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// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html#License
/*
*******************************************************************************
* Copyright (C) 2010-2014, International Business Machines
* Corporation and others. All Rights Reserved.
*******************************************************************************
* CollationIterator.java, ported from collationiterator.h/.cpp
*
* C++ version created on: 2010oct27
* created by: Markus W. Scherer
*/
package com.ibm.icu.impl.coll;
import com.ibm.icu.impl.Normalizer2Impl.Hangul;
import com.ibm.icu.impl.Trie2_32;
import com.ibm.icu.util.BytesTrie;
import com.ibm.icu.util.CharsTrie;
import com.ibm.icu.util.ICUException;
/**
* Collation element iterator and abstract character iterator.
*
* When a method returns a code point value, it must be in 0..10FFFF,
* except it can be negative as a sentinel value.
*/
public abstract class CollationIterator {
private static final class CEBuffer {
/** Large enough for CEs of most short strings. */
private static final int INITIAL_CAPACITY = 40;
CEBuffer() {}
void append(long ce) {
if(length >= INITIAL_CAPACITY) {
ensureAppendCapacity(1);
}
buffer[length++] = ce;
}
void appendUnsafe(long ce) {
buffer[length++] = ce;
}
void ensureAppendCapacity(int appCap) {
int capacity = buffer.length;
if((length + appCap) <= capacity) { return; }
do {
if(capacity < 1000) {
capacity *= 4;
} else {
capacity *= 2;
}
} while(capacity < (length + appCap));
long[] newBuffer = new long[capacity];
System.arraycopy(buffer, 0, newBuffer, 0, length);
buffer = newBuffer;
}
void incLength() {
// Use INITIAL_CAPACITY for a very simple fastpath.
// (Rather than buffer.getCapacity().)
if(length >= INITIAL_CAPACITY) {
ensureAppendCapacity(1);
}
++length;
}
long set(int i, long ce) {
return buffer[i] = ce;
}
long get(int i) { return buffer[i]; }
long[] getCEs() { return buffer; }
int length = 0;
private long[] buffer = new long[INITIAL_CAPACITY];
}
// State of combining marks skipped in discontiguous contraction.
// We create a state object on first use and keep it around deactivated between uses.
private static final class SkippedState {
// Born active but empty.
SkippedState() {}
void clear() {
oldBuffer.setLength(0);
pos = 0;
// The newBuffer is reset by setFirstSkipped().
}
boolean isEmpty() { return oldBuffer.length() == 0; }
boolean hasNext() { return pos < oldBuffer.length(); }
// Requires hasNext().
int next() {
int c = oldBuffer.codePointAt(pos);
pos += Character.charCount(c);
return c;
}
// Accounts for one more input code point read beyond the end of the marks buffer.
void incBeyond() {
assert(!hasNext());
++pos;
}
// Goes backward through the skipped-marks buffer.
// Returns the number of code points read beyond the skipped marks
// that need to be backtracked through normal input.
int backwardNumCodePoints(int n) {
int length = oldBuffer.length();
int beyond = pos - length;
if(beyond > 0) {
if(beyond >= n) {
// Not back far enough to re-enter the oldBuffer.
pos -= n;
return n;
} else {
// Back out all beyond-oldBuffer code points and re-enter the buffer.
pos = oldBuffer.offsetByCodePoints(length, beyond - n);
return beyond;
}
} else {
// Go backwards from inside the oldBuffer.
pos = oldBuffer.offsetByCodePoints(pos, -n);
return 0;
}
}
void setFirstSkipped(int c) {
skipLengthAtMatch = 0;
newBuffer.setLength(0);
newBuffer.appendCodePoint(c);
}
void skip(int c) {
newBuffer.appendCodePoint(c);
}
void recordMatch() { skipLengthAtMatch = newBuffer.length(); }
// Replaces the characters we consumed with the newly skipped ones.
void replaceMatch() {
// Note: UnicodeString.replace() pins pos to at most length().
int oldLength = oldBuffer.length();
if(pos > oldLength) { pos = oldLength; }
oldBuffer.delete(0, pos).insert(0, newBuffer, 0, skipLengthAtMatch);
pos = 0;
}
void saveTrieState(CharsTrie trie) { trie.saveState(state); }
void resetToTrieState(CharsTrie trie) { trie.resetToState(state); }
// Combining marks skipped in previous discontiguous-contraction matching.
// After that discontiguous contraction was completed, we start reading them from here.
private final StringBuilder oldBuffer = new StringBuilder();
// Combining marks newly skipped in current discontiguous-contraction matching.
// These might have been read from the normal text or from the oldBuffer.
private final StringBuilder newBuffer = new StringBuilder();
// Reading index in oldBuffer,
// or counter for how many code points have been read beyond oldBuffer (pos-oldBuffer.length()).
private int pos;
// newBuffer.length() at the time of the last matching character.
// When a partial match fails, we back out skipped and partial-matching input characters.
private int skipLengthAtMatch;
// We save the trie state before we attempt to match a character,
// so that we can skip it and try the next one.
private CharsTrie.State state = new CharsTrie.State();
};
/**
* Partially constructs the iterator.
* In Java, we cache partially constructed iterators
* and finish their setup when starting to work on text
* (via reset(boolean) and the setText(numeric, ...) methods of subclasses).
* This avoids memory allocations for iterators that remain unused.
*
* In C++, there is only one constructor, and iterators are
* stack-allocated as needed.
*/
public CollationIterator(CollationData d) {
trie = d.trie;
data = d;
numCpFwd = -1;
isNumeric = false;
ceBuffer = null;
}
public CollationIterator(CollationData d, boolean numeric) {
trie = d.trie;
data = d;
numCpFwd = -1;
isNumeric = numeric;
ceBuffer = new CEBuffer();
}
@Override
public boolean equals(Object other) {
// Subclasses: Call this method and then add more specific checks.
// Compare the iterator state but not the collation data (trie & data fields):
// Assume that the caller compares the data.
// Ignore skipped since that should be unused between calls to nextCE().
// (It only stays around to avoid another memory allocation.)
if(other == null) { return false; }
if(!this.getClass().equals(other.getClass())) { return false; }
CollationIterator o = (CollationIterator)other;
if(!(ceBuffer.length == o.ceBuffer.length &&
cesIndex == o.cesIndex &&
numCpFwd == o.numCpFwd &&
isNumeric == o.isNumeric)) {
return false;
}
for(int i = 0; i < ceBuffer.length; ++i) {
if(ceBuffer.get(i) != o.ceBuffer.get(i)) { return false; }
}
return true;
}
@Override
public int hashCode() {
// Dummy return to prevent compile warnings.
return 0;
}
/**
* Resets the iterator state and sets the position to the specified offset.
* Subclasses must implement, and must call the parent class method,
* or CollationIterator.reset().
*/
public abstract void resetToOffset(int newOffset);
public abstract int getOffset();
/**
* Returns the next collation element.
*/
public final long nextCE() {
if(cesIndex < ceBuffer.length) {
// Return the next buffered CE.
return ceBuffer.get(cesIndex++);
}
assert cesIndex == ceBuffer.length;
ceBuffer.incLength();
long cAndCE32 = handleNextCE32();
int c = (int)(cAndCE32 >> 32);
int ce32 = (int)cAndCE32;
int t = ce32 & 0xff;
if(t < Collation.SPECIAL_CE32_LOW_BYTE) { // Forced-inline of isSpecialCE32(ce32).
// Normal CE from the main data.
// Forced-inline of ceFromSimpleCE32(ce32).
return ceBuffer.set(cesIndex++,
((long)(ce32 & 0xffff0000) << 32) | ((long)(ce32 & 0xff00) << 16) | (t << 8));
}
CollationData d;
// The compiler should be able to optimize the previous and the following
// comparisons of t with the same constant.
if(t == Collation.SPECIAL_CE32_LOW_BYTE) {
if(c < 0) {
return ceBuffer.set(cesIndex++, Collation.NO_CE);
}
d = data.base;
ce32 = d.getCE32(c);
t = ce32 & 0xff;
if(t < Collation.SPECIAL_CE32_LOW_BYTE) {
// Normal CE from the base data.
return ceBuffer.set(cesIndex++,
((long)(ce32 & 0xffff0000) << 32) | ((long)(ce32 & 0xff00) << 16) | (t << 8));
}
} else {
d = data;
}
if(t == Collation.LONG_PRIMARY_CE32_LOW_BYTE) {
// Forced-inline of ceFromLongPrimaryCE32(ce32).
return ceBuffer.set(cesIndex++,
((long)(ce32 - t) << 32) | Collation.COMMON_SEC_AND_TER_CE);
}
return nextCEFromCE32(d, c, ce32);
}
/**
* Fetches all CEs.
* @return getCEsLength()
*/
public final int fetchCEs() {
while(nextCE() != Collation.NO_CE) {
// No need to loop for each expansion CE.
cesIndex = ceBuffer.length;
}
return ceBuffer.length;
}
/**
* Overwrites the current CE (the last one returned by nextCE()).
*/
final void setCurrentCE(long ce) {
assert cesIndex > 0;
ceBuffer.set(cesIndex - 1, ce);
}
/**
* Returns the previous collation element.
*/
public final long previousCE(UVector32 offsets) {
if(ceBuffer.length > 0) {
// Return the previous buffered CE.
return ceBuffer.get(--ceBuffer.length);
}
offsets.removeAllElements();
int limitOffset = getOffset();
int c = previousCodePoint();
if(c < 0) { return Collation.NO_CE; }
if(data.isUnsafeBackward(c, isNumeric)) {
return previousCEUnsafe(c, offsets);
}
// Simple, safe-backwards iteration:
// Get a CE going backwards, handle prefixes but no contractions.
int ce32 = data.getCE32(c);
CollationData d;
if(ce32 == Collation.FALLBACK_CE32) {
d = data.base;
ce32 = d.getCE32(c);
} else {
d = data;
}
if(Collation.isSimpleOrLongCE32(ce32)) {
return Collation.ceFromCE32(ce32);
}
appendCEsFromCE32(d, c, ce32, false);
if(ceBuffer.length > 1) {
offsets.addElement(getOffset());
// For an expansion, the offset of each non-initial CE is the limit offset,
// consistent with forward iteration.
while(offsets.size() <= ceBuffer.length) {
offsets.addElement(limitOffset);
};
}
return ceBuffer.get(--ceBuffer.length);
}
public final int getCEsLength() {
return ceBuffer.length;
}
public final long getCE(int i) {
return ceBuffer.get(i);
}
public final long[] getCEs() {
return ceBuffer.getCEs();
}
final void clearCEs() {
cesIndex = ceBuffer.length = 0;
}
public final void clearCEsIfNoneRemaining() {
if(cesIndex == ceBuffer.length) { clearCEs(); }
}
/**
* Returns the next code point (with post-increment).
* Public for identical-level comparison and for testing.
*/
public abstract int nextCodePoint();
/**
* Returns the previous code point (with pre-decrement).
* Public for identical-level comparison and for testing.
*/
public abstract int previousCodePoint();
protected final void reset() {
cesIndex = ceBuffer.length = 0;
if(skipped != null) { skipped.clear(); }
}
/**
* Resets the state as well as the numeric setting,
* and completes the initialization.
* Only exists in Java where we reset cached CollationIterator instances
* rather than stack-allocating temporary ones.
* (See also the constructor comments.)
*/
protected final void reset(boolean numeric) {
if(ceBuffer == null) {
ceBuffer = new CEBuffer();
}
reset();
isNumeric = numeric;
}
/**
* Returns the next code point and its local CE32 value.
* Returns Collation.FALLBACK_CE32 at the end of the text (c<0)
* or when c's CE32 value is to be looked up in the base data (fallback).
*
* The code point is used for fallbacks, context and implicit weights.
* It is ignored when the returned CE32 is not special (e.g., FFFD_CE32).
*
* Returns the code point in bits 63..32 (signed) and the CE32 in bits 31..0.
*/
protected long handleNextCE32() {
int c = nextCodePoint();
if(c < 0) { return NO_CP_AND_CE32; }
return makeCodePointAndCE32Pair(c, data.getCE32(c));
}
protected long makeCodePointAndCE32Pair(int c, int ce32) {
return ((long)c << 32) | (ce32 & 0xffffffffL);
}
protected static final long NO_CP_AND_CE32 = (-1L << 32) | (Collation.FALLBACK_CE32 & 0xffffffffL);
/**
* Called when handleNextCE32() returns a LEAD_SURROGATE_TAG for a lead surrogate code unit.
* Returns the trail surrogate in that case and advances past it,
* if a trail surrogate follows the lead surrogate.
* Otherwise returns any other code unit and does not advance.
*/
protected char handleGetTrailSurrogate() {
return 0;
}
/**
* Called when handleNextCE32() returns with c==0, to see whether it is a NUL terminator.
* (Not needed in Java.)
*/
/*protected boolean foundNULTerminator() {
return false;
}*/
/**
* @return false if surrogate code points U+D800..U+DFFF
* map to their own implicit primary weights (for UTF-16),
* or true if they map to CE(U+FFFD) (for UTF-8)
*/
protected boolean forbidSurrogateCodePoints() {
return false;
}
protected abstract void forwardNumCodePoints(int num);
protected abstract void backwardNumCodePoints(int num);
/**
* Returns the CE32 from the data trie.
* Normally the same as data.getCE32(), but overridden in the builder.
* Call this only when the faster data.getCE32() cannot be used.
*/
protected int getDataCE32(int c) {
return data.getCE32(c);
}
protected int getCE32FromBuilderData(int ce32) {
throw new ICUException("internal program error: should be unreachable");
}
protected final void appendCEsFromCE32(CollationData d, int c, int ce32,
boolean forward) {
while(Collation.isSpecialCE32(ce32)) {
switch(Collation.tagFromCE32(ce32)) {
case Collation.FALLBACK_TAG:
case Collation.RESERVED_TAG_3:
throw new ICUException("internal program error: should be unreachable");
case Collation.LONG_PRIMARY_TAG:
ceBuffer.append(Collation.ceFromLongPrimaryCE32(ce32));
return;
case Collation.LONG_SECONDARY_TAG:
ceBuffer.append(Collation.ceFromLongSecondaryCE32(ce32));
return;
case Collation.LATIN_EXPANSION_TAG:
ceBuffer.ensureAppendCapacity(2);
ceBuffer.set(ceBuffer.length, Collation.latinCE0FromCE32(ce32));
ceBuffer.set(ceBuffer.length + 1, Collation.latinCE1FromCE32(ce32));
ceBuffer.length += 2;
return;
case Collation.EXPANSION32_TAG: {
int index = Collation.indexFromCE32(ce32);
int length = Collation.lengthFromCE32(ce32);
ceBuffer.ensureAppendCapacity(length);
do {
ceBuffer.appendUnsafe(Collation.ceFromCE32(d.ce32s[index++]));
} while(--length > 0);
return;
}
case Collation.EXPANSION_TAG: {
int index = Collation.indexFromCE32(ce32);
int length = Collation.lengthFromCE32(ce32);
ceBuffer.ensureAppendCapacity(length);
do {
ceBuffer.appendUnsafe(d.ces[index++]);
} while(--length > 0);
return;
}
case Collation.BUILDER_DATA_TAG:
ce32 = getCE32FromBuilderData(ce32);
if(ce32 == Collation.FALLBACK_CE32) {
d = data.base;
ce32 = d.getCE32(c);
}
break;
case Collation.PREFIX_TAG:
if(forward) { backwardNumCodePoints(1); }
ce32 = getCE32FromPrefix(d, ce32);
if(forward) { forwardNumCodePoints(1); }
break;
case Collation.CONTRACTION_TAG: {
int index = Collation.indexFromCE32(ce32);
int defaultCE32 = d.getCE32FromContexts(index); // Default if no suffix match.
if(!forward) {
// Backward contractions are handled by previousCEUnsafe().
// c has contractions but they were not found.
ce32 = defaultCE32;
break;
}
int nextCp;
if(skipped == null && numCpFwd < 0) {
// Some portion of nextCE32FromContraction() pulled out here as an ASCII fast path,
// avoiding the function call and the nextSkippedCodePoint() overhead.
nextCp = nextCodePoint();
if(nextCp < 0) {
// No more text.
ce32 = defaultCE32;
break;
} else if((ce32 & Collation.CONTRACT_NEXT_CCC) != 0 &&
!CollationFCD.mayHaveLccc(nextCp)) {
// All contraction suffixes start with characters with lccc!=0
// but the next code point has lccc==0.
backwardNumCodePoints(1);
ce32 = defaultCE32;
break;
}
} else {
nextCp = nextSkippedCodePoint();
if(nextCp < 0) {
// No more text.
ce32 = defaultCE32;
break;
} else if((ce32 & Collation.CONTRACT_NEXT_CCC) != 0 &&
!CollationFCD.mayHaveLccc(nextCp)) {
// All contraction suffixes start with characters with lccc!=0
// but the next code point has lccc==0.
backwardNumSkipped(1);
ce32 = defaultCE32;
break;
}
}
ce32 = nextCE32FromContraction(d, ce32, d.contexts, index + 2, defaultCE32, nextCp);
if(ce32 == Collation.NO_CE32) {
// CEs from a discontiguous contraction plus the skipped combining marks
// have been appended already.
return;
}
break;
}
case Collation.DIGIT_TAG:
if(isNumeric) {
appendNumericCEs(ce32, forward);
return;
} else {
// Fetch the non-numeric-collation CE32 and continue.
ce32 = d.ce32s[Collation.indexFromCE32(ce32)];
break;
}
case Collation.U0000_TAG:
assert(c == 0);
// NUL-terminated input not supported in Java.
// Fetch the normal ce32 for U+0000 and continue.
ce32 = d.ce32s[0];
break;
case Collation.HANGUL_TAG: {
int[] jamoCE32s = d.jamoCE32s;
c -= Hangul.HANGUL_BASE;
int t = c % Hangul.JAMO_T_COUNT;
c /= Hangul.JAMO_T_COUNT;
int v = c % Hangul.JAMO_V_COUNT;
c /= Hangul.JAMO_V_COUNT;
if((ce32 & Collation.HANGUL_NO_SPECIAL_JAMO) != 0) {
// None of the Jamo CE32s are isSpecialCE32().
// Avoid recursive function calls and per-Jamo tests.
ceBuffer.ensureAppendCapacity(t == 0 ? 2 : 3);
ceBuffer.set(ceBuffer.length, Collation.ceFromCE32(jamoCE32s[c]));
ceBuffer.set(ceBuffer.length + 1, Collation.ceFromCE32(jamoCE32s[19 + v]));
ceBuffer.length += 2;
if(t != 0) {
ceBuffer.appendUnsafe(Collation.ceFromCE32(jamoCE32s[39 + t]));
}
return;
} else {
// We should not need to compute each Jamo code point.
// In particular, there should be no offset or implicit ce32.
appendCEsFromCE32(d, Collation.SENTINEL_CP, jamoCE32s[c], forward);
appendCEsFromCE32(d, Collation.SENTINEL_CP, jamoCE32s[19 + v], forward);
if(t == 0) { return; }
// offset 39 = 19 + 21 - 1:
// 19 = JAMO_L_COUNT
// 21 = JAMO_T_COUNT
// -1 = omit t==0
ce32 = jamoCE32s[39 + t];
c = Collation.SENTINEL_CP;
break;
}
}
case Collation.LEAD_SURROGATE_TAG: {
assert(forward); // Backward iteration should never see lead surrogate code _unit_ data.
assert(isLeadSurrogate(c));
char trail;
if(Character.isLowSurrogate(trail = handleGetTrailSurrogate())) {
c = Character.toCodePoint((char)c, trail);
ce32 &= Collation.LEAD_TYPE_MASK;
if(ce32 == Collation.LEAD_ALL_UNASSIGNED) {
ce32 = Collation.UNASSIGNED_CE32; // unassigned-implicit
} else if(ce32 == Collation.LEAD_ALL_FALLBACK ||
(ce32 = d.getCE32FromSupplementary(c)) == Collation.FALLBACK_CE32) {
// fall back to the base data
d = d.base;
ce32 = d.getCE32FromSupplementary(c);
}
} else {
// c is an unpaired surrogate.
ce32 = Collation.UNASSIGNED_CE32;
}
break;
}
case Collation.OFFSET_TAG:
assert(c >= 0);
ceBuffer.append(d.getCEFromOffsetCE32(c, ce32));
return;
case Collation.IMPLICIT_TAG:
assert(c >= 0);
if(isSurrogate(c) && forbidSurrogateCodePoints()) {
ce32 = Collation.FFFD_CE32;
break;
} else {
ceBuffer.append(Collation.unassignedCEFromCodePoint(c));
return;
}
}
}
ceBuffer.append(Collation.ceFromSimpleCE32(ce32));
}
// TODO: Propose widening the UTF16 method.
private static final boolean isSurrogate(int c) {
return (c & 0xfffff800) == 0xd800;
}
// TODO: Propose widening the UTF16 method.
protected static final boolean isLeadSurrogate(int c) {
return (c & 0xfffffc00) == 0xd800;
}
// TODO: Propose widening the UTF16 method.
protected static final boolean isTrailSurrogate(int c) {
return (c & 0xfffffc00) == 0xdc00;
}
// Main lookup trie of the data object.
protected final Trie2_32 trie;
protected final CollationData data;
private final long nextCEFromCE32(CollationData d, int c, int ce32) {
--ceBuffer.length; // Undo ceBuffer.incLength().
appendCEsFromCE32(d, c, ce32, true);
return ceBuffer.get(cesIndex++);
}
private final int getCE32FromPrefix(CollationData d, int ce32) {
int index = Collation.indexFromCE32(ce32);
ce32 = d.getCE32FromContexts(index); // Default if no prefix match.
index += 2;
// Number of code points read before the original code point.
int lookBehind = 0;
CharsTrie prefixes = new CharsTrie(d.contexts, index);
for(;;) {
int c = previousCodePoint();
if(c < 0) { break; }
++lookBehind;
BytesTrie.Result match = prefixes.nextForCodePoint(c);
if(match.hasValue()) {
ce32 = prefixes.getValue();
}
if(!match.hasNext()) { break; }
}
forwardNumCodePoints(lookBehind);
return ce32;
}
private final int nextSkippedCodePoint() {
if(skipped != null && skipped.hasNext()) { return skipped.next(); }
if(numCpFwd == 0) { return Collation.SENTINEL_CP; }
int c = nextCodePoint();
if(skipped != null && !skipped.isEmpty() && c >= 0) { skipped.incBeyond(); }
if(numCpFwd > 0 && c >= 0) { --numCpFwd; }
return c;
}
private final void backwardNumSkipped(int n) {
if(skipped != null && !skipped.isEmpty()) {
n = skipped.backwardNumCodePoints(n);
}
backwardNumCodePoints(n);
if(numCpFwd >= 0) { numCpFwd += n; }
}
private final int nextCE32FromContraction(
CollationData d, int contractionCE32,
CharSequence trieChars, int trieOffset, int ce32, int c) {
// c: next code point after the original one
// Number of code points read beyond the original code point.
// Needed for discontiguous contraction matching.
int lookAhead = 1;
// Number of code points read since the last match (initially only c).
int sinceMatch = 1;
// Normally we only need a contiguous match,
// and therefore need not remember the suffixes state from before a mismatch for retrying.
// If we are already processing skipped combining marks, then we do track the state.
CharsTrie suffixes = new CharsTrie(trieChars, trieOffset);
if(skipped != null && !skipped.isEmpty()) { skipped.saveTrieState(suffixes); }
BytesTrie.Result match = suffixes.firstForCodePoint(c);
for(;;) {
int nextCp;
if(match.hasValue()) {
ce32 = suffixes.getValue();
if(!match.hasNext() || (c = nextSkippedCodePoint()) < 0) {
return ce32;
}
if(skipped != null && !skipped.isEmpty()) { skipped.saveTrieState(suffixes); }
sinceMatch = 1;
} else if(match == BytesTrie.Result.NO_MATCH || (nextCp = nextSkippedCodePoint()) < 0) {
// No match for c, or partial match (BytesTrie.Result.NO_VALUE) and no further text.
// Back up if necessary, and try a discontiguous contraction.
if((contractionCE32 & Collation.CONTRACT_TRAILING_CCC) != 0 &&
// Discontiguous contraction matching extends an existing match.
// If there is no match yet, then there is nothing to do.
((contractionCE32 & Collation.CONTRACT_SINGLE_CP_NO_MATCH) == 0 ||
sinceMatch < lookAhead)) {
// The last character of at least one suffix has lccc!=0,
// allowing for discontiguous contractions.
// UCA S2.1.1 only processes non-starters immediately following
// "a match in the table" (sinceMatch=1).
if(sinceMatch > 1) {
// Return to the state after the last match.
// (Return to sinceMatch=0 and re-fetch the first partially-matched character.)
backwardNumSkipped(sinceMatch);
c = nextSkippedCodePoint();
lookAhead -= sinceMatch - 1;
sinceMatch = 1;
}
if(d.getFCD16(c) > 0xff) {
return nextCE32FromDiscontiguousContraction(
d, suffixes, ce32, lookAhead, c);
}
}
break;
} else {
// Continue after partial match (BytesTrie.Result.NO_VALUE) for c.
// It does not have a result value, therefore it is not itself "a match in the table".
// If a partially-matched c has ccc!=0 then
// it might be skipped in discontiguous contraction.
c = nextCp;
++sinceMatch;
}
++lookAhead;
match = suffixes.nextForCodePoint(c);
}
backwardNumSkipped(sinceMatch);
return ce32;
}
private final int nextCE32FromDiscontiguousContraction(
CollationData d, CharsTrie suffixes, int ce32,
int lookAhead, int c) {
// UCA section 3.3.2 Contractions:
// Contractions that end with non-starter characters
// are known as discontiguous contractions.
// ... discontiguous contractions must be detected in input text
// whenever the final sequence of non-starter characters could be rearranged
// so as to make a contiguous matching sequence that is canonically equivalent.
// UCA: http://www.unicode.org/reports/tr10/#S2.1
// S2.1 Find the longest initial substring S at each point that has a match in the table.
// S2.1.1 If there are any non-starters following S, process each non-starter C.
// S2.1.2 If C is not blocked from S, find if S + C has a match in the table.
// Note: A non-starter in a string is called blocked
// if there is another non-starter of the same canonical combining class or zero
// between it and the last character of canonical combining class 0.
// S2.1.3 If there is a match, replace S by S + C, and remove C.
// First: Is a discontiguous contraction even possible?
int fcd16 = d.getFCD16(c);
assert(fcd16 > 0xff); // The caller checked this already, as a shortcut.
int nextCp = nextSkippedCodePoint();
if(nextCp < 0) {
// No further text.
backwardNumSkipped(1);
return ce32;
}
++lookAhead;
int prevCC = fcd16 & 0xff;
fcd16 = d.getFCD16(nextCp);
if(fcd16 <= 0xff) {
// The next code point after c is a starter (S2.1.1 "process each non-starter").
backwardNumSkipped(2);
return ce32;
}
// We have read and matched (lookAhead-2) code points,
// read non-matching c and peeked ahead at nextCp.
// Return to the state before the mismatch and continue matching with nextCp.
if(skipped == null || skipped.isEmpty()) {
if(skipped == null) {
skipped = new SkippedState();
}
suffixes.reset();
if(lookAhead > 2) {
// Replay the partial match so far.
backwardNumCodePoints(lookAhead);
suffixes.firstForCodePoint(nextCodePoint());
for(int i = 3; i < lookAhead; ++i) {
suffixes.nextForCodePoint(nextCodePoint());
}
// Skip c (which did not match) and nextCp (which we will try now).
forwardNumCodePoints(2);
}
skipped.saveTrieState(suffixes);
} else {
// Reset to the trie state before the failed match of c.
skipped.resetToTrieState(suffixes);
}
skipped.setFirstSkipped(c);
// Number of code points read since the last match (at this point: c and nextCp).
int sinceMatch = 2;
c = nextCp;
for(;;) {
BytesTrie.Result match;
// "If C is not blocked from S, find if S + C has a match in the table." (S2.1.2)
if(prevCC < (fcd16 >> 8) && (match = suffixes.nextForCodePoint(c)).hasValue()) {
// "If there is a match, replace S by S + C, and remove C." (S2.1.3)
// Keep prevCC unchanged.
ce32 = suffixes.getValue();
sinceMatch = 0;
skipped.recordMatch();
if(!match.hasNext()) { break; }
skipped.saveTrieState(suffixes);
} else {
// No match for "S + C", skip C.
skipped.skip(c);
skipped.resetToTrieState(suffixes);
prevCC = fcd16 & 0xff;
}
if((c = nextSkippedCodePoint()) < 0) { break; }
++sinceMatch;
fcd16 = d.getFCD16(c);
if(fcd16 <= 0xff) {
// The next code point after c is a starter (S2.1.1 "process each non-starter").
break;
}
}
backwardNumSkipped(sinceMatch);
boolean isTopDiscontiguous = skipped.isEmpty();
skipped.replaceMatch();
if(isTopDiscontiguous && !skipped.isEmpty()) {
// We did get a match after skipping one or more combining marks,
// and we are not in a recursive discontiguous contraction.
// Append CEs from the contraction ce32
// and then from the combining marks that we skipped before the match.
c = Collation.SENTINEL_CP;
for(;;) {
appendCEsFromCE32(d, c, ce32, true);
// Fetch CE32s for skipped combining marks from the normal data, with fallback,
// rather than from the CollationData where we found the contraction.
if(!skipped.hasNext()) { break; }
c = skipped.next();
ce32 = getDataCE32(c);
if(ce32 == Collation.FALLBACK_CE32) {
d = data.base;
ce32 = d.getCE32(c);
} else {
d = data;
}
// Note: A nested discontiguous-contraction match
// replaces consumed combining marks with newly skipped ones
// and resets the reading position to the beginning.
}
skipped.clear();
ce32 = Collation.NO_CE32; // Signal to the caller that the result is in the ceBuffer.
}
return ce32;
}
/**
* Returns the previous CE when data.isUnsafeBackward(c, isNumeric).
*/
private final long previousCEUnsafe(int c, UVector32 offsets) {
// We just move through the input counting safe and unsafe code points
// without collecting the unsafe-backward substring into a buffer and
// switching to it.
// This is to keep the logic simple. Otherwise we would have to handle
// prefix matching going before the backward buffer, switching
// to iteration and back, etc.
// In the most important case of iterating over a normal string,
// reading from the string itself is already maximally fast.
// The only drawback there is that after getting the CEs we always
// skip backward to the safe character rather than switching out
// of a backwardBuffer.
// But this should not be the common case for previousCE(),
// and correctness and maintainability are more important than
// complex optimizations.
// Find the first safe character before c.
int numBackward = 1;
while((c = previousCodePoint()) >= 0) {
++numBackward;
if(!data.isUnsafeBackward(c, isNumeric)) {
break;
}
}
// Set the forward iteration limit.
// Note: This counts code points.
// We cannot enforce a limit in the middle of a surrogate pair or similar.
numCpFwd = numBackward;
// Reset the forward iterator.
cesIndex = 0;
assert(ceBuffer.length == 0);
// Go forward and collect the CEs.
int offset = getOffset();
while(numCpFwd > 0) {
// nextCE() normally reads one code point.
// Contraction matching and digit specials read more and check numCpFwd.
--numCpFwd;
// Append one or more CEs to the ceBuffer.
nextCE();
assert(ceBuffer.get(ceBuffer.length - 1) != Collation.NO_CE);
// No need to loop for getting each expansion CE from nextCE().
cesIndex = ceBuffer.length;
// However, we need to write an offset for each CE.
// This is for CollationElementIterator.getOffset() to return
// intermediate offsets from the unsafe-backwards segment.
assert(offsets.size() < ceBuffer.length);
offsets.addElement(offset);
// For an expansion, the offset of each non-initial CE is the limit offset,
// consistent with forward iteration.
offset = getOffset();
while(offsets.size() < ceBuffer.length) {
offsets.addElement(offset);
};
}
assert(offsets.size() == ceBuffer.length);
// End offset corresponding to just after the unsafe-backwards segment.
offsets.addElement(offset);
// Reset the forward iteration limit
// and move backward to before the segment for which we fetched CEs.
numCpFwd = -1;
backwardNumCodePoints(numBackward);
// Use the collected CEs and return the last one.
cesIndex = 0; // Avoid cesIndex > ceBuffer.length when that gets decremented.
return ceBuffer.get(--ceBuffer.length);
}
/**
* Turns a string of digits (bytes 0..9)
* into a sequence of CEs that will sort in numeric order.
*
* Starts from this ce32's digit value and consumes the following/preceding digits.
* The digits string must not be empty and must not have leading zeros.
*/
private final void appendNumericCEs(int ce32, boolean forward) {
// Collect digits.
// TODO: Use some kind of a byte buffer? We only store values 0..9.
StringBuilder digits = new StringBuilder();
if(forward) {
for(;;) {
char digit = Collation.digitFromCE32(ce32);
digits.append(digit);
if(numCpFwd == 0) { break; }
int c = nextCodePoint();
if(c < 0) { break; }
ce32 = data.getCE32(c);
if(ce32 == Collation.FALLBACK_CE32) {
ce32 = data.base.getCE32(c);
}
if(!Collation.hasCE32Tag(ce32, Collation.DIGIT_TAG)) {
backwardNumCodePoints(1);
break;
}
if(numCpFwd > 0) { --numCpFwd; }
}
} else {
for(;;) {
char digit = Collation.digitFromCE32(ce32);
digits.append(digit);
int c = previousCodePoint();
if(c < 0) { break; }
ce32 = data.getCE32(c);
if(ce32 == Collation.FALLBACK_CE32) {
ce32 = data.base.getCE32(c);
}
if(!Collation.hasCE32Tag(ce32, Collation.DIGIT_TAG)) {
forwardNumCodePoints(1);
break;
}
}
// Reverse the digit string.
digits.reverse();
}
int pos = 0;
do {
// Skip leading zeros.
while(pos < (digits.length() - 1) && digits.charAt(pos) == 0) { ++pos; }
// Write a sequence of CEs for at most 254 digits at a time.
int segmentLength = digits.length() - pos;
if(segmentLength > 254) { segmentLength = 254; }
appendNumericSegmentCEs(digits.subSequence(pos, pos + segmentLength));
pos += segmentLength;
} while(pos < digits.length());
}
/**
* Turns 1..254 digits into a sequence of CEs.
* Called by appendNumericCEs() for each segment of at most 254 digits.
*/
private final void appendNumericSegmentCEs(CharSequence digits) {
int length = digits.length();
assert(1 <= length && length <= 254);
assert(length == 1 || digits.charAt(0) != 0);
long numericPrimary = data.numericPrimary;
// Note: We use primary byte values 2..255: digits are not compressible.
if(length <= 7) {
// Very dense encoding for small numbers.
int value = digits.charAt(0);
for(int i = 1; i < length; ++i) {
value = value * 10 + digits.charAt(i);
}
// Primary weight second byte values:
// 74 byte values 2.. 75 for small numbers in two-byte primary weights.
// 40 byte values 76..115 for medium numbers in three-byte primary weights.
// 16 byte values 116..131 for large numbers in four-byte primary weights.
// 124 byte values 132..255 for very large numbers with 4..127 digit pairs.
int firstByte = 2;
int numBytes = 74;
if(value < numBytes) {
// Two-byte primary for 0..73, good for day & month numbers etc.
long primary = numericPrimary | ((firstByte + value) << 16);
ceBuffer.append(Collation.makeCE(primary));
return;
}
value -= numBytes;
firstByte += numBytes;
numBytes = 40;
if(value < numBytes * 254) {
// Three-byte primary for 74..10233=74+40*254-1, good for year numbers and more.
long primary = numericPrimary |
((firstByte + value / 254) << 16) | ((2 + value % 254) << 8);
ceBuffer.append(Collation.makeCE(primary));
return;
}
value -= numBytes * 254;
firstByte += numBytes;
numBytes = 16;
if(value < numBytes * 254 * 254) {
// Four-byte primary for 10234..1042489=10234+16*254*254-1.
long primary = numericPrimary | (2 + value % 254);
value /= 254;
primary |= (2 + value % 254) << 8;
value /= 254;
primary |= (firstByte + value % 254) << 16;
ceBuffer.append(Collation.makeCE(primary));
return;
}
// original value > 1042489
}
assert(length >= 7);
// The second primary byte value 132..255 indicates the number of digit pairs (4..127),
// then we generate primary bytes with those pairs.
// Omit trailing 00 pairs.
// Decrement the value for the last pair.
// Set the exponent. 4 pairs.132, 5 pairs.133, ..., 127 pairs.255.
int numPairs = (length + 1) / 2;
long primary = numericPrimary | ((132 - 4 + numPairs) << 16);
// Find the length without trailing 00 pairs.
while(digits.charAt(length - 1) == 0 && digits.charAt(length - 2) == 0) {
length -= 2;
}
// Read the first pair.
int pair;
int pos;
if((length & 1) != 0) {
// Only "half a pair" if we have an odd number of digits.
pair = digits.charAt(0);
pos = 1;
} else {
pair = digits.charAt(0) * 10 + digits.charAt(1);
pos = 2;
}
pair = 11 + 2 * pair;
// Add the pairs of digits between pos and length.
int shift = 8;
while(pos < length) {
if(shift == 0) {
// Every three pairs/bytes we need to store a 4-byte-primary CE
// and start with a new CE with the '0' primary lead byte.
primary |= pair;
ceBuffer.append(Collation.makeCE(primary));
primary = numericPrimary;
shift = 16;
} else {
primary |= pair << shift;
shift -= 8;
}
pair = 11 + 2 * (digits.charAt(pos) * 10 + digits.charAt(pos + 1));
pos += 2;
}
primary |= (pair - 1) << shift;
ceBuffer.append(Collation.makeCE(primary));
}
private CEBuffer ceBuffer;
private int cesIndex;
private SkippedState skipped;
// Number of code points to read forward, or -1.
// Used as a forward iteration limit in previousCEUnsafe().
private int numCpFwd;
// Numeric collation (CollationSettings.NUMERIC).
private boolean isNumeric;
}