/*
* Copyright (c) 2011, 2015, Oracle and/or its affiliates. All rights reserved.
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*
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*/
package com.sun.javafx.css;
import java.util.
Arrays;
import java.util.
HashMap;
import java.util.
Map;
/**
* A cache to store values from lookup.
* Consider that there are some number of StyleHelpers and that the
* StyleHelpers are shared. For a particular node, a style might come
* from its StyleHelper or the StyleHelper of one of its parents (ignoring
* Node.style for now). What makes a style unique is the set of StyleHelpers
* that go into its calculation. So, if node N has StyleHelper A and its
* parents have StyleHelper B and C, the opacity style (say) for N is going
* to be unique to the set of StyleHelpers [A B C]. Because StyleHelpers
* are chosen by the rules they match, and because StyleHelpers are shared,
* every node that has the set of StyleHelpers [A B C] will match the same
* selector for opacity (for a given pseudoclass state). Further, the value for
* opacity (in the given pseudoclass state) will not change for the given
* set of StyleHelpers. Therefore, rather than trying to cache a calculated
* value with an individual StyleHelper, the value can be cached with a key
* that uniquely identifies the set [A B C]. Subsequent lookups for the
* property do not need to be recalculated even if there are lookups in the
* value. Incidentally, resolved references will also be unique to a set of
* StyleHelpers and would only need to be resolved once (for a given
* pseudoclass state).
*
* Node.style puts a slight wrinkle in that the style might come from the
* Node rather than the cache. This can be handled in a relatively
* straight-forward manner. If Node.style is not empty or null and it
* contains the property, then that style should be used if the style
* compares less than the style that would have been applied. If there is
* some parent with Node.style that would affect the child Node's style,
* then the cached value can be used.
*
* The key is comprised of this helper's key, plus the
* keys of all this node's parents' helpers.
*
* The values in the cache styles that apply are determined
* by the node's state and the state of its parents. This unique combination
* of states reflects the state of the node and its parents at the time the
* style was first determined. Provided the node and its parents are in the
* same state, then the styles applied will be the same as what is in the
* cache.
*
* The value could be a Map, but there should not be a large number of
* entries. Computing the key from the long[], doing the lookup and
* resolving collisions is probably just as bad, if not worse, than
* finding the matching set of states by comparing the long[].
*
* Since all StyleHelpers are relevant to a Scene, valueCache is
* created by StyleManager.StylesheetContainer and is passed in.
* Note that all StyleHelper instances within a given Scene all
* share the same valueCache!
*/
public final class
StyleCache {
public
StyleCache() {
// no-op
}
public void
clear() {
if (
entries == null) return;
Thread.
dumpStack();
entries.
clear();
}
public
StyleCacheEntry getStyleCacheEntry(
StyleCacheEntry.
Key key) {
StyleCacheEntry entry = null;
if (
entries != null) {
entry =
entries.
get(
key);
}
return
entry;
}
public void
addStyleCacheEntry(
StyleCacheEntry.
Key key,
StyleCacheEntry entry) {
if (
entries == null) {
entries = new
HashMap<>(5);
}
entries.
put(
key,
entry);
}
public static final class
Key {
public
Key(int[]
styleMapIds, int
count) {
this.
styleMapIds = new int[
count];
System.
arraycopy(
styleMapIds, 0, this.
styleMapIds, 0,
count);
}
public
Key(
Key other) {
this(
other.
styleMapIds,
other.
styleMapIds.length);
}
public int[]
getStyleMapIds() {
return
styleMapIds;
}
@
Override public
String toString() {
return
Arrays.
toString(
styleMapIds);
}
@
Override
public int
hashCode() {
if (
hash ==
Integer.
MIN_VALUE) {
hash = 3;
if (
styleMapIds != null) {
for (int
i=0;
i<
styleMapIds.length;
i++) {
final int
id =
styleMapIds[
i];
hash = 17 * (
hash +
id);
}
}
}
return
hash;
}
@
Override
public boolean
equals(
Object obj) {
if (
obj == this) return true;
if (
obj == null ||
obj.
getClass() != this.
getClass()) {
return false;
}
final
Key other = (
Key)
obj;
if (this.
hash !=
other.
hash) return false;
// if one is null, so too must the other
if ((this.
styleMapIds == null) ^ (
other.
styleMapIds == null)) {
return false;
}
// if one is null, so is the other
if (this.
styleMapIds == null) {
return true;
}
if (this.
styleMapIds.length !=
other.
styleMapIds.length) {
return false;
}
for (int
i=0;
i<
styleMapIds.length;
i++) {
if (
styleMapIds[
i] !=
other.
styleMapIds[
i]) {
return false;
}
}
return true;
}
final int[]
styleMapIds;
private int
hash =
Integer.
MIN_VALUE;
}
private
Map<
StyleCacheEntry.
Key,
StyleCacheEntry>
entries;
}