kopia lustrzana https://github.com/onthegomap/planetiler
43 wiersze
1.3 KiB
Java
43 wiersze
1.3 KiB
Java
package com.onthegomap.planetiler.util;
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import com.onthegomap.planetiler.config.PlanetilerConfig;
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import java.util.function.IntFunction;
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/**
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* Caches a value that changes by integer zoom level to avoid recomputing it.
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*
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* @param <T> return type of the function
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*/
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public class CacheByZoom<T> {
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private final int minzoom;
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private final Object[] values;
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private final IntFunction<T> supplier;
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private CacheByZoom(int minzoom, int maxzoom, IntFunction<T> supplier) {
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this.minzoom = minzoom;
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values = new Object[maxzoom + 1 - minzoom];
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this.supplier = supplier;
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}
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/**
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* Returns a cache for {@code supplier} that can handle a min/max zoom range specified in {@code config}.
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*
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* @param supplier function that will be called with each zoom-level to get the value
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* @param <T> return type of the function
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* @return a cache for {@code supplier} by zom
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*/
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public static <T> CacheByZoom<T> create(IntFunction<T> supplier) {
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return new CacheByZoom<>(0, PlanetilerConfig.MAX_MAXZOOM, supplier);
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}
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public T get(int zoom) {
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@SuppressWarnings("unchecked") T[] casted = (T[]) values;
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int off = zoom - minzoom;
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if (values[off] != null) {
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return casted[off];
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}
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return casted[off] = supplier.apply(zoom);
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}
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}
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