com.google.common.base.CharMatcher Maven / Gradle / Ivy
/*
* Copyright (C) 2008 The Guava Authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.google.common.base;
import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;
import com.google.common.annotations.Beta;
import com.google.common.annotations.GwtCompatible;
import java.util.Arrays;
import javax.annotation.CheckReturnValue;
/**
* Determines a true or false value for any Java {@code char} value, just as {@link Predicate} does
* for any {@link Object}. Also offers basic text processing methods based on this function.
* Implementations are strongly encouraged to be side-effect-free and immutable.
*
* Throughout the documentation of this class, the phrase "matching character" is used to mean
* "any character {@code c} for which {@code this.matches(c)} returns {@code true}".
*
*
Note: This class deals only with {@code char} values; it does not understand
* supplementary Unicode code points in the range {@code 0x10000} to {@code 0x10FFFF}. Such logical
* characters are encoded into a {@code String} using surrogate pairs, and a {@code CharMatcher}
* treats these just as two separate characters.
*
*
Example usages:
* String trimmed = {@link #WHITESPACE WHITESPACE}.{@link #trimFrom trimFrom}(userInput);
* if ({@link #ASCII ASCII}.{@link #matchesAllOf matchesAllOf}(s)) { ... }
*
* See the Guava User Guide article on
* {@code CharMatcher}.
*
* @author Kevin Bourrillion
* @since 1.0
*/
@Beta // Possibly change from chars to code points; decide constants vs. methods
@GwtCompatible
public abstract class CharMatcher implements Predicate {
// Constants
/**
* Determines whether a character is a breaking whitespace (that is, a whitespace which can be
* interpreted as a break between words for formatting purposes). See {@link #WHITESPACE} for a
* discussion of that term.
*
* @since 2.0
*/
public static final CharMatcher BREAKING_WHITESPACE =
anyOf("\t\n\013\f\r \u0085\u1680\u2028\u2029\u205f\u3000")
.or(inRange('\u2000', '\u2006'))
.or(inRange('\u2008', '\u200a'))
.withToString("CharMatcher.BREAKING_WHITESPACE")
.precomputed();
/**
* Determines whether a character is ASCII, meaning that its code point is less than 128.
*/
public static final CharMatcher ASCII = inRange('\0', '\u007f', "CharMatcher.ASCII");
/**
* Determines whether a character is a digit according to
* Unicode.
*/
public static final CharMatcher DIGIT;
static {
CharMatcher digit = inRange('0', '9');
String zeroes =
"\u0660\u06f0\u07c0\u0966\u09e6\u0a66\u0ae6\u0b66\u0be6\u0c66"
+ "\u0ce6\u0d66\u0e50\u0ed0\u0f20\u1040\u1090\u17e0\u1810\u1946"
+ "\u19d0\u1b50\u1bb0\u1c40\u1c50\ua620\ua8d0\ua900\uaa50\uff10";
for (char base : zeroes.toCharArray()) {
digit = digit.or(inRange(base, (char) (base + 9)));
}
DIGIT = digit.withToString("CharMatcher.DIGIT").precomputed();
}
/**
* Determines whether a character is a digit according to {@link Character#isDigit(char) Java's
* definition}. If you only care to match ASCII digits, you can use {@code inRange('0', '9')}.
*/
public static final CharMatcher JAVA_DIGIT = new CharMatcher("CharMatcher.JAVA_DIGIT") {
@Override public boolean matches(char c) {
return Character.isDigit(c);
}
};
/**
* Determines whether a character is a letter according to {@link Character#isLetter(char) Java's
* definition}. If you only care to match letters of the Latin alphabet, you can use {@code
* inRange('a', 'z').or(inRange('A', 'Z'))}.
*/
public static final CharMatcher JAVA_LETTER = new CharMatcher("CharMatcher.JAVA_LETTER") {
@Override public boolean matches(char c) {
return Character.isLetter(c);
}
@Override public CharMatcher precomputed() {
return this;
}
};
/**
* Determines whether a character is a letter or digit according to {@link
* Character#isLetterOrDigit(char) Java's definition}.
*/
public static final CharMatcher JAVA_LETTER_OR_DIGIT =
new CharMatcher("CharMatcher.JAVA_LETTER_OR_DIGIT") {
@Override public boolean matches(char c) {
return Character.isLetterOrDigit(c);
}
};
/**
* Determines whether a character is upper case according to {@link Character#isUpperCase(char)
* Java's definition}.
*/
public static final CharMatcher JAVA_UPPER_CASE =
new CharMatcher("CharMatcher.JAVA_UPPER_CASE") {
@Override public boolean matches(char c) {
return Character.isUpperCase(c);
}
};
/**
* Determines whether a character is lower case according to {@link Character#isLowerCase(char)
* Java's definition}.
*/
public static final CharMatcher JAVA_LOWER_CASE =
new CharMatcher("CharMatcher.JAVA_LOWER_CASE") {
@Override public boolean matches(char c) {
return Character.isLowerCase(c);
}
};
/**
* Determines whether a character is an ISO control character as specified by {@link
* Character#isISOControl(char)}.
*/
public static final CharMatcher JAVA_ISO_CONTROL =
inRange('\u0000', '\u001f')
.or(inRange('\u007f', '\u009f'))
.withToString("CharMatcher.JAVA_ISO_CONTROL");
/**
* Determines whether a character is invisible; that is, if its Unicode category is any of
* SPACE_SEPARATOR, LINE_SEPARATOR, PARAGRAPH_SEPARATOR, CONTROL, FORMAT, SURROGATE, and
* PRIVATE_USE according to ICU4J.
*/
public static final CharMatcher INVISIBLE = inRange('\u0000', '\u0020')
.or(inRange('\u007f', '\u00a0'))
.or(is('\u00ad'))
.or(inRange('\u0600', '\u0604'))
.or(anyOf("\u06dd\u070f\u1680\u180e"))
.or(inRange('\u2000', '\u200f'))
.or(inRange('\u2028', '\u202f'))
.or(inRange('\u205f', '\u2064'))
.or(inRange('\u206a', '\u206f'))
.or(is('\u3000'))
.or(inRange('\ud800', '\uf8ff'))
.or(anyOf("\ufeff\ufff9\ufffa\ufffb"))
.withToString("CharMatcher.INVISIBLE")
.precomputed();
/**
* Determines whether a character is single-width (not double-width). When in doubt, this matcher
* errs on the side of returning {@code false} (that is, it tends to assume a character is
* double-width).
*
* Note: as the reference file evolves, we will modify this constant to keep it up to
* date.
*/
public static final CharMatcher SINGLE_WIDTH = inRange('\u0000', '\u04f9')
.or(is('\u05be'))
.or(inRange('\u05d0', '\u05ea'))
.or(is('\u05f3'))
.or(is('\u05f4'))
.or(inRange('\u0600', '\u06ff'))
.or(inRange('\u0750', '\u077f'))
.or(inRange('\u0e00', '\u0e7f'))
.or(inRange('\u1e00', '\u20af'))
.or(inRange('\u2100', '\u213a'))
.or(inRange('\ufb50', '\ufdff'))
.or(inRange('\ufe70', '\ufeff'))
.or(inRange('\uff61', '\uffdc'))
.withToString("CharMatcher.SINGLE_WIDTH")
.precomputed();
/** Matches any character. */
public static final CharMatcher ANY =
new CharMatcher("CharMatcher.ANY") {
@Override public boolean matches(char c) {
return true;
}
@Override public int indexIn(CharSequence sequence) {
return (sequence.length() == 0) ? -1 : 0;
}
@Override public int indexIn(CharSequence sequence, int start) {
int length = sequence.length();
Preconditions.checkPositionIndex(start, length);
return (start == length) ? -1 : start;
}
@Override public int lastIndexIn(CharSequence sequence) {
return sequence.length() - 1;
}
@Override public boolean matchesAllOf(CharSequence sequence) {
checkNotNull(sequence);
return true;
}
@Override public boolean matchesNoneOf(CharSequence sequence) {
return sequence.length() == 0;
}
@Override public String removeFrom(CharSequence sequence) {
checkNotNull(sequence);
return "";
}
@Override public String replaceFrom(CharSequence sequence, char replacement) {
char[] array = new char[sequence.length()];
Arrays.fill(array, replacement);
return new String(array);
}
@Override public String replaceFrom(CharSequence sequence, CharSequence replacement) {
StringBuilder retval = new StringBuilder(sequence.length() * replacement.length());
for (int i = 0; i < sequence.length(); i++) {
retval.append(replacement);
}
return retval.toString();
}
@Override public String collapseFrom(CharSequence sequence, char replacement) {
return (sequence.length() == 0) ? "" : String.valueOf(replacement);
}
@Override public String trimFrom(CharSequence sequence) {
checkNotNull(sequence);
return "";
}
@Override public int countIn(CharSequence sequence) {
return sequence.length();
}
@Override public CharMatcher and(CharMatcher other) {
return checkNotNull(other);
}
@Override public CharMatcher or(CharMatcher other) {
checkNotNull(other);
return this;
}
@Override public CharMatcher negate() {
return NONE;
}
@Override public CharMatcher precomputed() {
return this;
}
};
/** Matches no characters. */
public static final CharMatcher NONE =
new CharMatcher("CharMatcher.NONE") {
@Override public boolean matches(char c) {
return false;
}
@Override public int indexIn(CharSequence sequence) {
checkNotNull(sequence);
return -1;
}
@Override public int indexIn(CharSequence sequence, int start) {
int length = sequence.length();
Preconditions.checkPositionIndex(start, length);
return -1;
}
@Override public int lastIndexIn(CharSequence sequence) {
checkNotNull(sequence);
return -1;
}
@Override public boolean matchesAllOf(CharSequence sequence) {
return sequence.length() == 0;
}
@Override public boolean matchesNoneOf(CharSequence sequence) {
checkNotNull(sequence);
return true;
}
@Override public String removeFrom(CharSequence sequence) {
return sequence.toString();
}
@Override public String replaceFrom(CharSequence sequence, char replacement) {
return sequence.toString();
}
@Override public String replaceFrom(CharSequence sequence, CharSequence replacement) {
checkNotNull(replacement);
return sequence.toString();
}
@Override public String collapseFrom(CharSequence sequence, char replacement) {
return sequence.toString();
}
@Override public String trimFrom(CharSequence sequence) {
return sequence.toString();
}
@Override public int countIn(CharSequence sequence) {
checkNotNull(sequence);
return 0;
}
@Override public CharMatcher and(CharMatcher other) {
checkNotNull(other);
return this;
}
@Override public CharMatcher or(CharMatcher other) {
return checkNotNull(other);
}
@Override public CharMatcher negate() {
return ANY;
}
@Override void setBits(LookupTable table) {}
@Override public CharMatcher precomputed() {
return this;
}
};
// Static factories
/**
* Returns a {@code char} matcher that matches only one specified character.
*/
public static CharMatcher is(final char match) {
String description = new StringBuilder("CharMatcher.is(")
.append(Integer.toHexString(match))
.append(")")
.toString();
return new CharMatcher(description) {
@Override public boolean matches(char c) {
return c == match;
}
@Override public String replaceFrom(CharSequence sequence, char replacement) {
return sequence.toString().replace(match, replacement);
}
@Override public CharMatcher and(CharMatcher other) {
return other.matches(match) ? this : NONE;
}
@Override public CharMatcher or(CharMatcher other) {
return other.matches(match) ? other : super.or(other);
}
@Override public CharMatcher negate() {
return isNot(match);
}
@Override void setBits(LookupTable table) {
table.set(match);
}
@Override public CharMatcher precomputed() {
return this;
}
};
}
/**
* Returns a {@code char} matcher that matches any character except the one specified.
*
*
To negate another {@code CharMatcher}, use {@link #negate()}.
*/
public static CharMatcher isNot(final char match) {
String description = new StringBuilder("CharMatcher.isNot(")
.append(Integer.toHexString(match))
.append(")")
.toString();
return new CharMatcher(description) {
@Override public boolean matches(char c) {
return c != match;
}
@Override public CharMatcher and(CharMatcher other) {
return other.matches(match) ? super.and(other) : other;
}
@Override public CharMatcher or(CharMatcher other) {
return other.matches(match) ? ANY : this;
}
@Override public CharMatcher negate() {
return is(match);
}
};
}
/**
* Returns a {@code char} matcher that matches any character present in the given character
* sequence.
*/
public static CharMatcher anyOf(final CharSequence sequence) {
switch (sequence.length()) {
case 0:
return NONE;
case 1:
return is(sequence.charAt(0));
case 2:
final char match1 = sequence.charAt(0);
final char match2 = sequence.charAt(1);
return new CharMatcher(
new StringBuilder("CharMatcher.anyOf(\"").append(sequence).append("\")").toString()) {
@Override public boolean matches(char c) {
return c == match1 || c == match2;
}
@Override void setBits(LookupTable table) {
table.set(match1);
table.set(match2);
}
@Override public CharMatcher precomputed() {
return this;
}
};
}
final char[] chars = sequence.toString().toCharArray();
Arrays.sort(chars);
return new CharMatcher(new StringBuilder("CharMatcher.anyOf(\"").append(chars)
.append("\")").toString()) {
@Override public boolean matches(char c) {
return Arrays.binarySearch(chars, c) >= 0;
}
};
}
/**
* Returns a {@code char} matcher that matches any character not present in the given character
* sequence.
*/
public static CharMatcher noneOf(CharSequence sequence) {
return anyOf(sequence).negate();
}
/**
* Returns a {@code char} matcher that matches any character in a given range (both endpoints are
* inclusive). For example, to match any lowercase letter of the English alphabet, use {@code
* CharMatcher.inRange('a', 'z')}.
*
* @throws IllegalArgumentException if {@code endInclusive < startInclusive}
*/
public static CharMatcher inRange(final char startInclusive, final char endInclusive) {
checkArgument(endInclusive >= startInclusive);
String description = new StringBuilder("CharMatcher.inRange(")
.append(Integer.toHexString(startInclusive))
.append(", ")
.append(Integer.toHexString(endInclusive))
.append(")")
.toString();
return inRange(startInclusive, endInclusive, description);
}
static CharMatcher inRange(final char startInclusive, final char endInclusive,
String description) {
return new CharMatcher(description) {
@Override public boolean matches(char c) {
return startInclusive <= c && c <= endInclusive;
}
@Override void setBits(LookupTable table) {
char c = startInclusive;
while (true) {
table.set(c);
if (c++ == endInclusive) {
break;
}
}
}
@Override public CharMatcher precomputed() {
return this;
}
};
}
/**
* Returns a matcher with identical behavior to the given {@link Character}-based predicate, but
* which operates on primitive {@code char} instances instead.
*/
public static CharMatcher forPredicate(final Predicate predicate) {
checkNotNull(predicate);
if (predicate instanceof CharMatcher) {
return (CharMatcher) predicate;
}
String description = new StringBuilder("CharMatcher.forPredicate(")
.append(predicate)
.append(')')
.toString();
return new CharMatcher(description) {
@Override public boolean matches(char c) {
return predicate.apply(c);
}
@Override public boolean apply(Character character) {
return predicate.apply(checkNotNull(character));
}
};
}
// State
final String description;
// Constructors
/**
* Sets the {@code toString()} from the given description.
*/
CharMatcher(String description) {
this.description = description;
}
/**
* Constructor for use by subclasses. When subclassing, you may want to override
* {@code toString()} to provide a useful description.
*/
protected CharMatcher() {
description = "UnknownCharMatcher";
}
// Abstract methods
/** Determines a true or false value for the given character. */
public abstract boolean matches(char c);
// Non-static factories
/**
* Returns a matcher that matches any character not matched by this matcher.
*/
public CharMatcher negate() {
final CharMatcher original = this;
return new CharMatcher(original + ".negate()") {
@Override public boolean matches(char c) {
return !original.matches(c);
}
@Override public boolean matchesAllOf(CharSequence sequence) {
return original.matchesNoneOf(sequence);
}
@Override public boolean matchesNoneOf(CharSequence sequence) {
return original.matchesAllOf(sequence);
}
@Override public int countIn(CharSequence sequence) {
return sequence.length() - original.countIn(sequence);
}
@Override public CharMatcher negate() {
return original;
}
};
}
/**
* Returns a matcher that matches any character matched by both this matcher and {@code other}.
*/
public CharMatcher and(CharMatcher other) {
return new And(this, checkNotNull(other));
}
private static class And extends CharMatcher {
final CharMatcher first;
final CharMatcher second;
And(CharMatcher a, CharMatcher b) {
this(a, b, "CharMatcher.and(" + a + ", " + b + ")");
}
And(CharMatcher a, CharMatcher b, String description) {
super(description);
first = checkNotNull(a);
second = checkNotNull(b);
}
@Override
public CharMatcher and(CharMatcher other) {
return new And(this, other);
}
@Override
public boolean matches(char c) {
return first.matches(c) && second.matches(c);
}
@Override
CharMatcher withToString(String description) {
return new And(first, second, description);
}
}
/**
* Returns a matcher that matches any character matched by either this matcher or {@code other}.
*/
public CharMatcher or(CharMatcher other) {
return new Or(this, checkNotNull(other));
}
private static class Or extends CharMatcher {
final CharMatcher first;
final CharMatcher second;
Or(CharMatcher a, CharMatcher b, String description) {
super(description);
first = checkNotNull(a);
second = checkNotNull(b);
}
Or(CharMatcher a, CharMatcher b) {
this(a, b, "CharMatcher.or(" + a + ", " + b + ")");
}
@Override
public CharMatcher or(CharMatcher other) {
return new Or(this, checkNotNull(other));
}
@Override
public boolean matches(char c) {
return first.matches(c) || second.matches(c);
}
@Override
CharMatcher withToString(String description) {
return new Or(first, second, description);
}
}
/**
* Returns a {@code char} matcher functionally equivalent to this one, but which may be faster to
* query than the original; your mileage may vary. Precomputation takes time and is likely to be
* worthwhile only if the precomputed matcher is queried many thousands of times.
*
*
This method has no effect (returns {@code this}) when called in GWT: it's unclear whether a
* precomputed matcher is faster, but it certainly consumes more memory, which doesn't seem like a
* worthwhile tradeoff in a browser.
*/
public CharMatcher precomputed() {
return Platform.precomputeCharMatcher(this);
}
/**
* Construct an array of all possible chars in the slowest way possible.
*/
char[] slowGetChars() {
char[] allChars = new char[65536];
int size = 0;
for (int c = Character.MIN_VALUE; c <= Character.MAX_VALUE; c++) {
if (matches((char) c)) {
allChars[size++] = (char) c;
}
}
char[] retValue = new char[size];
System.arraycopy(allChars, 0, retValue, 0, size);
return retValue;
}
/**
* This is the actual implementation of {@link #precomputed}, but we bounce calls through a method
* on {@link Platform} so that we can have different behavior in GWT.
*
*
If the number of matched characters is small enough, we try to build a small hash
* table to contain all of the characters. Otherwise, we record the characters in eight-kilobyte
* bit array. In many situations this produces a matcher which is faster to query
* than the original.
*/
CharMatcher precomputedInternal() {
final char[] chars = slowGetChars();
int totalCharacters = chars.length;
if (totalCharacters == 0) {
return NONE;
} else if (totalCharacters == 1) {
return is(chars[0]);
} else if (totalCharacters < SmallCharMatcher.MAX_SIZE) {
return SmallCharMatcher.from(chars, toString());
} else if (totalCharacters < MediumCharMatcher.MAX_SIZE) {
return MediumCharMatcher.from(chars, toString());
}
// Otherwise, make the full lookup table.
final LookupTable table = new LookupTable();
setBits(table);
final CharMatcher outer = this;
return new CharMatcher(outer.toString()) {
@Override public boolean matches(char c) {
return table.get(c);
}
// TODO(kevinb): make methods like negate() smart?
@Override public CharMatcher precomputed() {
return this;
}
};
}
/**
* Subclasses should provide a new CharMatcher with the same characteristics as {@code this},
* but with their {@code toString} method overridden with the new description.
*
*
This is unsupported by default.
*/
CharMatcher withToString(String description) {
throw new UnsupportedOperationException();
}
/**
* For use by implementors; sets the bit corresponding to each character ('\0' to '{@literal
* \}uFFFF') that matches this matcher in the given bit array, leaving all other bits untouched.
*
*
The default implementation loops over every possible character value, invoking {@link
* #matches} for each one.
*/
void setBits(LookupTable table) {
char c = Character.MIN_VALUE;
while (true) {
if (matches(c)) {
table.set(c);
}
if (c++ == Character.MAX_VALUE) {
break;
}
}
}
/**
* A bit array with one bit per {@code char} value, used by {@link CharMatcher#precomputed}.
*
*
TODO(kevinb): possibly share a common BitArray class with BloomFilter and others... a
* simpler java.util.BitSet.
*/
private static final class LookupTable {
int[] data = new int[2048];
void set(char index) {
data[index >> 5] |= (1 << index);
}
boolean get(char index) {
return (data[index >> 5] & (1 << index)) != 0;
}
}
// Text processing routines
/**
* Returns {@code true} if a character sequence contains at least one matching character.
* Equivalent to {@code !matchesNoneOf(sequence)}.
*
*
The default implementation iterates over the sequence, invoking {@link #matches} for each
* character, until this returns {@code true} or the end is reached.
*
* @param sequence the character sequence to examine, possibly empty
* @return {@code true} if this matcher matches at least one character in the sequence
* @since 8.0
*/
public boolean matchesAnyOf(CharSequence sequence) {
return !matchesNoneOf(sequence);
}
/**
* Returns {@code true} if a character sequence contains only matching characters.
*
*
The default implementation iterates over the sequence, invoking {@link #matches} for each
* character, until this returns {@code false} or the end is reached.
*
* @param sequence the character sequence to examine, possibly empty
* @return {@code true} if this matcher matches every character in the sequence, including when
* the sequence is empty
*/
public boolean matchesAllOf(CharSequence sequence) {
for (int i = sequence.length() - 1; i >= 0; i--) {
if (!matches(sequence.charAt(i))) {
return false;
}
}
return true;
}
/**
* Returns {@code true} if a character sequence contains no matching characters. Equivalent to
* {@code !matchesAnyOf(sequence)}.
*
*
The default implementation iterates over the sequence, invoking {@link #matches} for each
* character, until this returns {@code false} or the end is reached.
*
* @param sequence the character sequence to examine, possibly empty
* @return {@code true} if this matcher matches every character in the sequence, including when
* the sequence is empty
*/
public boolean matchesNoneOf(CharSequence sequence) {
return indexIn(sequence) == -1;
}
/**
* Returns the index of the first matching character in a character sequence, or {@code -1} if no
* matching character is present.
*
*
The default implementation iterates over the sequence in forward order calling {@link
* #matches} for each character.
*
* @param sequence the character sequence to examine from the beginning
* @return an index, or {@code -1} if no character matches
*/
public int indexIn(CharSequence sequence) {
int length = sequence.length();
for (int i = 0; i < length; i++) {
if (matches(sequence.charAt(i))) {
return i;
}
}
return -1;
}
/**
* Returns the index of the first matching character in a character sequence, starting from a
* given position, or {@code -1} if no character matches after that position.
*
*
The default implementation iterates over the sequence in forward order, beginning at {@code
* start}, calling {@link #matches} for each character.
*
* @param sequence the character sequence to examine
* @param start the first index to examine; must be nonnegative and no greater than {@code
* sequence.length()}
* @return the index of the first matching character, guaranteed to be no less than {@code start},
* or {@code -1} if no character matches
* @throws IndexOutOfBoundsException if start is negative or greater than {@code
* sequence.length()}
*/
public int indexIn(CharSequence sequence, int start) {
int length = sequence.length();
Preconditions.checkPositionIndex(start, length);
for (int i = start; i < length; i++) {
if (matches(sequence.charAt(i))) {
return i;
}
}
return -1;
}
/**
* Returns the index of the last matching character in a character sequence, or {@code -1} if no
* matching character is present.
*
*
The default implementation iterates over the sequence in reverse order calling {@link
* #matches} for each character.
*
* @param sequence the character sequence to examine from the end
* @return an index, or {@code -1} if no character matches
*/
public int lastIndexIn(CharSequence sequence) {
for (int i = sequence.length() - 1; i >= 0; i--) {
if (matches(sequence.charAt(i))) {
return i;
}
}
return -1;
}
/**
* Returns the number of matching characters found in a character sequence.
*/
public int countIn(CharSequence sequence) {
int count = 0;
for (int i = 0; i < sequence.length(); i++) {
if (matches(sequence.charAt(i))) {
count++;
}
}
return count;
}
/**
* Returns a string containing all non-matching characters of a character sequence, in order. For
* example:
{@code
*
* CharMatcher.is('a').removeFrom("bazaar")}
*
* ... returns {@code "bzr"}.
*/
@CheckReturnValue
public String removeFrom(CharSequence sequence) {
String string = sequence.toString();
int pos = indexIn(string);
if (pos == -1) {
return string;
}
char[] chars = string.toCharArray();
int spread = 1;
// This unusual loop comes from extensive benchmarking
OUT: while (true) {
pos++;
while (true) {
if (pos == chars.length) {
break OUT;
}
if (matches(chars[pos])) {
break;
}
chars[pos - spread] = chars[pos];
pos++;
}
spread++;
}
return new String(chars, 0, pos - spread);
}
/**
* Returns a string containing all matching characters of a character sequence, in order. For
* example: {@code
*
* CharMatcher.is('a').retainFrom("bazaar")}
*
* ... returns {@code "aaa"}.
*/
@CheckReturnValue
public String retainFrom(CharSequence sequence) {
return negate().removeFrom(sequence);
}
/**
* Returns a string copy of the input character sequence, with each character that matches this
* matcher replaced by a given replacement character. For example: {@code
*
* CharMatcher.is('a').replaceFrom("radar", 'o')}
*
* ... returns {@code "rodor"}.
*
* The default implementation uses {@link #indexIn(CharSequence)} to find the first matching
* character, then iterates the remainder of the sequence calling {@link #matches(char)} for each
* character.
*
* @param sequence the character sequence to replace matching characters in
* @param replacement the character to append to the result string in place of each matching
* character in {@code sequence}
* @return the new string
*/
@CheckReturnValue
public String replaceFrom(CharSequence sequence, char replacement) {
String string = sequence.toString();
int pos = indexIn(string);
if (pos == -1) {
return string;
}
char[] chars = string.toCharArray();
chars[pos] = replacement;
for (int i = pos + 1; i < chars.length; i++) {
if (matches(chars[i])) {
chars[i] = replacement;
}
}
return new String(chars);
}
/**
* Returns a string copy of the input character sequence, with each character that matches this
* matcher replaced by a given replacement sequence. For example:
{@code
*
* CharMatcher.is('a').replaceFrom("yaha", "oo")}
*
* ... returns {@code "yoohoo"}.
*
* Note: If the replacement is a fixed string with only one character, you are better
* off calling {@link #replaceFrom(CharSequence, char)} directly.
*
* @param sequence the character sequence to replace matching characters in
* @param replacement the characters to append to the result string in place of each matching
* character in {@code sequence}
* @return the new string
*/
@CheckReturnValue
public String replaceFrom(CharSequence sequence, CharSequence replacement) {
int replacementLen = replacement.length();
if (replacementLen == 0) {
return removeFrom(sequence);
}
if (replacementLen == 1) {
return replaceFrom(sequence, replacement.charAt(0));
}
String string = sequence.toString();
int pos = indexIn(string);
if (pos == -1) {
return string;
}
int len = string.length();
StringBuilder buf = new StringBuilder((len * 3 / 2) + 16);
int oldpos = 0;
do {
buf.append(string, oldpos, pos);
buf.append(replacement);
oldpos = pos + 1;
pos = indexIn(string, oldpos);
} while (pos != -1);
buf.append(string, oldpos, len);
return buf.toString();
}
/**
* Returns a substring of the input character sequence that omits all characters this matcher
* matches from the beginning and from the end of the string. For example:
{@code
*
* CharMatcher.anyOf("ab").trimFrom("abacatbab")}
*
* ... returns {@code "cat"}.
*
* Note that:
{@code
*
* CharMatcher.inRange('\0', ' ').trimFrom(str)}
*
* ... is equivalent to {@link String#trim()}.
*/
@CheckReturnValue
public String trimFrom(CharSequence sequence) {
int len = sequence.length();
int first;
int last;
for (first = 0; first < len; first++) {
if (!matches(sequence.charAt(first))) {
break;
}
}
for (last = len - 1; last > first; last--) {
if (!matches(sequence.charAt(last))) {
break;
}
}
return sequence.subSequence(first, last + 1).toString();
}
/**
* Returns a substring of the input character sequence that omits all characters this matcher
* matches from the beginning of the string. For example: {@code
*
* CharMatcher.anyOf("ab").trimLeadingFrom("abacatbab")}
*
* ... returns {@code "catbab"}.
*/
@CheckReturnValue
public String trimLeadingFrom(CharSequence sequence) {
int len = sequence.length();
int first;
for (first = 0; first < len; first++) {
if (!matches(sequence.charAt(first))) {
break;
}
}
return sequence.subSequence(first, len).toString();
}
/**
* Returns a substring of the input character sequence that omits all characters this matcher
* matches from the end of the string. For example: {@code
*
* CharMatcher.anyOf("ab").trimTrailingFrom("abacatbab")}
*
* ... returns {@code "abacat"}.
*/
@CheckReturnValue
public String trimTrailingFrom(CharSequence sequence) {
int len = sequence.length();
int last;
for (last = len - 1; last >= 0; last--) {
if (!matches(sequence.charAt(last))) {
break;
}
}
return sequence.subSequence(0, last + 1).toString();
}
/**
* Returns a string copy of the input character sequence, with each group of consecutive
* characters that match this matcher replaced by a single replacement character. For example:
* {@code
*
* CharMatcher.anyOf("eko").collapseFrom("bookkeeper", '-')}
*
* ... returns {@code "b-p-r"}.
*
* The default implementation uses {@link #indexIn(CharSequence)} to find the first matching
* character, then iterates the remainder of the sequence calling {@link #matches(char)} for each
* character.
*
* @param sequence the character sequence to replace matching groups of characters in
* @param replacement the character to append to the result string in place of each group of
* matching characters in {@code sequence}
* @return the new string
*/
@CheckReturnValue
public String collapseFrom(CharSequence sequence, char replacement) {
int first = indexIn(sequence);
if (first == -1) {
return sequence.toString();
}
// TODO(kevinb): see if this implementation can be made faster
StringBuilder builder = new StringBuilder(sequence.length())
.append(sequence.subSequence(0, first))
.append(replacement);
boolean in = true;
for (int i = first + 1; i < sequence.length(); i++) {
char c = sequence.charAt(i);
if (matches(c)) {
if (!in) {
builder.append(replacement);
in = true;
}
} else {
builder.append(c);
in = false;
}
}
return builder.toString();
}
/**
* Collapses groups of matching characters exactly as {@link #collapseFrom} does, except that
* groups of matching characters at the start or end of the sequence are removed without
* replacement.
*/
@CheckReturnValue
public String trimAndCollapseFrom(CharSequence sequence, char replacement) {
int first = negate().indexIn(sequence);
if (first == -1) {
return ""; // everything matches. nothing's left.
}
StringBuilder builder = new StringBuilder(sequence.length());
boolean inMatchingGroup = false;
for (int i = first; i < sequence.length(); i++) {
char c = sequence.charAt(i);
if (matches(c)) {
inMatchingGroup = true;
} else {
if (inMatchingGroup) {
builder.append(replacement);
inMatchingGroup = false;
}
builder.append(c);
}
}
return builder.toString();
}
// Predicate interface
/**
* Returns {@code true} if this matcher matches the given character.
*
* @throws NullPointerException if {@code character} is null
*/
@Override public boolean apply(Character character) {
return matches(character);
}
/**
* Returns a string representation of this {@code CharMatcher}, such as
* {@code CharMatcher.or(WHITESPACE, JAVA_DIGIT)}.
*/
@Override
public String toString() {
return description;
}
/**
* Determines whether a character is whitespace according to the latest Unicode standard, as
* illustrated
* here.
* This is not the same definition used by other Java APIs. (See a
* comparison of several
* definitions of "whitespace".)
*
*
Note: as the Unicode definition evolves, we will modify this constant to keep it up
* to date.
*/
public static final CharMatcher WHITESPACE = new CharMatcher("CharMatcher.WHITESPACE") {
/**
* A special-case CharMatcher for Unicode whitespace characters that is extremely
* efficient both in space required and in time to check for matches.
*
* Implementation details.
* It turns out that all current (early 2012) Unicode characters are unique modulo 79:
* so we can construct a lookup table of exactly 79 entries, and just check the character code
* mod 79, and see if that character is in the table.
*
* There is a 1 at the beginning of the table so that the null character is not listed
* as whitespace.
*
* Other things we tried that did not prove to be beneficial, mostly due to speed concerns:
*
* * Binary search into the sorted list of characters, i.e., what
* CharMatcher.anyOf() does
* * Perfect hash function into a table of size 26 (using an offset table and a special
* Jenkins hash function)
* * Perfect-ish hash function that required two lookups into a single table of size 26.
* * Using a power-of-2 sized hash table (size 64) with linear probing.
*
* --Christopher Swenson, February 2012.
*/
// Mod-79 lookup table.
private final char[] table = {1, 0, 160, 0, 0, 0, 0, 0, 0, 9, 10, 11, 12, 13, 0, 0,
8232, 8233, 0, 0, 0, 0, 0, 8239, 0, 0, 0, 0, 0, 0, 0, 0, 32, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
12288, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 133, 8192, 8193, 8194, 8195, 8196, 8197, 8198, 8199,
8200, 8201, 8202, 0, 0, 0, 0, 0, 8287, 5760, 0, 0, 6158, 0, 0, 0};
@Override public boolean matches(char c) {
return table[c % 79] == c;
}
@Override public CharMatcher precomputed() {
return this;
}
};
}