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// Copyright (C) 2009 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 com.google.gerrit.prettify.common;
import java.util.ArrayList;
import java.util.List;
public class SparseFileContent {
protected List<Range> ranges;
protected int size;
private transient int currentRangeIdx;
public SparseFileContent() {
ranges = new ArrayList<>();
}
public int size() {
return size;
}
public void setSize(int s) {
size = s;
}
public String get(int idx) {
final String line = getLine(idx);
if (line == null) {
throw new ArrayIndexOutOfBoundsException(idx);
}
return line;
}
public boolean contains(int idx) {
return getLine(idx) != null;
}
public int first() {
return ranges.isEmpty() ? size() : ranges.get(0).base;
}
public int next(int idx) {
// Most requests are sequential in nature, fetching the next
// line from the current range, or the immediate next range.
//
int high = ranges.size();
if (currentRangeIdx < high) {
Range cur = ranges.get(currentRangeIdx);
if (cur.contains(idx + 1)) {
return idx + 1;
}
if (++currentRangeIdx < high) {
// Its not plus one, its the base of the next range.
//
return ranges.get(currentRangeIdx).base;
}
}
// Binary search for the current value, since we know its a sorted list.
//
int low = 0;
do {
final int mid = (low + high) / 2;
final Range cur = ranges.get(mid);
if (cur.contains(idx)) {
if (cur.contains(idx + 1)) {
// Trivial plus one case above failed due to wrong currentRangeIdx.
// Reset the cache so we don't miss in the future.
//
currentRangeIdx = mid;
return idx + 1;
}
if (mid + 1 < ranges.size()) {
// Its the base of the next range.
currentRangeIdx = mid + 1;
return ranges.get(currentRangeIdx).base;
}
// No more lines in the file.
//
return size();
}
if (idx < cur.base) {
high = mid;
} else {
low = mid + 1;
}
} while (low < high);
return size();
}
private String getLine(int idx) {
// Most requests are sequential in nature, fetching the next
// line from the current range, or the next range.
//
int high = ranges.size();
if (currentRangeIdx < high) {
Range cur = ranges.get(currentRangeIdx);
if (cur.contains(idx)) {
return cur.get(idx);
}
if (++currentRangeIdx < high) {
final Range next = ranges.get(currentRangeIdx);
if (next.contains(idx)) {
return next.get(idx);
}
}
}
// Binary search for the range, since we know its a sorted list.
//
if (ranges.isEmpty()) {
return null;
}
int low = 0;
do {
final int mid = (low + high) / 2;
final Range cur = ranges.get(mid);
if (cur.contains(idx)) {
currentRangeIdx = mid;
return cur.get(idx);
}
if (idx < cur.base) {
high = mid;
} else {
low = mid + 1;
}
} while (low < high);
return null;
}
public void addLine(int i, String content) {
final Range r;
if (!ranges.isEmpty() && i == last().end()) {
r = last();
} else {
r = new Range(i);
ranges.add(r);
}
r.lines.add(content);
}
private Range last() {
return ranges.get(ranges.size() - 1);
}
@Override
public String toString() {
final StringBuilder b = new StringBuilder();
b.append("SparseFileContent[\n");
for (Range r : ranges) {
b.append(" ");
b.append(r.toString());
b.append('\n');
}
b.append("]");
return b.toString();
}
static class Range {
protected int base;
protected List<String> lines;
private Range(int b) {
base = b;
lines = new ArrayList<>();
}
protected Range() {}
private String get(int i) {
return lines.get(i - base);
}
private int end() {
return base + lines.size();
}
private boolean contains(int i) {
return base <= i && i < end();
}
@Override
public String toString() {
// Usage of [ and ) is intentional to denote inclusive/exclusive range
return "Range[" + base + "," + end() + ")";
}
}
}
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