1 #include "Python.h"
2 #include "Python-ast.h"
3 #include "node.h"
4 #include "token.h"
5 #include "graminit.h"
6 #include "code.h"
7 #include "symtable.h"
8 #include "ast.h"
9
10 #define UNDEFINED_FUTURE_FEATURE "future feature %.100s is not defined"
11 #define ERR_LATE_FUTURE \
12 "from __future__ imports must occur at the beginning of the file"
13
14 static int
future_check_features(PyFutureFeatures * ff,stmt_ty s,PyObject * filename)15 future_check_features(PyFutureFeatures *ff, stmt_ty s, PyObject *filename)
16 {
17 int i;
18 asdl_seq *names;
19
20 assert(s->kind == ImportFrom_kind);
21
22 names = s->v.ImportFrom.names;
23 for (i = 0; i < asdl_seq_LEN(names); i++) {
24 alias_ty name = (alias_ty)asdl_seq_GET(names, i);
25 const char *feature = PyUnicode_AsUTF8(name->name);
26 if (!feature)
27 return 0;
28 if (strcmp(feature, FUTURE_NESTED_SCOPES) == 0) {
29 continue;
30 } else if (strcmp(feature, FUTURE_GENERATORS) == 0) {
31 continue;
32 } else if (strcmp(feature, FUTURE_DIVISION) == 0) {
33 continue;
34 } else if (strcmp(feature, FUTURE_ABSOLUTE_IMPORT) == 0) {
35 continue;
36 } else if (strcmp(feature, FUTURE_WITH_STATEMENT) == 0) {
37 continue;
38 } else if (strcmp(feature, FUTURE_PRINT_FUNCTION) == 0) {
39 continue;
40 } else if (strcmp(feature, FUTURE_UNICODE_LITERALS) == 0) {
41 continue;
42 } else if (strcmp(feature, FUTURE_BARRY_AS_BDFL) == 0) {
43 ff->ff_features |= CO_FUTURE_BARRY_AS_BDFL;
44 } else if (strcmp(feature, FUTURE_GENERATOR_STOP) == 0) {
45 continue;
46 } else if (strcmp(feature, FUTURE_ANNOTATIONS) == 0) {
47 ff->ff_features |= CO_FUTURE_ANNOTATIONS;
48 } else if (strcmp(feature, "braces") == 0) {
49 PyErr_SetString(PyExc_SyntaxError,
50 "not a chance");
51 PyErr_SyntaxLocationObject(filename, s->lineno, s->col_offset + 1);
52 return 0;
53 } else {
54 PyErr_Format(PyExc_SyntaxError,
55 UNDEFINED_FUTURE_FEATURE, feature);
56 PyErr_SyntaxLocationObject(filename, s->lineno, s->col_offset + 1);
57 return 0;
58 }
59 }
60 return 1;
61 }
62
63 static int
future_parse(PyFutureFeatures * ff,mod_ty mod,PyObject * filename)64 future_parse(PyFutureFeatures *ff, mod_ty mod, PyObject *filename)
65 {
66 int i, done = 0, prev_line = 0;
67
68 if (!(mod->kind == Module_kind || mod->kind == Interactive_kind))
69 return 1;
70
71 if (asdl_seq_LEN(mod->v.Module.body) == 0)
72 return 1;
73
74 /* A subsequent pass will detect future imports that don't
75 appear at the beginning of the file. There's one case,
76 however, that is easier to handle here: A series of imports
77 joined by semi-colons, where the first import is a future
78 statement but some subsequent import has the future form
79 but is preceded by a regular import.
80 */
81
82 i = 0;
83 if (_PyAST_GetDocString(mod->v.Module.body) != NULL)
84 i++;
85
86 for (; i < asdl_seq_LEN(mod->v.Module.body); i++) {
87 stmt_ty s = (stmt_ty)asdl_seq_GET(mod->v.Module.body, i);
88
89 if (done && s->lineno > prev_line)
90 return 1;
91 prev_line = s->lineno;
92
93 /* The tests below will return from this function unless it is
94 still possible to find a future statement. The only things
95 that can precede a future statement are another future
96 statement and a doc string.
97 */
98
99 if (s->kind == ImportFrom_kind) {
100 identifier modname = s->v.ImportFrom.module;
101 if (modname &&
102 _PyUnicode_EqualToASCIIString(modname, "__future__")) {
103 if (done) {
104 PyErr_SetString(PyExc_SyntaxError,
105 ERR_LATE_FUTURE);
106 PyErr_SyntaxLocationObject(filename, s->lineno, s->col_offset);
107 return 0;
108 }
109 if (!future_check_features(ff, s, filename))
110 return 0;
111 ff->ff_lineno = s->lineno;
112 }
113 else {
114 done = 1;
115 }
116 }
117 else {
118 done = 1;
119 }
120 }
121 return 1;
122 }
123
124
125 PyFutureFeatures *
PyFuture_FromASTObject(mod_ty mod,PyObject * filename)126 PyFuture_FromASTObject(mod_ty mod, PyObject *filename)
127 {
128 PyFutureFeatures *ff;
129
130 ff = (PyFutureFeatures *)PyObject_Malloc(sizeof(PyFutureFeatures));
131 if (ff == NULL) {
132 PyErr_NoMemory();
133 return NULL;
134 }
135 ff->ff_features = 0;
136 ff->ff_lineno = -1;
137
138 if (!future_parse(ff, mod, filename)) {
139 PyObject_Free(ff);
140 return NULL;
141 }
142 return ff;
143 }
144
145
146 PyFutureFeatures *
PyFuture_FromAST(mod_ty mod,const char * filename_str)147 PyFuture_FromAST(mod_ty mod, const char *filename_str)
148 {
149 PyFutureFeatures *ff;
150 PyObject *filename;
151
152 filename = PyUnicode_DecodeFSDefault(filename_str);
153 if (filename == NULL)
154 return NULL;
155 ff = PyFuture_FromASTObject(mod, filename);
156 Py_DECREF(filename);
157 return ff;
158 }
159