Package com.ibm.icu.util
Class CharsTrie
- java.lang.Object
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- com.ibm.icu.util.CharsTrie
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- All Implemented Interfaces:
Cloneable
,Iterable<CharsTrie.Entry>
public final class CharsTrie extends Object implements Cloneable, Iterable<CharsTrie.Entry>
Light-weight, non-const reader class for a CharsTrie. Traverses a char-serialized data structure with minimal state, for mapping strings (16-bit-unit sequences) to non-negative integer values.This class is not intended for public subclassing.
- Author:
- Markus W. Scherer
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Nested Class Summary
Nested Classes Modifier and Type Class Description static class
CharsTrie.Entry
Return value type for the Iterator.static class
CharsTrie.Iterator
Iterator for all of the (string, value) pairs in a CharsTrie.static class
CharsTrie.State
CharsTrie state object, for saving a trie's current state and resetting the trie back to this state later.
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Constructor Summary
Constructors Constructor Description CharsTrie(CharSequence trieChars, int offset)
Constructs a CharsTrie reader instance.
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description Object
clone()
Clones this trie reader object and its state, but not the char array which will be shared.BytesTrie.Result
current()
Determines whether the string so far matches, whether it has a value, and whether another input char can continue a matching string.BytesTrie.Result
first(int inUnit)
Traverses the trie from the initial state for this input char.BytesTrie.Result
firstForCodePoint(int cp)
Traverses the trie from the initial state for the one or two UTF-16 code units for this input code point.int
getNextChars(Appendable out)
Finds each char which continues the string from the current state.long
getUniqueValue()
Determines whether all strings reachable from the current state map to the same value, and if so, returns that value.int
getValue()
Returns a matching string's value if called immediately after current()/first()/next() returned Result.INTERMEDIATE_VALUE or Result.FINAL_VALUE.CharsTrie.Iterator
iterator()
Iterates from the current state of this trie.CharsTrie.Iterator
iterator(int maxStringLength)
Iterates from the current state of this trie.static CharsTrie.Iterator
iterator(CharSequence trieChars, int offset, int maxStringLength)
Iterates from the root of a char-serialized BytesTrie.BytesTrie.Result
next(int inUnit)
Traverses the trie from the current state for this input char.BytesTrie.Result
next(CharSequence s, int sIndex, int sLimit)
Traverses the trie from the current state for this string.BytesTrie.Result
nextForCodePoint(int cp)
Traverses the trie from the current state for the one or two UTF-16 code units for this input code point.CharsTrie
reset()
Resets this trie to its initial state.CharsTrie
resetToState(CharsTrie.State state)
Resets this trie to the saved state.CharsTrie
saveState(CharsTrie.State state)
Saves the state of this trie.-
Methods inherited from class java.lang.Object
equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
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Methods inherited from interface java.lang.Iterable
forEach, spliterator
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Constructor Detail
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CharsTrie
public CharsTrie(CharSequence trieChars, int offset)
Constructs a CharsTrie reader instance.The CharSequence must contain a copy of a char sequence from the CharsTrieBuilder, with the offset indicating the first char of that sequence. The CharsTrie object will not read more chars than the CharsTrieBuilder generated in the corresponding build() call.
The CharSequence is not copied/cloned and must not be modified while the CharsTrie object is in use.
- Parameters:
trieChars
- CharSequence that contains the serialized trie.offset
- Root offset of the trie in the CharSequence.
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Method Detail
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clone
public Object clone() throws CloneNotSupportedException
Clones this trie reader object and its state, but not the char array which will be shared.- Overrides:
clone
in classObject
- Returns:
- A shallow clone of this trie.
- Throws:
CloneNotSupportedException
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reset
public CharsTrie reset()
Resets this trie to its initial state.- Returns:
- this
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saveState
public CharsTrie saveState(CharsTrie.State state)
Saves the state of this trie.- Parameters:
state
- The State object to hold the trie's state.- Returns:
- this
- See Also:
resetToState(com.ibm.icu.util.CharsTrie.State)
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resetToState
public CharsTrie resetToState(CharsTrie.State state)
Resets this trie to the saved state.- Parameters:
state
- The State object which holds a saved trie state.- Returns:
- this
- Throws:
IllegalArgumentException
- if the state object contains no state, or the state of a different trie- See Also:
saveState(com.ibm.icu.util.CharsTrie.State)
,reset()
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current
public BytesTrie.Result current()
Determines whether the string so far matches, whether it has a value, and whether another input char can continue a matching string.- Returns:
- The match/value Result.
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first
public BytesTrie.Result first(int inUnit)
Traverses the trie from the initial state for this input char. Equivalent to reset().next(inUnit).- Parameters:
inUnit
- Input char value. Values below 0 and above 0xffff will never match.- Returns:
- The match/value Result.
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firstForCodePoint
public BytesTrie.Result firstForCodePoint(int cp)
Traverses the trie from the initial state for the one or two UTF-16 code units for this input code point. Equivalent to reset().nextForCodePoint(cp).- Parameters:
cp
- A Unicode code point 0..0x10ffff.- Returns:
- The match/value Result.
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next
public BytesTrie.Result next(int inUnit)
Traverses the trie from the current state for this input char.- Parameters:
inUnit
- Input char value. Values below 0 and above 0xffff will never match.- Returns:
- The match/value Result.
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nextForCodePoint
public BytesTrie.Result nextForCodePoint(int cp)
Traverses the trie from the current state for the one or two UTF-16 code units for this input code point.- Parameters:
cp
- A Unicode code point 0..0x10ffff.- Returns:
- The match/value Result.
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next
public BytesTrie.Result next(CharSequence s, int sIndex, int sLimit)
Traverses the trie from the current state for this string. Equivalent toResult result=current(); for(each c in s) if(!result.hasNext()) return Result.NO_MATCH; result=next(c); return result;
- Parameters:
s
- Contains a string.sIndex
- The start index of the string in s.sLimit
- The (exclusive) end index of the string in s.- Returns:
- The match/value Result.
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getValue
public int getValue()
Returns a matching string's value if called immediately after current()/first()/next() returned Result.INTERMEDIATE_VALUE or Result.FINAL_VALUE. getValue() can be called multiple times. Do not call getValue() after Result.NO_MATCH or Result.NO_VALUE!- Returns:
- The value for the string so far.
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getUniqueValue
public long getUniqueValue()
Determines whether all strings reachable from the current state map to the same value, and if so, returns that value.- Returns:
- The unique value in bits 32..1 with bit 0 set, if all strings reachable from the current state map to the same value; otherwise returns 0.
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getNextChars
public int getNextChars(Appendable out)
Finds each char which continues the string from the current state. That is, each char c for which it would be next(c)!=Result.NO_MATCH now.- Parameters:
out
- Each next char is appended to this object. (Only uses the out.append(c) method.)- Returns:
- The number of chars which continue the string from here.
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iterator
public CharsTrie.Iterator iterator()
Iterates from the current state of this trie.- Specified by:
iterator
in interfaceIterable<CharsTrie.Entry>
- Returns:
- A new CharsTrie.Iterator.
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iterator
public CharsTrie.Iterator iterator(int maxStringLength)
Iterates from the current state of this trie.- Parameters:
maxStringLength
- If 0, the iterator returns full strings. Otherwise, the iterator returns strings with this maximum length.- Returns:
- A new CharsTrie.Iterator.
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iterator
public static CharsTrie.Iterator iterator(CharSequence trieChars, int offset, int maxStringLength)
Iterates from the root of a char-serialized BytesTrie.- Parameters:
trieChars
- CharSequence that contains the serialized trie.offset
- Root offset of the trie in the CharSequence.maxStringLength
- If 0, the iterator returns full strings. Otherwise, the iterator returns strings with this maximum length.- Returns:
- A new CharsTrie.Iterator.
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