| Clover coverage report - PLT Utilities Test Coverage (plt-20120304-r5436) |
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| Source file | Conditionals | Statements | Methods | TOTAL | |||||||||||||||
| NoDuplicatesIterator.java | 100% | 83.3% | 71.4% | 82.8% |
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| 1 | /*BEGIN_COPYRIGHT_BLOCK* | |
| 2 | ||
| 3 | PLT Utilities BSD License | |
| 4 | ||
| 5 | Copyright (c) 2007-2010 JavaPLT group at Rice University | |
| 6 | All rights reserved. | |
| 7 | ||
| 8 | Developed by: Java Programming Languages Team | |
| 9 | Rice University | |
| 10 | http://www.cs.rice.edu/~javaplt/ | |
| 11 | ||
| 12 | Redistribution and use in source and binary forms, with or without modification, are permitted | |
| 13 | provided that the following conditions are met: | |
| 14 | ||
| 15 | - Redistributions of source code must retain the above copyright notice, this list of conditions | |
| 16 | and the following disclaimer. | |
| 17 | - Redistributions in binary form must reproduce the above copyright notice, this list of | |
| 18 | conditions and the following disclaimer in the documentation and/or other materials provided | |
| 19 | with the distribution. | |
| 20 | - Neither the name of the JavaPLT group, Rice University, nor the names of the library's | |
| 21 | contributors may be used to endorse or promote products derived from this software without | |
| 22 | specific prior written permission. | |
| 23 | ||
| 24 | THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR | |
| 25 | IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND | |
| 26 | FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS AND | |
| 27 | CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | |
| 28 | DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
| 29 | DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER | |
| 30 | IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT | |
| 31 | OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
| 32 | ||
| 33 | *END_COPYRIGHT_BLOCK*/ | |
| 34 | ||
| 35 | package edu.rice.cs.plt.iter; | |
| 36 | ||
| 37 | import java.util.NoSuchElementException; | |
| 38 | import java.util.Set; | |
| 39 | import java.util.Iterator; | |
| 40 | import java.util.HashSet; | |
| 41 | import edu.rice.cs.plt.object.Composite; | |
| 42 | import edu.rice.cs.plt.object.ObjectUtil; | |
| 43 | import edu.rice.cs.plt.tuple.Option; | |
| 44 | import edu.rice.cs.plt.tuple.OptionUnwrapException; | |
| 45 | ||
| 46 | /** | |
| 47 | * An Iterator that returns each value only once. Values are compared via {@code equals()} and | |
| 48 | * hashed in order to detect duplicates. A set of previously-seen values is maintained, which | |
| 49 | * requires space linear in the number of times {@code next()} has been invoked. | |
| 50 | */ | |
| 51 | public class NoDuplicatesIterator<T> extends ReadOnlyIterator<T> implements Composite { | |
| 52 | ||
| 53 | private final Iterator<? extends T> _i; | |
| 54 | private final Set<T> _seen; | |
| 55 | private Option<T> _lookahead; | |
| 56 | ||
| 57 | 151 | public NoDuplicatesIterator(Iterator<? extends T> i) { |
| 58 | 151 | _i = i; |
| 59 | 151 | _seen = new HashSet<T>(); |
| 60 | 151 | advanceLookahead(); |
| 61 | } | |
| 62 | ||
| 63 | 0 | public int compositeHeight() { return ObjectUtil.compositeHeight(_i) + 1; } |
| 64 | 0 | public int compositeSize() { return ObjectUtil.compositeSize(_i) + 1; } |
| 65 | ||
| 66 | 378 | public boolean hasNext() { return _lookahead.isSome(); } |
| 67 | ||
| 68 | 237 | public T next() { |
| 69 | 237 | try { |
| 70 | 237 | T result = _lookahead.unwrap(); |
| 71 | 237 | advanceLookahead(); |
| 72 | 237 | return result; |
| 73 | } | |
| 74 | 0 | catch (OptionUnwrapException e) { throw new NoSuchElementException(); } |
| 75 | } | |
| 76 | ||
| 77 | /** | |
| 78 | * Finds the next unique value in {@code _i}. Ignores the previous value of | |
| 79 | * {@code _lookahead}. If a value is found, sets {@code _lookahead} to that | |
| 80 | * value; otherwise, sets it to Option.none. | |
| 81 | */ | |
| 82 | 388 | private void advanceLookahead() { |
| 83 | // This class is similar to FilteredIterator, but can't be implemented | |
| 84 | // as an instance because we need to manipulate the "seen" set here, before | |
| 85 | // a "next" value is returned. Otherwise, the lookahead test fails to | |
| 86 | // consider the most recently-seen value. | |
| 87 | 388 | _lookahead = Option.none(); |
| 88 | 388 | while (_i.hasNext() && _lookahead.isNone()) { |
| 89 | 291 | T next = _i.next(); |
| 90 | 291 | if (!_seen.contains(next)) { |
| 91 | 237 | _lookahead = Option.some(next); |
| 92 | 237 | _seen.add(next); |
| 93 | } | |
| 94 | } | |
| 95 | } | |
| 96 | ||
| 97 | ||
| 98 | /** Call the constructor (allows {@code T} to be inferred) */ | |
| 99 | 15 | public static <T> NoDuplicatesIterator<T> make(Iterator<? extends T> i) { |
| 100 | 15 | return new NoDuplicatesIterator<T>(i); |
| 101 | } | |
| 102 | ||
| 103 | } |
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