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With inspiration from other libraries
// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html#License
/*
*******************************************************************************
*
* Copyright (C) 1999-2015, International Business Machines
* Corporation and others. All Rights Reserved.
*
*******************************************************************************
* CollationWeights.java, ported from collationweights.h/.cpp
*
* C++ version created on: 2001mar08 as ucol_wgt.h
* created by: Markus W. Scherer
*/
package com.ibm.icu.impl.coll;
import java.util.Arrays;
/**
* Allocates n collation element weights between two exclusive limits.
* Used only internally by the collation tailoring builder.
*/
public final class CollationWeights {
public CollationWeights() {}
public void initForPrimary(boolean compressible) {
middleLength=1;
minBytes[1] = Collation.MERGE_SEPARATOR_BYTE + 1;
maxBytes[1] = Collation.TRAIL_WEIGHT_BYTE;
if(compressible) {
minBytes[2] = Collation.PRIMARY_COMPRESSION_LOW_BYTE + 1;
maxBytes[2] = Collation.PRIMARY_COMPRESSION_HIGH_BYTE - 1;
} else {
minBytes[2] = 2;
maxBytes[2] = 0xff;
}
minBytes[3] = 2;
maxBytes[3] = 0xff;
minBytes[4] = 2;
maxBytes[4] = 0xff;
}
public void initForSecondary() {
// We use only the lower 16 bits for secondary weights.
middleLength=3;
minBytes[1] = 0;
maxBytes[1] = 0;
minBytes[2] = 0;
maxBytes[2] = 0;
minBytes[3] = Collation.LEVEL_SEPARATOR_BYTE + 1;
maxBytes[3] = 0xff;
minBytes[4] = 2;
maxBytes[4] = 0xff;
}
public void initForTertiary() {
// We use only the lower 16 bits for tertiary weights.
middleLength=3;
minBytes[1] = 0;
maxBytes[1] = 0;
minBytes[2] = 0;
maxBytes[2] = 0;
// We use only 6 bits per byte.
// The other bits are used for case & quaternary weights.
minBytes[3] = Collation.LEVEL_SEPARATOR_BYTE + 1;
maxBytes[3] = 0x3f;
minBytes[4] = 2;
maxBytes[4] = 0x3f;
}
/**
* Determine heuristically
* what ranges to use for a given number of weights between (excluding)
* two limits.
*
* @param lowerLimit A collation element weight; the ranges will be filled to cover
* weights greater than this one.
* @param upperLimit A collation element weight; the ranges will be filled to cover
* weights less than this one.
* @param n The number of collation element weights w necessary such that
* lowerLimit= rangeCount) {
return 0xffffffffL;
} else {
/* get the next weight */
WeightRange range = ranges[rangeIndex];
long weight = range.start;
if(--range.count == 0) {
/* this range is finished */
++rangeIndex;
} else {
/* increment the weight for the next value */
range.start = incWeight(weight, range.length);
assert(range.start <= range.end);
}
return weight;
}
}
/** @internal */
private static final class WeightRange implements Comparable {
long start, end;
int length, count;
@Override
public int compareTo(WeightRange other) {
long l=start;
long r=other.start;
if(lr) {
return 1;
} else {
return 0;
}
}
}
/* helper functions for CE weights */
public static int lengthOfWeight(long weight) {
if((weight&0xffffff)==0) {
return 1;
} else if((weight&0xffff)==0) {
return 2;
} else if((weight&0xff)==0) {
return 3;
} else {
return 4;
}
}
private static int getWeightTrail(long weight, int length) {
return (int)(weight>>(8*(4-length)))&0xff;
}
private static long setWeightTrail(long weight, int length, int trail) {
length=8*(4-length);
return (weight&(0xffffff00L<>idx;
} else {
// Do not use int>>32 because on some platforms that does not shift at all
// while we need it to become 0.
// PowerPC: 0xffffffff>>32 = 0 (wanted)
// x86: 0xffffffff>>32 = 0xffffffff (not wanted)
//
// ANSI C99 6.5.7 Bitwise shift operators:
// "If the value of the right operand is negative
// or is greater than or equal to the width of the promoted left operand,
// the behavior is undefined."
mask=0;
}
idx=32-idx;
mask|=0xffffff00L< 0);
}
}
}
private long incWeightByOffset(long weight, int length, int offset) {
for(;;) {
offset += getWeightByte(weight, length);
if(offset <= maxBytes[length]) {
return setWeightByte(weight, length, offset);
} else {
// Split the offset between this byte and the previous one.
offset -= minBytes[length];
weight = setWeightByte(weight, length, minBytes[length] + offset % countBytes(length));
offset /= countBytes(length);
--length;
assert(length > 0);
}
}
}
private void lengthenRange(WeightRange range) {
int length=range.length+1;
range.start=setWeightTrail(range.start, length, minBytes[length]);
range.end=setWeightTrail(range.end, length, maxBytes[length]);
range.count*=countBytes(length);
range.length=length;
}
/**
* Takes two CE weights and calculates the
* possible ranges of weights between the two limits, excluding them.
* For weights with up to 4 bytes there are up to 2*4-1=7 ranges.
*/
private boolean getWeightRanges(long lowerLimit, long upperLimit) {
assert(lowerLimit != 0);
assert(upperLimit != 0);
/* get the lengths of the limits */
int lowerLength=lengthOfWeight(lowerLimit);
int upperLength=lengthOfWeight(upperLimit);
// printf("length of lower limit 0x%08lx is %ld\n", lowerLimit, lowerLength);
// printf("length of upper limit 0x%08lx is %ld\n", upperLimit, upperLength);
assert(lowerLength>=middleLength);
// Permit upperLength=upperLimit) {
// printf("error: no space between lower & upper limits\n");
return false;
}
/* check that neither is a prefix of the other */
if(lowerLength=upperLimit has caught it */
WeightRange[] lower = new WeightRange[5]; /* [0] and [1] are not used - this simplifies indexing */
WeightRange middle = new WeightRange();
WeightRange[] upper = new WeightRange[5];
/*
* With the limit lengths of 1..4, there are up to 7 ranges for allocation:
* range minimum length
* lower[4] 4
* lower[3] 3
* lower[2] 2
* middle 1
* upper[2] 2
* upper[3] 3
* upper[4] 4
*
* We are now going to calculate up to 7 ranges.
* Some of them will typically overlap, so we will then have to merge and eliminate ranges.
*/
long weight=lowerLimit;
for(int length=lowerLength; length>middleLength; --length) {
int trail=getWeightTrail(weight, length);
if(trailmiddleLength; --length) {
int trail=getWeightTrail(weight, length);
if(trail>minBytes[length]) {
upper[length] = new WeightRange();
upper[length].start=setWeightTrail(weight, length, minBytes[length]);
upper[length].end=decWeightTrail(weight, length);
upper[length].length=length;
upper[length].count=trail-minBytes[length];
}
weight=truncateWeight(weight, length-1);
}
middle.end=decWeightTrail(weight, middleLength);
/* set the middle range */
middle.length=middleLength;
if(middle.end>=middle.start) {
middle.count=(int)((middle.end-middle.start)>>(8*(4-middleLength)))+1;
} else {
/* no middle range, eliminate overlaps */
for(int length=4; length>middleLength; --length) {
if(lower[length] != null && upper[length] != null &&
lower[length].count>0 && upper[length].count>0) {
// Note: The lowerEnd and upperStart weights are versions of
// lowerLimit and upperLimit (which are lowerLimitupperStart) {
// These two lower and upper ranges collide.
// Since lowerLimitupperStart is only possible
// if the leading bytes are equal
// and lastByte(lowerEnd)>lastByte(upperStart).
assert(truncateWeight(lowerEnd, length-1)==
truncateWeight(upperStart, length-1));
// Intersect these two ranges.
lower[length].end=upper[length].end;
lower[length].count=
getWeightTrail(lower[length].end, length)-
getWeightTrail(lower[length].start, length)+1;
// count might be <=0 in which case there is no room,
// and the range-collecting code below will ignore this range.
merged=true;
} else if(lowerEnd==upperStart) {
// Not possible, unless minByte==maxByte which is not allowed.
assert(minBytes[length]countBytes
merged=true;
}
}
if(merged) {
// Remove all shorter ranges.
// There was no room available for them between the ranges we just merged.
upper[length].count=0;
while(--length>middleLength) {
lower[length]=upper[length]=null;
}
break;
}
}
}
}
/* print ranges
for(int length=4; length>=2; --length) {
if(lower[length].count>0) {
printf("lower[%ld] .start=0x%08lx .end=0x%08lx .count=%ld\n", length, lower[length].start, lower[length].end, lower[length].count);
}
}
if(middle.count>0) {
printf("middle .start=0x%08lx .end=0x%08lx .count=%ld\n", middle.start, middle.end, middle.count);
}
for(int length=2; length<=4; ++length) {
if(upper[length].count>0) {
printf("upper[%ld] .start=0x%08lx .end=0x%08lx .count=%ld\n", length, upper[length].start, upper[length].end, upper[length].count);
}
} */
/* copy the ranges, shortest first, into the result array */
rangeCount=0;
if(middle.count>0) {
ranges[0] = middle;
rangeCount=1;
}
for(int length=middleLength+1; length<=4; ++length) {
/* copy upper first so that later the middle range is more likely the first one to use */
if(upper[length] != null && upper[length].count>0) {
ranges[rangeCount++]=upper[length];
}
if(lower[length] != null && lower[length].count>0) {
ranges[rangeCount++]=lower[length];
}
}
return rangeCount>0;
}
private boolean allocWeightsInShortRanges(int n, int minLength) {
// See if the first few minLength and minLength+1 ranges have enough weights.
for(int i = 0; i < rangeCount && ranges[i].length <= (minLength + 1); ++i) {
if(n <= ranges[i].count) {
// Use the first few minLength and minLength+1 ranges.
if(ranges[i].length > minLength) {
// Reduce the number of weights from the last minLength+1 range
// which might sort before some minLength ranges,
// so that we use all weights in the minLength ranges.
ranges[i].count = n;
}
rangeCount = i + 1;
// printf("take first %ld ranges\n", rangeCount);
if(rangeCount>1) {
/* sort the ranges by weight values */
Arrays.sort(ranges, 0, rangeCount);
}
return true;
}
n -= ranges[i].count; // still >0
}
return false;
}
private boolean allocWeightsInMinLengthRanges(int n, int minLength) {
// See if the minLength ranges have enough weights
// when we split one and lengthen the following ones.
int count = 0;
int minLengthRangeCount;
for(minLengthRangeCount = 0;
minLengthRangeCount < rangeCount &&
ranges[minLengthRangeCount].length == minLength;
++minLengthRangeCount) {
count += ranges[minLengthRangeCount].count;
}
int nextCountBytes = countBytes(minLength + 1);
if(n > count * nextCountBytes) { return false; }
// Use the minLength ranges. Merge them, and then split again as necessary.
long start = ranges[0].start;
long end = ranges[0].end;
for(int i = 1; i < minLengthRangeCount; ++i) {
if(ranges[i].start < start) { start = ranges[i].start; }
if(ranges[i].end > end) { end = ranges[i].end; }
}
// Calculate how to split the range between minLength (count1) and minLength+1 (count2).
// Goal:
// count1 + count2 * nextCountBytes = n
// count1 + count2 = count
// These turn into
// (count - count2) + count2 * nextCountBytes = n
// and then into the following count1 & count2 computations.
int count2 = (n - count) / (nextCountBytes - 1); // number of weights to be lengthened
int count1 = count - count2; // number of minLength weights
if(count2 == 0 || (count1 + count2 * nextCountBytes) < n) {
// round up
++count2;
--count1;
assert((count1 + count2 * nextCountBytes) >= n);
}
ranges[0].start = start;
if(count1 == 0) {
// Make one long range.
ranges[0].end = end;
ranges[0].count = count;
lengthenRange(ranges[0]);
rangeCount = 1;
} else {
// Split the range, lengthen the second part.
// printf("split the range number %ld (out of %ld minLength ranges) by %ld:%ld\n",
// splitRange, rangeCount, count1, count2);
// Next start = start + count1. First end = 1 before that.
ranges[0].end = incWeightByOffset(start, minLength, count1 - 1);
ranges[0].count = count1;
if(ranges[1] == null) {
ranges[1] = new WeightRange();
}
ranges[1].start = incWeight(ranges[0].end, minLength);
ranges[1].end = end;
ranges[1].length = minLength; // +1 when lengthened
ranges[1].count = count2; // *countBytes when lengthened
lengthenRange(ranges[1]);
rangeCount = 2;
}
return true;
}
private int middleLength;
private int[] minBytes = new int[5]; // for byte 1, 2, 3, 4
private int[] maxBytes = new int[5];
private WeightRange[] ranges = new WeightRange[7];
private int rangeIndex;
private int rangeCount;
}