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1
3 package org.python.compiler;
4
5 import org.python.parser.*;
6 import org.python.parser.ast.*;
7 import org.python.parser.ast.Module;
8
9 public class Future extends Object  implements PythonGrammarTreeConstants {
10
11 private boolean division;
12 private boolean generators;
13
14 private static final String FUTURE = "__future__";
15
16 private boolean check(ImportFrom cand) throws Exception {
17 if (!cand.module.equals(FUTURE))
18 return false;
19 int n = cand.names.length;
20 if (n == 0) {
21 throw new ParseException(
22 "future statement does not support import *",cand);
23 }
24 for (int i = 0; i < n; i++) {
25 String feature = cand.names[i].name;
26 if (feature.equals("nested_scopes")) {
28 continue;
29 }
30 if (feature.equals("division")) {
31 division = true;
32 continue;
33 }
34 if (feature.equals("generators")) {
35 generators = true;
36 continue;
37 }
38 throw new ParseException("future feature "+feature+
39 " is not defined",cand);
40 }
41 return true;
42 }
43
44 public void preprocessFutures(modType node,
45 org.python.core.CompilerFlags cflags)
46 throws Exception
47 {
48 if (cflags != null) {
49 division = cflags.division;
50 }
51 int beg = 0;
52 stmtType[] suite = null;
53 if (node instanceof Module) {
54 suite = ((Module) node).body;
55 if (suite.length > 0 && suite[0] instanceof Expr &&
56 ((Expr) suite[0]).value instanceof Str) {
57 beg++;
58 }
59 } else if (node instanceof Interactive) {
60 suite = ((Interactive) node).body;
61 } else {
62 return;
63 }
64
65 for (int i = beg; i < suite.length; i++) {
66 stmtType stmt = suite[i];
67 if (!(stmt instanceof ImportFrom))
68 break;
69 stmt.from_future_checked = true;
70 if (!check((ImportFrom) stmt))
71 break;
72 }
73
74 if (cflags != null) {
75 cflags.division = cflags.division || division;
76 }
77 if (cflags != null) {
78 cflags.generator_allowed = cflags.generator_allowed || generators;
79 }
80 }
81
82
83 public static void checkFromFuture(ImportFrom node) throws Exception {
84 if (node.from_future_checked)
85 return;
86 if (node.module.equals(FUTURE)) {
87 throw new ParseException("from __future__ imports must occur " +
88 "at the beginning of the file",node);
89 }
90 node.from_future_checked = true;
91 }
92
93 public boolean areDivisionOn() {
94 return division;
95 }
96
97 }
98 |
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