntaxLocationObject(filename, s->lineno, s->col_offset + 1);
45 return 0;
46 } else {
47 PyErr_Format(PyExc_SyntaxError,
48 UNDEFINED_FUTURE_FEATURE, feature);
49 PyErr_SyntaxLocationObject(filename, s->lineno, s->col_offset + 1);
50 return 0;
51 }
52 }
53 return 1;
54 }
55
56 static int
future_parse(PyFutureFeatures * ff,mod_ty mod,PyObject * filename)57 future_parse(PyFutureFeatures *ff, mod_ty mod, PyObject *filename)
58 {
59 int i, done = 0, prev_line = 0;
60
61 if (!(mod->kind == Module_kind || mod->kind == Interactive_kind))
62 return 1;
63
64 if (asdl_seq_LEN(mod->v.Module.body) == 0)
65 return 1;
66
67 /* A subsequent pass will detect future imports that don't
68 appear at the beginning of the file. There's one case,
69 however, that is easier to handle here: A series of imports
70 joined by semi-colons, where the first import is a future
71 statement but some subsequent import has the future form
72 but is preceded by a regular import.
73 */
74
75 i = 0;
76 if (_PyAST_GetDocString(mod->v.Module.body) != NULL)
77 i++;
78
79 for (; i < asdl_seq_LEN(mod->v.Module.body); i++) {
80 stmt_ty s = (stmt_ty)asdl_seq_GET(mod->v.Module.body, i);
81
82 if (done && s->lineno > prev_line)
83 return 1;
84 prev_line = s->lineno;
85
86 /* The tests below will return from this function unless it is
87 still possible to find a future statement. The only things
88 that can precede a future statement are another future
89 statement and a doc string.
90 */
91
92 if (s->kind == ImportFrom_kind) {
93 identifier modname = s->v.ImportFrom.module;
94 if (modname &&
95 _PyUnicode_EqualToASCIIString(modname, "__future__")) {
96 if (done) {
97 PyErr_SetString(PyExc_SyntaxError,
98 ERR_LATE_FUTURE);
99 PyErr_SyntaxLocationObject(filename, s->lineno, s->col_offset);
100 return 0;
101 }
102 if (!future_check_features(ff, s, filename))
103 return 0;
104 ff->ff_lineno = s->lineno;
105 }
106 else {
107 done = 1;
108 }
109 }
110 else {
111 done = 1;
112 }
113 }
114 return 1;
115 }
116
117
118 PyFutureFeatures *
_PyFuture_FromAST(mod_ty mod,PyObject * filename)119 _PyFuture_FromAST(mod_ty mod, PyObject *filename)
120 {
121 PyFutureFeatures *ff;
122
123 ff = (PyFutureFeatures *)PyObject_Malloc(sizeof(PyFutureFeatures));
124 if (ff == NULL) {
125 PyErr_NoMemory();
126 return NULL;
127 }
128 ff->ff_features = 0;
129 ff->ff_lineno = -1;
130
131 if (!future_parse(ff, mod, filename)) {
132 PyObject_Free(ff);
133 return NULL;
134 }
135 return ff;
136 }
137