| /* |
| * Copyright (C) 2009 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 com.google.common.annotations.GwtIncompatible; |
| import java.util.ArrayList; |
| import java.util.Collections; |
| import java.util.Iterator; |
| import java.util.LinkedHashMap; |
| import java.util.List; |
| import java.util.Map; |
| import java.util.regex.Pattern; |
| |
| /** |
| * Extracts non-overlapping substrings from an input string, typically by recognizing appearances of |
| * a <i>separator</i> sequence. This separator can be specified as a single {@linkplain #on(char) |
| * character}, fixed {@linkplain #on(String) string}, {@linkplain #onPattern regular expression} or |
| * {@link #on(CharMatcher) CharMatcher} instance. Or, instead of using a separator at all, a |
| * splitter can extract adjacent substrings of a given {@linkplain #fixedLength fixed length}. |
| * |
| * <p>For example, this expression: |
| * |
| * <pre>{@code |
| * Splitter.on(',').split("foo,bar,qux") |
| * }</pre> |
| * |
| * ... produces an {@code Iterable} containing {@code "foo"}, {@code "bar"} and {@code "qux"}, in |
| * that order. |
| * |
| * <p>By default, {@code Splitter}'s behavior is simplistic and unassuming. The following |
| * expression: |
| * |
| * <pre>{@code |
| * Splitter.on(',').split(" foo,,, bar ,") |
| * }</pre> |
| * |
| * ... yields the substrings {@code [" foo", "", "", " bar ", ""]}. If this is not the desired |
| * behavior, use configuration methods to obtain a <i>new</i> splitter instance with modified |
| * behavior: |
| * |
| * <pre>{@code |
| * private static final Splitter MY_SPLITTER = Splitter.on(',') |
| * .trimResults() |
| * .omitEmptyStrings(); |
| * }</pre> |
| * |
| * <p>Now {@code MY_SPLITTER.split("foo,,, bar ,")} returns just {@code ["foo", "bar"]}. Note that |
| * the order in which these configuration methods are called is never significant. |
| * |
| * <p><b>Warning:</b> Splitter instances are immutable. Invoking a configuration method has no |
| * effect on the receiving instance; you must store and use the new splitter instance it returns |
| * instead. |
| * |
| * <pre>{@code |
| * // Do NOT do this |
| * Splitter splitter = Splitter.on('/'); |
| * splitter.trimResults(); // does nothing! |
| * return splitter.split("wrong / wrong / wrong"); |
| * }</pre> |
| * |
| * <p>For separator-based splitters that do not use {@code omitEmptyStrings}, an input string |
| * containing {@code n} occurrences of the separator naturally yields an iterable of size {@code n + |
| * 1}. So if the separator does not occur anywhere in the input, a single substring is returned |
| * containing the entire input. Consequently, all splitters split the empty string to {@code [""]} |
| * (note: even fixed-length splitters). |
| * |
| * <p>Splitter instances are thread-safe immutable, and are therefore safe to store as {@code static |
| * final} constants. |
| * |
| * <p>The {@link Joiner} class provides the inverse operation to splitting, but note that a |
| * round-trip between the two should be assumed to be lossy. |
| * |
| * <p>See the Guava User Guide article on <a |
| * href="https://github.com/google/guava/wiki/StringsExplained#splitter">{@code Splitter}</a>. |
| * |
| * @author Julien Silland |
| * @author Jesse Wilson |
| * @author Kevin Bourrillion |
| * @author Louis Wasserman |
| * @since 1.0 |
| */ |
| @GwtCompatible(emulated = true) |
| public final class Splitter { |
| private final CharMatcher trimmer; |
| private final boolean omitEmptyStrings; |
| private final Strategy strategy; |
| private final int limit; |
| |
| private Splitter(Strategy strategy) { |
| this(strategy, false, CharMatcher.none(), Integer.MAX_VALUE); |
| } |
| |
| private Splitter(Strategy strategy, boolean omitEmptyStrings, CharMatcher trimmer, int limit) { |
| this.strategy = strategy; |
| this.omitEmptyStrings = omitEmptyStrings; |
| this.trimmer = trimmer; |
| this.limit = limit; |
| } |
| |
| /** |
| * Returns a splitter that uses the given single-character separator. For example, {@code |
| * Splitter.on(',').split("foo,,bar")} returns an iterable containing {@code ["foo", "", "bar"]}. |
| * |
| * @param separator the character to recognize as a separator |
| * @return a splitter, with default settings, that recognizes that separator |
| */ |
| public static Splitter on(char separator) { |
| return on(CharMatcher.is(separator)); |
| } |
| |
| /** |
| * Returns a splitter that considers any single character matched by the given {@code CharMatcher} |
| * to be a separator. For example, {@code |
| * Splitter.on(CharMatcher.anyOf(";,")).split("foo,;bar,quux")} returns an iterable containing |
| * {@code ["foo", "", "bar", "quux"]}. |
| * |
| * @param separatorMatcher a {@link CharMatcher} that determines whether a character is a |
| * separator |
| * @return a splitter, with default settings, that uses this matcher |
| */ |
| public static Splitter on(final CharMatcher separatorMatcher) { |
| checkNotNull(separatorMatcher); |
| |
| return new Splitter( |
| new Strategy() { |
| @Override |
| public SplittingIterator iterator(Splitter splitter, final CharSequence toSplit) { |
| return new SplittingIterator(splitter, toSplit) { |
| @Override |
| int separatorStart(int start) { |
| return separatorMatcher.indexIn(toSplit, start); |
| } |
| |
| @Override |
| int separatorEnd(int separatorPosition) { |
| return separatorPosition + 1; |
| } |
| }; |
| } |
| }); |
| } |
| |
| /** |
| * Returns a splitter that uses the given fixed string as a separator. For example, {@code |
| * Splitter.on(", ").split("foo, bar,baz")} returns an iterable containing {@code ["foo", |
| * "bar,baz"]}. |
| * |
| * @param separator the literal, nonempty string to recognize as a separator |
| * @return a splitter, with default settings, that recognizes that separator |
| */ |
| public static Splitter on(final String separator) { |
| checkArgument(separator.length() != 0, "The separator may not be the empty string."); |
| if (separator.length() == 1) { |
| return Splitter.on(separator.charAt(0)); |
| } |
| return new Splitter( |
| new Strategy() { |
| @Override |
| public SplittingIterator iterator(Splitter splitter, CharSequence toSplit) { |
| return new SplittingIterator(splitter, toSplit) { |
| @Override |
| public int separatorStart(int start) { |
| int separatorLength = separator.length(); |
| |
| positions: |
| for (int p = start, last = toSplit.length() - separatorLength; p <= last; p++) { |
| for (int i = 0; i < separatorLength; i++) { |
| if (toSplit.charAt(i + p) != separator.charAt(i)) { |
| continue positions; |
| } |
| } |
| return p; |
| } |
| return -1; |
| } |
| |
| @Override |
| public int separatorEnd(int separatorPosition) { |
| return separatorPosition + separator.length(); |
| } |
| }; |
| } |
| }); |
| } |
| |
| /** |
| * Returns a splitter that considers any subsequence matching {@code pattern} to be a separator. |
| * For example, {@code Splitter.on(Pattern.compile("\r?\n")).split(entireFile)} splits a string |
| * into lines whether it uses DOS-style or UNIX-style line terminators. |
| * |
| * @param separatorPattern the pattern that determines whether a subsequence is a separator. This |
| * pattern may not match the empty string. |
| * @return a splitter, with default settings, that uses this pattern |
| * @throws IllegalArgumentException if {@code separatorPattern} matches the empty string |
| */ |
| @GwtIncompatible // java.util.regex |
| public static Splitter on(Pattern separatorPattern) { |
| return on(new JdkPattern(separatorPattern)); |
| } |
| |
| private static Splitter on(final CommonPattern separatorPattern) { |
| checkArgument( |
| !separatorPattern.matcher("").matches(), |
| "The pattern may not match the empty string: %s", |
| separatorPattern); |
| |
| return new Splitter( |
| new Strategy() { |
| @Override |
| public SplittingIterator iterator(final Splitter splitter, CharSequence toSplit) { |
| final CommonMatcher matcher = separatorPattern.matcher(toSplit); |
| return new SplittingIterator(splitter, toSplit) { |
| @Override |
| public int separatorStart(int start) { |
| return matcher.find(start) ? matcher.start() : -1; |
| } |
| |
| @Override |
| public int separatorEnd(int separatorPosition) { |
| return matcher.end(); |
| } |
| }; |
| } |
| }); |
| } |
| |
| /** |
| * Returns a splitter that considers any subsequence matching a given pattern (regular expression) |
| * to be a separator. For example, {@code Splitter.onPattern("\r?\n").split(entireFile)} splits a |
| * string into lines whether it uses DOS-style or UNIX-style line terminators. This is equivalent |
| * to {@code Splitter.on(Pattern.compile(pattern))}. |
| * |
| * @param separatorPattern the pattern that determines whether a subsequence is a separator. This |
| * pattern may not match the empty string. |
| * @return a splitter, with default settings, that uses this pattern |
| * @throws IllegalArgumentException if {@code separatorPattern} matches the empty string or is a |
| * malformed expression |
| */ |
| @GwtIncompatible // java.util.regex |
| public static Splitter onPattern(String separatorPattern) { |
| return on(Platform.compilePattern(separatorPattern)); |
| } |
| |
| /** |
| * Returns a splitter that divides strings into pieces of the given length. For example, {@code |
| * Splitter.fixedLength(2).split("abcde")} returns an iterable containing {@code ["ab", "cd", |
| * "e"]}. The last piece can be smaller than {@code length} but will never be empty. |
| * |
| * <p><b>Note:</b> if {@link #fixedLength} is used in conjunction with {@link #limit}, the final |
| * split piece <i>may be longer than the specified fixed length</i>. This is because the splitter |
| * will <i>stop splitting when the limit is reached</i>, and just return the final piece as-is. |
| * |
| * <p><b>Exception:</b> for consistency with separator-based splitters, {@code split("")} does not |
| * yield an empty iterable, but an iterable containing {@code ""}. This is the only case in which |
| * {@code Iterables.size(split(input))} does not equal {@code IntMath.divide(input.length(), |
| * length, CEILING)}. To avoid this behavior, use {@code omitEmptyStrings}. |
| * |
| * @param length the desired length of pieces after splitting, a positive integer |
| * @return a splitter, with default settings, that can split into fixed sized pieces |
| * @throws IllegalArgumentException if {@code length} is zero or negative |
| */ |
| public static Splitter fixedLength(final int length) { |
| checkArgument(length > 0, "The length may not be less than 1"); |
| |
| return new Splitter( |
| new Strategy() { |
| @Override |
| public SplittingIterator iterator(final Splitter splitter, CharSequence toSplit) { |
| return new SplittingIterator(splitter, toSplit) { |
| @Override |
| public int separatorStart(int start) { |
| int nextChunkStart = start + length; |
| return (nextChunkStart < toSplit.length() ? nextChunkStart : -1); |
| } |
| |
| @Override |
| public int separatorEnd(int separatorPosition) { |
| return separatorPosition; |
| } |
| }; |
| } |
| }); |
| } |
| |
| /** |
| * Returns a splitter that behaves equivalently to {@code this} splitter, but automatically omits |
| * empty strings from the results. For example, {@code |
| * Splitter.on(',').omitEmptyStrings().split(",a,,,b,c,,")} returns an iterable containing only |
| * {@code ["a", "b", "c"]}. |
| * |
| * <p>If either {@code trimResults} option is also specified when creating a splitter, that |
| * splitter always trims results first before checking for emptiness. So, for example, {@code |
| * Splitter.on(':').omitEmptyStrings().trimResults().split(": : : ")} returns an empty iterable. |
| * |
| * <p>Note that it is ordinarily not possible for {@link #split(CharSequence)} to return an empty |
| * iterable, but when using this option, it can (if the input sequence consists of nothing but |
| * separators). |
| * |
| * @return a splitter with the desired configuration |
| */ |
| public Splitter omitEmptyStrings() { |
| return new Splitter(strategy, true, trimmer, limit); |
| } |
| |
| /** |
| * Returns a splitter that behaves equivalently to {@code this} splitter but stops splitting after |
| * it reaches the limit. The limit defines the maximum number of items returned by the iterator, |
| * or the maximum size of the list returned by {@link #splitToList}. |
| * |
| * <p>For example, {@code Splitter.on(',').limit(3).split("a,b,c,d")} returns an iterable |
| * containing {@code ["a", "b", "c,d"]}. When omitting empty strings, the omitted strings do not |
| * count. Hence, {@code Splitter.on(',').limit(3).omitEmptyStrings().split("a,,,b,,,c,d")} returns |
| * an iterable containing {@code ["a", "b", "c,d"}. When trim is requested, all entries are |
| * trimmed, including the last. Hence {@code Splitter.on(',').limit(3).trimResults().split(" a , b |
| * , c , d ")} results in {@code ["a", "b", "c , d"]}. |
| * |
| * @param limit the maximum number of items returned |
| * @return a splitter with the desired configuration |
| * @since 9.0 |
| */ |
| public Splitter limit(int limit) { |
| checkArgument(limit > 0, "must be greater than zero: %s", limit); |
| return new Splitter(strategy, omitEmptyStrings, trimmer, limit); |
| } |
| |
| /** |
| * Returns a splitter that behaves equivalently to {@code this} splitter, but automatically |
| * removes leading and trailing {@linkplain CharMatcher#whitespace whitespace} from each returned |
| * substring; equivalent to {@code trimResults(CharMatcher.whitespace())}. For example, {@code |
| * Splitter.on(',').trimResults().split(" a, b ,c ")} returns an iterable containing {@code ["a", |
| * "b", "c"]}. |
| * |
| * @return a splitter with the desired configuration |
| */ |
| public Splitter trimResults() { |
| return trimResults(CharMatcher.whitespace()); |
| } |
| |
| /** |
| * Returns a splitter that behaves equivalently to {@code this} splitter, but removes all leading |
| * or trailing characters matching the given {@code CharMatcher} from each returned substring. For |
| * example, {@code Splitter.on(',').trimResults(CharMatcher.is('_')).split("_a ,_b_ ,c__")} |
| * returns an iterable containing {@code ["a ", "b_ ", "c"]}. |
| * |
| * @param trimmer a {@link CharMatcher} that determines whether a character should be removed from |
| * the beginning/end of a subsequence |
| * @return a splitter with the desired configuration |
| */ |
| // TODO(kevinb): throw if a trimmer was already specified! |
| public Splitter trimResults(CharMatcher trimmer) { |
| checkNotNull(trimmer); |
| return new Splitter(strategy, omitEmptyStrings, trimmer, limit); |
| } |
| |
| /** |
| * Splits {@code sequence} into string components and makes them available through an {@link |
| * Iterator}, which may be lazily evaluated. If you want an eagerly computed {@link List}, use |
| * {@link #splitToList(CharSequence)}. |
| * |
| * @param sequence the sequence of characters to split |
| * @return an iteration over the segments split from the parameter |
| */ |
| public Iterable<String> split(final CharSequence sequence) { |
| checkNotNull(sequence); |
| |
| return new Iterable<String>() { |
| @Override |
| public Iterator<String> iterator() { |
| return splittingIterator(sequence); |
| } |
| |
| @Override |
| public String toString() { |
| return Joiner.on(", ") |
| .appendTo(new StringBuilder().append('['), this) |
| .append(']') |
| .toString(); |
| } |
| }; |
| } |
| |
| private Iterator<String> splittingIterator(CharSequence sequence) { |
| return strategy.iterator(this, sequence); |
| } |
| |
| /** |
| * Splits {@code sequence} into string components and returns them as an immutable list. If you |
| * want an {@link Iterable} which may be lazily evaluated, use {@link #split(CharSequence)}. |
| * |
| * @param sequence the sequence of characters to split |
| * @return an immutable list of the segments split from the parameter |
| * @since 15.0 |
| */ |
| public List<String> splitToList(CharSequence sequence) { |
| checkNotNull(sequence); |
| |
| Iterator<String> iterator = splittingIterator(sequence); |
| List<String> result = new ArrayList<>(); |
| |
| while (iterator.hasNext()) { |
| result.add(iterator.next()); |
| } |
| |
| return Collections.unmodifiableList(result); |
| } |
| |
| /** |
| * Returns a {@code MapSplitter} which splits entries based on this splitter, and splits entries |
| * into keys and values using the specified separator. |
| * |
| * @since 10.0 |
| */ |
| @Beta |
| public MapSplitter withKeyValueSeparator(String separator) { |
| return withKeyValueSeparator(on(separator)); |
| } |
| |
| /** |
| * Returns a {@code MapSplitter} which splits entries based on this splitter, and splits entries |
| * into keys and values using the specified separator. |
| * |
| * @since 14.0 |
| */ |
| @Beta |
| public MapSplitter withKeyValueSeparator(char separator) { |
| return withKeyValueSeparator(on(separator)); |
| } |
| |
| /** |
| * Returns a {@code MapSplitter} which splits entries based on this splitter, and splits entries |
| * into keys and values using the specified key-value splitter. |
| * |
| * <p>Note: Any configuration option configured on this splitter, such as {@link #trimResults}, |
| * does not change the behavior of the {@code keyValueSplitter}. |
| * |
| * <p>Example: |
| * |
| * <pre>{@code |
| * String toSplit = " x -> y, z-> a "; |
| * Splitter outerSplitter = Splitter.on(',').trimResults(); |
| * MapSplitter mapSplitter = outerSplitter.withKeyValueSeparator(Splitter.on("->")); |
| * Map<String, String> result = mapSplitter.split(toSplit); |
| * assertThat(result).isEqualTo(ImmutableMap.of("x ", " y", "z", " a")); |
| * }</pre> |
| * |
| * @since 10.0 |
| */ |
| @Beta |
| public MapSplitter withKeyValueSeparator(Splitter keyValueSplitter) { |
| return new MapSplitter(this, keyValueSplitter); |
| } |
| |
| /** |
| * An object that splits strings into maps as {@code Splitter} splits iterables and lists. Like |
| * {@code Splitter}, it is thread-safe and immutable. The common way to build instances is by |
| * providing an additional {@linkplain Splitter#withKeyValueSeparator key-value separator} to |
| * {@link Splitter}. |
| * |
| * @since 10.0 |
| */ |
| @Beta |
| public static final class MapSplitter { |
| private static final String INVALID_ENTRY_MESSAGE = "Chunk [%s] is not a valid entry"; |
| private final Splitter outerSplitter; |
| private final Splitter entrySplitter; |
| |
| private MapSplitter(Splitter outerSplitter, Splitter entrySplitter) { |
| this.outerSplitter = outerSplitter; // only "this" is passed |
| this.entrySplitter = checkNotNull(entrySplitter); |
| } |
| |
| /** |
| * Splits {@code sequence} into substrings, splits each substring into an entry, and returns an |
| * unmodifiable map with each of the entries. For example, {@code |
| * Splitter.on(';').trimResults().withKeyValueSeparator("=>").split("a=>b ; c=>b")} will return |
| * a mapping from {@code "a"} to {@code "b"} and {@code "c"} to {@code "b"}. |
| * |
| * <p>The returned map preserves the order of the entries from {@code sequence}. |
| * |
| * @throws IllegalArgumentException if the specified sequence does not split into valid map |
| * entries, or if there are duplicate keys |
| */ |
| public Map<String, String> split(CharSequence sequence) { |
| Map<String, String> map = new LinkedHashMap<>(); |
| for (String entry : outerSplitter.split(sequence)) { |
| Iterator<String> entryFields = entrySplitter.splittingIterator(entry); |
| |
| checkArgument(entryFields.hasNext(), INVALID_ENTRY_MESSAGE, entry); |
| String key = entryFields.next(); |
| checkArgument(!map.containsKey(key), "Duplicate key [%s] found.", key); |
| |
| checkArgument(entryFields.hasNext(), INVALID_ENTRY_MESSAGE, entry); |
| String value = entryFields.next(); |
| map.put(key, value); |
| |
| checkArgument(!entryFields.hasNext(), INVALID_ENTRY_MESSAGE, entry); |
| } |
| return Collections.unmodifiableMap(map); |
| } |
| } |
| |
| private interface Strategy { |
| Iterator<String> iterator(Splitter splitter, CharSequence toSplit); |
| } |
| |
| private abstract static class SplittingIterator extends AbstractIterator<String> { |
| final CharSequence toSplit; |
| final CharMatcher trimmer; |
| final boolean omitEmptyStrings; |
| |
| /** |
| * Returns the first index in {@code toSplit} at or after {@code start} that contains the |
| * separator. |
| */ |
| abstract int separatorStart(int start); |
| |
| /** |
| * Returns the first index in {@code toSplit} after {@code separatorPosition} that does not |
| * contain a separator. This method is only invoked after a call to {@code separatorStart}. |
| */ |
| abstract int separatorEnd(int separatorPosition); |
| |
| int offset = 0; |
| int limit; |
| |
| protected SplittingIterator(Splitter splitter, CharSequence toSplit) { |
| this.trimmer = splitter.trimmer; |
| this.omitEmptyStrings = splitter.omitEmptyStrings; |
| this.limit = splitter.limit; |
| this.toSplit = toSplit; |
| } |
| |
| @Override |
| protected String computeNext() { |
| /* |
| * The returned string will be from the end of the last match to the beginning of the next |
| * one. nextStart is the start position of the returned substring, while offset is the place |
| * to start looking for a separator. |
| */ |
| int nextStart = offset; |
| while (offset != -1) { |
| int start = nextStart; |
| int end; |
| |
| int separatorPosition = separatorStart(offset); |
| if (separatorPosition == -1) { |
| end = toSplit.length(); |
| offset = -1; |
| } else { |
| end = separatorPosition; |
| offset = separatorEnd(separatorPosition); |
| } |
| if (offset == nextStart) { |
| /* |
| * This occurs when some pattern has an empty match, even if it doesn't match the empty |
| * string -- for example, if it requires lookahead or the like. The offset must be |
| * increased to look for separators beyond this point, without changing the start position |
| * of the next returned substring -- so nextStart stays the same. |
| */ |
| offset++; |
| if (offset > toSplit.length()) { |
| offset = -1; |
| } |
| continue; |
| } |
| |
| while (start < end && trimmer.matches(toSplit.charAt(start))) { |
| start++; |
| } |
| while (end > start && trimmer.matches(toSplit.charAt(end - 1))) { |
| end--; |
| } |
| |
| if (omitEmptyStrings && start == end) { |
| // Don't include the (unused) separator in next split string. |
| nextStart = offset; |
| continue; |
| } |
| |
| if (limit == 1) { |
| // The limit has been reached, return the rest of the string as the |
| // final item. This is tested after empty string removal so that |
| // empty strings do not count towards the limit. |
| end = toSplit.length(); |
| offset = -1; |
| // Since we may have changed the end, we need to trim it again. |
| while (end > start && trimmer.matches(toSplit.charAt(end - 1))) { |
| end--; |
| } |
| } else { |
| limit--; |
| } |
| |
| return toSplit.subSequence(start, end).toString(); |
| } |
| return endOfData(); |
| } |
| } |
| } |
