/*
* Copyright (C) 2012 Facebook, Inc.
*
* 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.facebook.stats.cardinality;
interface Model {
SymbolInfo getSymbolInfo(int symbol);
SymbolInfo countToSymbol(int count);
/**
* The lg(MAX_COUNT) of the model.
* <p/>
* The arithmetic coding implementation uses shifting instead of
* multiplication and division, because shifting is significantly
* faster. For this to work, the max count must be a power of 2,
* and this method gives the coder shift size.
*/
int log2MaxCount();
public static final class SymbolInfo {
private final int symbol;
private final int lowCount;
private final int highCount;
public SymbolInfo(int symbol, int lowCount, int highCount) {
this.symbol = symbol;
this.lowCount = lowCount;
this.highCount = highCount;
}
public int symbol() {
return symbol;
}
public int lowCount() {
return lowCount;
}
public int highCount() {
return highCount;
}
@Override
public String toString() {
final StringBuilder sb = new StringBuilder();
sb.append("SymbolInfo");
sb.append("{symbol=").append(symbol);
sb.append(", lowCount=").append(lowCount);
sb.append(", highCount=").append(highCount);
sb.append('}');
return sb.toString();
}
}
}