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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.tensor.impl;
import com.yahoo.tensor.Tensor;
import java.util.Arrays;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
/**
* A label is a value of a mapped dimension of a tensor.
* This class provides a mapping of labels to numbers which allow for more efficient computation with
* mapped tensor dimensions.
*
* @author baldersheim
*/
public class Label {
private static final String[] SMALL_INDEXES = createSmallIndexesAsStrings(1000);
private final static Map<String, Integer> string2Enum = new ConcurrentHashMap<>();
// Index 0 is unused, that is a valid positive number
// 1(-1) is reserved for the Tensor.INVALID_INDEX
private static volatile String[] uniqueStrings = {"UNIQUE_UNUSED_MAGIC", "Tensor.INVALID_INDEX"};
private static int numUniqeStrings = 2;
private static String[] createSmallIndexesAsStrings(int count) {
String[] asStrings = new String[count];
for (int i = 0; i < count; i++) {
asStrings[i] = String.valueOf(i);
}
return asStrings;
}
private static int addNewUniqueString(String s) {
synchronized (string2Enum) {
if (numUniqeStrings >= uniqueStrings.length) {
uniqueStrings = Arrays.copyOf(uniqueStrings, uniqueStrings.length*2);
}
uniqueStrings[numUniqeStrings] = s;
return -numUniqeStrings++;
}
}
private static String asNumericString(long index) {
return ((index >= 0) && (index < SMALL_INDEXES.length)) ? SMALL_INDEXES[(int)index] : String.valueOf(index);
}
private static boolean validNumericIndex(String s) {
if (s.isEmpty() || ((s.length() > 1) && (s.charAt(0) == '0'))) return false;
for (int i = 0; i < s.length(); i++) {
char c = s.charAt(i);
if ((c < '0') || (c > '9')) return false;
}
return true;
}
public static int toNumber(String s) {
if (s == null) { return Tensor.invalidIndex; }
try {
if (validNumericIndex(s)) {
return Integer.parseInt(s);
}
} catch (NumberFormatException e) {
}
return string2Enum.computeIfAbsent(s, Label::addNewUniqueString);
}
public static String fromNumber(int v) {
if (v >= 0) {
return asNumericString(v);
} else {
if (v == Tensor.invalidIndex) { return null; }
return uniqueStrings[-v];
}
}
public static String fromNumber(long v) {
return fromNumber(Convert.safe2Int(v));
}
}
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