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/*
* Copyright (C) 2012 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package android.text;
import java.lang.reflect.Array;
import java.util.Arrays;
/**
* A cached set of spans. Caches the result of {@link Spanned#getSpans(int, int, Class)} and then
* provides faster access to {@link Spanned#nextSpanTransition(int, int, Class)}.
*
* Fields are left public for a convenient direct access.
*
* Note that empty spans are ignored by this class.
* @hide
*/
public class SpanSet<E> {
private final Class<? extends E> classType;
int numberOfSpans;
E[] spans;
int[] spanStarts;
int[] spanEnds;
int[] spanFlags;
SpanSet(Class<? extends E> type) {
classType = type;
numberOfSpans = 0;
}
@SuppressWarnings("unchecked")
public void init(Spanned spanned, int start, int limit) {
final E[] allSpans = spanned.getSpans(start, limit, classType);
final int length = allSpans.length;
if (length > 0 && (spans == null || spans.length < length)) {
// These arrays may end up being too large because of the discarded empty spans
spans = (E[]) Array.newInstance(classType, length);
spanStarts = new int[length];
spanEnds = new int[length];
spanFlags = new int[length];
}
int prevNumberOfSpans = numberOfSpans;
numberOfSpans = 0;
for (int i = 0; i < length; i++) {
final E span = allSpans[i];
final int spanStart = spanned.getSpanStart(span);
final int spanEnd = spanned.getSpanEnd(span);
if (spanStart == spanEnd) continue;
final int spanFlag = spanned.getSpanFlags(span);
spans[numberOfSpans] = span;
spanStarts[numberOfSpans] = spanStart;
spanEnds[numberOfSpans] = spanEnd;
spanFlags[numberOfSpans] = spanFlag;
numberOfSpans++;
}
// cleanup extra spans left over from previous init() call
if (numberOfSpans < prevNumberOfSpans) {
// prevNumberofSpans was > 0, therefore spans != null
Arrays.fill(spans, numberOfSpans, prevNumberOfSpans, null);
}
}
/**
* Returns true if there are spans intersecting the given interval.
* @param end must be strictly greater than start
*/
public boolean hasSpansIntersecting(int start, int end) {
for (int i = 0; i < numberOfSpans; i++) {
// equal test is valid since both intervals are not empty by construction
if (spanStarts[i] >= end || spanEnds[i] <= start) continue;
return true;
}
return false;
}
/**
* Similar to {@link Spanned#nextSpanTransition(int, int, Class)}
*/
int getNextTransition(int start, int limit) {
for (int i = 0; i < numberOfSpans; i++) {
final int spanStart = spanStarts[i];
final int spanEnd = spanEnds[i];
if (spanStart > start && spanStart < limit) limit = spanStart;
if (spanEnd > start && spanEnd < limit) limit = spanEnd;
}
return limit;
}
/**
* Removes all internal references to the spans to avoid memory leaks.
*/
public void recycle() {
if (spans != null) {
Arrays.fill(spans, 0, numberOfSpans, null);
}
}
}
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