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
9 #define UNDEFINED_FUTURE_FEATURE "future feature %.100s is not defined"
10 #define ERR_LATE_FUTURE \
11 "from __future__ imports must occur at the beginning of the file"
12
13 static int
future_check_features(PyFutureFeatures * ff,stmt_ty s,PyObject * filename)14 future_check_features(PyFutureFeatures *ff, stmt_ty s, PyObject *filename)
15 {
16 int i;
17 asdl_seq *names;
18
19 assert(s->kind == ImportFrom_kind);
20
21 names = s->v.ImportFrom.names;
22 for (i = 0; i < asdl_seq_LEN(names); i++) {
23 alias_ty name = (alias_ty)asdl_seq_GET(names, i);
24 const char *feature = PyUnicode_AsUTF8(name->name);
25 if (!feature)
26 return 0;
27 if (strcmp(feature, FUTURE_NESTED_SCOPES) == 0) {
28 continue;
29 } else if (strcmp(feature, FUTURE_GENERATORS) == 0) {
30 continue;
31 } else if (strcmp(feature, FUTURE_DIVISION) == 0) {
32 continue;
33 } else if (strcmp(feature, FUTURE_ABSOLUTE_IMPORT) == 0) {
34 continue;
35 } else if (strcmp(feature, FUTURE_WITH_STATEMENT) == 0) {
36 continue;
37 } else if (strcmp(feature, FUTURE_PRINT_FUNCTION) == 0) {
38 continue;
39 } else if (strcmp(feature, FUTURE_UNICODE_LITERALS) == 0) {
40 continue;
41 } else if (strcmp(feature, FUTURE_BARRY_AS_BDFL) == 0) {
42 ff->ff_features |= CO_FUTURE_BARRY_AS_BDFL;
43 } else if (strcmp(feature, FUTURE_GENERATOR_STOP) == 0) {
44 continue;
45 } else if (strcmp(feature, FUTURE_ANNOTATIONS) == 0) {
46 ff->ff_features |= CO_FUTURE_ANNOTATIONS;
47 } else if (strcmp(feature, "braces") == 0) {
48 PyErr_SetString(PyExc_SyntaxError,
49 "not a chance");
50 PyErr_SyntaxLocationObject(filename, s->lineno, s->col_offset);
51 return 0;
52 } else {
53 PyErr_Format(PyExc_SyntaxError,
54 UNDEFINED_FUTURE_FEATURE, feature);
55 PyErr_SyntaxLocationObject(filename, s->lineno, s->col_offset);
56 return 0;
57 }
58 }
59 return 1;
60 }
61
62 static int
future_parse(PyFutureFeatures * ff,mod_ty mod,PyObject * filename)63 future_parse(PyFutureFeatures *ff, mod_ty mod, PyObject *filename)
64 {
65 int i, done = 0, prev_line = 0;
66 stmt_ty first;
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 first = (stmt_ty)asdl_seq_GET(mod->v.Module.body, i);
84 if (first->kind == Expr_kind
85 && (first->v.Expr.value->kind == Str_kind
86 || (first->v.Expr.value->kind == Constant_kind
87 && PyUnicode_CheckExact(first->v.Expr.value->v.Constant.value))))
88 i++;
89
90 for (; i < asdl_seq_LEN(mod->v.Module.body); i++) {
91 stmt_ty s = (stmt_ty)asdl_seq_GET(mod->v.Module.body, i);
92
93 if (done && s->lineno > prev_line)
94 return 1;
95 prev_line = s->lineno;
96
97 /* The tests below will return from this function unless it is
98 still possible to find a future statement. The only things
99 that can precede a future statement are another future
100 statement and a doc string.
101 */
102
103 if (s->kind == ImportFrom_kind) {
104 identifier modname = s->v.ImportFrom.module;
105 if (modname &&
106 _PyUnicode_EqualToASCIIString(modname, "__future__")) {
107 if (done) {
108 PyErr_SetString(PyExc_SyntaxError,
109 ERR_LATE_FUTURE);
110 PyErr_SyntaxLocationObject(filename, s->lineno, s->col_offset);
111 return 0;
112 }
113 if (!future_check_features(ff, s, filename))
114 return 0;
115 ff->ff_lineno = s->lineno;
116 }
117 else {
118 done = 1;
119 }
120 }
121 else {
122 done = 1;
123 }
124 }
125 return 1;
126 }
127
128
129 PyFutureFeatures *
PyFuture_FromASTObject(mod_ty mod,PyObject * filename)130 PyFuture_FromASTObject(mod_ty mod, PyObject *filename)
131 {
132 PyFutureFeatures *ff;
133
134 ff = (PyFutureFeatures *)PyObject_Malloc(sizeof(PyFutureFeatures));
135 if (ff == NULL) {
136 PyErr_NoMemory();
137 return NULL;
138 }
139 ff->ff_features = 0;
140 ff->ff_lineno = -1;
141
142 if (!future_parse(ff, mod, filename)) {
143 PyObject_Free(ff);
144 return NULL;
145 }
146 return ff;
147 }
148
149
150 PyFutureFeatures *
PyFuture_FromAST(mod_ty mod,const char * filename_str)151 PyFuture_FromAST(mod_ty mod, const char *filename_str)
152 {
153 PyFutureFeatures *ff;
154 PyObject *filename;
155
156 filename = PyUnicode_DecodeFSDefault(filename_str);
157 if (filename == NULL)
158 return NULL;
159 ff = PyFuture_FromASTObject(mod, filename);
160 Py_DECREF(filename);
161 return ff;
162 }
163