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 ff->ff_features |= CO_FUTURE_GENERATOR_STOP;
45 } else if (strcmp(feature, "braces") == 0) {
46 PyErr_SetString(PyExc_SyntaxError,
47 "not a chance");
48 PyErr_SyntaxLocationObject(filename, s->lineno, s->col_offset);
49 return 0;
50 } else {
51 PyErr_Format(PyExc_SyntaxError,
52 UNDEFINED_FUTURE_FEATURE, feature);
53 PyErr_SyntaxLocationObject(filename, s->lineno, s->col_offset);
54 return 0;
55 }
56 }
57 return 1;
58 }
59
60 static int
future_parse(PyFutureFeatures * ff,mod_ty mod,PyObject * filename)61 future_parse(PyFutureFeatures *ff, mod_ty mod, PyObject *filename)
62 {
63 int i, done = 0, prev_line = 0;
64 stmt_ty first;
65
66 if (!(mod->kind == Module_kind || mod->kind == Interactive_kind))
67 return 1;
68
69 if (asdl_seq_LEN(mod->v.Module.body) == 0)
70 return 1;
71
72 /* A subsequent pass will detect future imports that don't
73 appear at the beginning of the file. There's one case,
74 however, that is easier to handle here: A series of imports
75 joined by semi-colons, where the first import is a future
76 statement but some subsequent import has the future form
77 but is preceded by a regular import.
78 */
79
80 i = 0;
81 first = (stmt_ty)asdl_seq_GET(mod->v.Module.body, i);
82 if (first->kind == Expr_kind
83 && (first->v.Expr.value->kind == Str_kind
84 || (first->v.Expr.value->kind == Constant_kind
85 && PyUnicode_CheckExact(first->v.Expr.value->v.Constant.value))))
86 i++;
87
88
89 for (; i < asdl_seq_LEN(mod->v.Module.body); i++) {
90 stmt_ty s = (stmt_ty)asdl_seq_GET(mod->v.Module.body, i);
91
92 if (done && s->lineno > prev_line)
93 return 1;
94 prev_line = s->lineno;
95
96 /* The tests below will return from this function unless it is
97 still possible to find a future statement. The only things
98 that can precede a future statement are another future
99 statement and a doc string.
100 */
101
102 if (s->kind == ImportFrom_kind) {
103 identifier modname = s->v.ImportFrom.module;
104 if (modname &&
105 _PyUnicode_EqualToASCIIString(modname, "__future__")) {
106 if (done) {
107 PyErr_SetString(PyExc_SyntaxError,
108 ERR_LATE_FUTURE);
109 PyErr_SyntaxLocationObject(filename, s->lineno, s->col_offset);
110 return 0;
111 }
112 if (!future_check_features(ff, s, filename))
113 return 0;
114 ff->ff_lineno = s->lineno;
115 }
116 else {
117 done = 1;
118 }
119 }
120 else {
121 done = 1;
122 }
123 }
124 return 1;
125 }
126
127
128 PyFutureFeatures *
PyFuture_FromASTObject(mod_ty mod,PyObject * filename)129 PyFuture_FromASTObject(mod_ty mod, PyObject *filename)
130 {
131 PyFutureFeatures *ff;
132
133 ff = (PyFutureFeatures *)PyObject_Malloc(sizeof(PyFutureFeatures));
134 if (ff == NULL) {
135 PyErr_NoMemory();
136 return NULL;
137 }
138 ff->ff_features = 0;
139 ff->ff_lineno = -1;
140
141 if (!future_parse(ff, mod, filename)) {
142 PyObject_Free(ff);
143 return NULL;
144 }
145 return ff;
146 }
147
148
149 PyFutureFeatures *
PyFuture_FromAST(mod_ty mod,const char * filename_str)150 PyFuture_FromAST(mod_ty mod, const char *filename_str)
151 {
152 PyFutureFeatures *ff;
153 PyObject *filename;
154
155 filename = PyUnicode_DecodeFSDefault(filename_str);
156 if (filename == NULL)
157 return NULL;
158 ff = PyFuture_FromASTObject(mod, filename);
159 Py_DECREF(filename);
160 return ff;
161 }
162