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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 "compile.h"
8 #include "symtable.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
15 future_check_features(PyFutureFeatures *ff, stmt_ty s, const char *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 = PyString_AsString(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 ff->ff_features |= CO_FUTURE_DIVISION;
34 } else if (strcmp(feature, FUTURE_ABSOLUTE_IMPORT) == 0) {
35 ff->ff_features |= CO_FUTURE_ABSOLUTE_IMPORT;
36 } else if (strcmp(feature, FUTURE_WITH_STATEMENT) == 0) {
37 ff->ff_features |= CO_FUTURE_WITH_STATEMENT;
38 } else if (strcmp(feature, FUTURE_PRINT_FUNCTION) == 0) {
39 ff->ff_features |= CO_FUTURE_PRINT_FUNCTION;
40 } else if (strcmp(feature, FUTURE_UNICODE_LITERALS) == 0) {
41 ff->ff_features |= CO_FUTURE_UNICODE_LITERALS;
42 } else if (strcmp(feature, "braces") == 0) {
43 PyErr_SetString(PyExc_SyntaxError,
44 "not a chance");
45 PyErr_SyntaxLocation(filename, s->lineno);
46 return 0;
47 } else {
48 PyErr_Format(PyExc_SyntaxError,
49 UNDEFINED_FUTURE_FEATURE, feature);
50 PyErr_SyntaxLocation(filename, s->lineno);
51 return 0;
52 }
53 }
54 return 1;
55 }
56
57 static int
58 future_parse(PyFutureFeatures *ff, mod_ty mod, const char *filename)
59 {
60 int i, found_docstring = 0, done = 0, prev_line = 0;
61
62 static PyObject *future;
63 if (!future) {
64 future = PyString_InternFromString("__future__");
65 if (!future)
66 return 0;
67 }
68
69 if (!(mod->kind == Module_kind || mod->kind == Interactive_kind))
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
81 for (i = 0; i < asdl_seq_LEN(mod->v.Module.body); i++) {
82 stmt_ty s = (stmt_ty)asdl_seq_GET(mod->v.Module.body, i);
83
84 if (done && s->lineno > prev_line)
85 return 1;
86 prev_line = s->lineno;
87
88 /* The tests below will return from this function unless it is
89 still possible to find a future statement. The only things
90 that can precede a future statement are another future
91 statement and a doc string.
92 */
93
94 if (s->kind == ImportFrom_kind) {
95 if (s->v.ImportFrom.module == future) {
96 if (done) {
97 PyErr_SetString(PyExc_SyntaxError,
98 ERR_LATE_FUTURE);
99 PyErr_SyntaxLocation(filename,
100 s->lineno);
101 return 0;
102 }
103 if (!future_check_features(ff, s, filename))
104 return 0;
105 ff->ff_lineno = s->lineno;
106 }
107 else
108 done = 1;
109 }
110 else if (s->kind == Expr_kind && !found_docstring) {
111 expr_ty e = s->v.Expr.value;
112 if (e->kind != Str_kind)
113 done = 1;
114 else
115 found_docstring = 1;
116 }
117 else
118 done = 1;
119 }
120 return 1;
121 }
122
123
124 PyFutureFeatures *
125 PyFuture_FromAST(mod_ty mod, const char *filename)
126 {
127 PyFutureFeatures *ff;
128
129 ff = (PyFutureFeatures *)PyObject_Malloc(sizeof(PyFutureFeatures));
130 if (ff == NULL) {
131 PyErr_NoMemory();
132 return NULL;
133 }
134 ff->ff_features = 0;
135 ff->ff_lineno = -1;
136
137 if (!future_parse(ff, mod, filename)) {
138 PyObject_Free(ff);
139 return NULL;
140 }
141 return ff;
142 }