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Java > Open Source Codes > org > python > core > PyXRange


1 // Copyright (c) Corporation for National Research Initiatives
2 package org.python.core;
3
4 /**
5 Used to implement the builtin xrange function.
6
7 Significant patches contributed by Jason Orendorff - jorendor@cbu.edu
8
9 @author Jim Hugunin - hugunin@python.org
10 @since JPython 0.3
11 **/
12
13 public class PyXRange extends PySequence {
14     public int start, stop, step; // directly from xrange(start, stop, step)
15 int cycleLength; // The length of an uncopied xrange
16 int copies; // The number of copies made (used to implement
17 // xrange(x,y,z)*n)
18
19     public PyXRange(int start, int stop, int step) {
20         if (step == 0)
21             throw Py.ValueError("zero step for xrange()");
22         this.start = start;
23         this.stop = stop;
24         this.step = step;
25         int oneLessThanStep = step + (step > 0 ? -1 : 1);
26         cycleLength = (stop - start + oneLessThanStep) / step;
27         if (cycleLength < 0) {
28             cycleLength = 0;
29         }
30         this.stop = start + cycleLength*step;
31         copies = 1;
32     }
33
34     public int __len__() {
35         return cycleLength*copies;
36     }
37
38     private int getInt(int i) {
39         if (cycleLength == 0) { // avoid divide by zero errors
40 return start;
41         } else {
42             return start + (i % cycleLength)*step;
43         }
44     }
45
46     protected PyObject pyget(int i) {
47         return new PyInteger(getInt(i));
48     }
49
50     protected PyObject getslice(int start, int stop, int step) {
51         Py.DeprecationWarning("xrange object slicing is deprecated; " +
52                               "convert to list instead");
53         if (copies != 1) {
54             throw Py.TypeError("cannot slice a replicated range");
55         }
56         int len = sliceLength(start, stop, step);
57         int xslice_start = getInt(start);
58         int xslice_step = this.step * step;
59         int xslice_stop = xslice_start + xslice_step * len;
60         return new PyXRange(xslice_start, xslice_stop, xslice_step);
61     }
62
63
64     protected PyObject repeat(int howmany) {
65         Py.DeprecationWarning("xrange object multiplication is deprecated; " +
66                               "convert to list instead");
67         PyXRange x = new PyXRange(start, stop, step);
68         x.copies = copies*howmany;
69         return x;
70     }
71
72     public PyObject __add__(PyObject generic_other) {
73         throw Py.TypeError("cannot concatenate xrange objects");
74     }
75
76     public PyObject __findattr__(String JavaDoc name) {
77         String JavaDoc msg = "xrange object's 'start', 'stop' and 'step' " +
78                      "attributes are deprecated";
79         if (name == "start") {
80             Py.DeprecationWarning(msg);
81             return Py.newInteger(start);
82         } else if (name == "stop") {
83             Py.DeprecationWarning(msg);
84             return Py.newInteger(stop);
85         } else if (name == "step") {
86             Py.DeprecationWarning(msg);
87             return Py.newInteger(step);
88         } else {
89             return super.__findattr__(name);
90         }
91     }
92
93     public int hashCode() {
94         // Not the greatest hash function
95 // but then again hashing xrange's is rather uncommon
96 return stop^start^step;
97     }
98
99     public String JavaDoc toString() {
100         StringBuffer JavaDoc buf = new StringBuffer JavaDoc("xrange(");
101         if (start != 0) {
102             buf.append(start);
103             buf.append(", ");
104         }
105         buf.append(__len__() * step + start);
106         if (step != 1) {
107             buf.append(", ");
108             buf.append(step);
109         }
110         buf.append(")");
111         return buf.toString();
112     }
113
114     public PyList tolist() {
115         Py.DeprecationWarning("xrange.tolist() is deprecated; " +
116                               "use list(xrange) instead");
117         PyList list = new PyList();
118         int count = __len__();
119         for (int i=0; i<count; i++) {
120             list.append(pyget(i));
121         }
122         return list;
123     }
124 }
125
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