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////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2018-2022 Saxonica Limited
// This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0.
// If a copy of the MPL was not distributed with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
// This Source Code Form is "Incompatible With Secondary Licenses", as defined by the Mozilla Public License, v. 2.0.
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
package net.sf.saxon.str;
import net.sf.saxon.expr.sort.AtomicMatchKey;
import net.sf.saxon.serialize.charcode.UTF16CharacterSet;
import net.sf.saxon.serialize.charcode.XMLCharacterData;
import net.sf.saxon.value.AtomicValue;
import net.sf.saxon.value.Base64BinaryValue;
import net.sf.saxon.z.IntIterator;
import java.util.function.IntPredicate;
/**
* A UnicodeString is a sequence of Unicode codepoints that supports codepoint addressing.
* The interface is future-proofed to support code points in the range 0 to 2^31, and string lengths of
* up to 2^63 characters. Implementations may (and do) impose lower limits.
*/
public abstract class UnicodeString implements AtomicMatchKey, Comparable {
/**
* Ensure that the implementation is capable of counting codepoints in the string. This is
* normally a null operation, but it may cause internal reorganisation.
* @return this {@code UnicodeString}, or another that represents the same sequence
* of characters.
*/
public UnicodeString tidy() {
return this;
}
public UnicodeString economize() {
return this;
}
/**
* Get the length of the string
* @return the number of code points in the string
*/
public abstract long length();
/**
* Get the length of the string, provided it is less than 2^31 characters
* @return the length of the string if it fits within a Java {@code int}
* @throws UnsupportedOperationException if the string is longer than 2^31 characters
*/
public int length32() {
return requireInt(length());
}
/**
* Get the estimated length of the string, suitable for space allocation.
*
* @return for a {@code UnicodeString}, the actual length of the string in codepoints
*/
public long estimatedLength() {
return length();
}
/**
* Ask whether the string is empty
* @return true if the length of the string is zero
*/
public boolean isEmpty() {
return length() == 0;
}
/**
* Get the number of bits needed to hold all the characters in this string
* @return 7 for ascii characters (not used??), 8 for latin-1, 16 for BMP, 24 for general Unicode.
*/
public abstract int getWidth();
/**
* Get the position of the first occurrence of the specified codepoint,
* starting the search at the beginning
*
* @param codePoint the sought codePoint
* @return the position (0-based) of the first occurrence found, or -1 if not found,
* counting codePoints rather than UTF16 chars.
* @throws UnsupportedOperationException if the {@code UnicodeString} has not been prepared
* for codePoint access
*/
public long indexOf(int codePoint) {
return indexOf(codePoint, 0);
}
/**
* Get the position of the first occurrence of the specified codepoint,
* starting the search at a given position in the string
* @param codePoint the sought codePoint
* @param from the position from which the search should start (0-based)
* @return the position (0-based) of the first occurrence found, or -1 if not found
* @throws UnsupportedOperationException if the {@code UnicodeString} has not been prepared
* for codePoint access
*/
public abstract long indexOf(int codePoint, long from);
/**
* Get the position of the first occurrence of a codepoint that matches a supplied predicate,
* starting the search at a given position in the string
*
* @param predicate condition that the codepoint must satisfy
* @param from the position from which the search should start (0-based)
* @return the position (0-based) of the first codepoint to match the predicate, or -1 if not found
* @throws UnsupportedOperationException if the {@code UnicodeString} has not been prepared
* for codePoint access
*/
public long indexWhere(IntPredicate predicate, long from) {
IntIterator iter = codePoints();
long i = 0;
while (iter.hasNext()) {
int ch = iter.next();
if (i >= from && predicate.test(ch)) {
return i;
}
i++;
}
return -1;
}
/**
* Get the first position, at or beyond from, where another string appears as a substring
* of this string, comparing codepoints.
*
* @param other the other (sought) string
* @param from the position (0-based) where searching is to start (counting in codepoints)
* @return the first position where the substring is found, or -1 if it is not found
*/
public long indexOf(UnicodeString other, long from) {
if (from < 0 || from >= length()) {
return -1;
}
if (other.isEmpty()) {
return from;
}
int initial = other.codePointAt(0);
long len = other.length();
long lastPossible = length() - len;
while (from <= lastPossible) {
long i = indexOf(initial, from);
if (i < 0) {
return -1;
}
if (hasSubstring(other, i)) {
return i;
}
from = i + 1;
}
return -1;
}
/**
* Ask whether this string has another string as its content starting at a given offset
*
* @param other the other string
* @param offset the starting position in this string (counting in codepoints)
* @return true if the other string appears as a substring of this string starting at the
* given position.
*/
public boolean hasSubstring(UnicodeString other, long offset) {
if (offset < 0 || offset > length()) {
throw new IndexOutOfBoundsException();
}
long len = other.length();
if (len + offset > length()) {
return false;
}
for (long k = 0; k < len; k++) {
if (codePointAt(offset + k) != other.codePointAt(k)) {
return false;
}
}
return true;
}
/**
* Get an iterator over the code points present in the string.
*
* @return an iterator that delivers the individual code points
*/
public abstract IntIterator codePoints();
/**
* Get the code point at a given position in the string
* @param index the given position (0-based)
* @return the code point at the given position
* @throws IndexOutOfBoundsException if the index is out of range
*/
public abstract int codePointAt(long index);
/**
* Get a substring of this codepoint sequence, with a given start position,
* finishing at the end of the string
*
* @param start the start position (0-based): that is, the position of the first
* code point to be included
* @return the requested substring
* @throws IndexOutOfBoundsException if the start position is out of range
*/
public UnicodeString substring(long start) {
return substring(start, length());
}
/**
* Get a substring of this string, with a given start and end position
*
* @param start the start position (0-based): that is, the position of the first
* code point to be included
* @param end the end position (0-based): specifically, the position of the first
* code point not to be included
* @return the requested substring
* @throws IndexOutOfBoundsException if the start/end positions are out of range (the conditions
* are the same as for String.substring())
*/
public abstract UnicodeString substring(long start, long end);
/**
* Get a substring of this string, starting at position 0, with a given end position
* @param end the end position (0-based): specifically, the position of the first
* code point not to be included
* @return the requested substring
* @throws IndexOutOfBoundsException if the end position is out of range
*/
public UnicodeString prefix(long end) {
return substring(0, end);
}
/**
* Concatenate with another string, returning a new string
* @param other the string to be appended
* @return the result of concatenating this string followed by the other
*/
public UnicodeString concat(UnicodeString other) {
return ZenoString.of(this).concat(other);
}
protected void checkSubstringBounds(long start, long end) {
if (start < 0) {
throw new IndexOutOfBoundsException("UnicodeString.substring(): start (" + start + ") < 0");
}
if (end < start) {
throw new IndexOutOfBoundsException("UnicodeString.substring(): end (" + end + ") < start ( + start + ");
}
if (end > length()) {
throw new IndexOutOfBoundsException("UnicodeString.substring(): end (" + end + ") > length (" + length() + ")");
}
}
/**
* Diagnostic method: verify that all the characters in the string are valid XML codepoints
* @throws IllegalStateException if the contents are invalid
*/
public void verifyCharacters() {
IntIterator iter = codePoints();
int p = 0;
while (iter.hasNext()) {
int x = iter.next();
if (!XMLCharacterData.isValid11(x)) {
throw new IllegalStateException("Invalid char " + x + " in " + getClass() + " at offset " + p);
}
p++;
}
}
@Override
public boolean equals(Object obj) {
if (obj instanceof UnicodeString) {
UnicodeString other = (UnicodeString) obj;
IntIterator iter1 = codePoints();
IntIterator iter2 = other.codePoints();
while (true) {
boolean more1 = iter1.hasNext();
boolean more2 = iter2.hasNext();
if (more1 && more2) {
int ch1 = iter1.next();
int ch2 = iter2.next();
if (ch1 != ch2) {
return false;
}
} else {
return !(more1 || more2);
}
}
} else {
return false;
}
}
/**
* Compute a hashCode. All implementations of {@code UnicodeString} use compatible hash codes and the
* hashing algorithm is therefore identical to that for {@code java.lang.String}. This means
* that for strings containing Astral characters, the hash code needs to be computed by decomposing
* an Astral character into a surrogate pair.
*
* @return the hash code
*/
public int hashCode() {
int h = 0;
IntIterator iter = codePoints();
while (iter.hasNext()) {
int cp = iter.next();
if ((cp & 0xff0000) != 0) {
h = 31 * h + UTF16CharacterSet.highSurrogate(cp);
h = 31 * h + UTF16CharacterSet.lowSurrogate(cp);
} else {
h = 31 * h + cp;
}
}
return h;
}
/**
* Compare this string to another using codepoint comparison
* @param other the other string
* @return -1 if this string comes first, 0 if they are equal, +1 if the other string comes first
*/
@Override
public int compareTo(UnicodeString other) {
IntIterator iter1 = codePoints();
IntIterator iter2 = other.codePoints();
while (true) {
boolean more1 = iter1.hasNext();
boolean more2 = iter2.hasNext();
if (more1 && more2) {
int ch1 = iter1.next();
int ch2 = iter2.next();
int diff = ch1 - ch2;
if (diff != 0) {
return diff;
}
} else if (!more1 && !more2) {
return 0;
} else {
return more1 ? 1 : -1;
}
}
}
/**
* Get the codepoints of the string as a byte array, allocating three
* bytes per character. (Max unicode codepoint = x10FFFF)
*
* @return a byte array that can act as a collation key
*/
private byte[] getCodepointCollationKey() {
UnicodeString prep = tidy();
int len = requireInt(prep.length());
byte[] result = new byte[len * 3];
IntIterator iter = prep.codePoints();
int j=0;
while (iter.hasNext()) {
int c = iter.next();
result[j++] = (byte) (c >> 16);
result[j++] = (byte) (c >> 8);
result[j++] = (byte) c;
}
return result;
}
/**
* Get an atomic value that encapsulates this match key. Needed to support the collation-key() function.
*
* @return an atomic value that encapsulates this match key
*/
@Override
public AtomicValue asAtomic() {
return new Base64BinaryValue(getCodepointCollationKey());
}
/**
* Utility method for use where strings longer than 2^31 characters cannot yet be handled.
* @param value the actual value of a character position within a string, or the length of
* a string
* @return the value as an integer if it is within range
* @throws UnsupportedOperationException if the supplied value exceeds {@link Integer#MAX_VALUE}
*/
public static int requireInt(long value) {
if (value > Integer.MAX_VALUE) {
throw new UnsupportedOperationException("String offset exceeds 2^31 characters");
}
return (int) value;
}
/**
* Copy this string, as a sequence of 8-bit characters, to a specified array
* @param target the target array: the caller must ensure there is sufficient capacity
* @param offset the position in the target array
* @throws UnsupportedOperationException if this UnicodeString is capable of containing characters
* needing more than 8 bits
*/
void copy8bit(byte[] target, int offset) {
throw new UnsupportedOperationException();
}
/**
* Copy this string, as a sequence of 16-bit characters, to a specified array
*
* @param target the target array: the caller must ensure there is sufficient capacity
* @param offset the position in the target array
* @throws UnsupportedOperationException if this UnicodeString is capable of containing characters
* needing more than 16 bits
*/
void copy16bit(char[] target, int offset) {
throw new UnsupportedOperationException();
}
/**
* Copy this string, as a sequence of 24-bit characters, to a specified array
*
* @param target the target array: the caller must ensure there is sufficient capacity
* @param offset the position in the target array as a byte offset (that is, the character
* offset times 3)
*/
void copy24bit(byte[] target, int offset) {
throw new UnsupportedOperationException();
}
}