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* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 org.apache.sshd.common.util;
import java.time.Duration;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.Deque;
import java.util.EnumSet;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.NavigableSet;
import java.util.Objects;
import java.util.Set;
import java.util.SortedSet;
import java.util.TreeSet;
import java.util.concurrent.atomic.AtomicReference;
import java.util.function.Consumer;
import java.util.function.Function;
import java.util.function.Predicate;
import java.util.function.Supplier;
import java.util.stream.Collector;
import java.util.stream.Collectors;
import java.util.stream.Stream;
import java.util.stream.StreamSupport;
import org.apache.sshd.common.util.functors.UnaryEquator;
/**
* @author Apache MINA SSHD Project
*/
public final class GenericUtils {
public static final byte[] EMPTY_BYTE_ARRAY = {};
public static final char[] EMPTY_CHAR_ARRAY = {};
public static final String[] EMPTY_STRING_ARRAY = {};
public static final Object[] EMPTY_OBJECT_ARRAY = {};
public static final boolean[] EMPTY_BOOLEAN_ARRAY = {};
/**
* A value indicating a {@code null} value - to be used as a placeholder where {@code null}s are not allowed
*/
public static final Object NULL = new Object();
/**
* The complement of {@link String#CASE_INSENSITIVE_ORDER}
*/
@SuppressWarnings("PMD.UseEqualsToCompareStrings")
public static final Comparator CASE_SENSITIVE_ORDER = (s1, s2) -> {
if (s1 == s2) {
return 0;
} else {
return s1.compareTo(s2);
}
};
public static final String QUOTES = "\"'";
private GenericUtils() {
throw new UnsupportedOperationException("No instance");
}
public static String trimToEmpty(String s) {
if (s == null) {
return "";
} else {
return s.trim();
}
}
public static String replaceWhitespaceAndTrim(String s) {
if (s != null) {
s = s.replace('\t', ' ');
}
return trimToEmpty(s);
}
/**
*
* Replace a String with another String inside a larger String, for the first max values of the search
* String.
*
*
*
* A {@code null} reference passed to this method is a no-op.
*
*
* @param text text to search and replace in
* @param repl String to search for
* @param with String to replace with
* @param max maximum number of values to replace, or -1 if no maximum
* @return the text with any replacements processed
* @author Arnout J. Kuiper [email protected]
* @author Magesh Umasankar
* @author Bruce Atherton
* @author Antoine Levy-Lambert
*/
@SuppressWarnings("PMD.AssignmentInOperand")
public static String replace(String text, String repl, String with, int max) {
if ((text == null) || (repl == null) || (with == null) || (repl.length() == 0)) {
return text;
}
int start = 0;
StringBuilder buf = new StringBuilder(text.length());
for (int end = text.indexOf(repl, start); end != -1; end = text.indexOf(repl, start)) {
buf.append(text.substring(start, end)).append(with);
start = end + repl.length();
if (--max == 0) {
break;
}
}
buf.append(text.substring(start));
return buf.toString();
}
/**
* @param s The {@link String} value to calculate the hash code on - may be {@code null}/empty in which case a
* value of zero is returned
* @return The calculated hash code
* @see #hashCode(String, Boolean)
*/
public static int hashCode(String s) {
return hashCode(s, null);
}
/**
* @param s The {@link String} value to calculate the hash code on - may be {@code null}/empty in which
* case a value of zero is returned
* @param useUppercase Whether to convert the string to uppercase, lowercase or not at all:
*
* - {@code null} - no conversion
* - {@link Boolean#TRUE} - get hash code of uppercase
* - {@link Boolean#FALSE} - get hash code of lowercase
*
* @return The calculated hash code
*/
public static int hashCode(String s, Boolean useUppercase) {
if (isEmpty(s)) {
return 0;
} else if (useUppercase == null) {
return s.hashCode();
} else if (useUppercase.booleanValue()) {
return s.toUpperCase().hashCode();
} else {
return s.toLowerCase().hashCode();
}
}
public static int safeCompare(String s1, String s2, boolean caseSensitive) {
if (UnaryEquator.isSameReference(s1, s2)) {
return 0;
} else if (s1 == null) {
return +1; // push null(s) to end
} else if (s2 == null) {
return -1; // push null(s) to end
} else if (caseSensitive) {
return s1.compareTo(s2);
} else {
return s1.compareToIgnoreCase(s2);
}
}
public static int length(CharSequence cs) {
return cs == null ? 0 : cs.length();
}
public static boolean isEmpty(CharSequence cs) {
return length(cs) <= 0;
}
public static boolean isNotEmpty(CharSequence cs) {
return !isEmpty(cs);
}
/**
*
* Checks if a CharSequence is empty (""), null or whitespace only.
*
*
*
* Whitespace is defined by {@link Character#isWhitespace(char)}.
*
*
*
* GenericUtils.isBlank(null) = true
* GenericUtils.isBlank("") = true
* GenericUtils.isBlank(" ") = true
* GenericUtils.isBlank("bob") = false
* GenericUtils.isBlank(" bob ") = false
*
*
* @param cs the CharSequence to check, may be null
* @return {@code true} if the CharSequence is null, empty or whitespace only
*/
public static boolean isBlank(final CharSequence cs) {
int strLen = cs != null ? cs.length() : 0;
if (cs == null || strLen == 0) {
return true;
}
for (int i = 0; i < strLen; i++) {
if (!Character.isWhitespace(cs.charAt(i))) {
return false;
}
}
return true;
}
public static boolean isNotBlank(final CharSequence cs) {
return !isBlank(cs);
}
public static List filterToNotBlank(final List values) {
return values.stream().filter(GenericUtils::isNotBlank).collect(Collectors.toList());
}
public static int indexOf(CharSequence cs, char c) {
int len = length(cs);
for (int pos = 0; pos < len; pos++) {
char ch = cs.charAt(pos);
if (ch == c) {
return pos;
}
}
return -1;
}
public static int lastIndexOf(CharSequence cs, char c) {
int len = length(cs);
for (int pos = len - 1; pos >= 0; pos--) {
char ch = cs.charAt(pos);
if (ch == c) {
return pos;
}
}
return -1;
}
// a List would be better, but we want to be compatible with String.split(...)
public static String[] split(String s, char ch) {
if (isEmpty(s)) {
return EMPTY_STRING_ARRAY;
}
int lastPos = 0;
int curPos = s.indexOf(ch);
if (curPos < 0) {
return new String[] { s };
}
Collection values = new LinkedList<>();
do {
String v = s.substring(lastPos, curPos);
values.add(v);
// skip separator
lastPos = curPos + 1;
if (lastPos >= s.length()) {
break;
}
curPos = s.indexOf(ch, lastPos);
if (curPos < lastPos) {
break; // no more separators
}
} while (curPos < s.length());
// check if any leftovers
if (lastPos < s.length()) {
String v = s.substring(lastPos);
values.add(v);
}
return values.toArray(new String[values.size()]);
}
public static String join(T[] values, char ch) {
return join(isEmpty(values) ? Collections. emptyList() : Arrays.asList(values), ch);
}
public static String join(Iterable iter, char ch) {
return join((iter == null) ? null : iter.iterator(), ch);
}
public static String join(Iterator iter, char ch) {
if ((iter == null) || (!iter.hasNext())) {
return "";
}
StringBuilder sb = new StringBuilder();
do { // we already asked hasNext...
Object o = iter.next();
if (sb.length() > 0) {
sb.append(ch);
}
sb.append(Objects.toString(o));
} while (iter.hasNext());
return sb.toString();
}
public static String join(T[] values, CharSequence sep) {
return join(isEmpty(values) ? Collections. emptyList() : Arrays.asList(values), sep);
}
public static String join(Iterable iter, CharSequence sep) {
return join((iter == null) ? null : iter.iterator(), sep);
}
public static String join(Iterator iter, CharSequence sep) {
if ((iter == null) || (!iter.hasNext())) {
return "";
}
StringBuilder sb = new StringBuilder();
do { // we already asked hasNext...
Object o = iter.next();
if (sb.length() > 0) {
sb.append(sep);
}
sb.append(Objects.toString(o));
} while (iter.hasNext());
return sb.toString();
}
public static int size(Collection c) {
return (c == null) ? 0 : c.size();
}
public static boolean isEmpty(Collection c) {
return size(c) <= 0;
}
public static boolean isNotEmpty(Collection c) {
return !isEmpty(c);
}
/**
*
* @param Generic element type
* @param c1 First collection
* @param c2 Second collection
* @return {@code true} if the following holds:
*
* - Same size - Note: {@code null} collections are consider equal to empty ones
*
* - First collection contains all elements of second one and vice versa
*
*/
public static boolean equals(Collection c1, Collection c2) {
if (isEmpty(c1)) {
return isEmpty(c2);
} else if (isEmpty(c2)) {
return false;
}
return (c1.size() == c2.size())
&& c1.containsAll(c2)
&& c2.containsAll(c1);
}
@SafeVarargs
public static int length(T... a) {
return (a == null) ? 0 : a.length;
}
public static boolean isEmpty(Iterable iter) {
if (iter == null) {
return true;
} else if (iter instanceof Collection) {
return isEmpty((Collection) iter);
} else {
return isEmpty(iter.iterator());
}
}
public static boolean isNotEmpty(Iterable iter) {
return !isEmpty(iter);
}
public static boolean isEmpty(Iterator iter) {
return (iter == null) || (!iter.hasNext());
}
public static boolean isNotEmpty(Iterator iter) {
return !isEmpty(iter);
}
public static boolean isEmpty(T[] a) {
return length(a) <= 0;
}
public static int length(char[] chars) {
return (chars == null) ? 0 : chars.length;
}
public static boolean isEmpty(char[] chars) {
return length(chars) <= 0;
}
/**
* Compares 2 character arrays - Note: {@code null} and empty are considered equal
*
* @param c1 1st array
* @param c2 2nd array
* @return Negative is 1st array comes first in lexicographical order, positive if 2nd array comes first and zero
* if equal
*/
public static int compare(char[] c1, char[] c2) {
int l1 = length(c1);
int l2 = length(c2);
int cmpLen = Math.min(l1, l2);
for (int index = 0; index < cmpLen; index++) {
char c11 = c1[index];
char c22 = c2[index];
int nRes = Character.compare(c11, c22);
if (nRes != 0) {
return nRes;
}
}
int nRes = Integer.compare(l1, l2);
if (nRes != 0) {
return nRes;
}
return 0;
}
@SafeVarargs // there is no EnumSet.of(...) so we have to provide our own
public static > Set of(E... values) {
return of(isEmpty(values) ? Collections.emptySet() : Arrays.asList(values));
}
public static > Set of(Collection values) {
if (isEmpty(values)) {
return Collections.emptySet();
}
Set result = null;
for (E v : values) {
/*
* A trick to compensate for the fact that we do not have the enum Class to invoke EnumSet.noneOf
*/
if (result == null) {
result = EnumSet.of(v);
} else {
result.add(v);
}
}
return result;
}
public static int findFirstDifferentValueIndex(List c1, List c2) {
return findFirstDifferentValueIndex(c1, c2, UnaryEquator.defaultEquality());
}
public static int findFirstDifferentValueIndex(
List c1, List c2, UnaryEquator equator) {
Objects.requireNonNull(equator, "No equator provided");
int l1 = size(c1);
int l2 = size(c2);
for (int index = 0, count = Math.min(l1, l2); index < count; index++) {
T v1 = c1.get(index);
T v2 = c2.get(index);
if (!equator.test(v1, v2)) {
return index;
}
}
// all common length items are equal - check length
if (l1 < l2) {
return l1;
} else if (l2 < l1) {
return l2;
} else {
return -1;
}
}
public static int findFirstDifferentValueIndex(Iterable c1, Iterable c2) {
return findFirstDifferentValueIndex(c1, c2, UnaryEquator.defaultEquality());
}
public static int findFirstDifferentValueIndex(
Iterable c1, Iterable c2, UnaryEquator equator) {
return findFirstDifferentValueIndex(iteratorOf(c1), iteratorOf(c2), equator);
}
public static int findFirstDifferentValueIndex(Iterator i1, Iterator i2) {
return findFirstDifferentValueIndex(i1, i2, UnaryEquator.defaultEquality());
}
public static int findFirstDifferentValueIndex(
Iterator i1, Iterator i2, UnaryEquator equator) {
Objects.requireNonNull(equator, "No equator provided");
i1 = iteratorOf(i1);
i2 = iteratorOf(i2);
for (int index = 0;; index++) {
if (i1.hasNext()) {
if (i2.hasNext()) {
T v1 = i1.next();
T v2 = i2.next();
if (!equator.test(v1, v2)) {
return index;
}
} else {
return index;
}
} else if (i2.hasNext()) {
return index;
} else {
return -1; // neither has a next value - both exhausted at the same time
}
}
}
public static boolean containsAny(
Collection coll, Iterable values) {
if (isEmpty(coll)) {
return false;
}
for (T v : values) {
if (coll.contains(v)) {
return true;
}
}
return false;
}
public static void forEach(
Iterable values, Consumer consumer) {
if (isNotEmpty(values)) {
values.forEach(consumer);
}
}
public static List map(
Collection values, Function mapper) {
return stream(values).map(mapper).collect(Collectors.toList());
}
public static NavigableSet mapSort(
Collection values, Function mapper, Comparator comparator) {
return stream(values).map(mapper).collect(toSortedSet(comparator));
}
public static Collector> toSortedSet(Comparator comparator) {
return Collectors.toCollection(() -> new TreeSet<>(comparator));
}
public static Stream stream(Iterable values) {
if (isEmpty(values)) {
return Stream.empty();
} else if (values instanceof Collection) {
return ((Collection) values).stream();
} else {
return StreamSupport.stream(values.spliterator(), false);
}
}
@SafeVarargs
public static List unmodifiableList(T... values) {
return unmodifiableList(asList(values));
}
public static List unmodifiableList(Collection values) {
if (isEmpty(values)) {
return Collections.emptyList();
} else {
return Collections.unmodifiableList(new ArrayList<>(values));
}
}
public static List unmodifiableList(Stream values) {
return unmodifiableList(values.collect(Collectors.toList()));
}
@SafeVarargs
public static List asList(T... values) {
return isEmpty(values) ? Collections.emptyList() : Arrays.asList(values);
}
@SafeVarargs
public static Set asSet(T... values) {
return new HashSet<>(asList(values));
}
@SafeVarargs
public static > NavigableSet asSortedSet(V... values) {
return asSortedSet(Comparator.naturalOrder(), values);
}
public static > NavigableSet asSortedSet(Collection values) {
return asSortedSet(Comparator.naturalOrder(), values);
}
/**
* @param The element type
* @param comp The (non-{@code null}) {@link Comparator} to use
* @param values The values to be added (ignored if {@code null})
* @return A {@link NavigableSet} containing the values (if any) sorted using the provided comparator
*/
@SafeVarargs
public static NavigableSet asSortedSet(Comparator comp, V... values) {
return asSortedSet(comp, isEmpty(values) ? Collections.emptyList() : Arrays.asList(values));
}
/**
* @param The element type
* @param comp The (non-{@code null}) {@link Comparator} to use
* @param values The values to be added (ignored if {@code null}/empty)
* @return A {@link NavigableSet} containing the values (if any) sorted using the provided comparator
*/
public static NavigableSet asSortedSet(
Comparator comp, Collection values) {
NavigableSet set = new TreeSet<>(Objects.requireNonNull(comp, "No comparator"));
if (size(values) > 0) {
set.addAll(values);
}
return set;
}
@SafeVarargs
public static T findFirstMatchingMember(Predicate acceptor, T... values) {
return findFirstMatchingMember(acceptor,
isEmpty(values) ? Collections.emptyList() : Arrays.asList(values));
}
public static T findFirstMatchingMember(
Predicate acceptor, Collection values) {
List matches = selectMatchingMembers(acceptor, values);
return GenericUtils.isEmpty(matches) ? null : matches.get(0);
}
/**
* Returns a list of all the values that were accepted by a predicate
*
* @param The type of value being evaluated
* @param acceptor The {@link Predicate} to consult whether a member is selected
* @param values The values to be scanned
* @return A {@link List} of all the values that were accepted by the predicate
*/
@SafeVarargs
public static List selectMatchingMembers(Predicate acceptor, T... values) {
return selectMatchingMembers(acceptor,
isEmpty(values) ? Collections.emptyList() : Arrays.asList(values));
}
/**
* Returns a list of all the values that were accepted by a predicate
*
* @param The type of value being evaluated
* @param acceptor The {@link Predicate} to consult whether a member is selected
* @param values The values to be scanned
* @return A {@link List} of all the values that were accepted by the predicate
*/
public static List selectMatchingMembers(
Predicate acceptor, Collection values) {
return GenericUtils.stream(values)
.filter(acceptor)
.collect(Collectors.toList());
}
/**
* @param s The {@link CharSequence} to be checked
* @return If the sequence contains any of the {@link #QUOTES} on both ends, then they are stripped,
* otherwise nothing is done
* @see #stripDelimiters(CharSequence, char)
*/
public static CharSequence stripQuotes(CharSequence s) {
if (isEmpty(s)) {
return s;
}
for (int index = 0; index < QUOTES.length(); index++) {
char delim = QUOTES.charAt(index);
CharSequence v = stripDelimiters(s, delim);
if (v != s) { // if stripped one don't continue
return v;
}
}
return s;
}
/**
* @param s The {@link CharSequence} to be checked
* @param delim The expected delimiter
* @return If the sequence contains the delimiter on both ends, then it is are stripped, otherwise
* nothing is done
*/
public static CharSequence stripDelimiters(CharSequence s, char delim) {
if (isEmpty(s) || (s.length() < 2)) {
return s;
}
int lastPos = s.length() - 1;
if ((s.charAt(0) != delim) || (s.charAt(lastPos) != delim)) {
return s;
} else {
return s.subSequence(1, lastPos);
}
}
/**
* Wraps a value into a {@link Supplier}
*
* @param Type of value being supplied
* @param value The value to be supplied
* @return The supplier wrapper
*/
public static Supplier supplierOf(T value) {
return () -> value;
}
/**
* Resolves to an always non-{@code null} iterator
*
* @param Type of value being iterated
* @param iterable The {@link Iterable} instance
* @return A non-{@code null} iterator which may be empty if no iterable instance or no iterator returned
* from it
* @see #iteratorOf(Iterator)
*/
public static Iterator iteratorOf(Iterable iterable) {
return iteratorOf((iterable == null) ? null : iterable.iterator());
}
/**
* @param Generic base class
* @param Generic child class
* @return An identity {@link Function} that returns its input child class as a base class
*/
public static Function downcast() {
return t -> t;
}
/**
* Returns the first element in iterable - it has some optimization for {@link List}-s {@link Deque}-s and
* {@link SortedSet}s.
*
* @param Type of element
* @param it The {@link Iterable} instance - ignored if {@code null}/empty
* @return first element by iteration or {@code null} if none available
*/
public static T head(Iterable it) {
if (it == null) {
return null;
} else if (it instanceof Deque) { // check before (!) instanceof List since LinkedList implements List
Deque l = (Deque) it;
return !l.isEmpty() ? l.getFirst() : null;
} else if (it instanceof List) {
List l = (List) it;
return !l.isEmpty() ? l.get(0) : null;
} else if (it instanceof SortedSet) {
SortedSet s = (SortedSet) it;
return !s.isEmpty() ? s.first() : null;
} else {
Iterator iter = it.iterator();
return ((iter == null) || (!iter.hasNext())) ? null : iter.next();
}
}
/**
* Resolves to an always non-{@code null} iterator
*
* @param Type of value being iterated
* @param iter The {@link Iterator} instance
* @return A non-{@code null} iterator which may be empty if no iterator instance
* @see Collections#emptyIterator()
*/
public static Iterator iteratorOf(Iterator iter) {
return (iter == null) ? Collections.emptyIterator() : iter;
}
public static Iterable wrapIterable(
Iterable iter, Function mapper) {
return () -> wrapIterator(iter, mapper);
}
@SuppressWarnings({ "unchecked", "rawtypes" })
public static Iterator wrapIterator(
Iterable iter, Function mapper) {
return (Iterator) stream(iter).map(mapper).iterator();
}
public static Iterator wrapIterator(
Iterator iter, Function mapper) {
Iterator iterator = iteratorOf(iter);
return new Iterator() {
@Override
public boolean hasNext() {
return iterator.hasNext();
}
@Override
public V next() {
U value = iterator.next();
return mapper.apply(value);
}
};
}
/**
* @param Generic return type
* @param values The source values - ignored if {@code null}
* @param type The (never @code null) type of values to select - any value whose type is assignable to this type
* will be selected by the iterator.
* @return The first value that matches the specified type - {@code null} if none found
*/
public static T selectNextMatchingValue(Iterator values, Class type) {
Objects.requireNonNull(type, "No type selector specified");
if (values == null) {
return null;
}
while (values.hasNext()) {
Object o = values.next();
if (o == null) {
continue;
}
Class t = o.getClass();
if (type.isAssignableFrom(t)) {
return type.cast(o);
}
}
return null;
}
/**
* Wraps a group of {@link Supplier}s of {@link Iterable} instances into a "unified" {@link Iterable} of
* their values, in the same order as the suppliers - i.e., once the values from a specific supplier are exhausted,
* the next one is consulted, and so on, until all suppliers have been consulted
*
* @param Type of value being iterated
* @param providers The providers - ignored if {@code null} (i.e., return an empty iterable instance)
* @return The wrapping instance
*/
public static Iterable multiIterableSuppliers(
Iterable>> providers) {
return () -> stream(providers). flatMap(s -> stream(s.get())).map(Function.identity()).iterator();
}
/**
* The delegate Suppliers get() method is called exactly once and the result is cached.
*
* @param Generic type of supplied value
* @param delegate The actual Supplier
* @return The memoized Supplier
*/
public static Supplier memoizeLock(Supplier delegate) {
AtomicReference value = new AtomicReference<>();
return () -> {
T val = value.get();
if (val == null) {
synchronized (value) {
val = value.get();
if (val == null) {
val = Objects.requireNonNull(delegate.get());
value.set(val);
}
}
}
return val;
};
}
/**
* Check if a duration is positive
*
* @param d the duration
* @return true if the duration is greater than zero
*/
public static boolean isPositive(Duration d) {
return !isNegativeOrNull(d);
}
/**
* Check if a duration is negative or zero
*
* @param d the duration
* @return true if the duration is negative or zero
*/
public static boolean isNegativeOrNull(Duration d) {
return d.isNegative() || d.isZero();
}
}
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