Class RuleBasedBreakIterator

  • All Implemented Interfaces:
    Cloneable

    public class RuleBasedBreakIterator
    extends BreakIterator
    Rule Based Break Iterator This is a port of the C++ class RuleBasedBreakIterator from ICU4C.
    • Field Detail

      • fRData

        @Deprecated
        public com.ibm.icu.impl.RBBIDataWrapper fRData
        Deprecated.
        This API is ICU internal only.
        The rule data for this BreakIterator instance. Not intended for public use. Declared public for testing purposes only.
      • fDebugEnv

        @Deprecated
        public static final String fDebugEnv
        Deprecated.
        This API is ICU internal only.
        Control debug, trace and dump options.
    • Constructor Detail

      • RuleBasedBreakIterator

        public RuleBasedBreakIterator​(String rules)
        Construct a RuleBasedBreakIterator from a set of rules supplied as a string.
        Parameters:
        rules - The break rules to be used.
    • Method Detail

      • getInstanceFromCompiledRules

        public static RuleBasedBreakIterator getInstanceFromCompiledRules​(InputStream is)
                                                                   throws IOException
        Create a break iterator from a precompiled set of break rules. Creating a break iterator from the binary rules is much faster than creating one from source rules. The binary rules are generated by the RuleBasedBreakIterator.compileRules() function. Binary break iterator rules are not guaranteed to be compatible between different versions of ICU.
        Parameters:
        is - an input stream supplying the compiled binary rules.
        Throws:
        IOException - if there is an error while reading the rules from the InputStream.
        See Also:
        compileRules(String, OutputStream)
      • getInstanceFromCompiledRules

        @Deprecated
        public static RuleBasedBreakIterator getInstanceFromCompiledRules​(ByteBuffer bytes)
                                                                   throws IOException
        Deprecated.
        This API is ICU internal only.
        Create a break iterator from a precompiled set of break rules. Creating a break iterator from the binary rules is much faster than creating one from source rules. The binary rules are generated by the RuleBasedBreakIterator.compileRules() function. Binary break iterator rules are not guaranteed to be compatible between different versions of ICU.
        Parameters:
        bytes - a buffer supplying the compiled binary rules.
        Throws:
        IOException - if there is an error while reading the rules from the buffer.
        See Also:
        compileRules(String, OutputStream)
      • clone

        public Object clone()
        Clones this iterator.
        Overrides:
        clone in class BreakIterator
        Returns:
        A newly-constructed RuleBasedBreakIterator with the same behavior as this one.
      • equals

        public boolean equals​(Object that)
        Returns true if both BreakIterators are of the same class, have the same rules, and iterate over the same text.
        Overrides:
        equals in class Object
      • toString

        public String toString()
        Returns the description (rules) used to create this iterator. (In ICU4C, the same function is RuleBasedBreakIterator::getRules())
        Overrides:
        toString in class Object
      • hashCode

        public int hashCode()
        Compute a hashcode for this BreakIterator
        Overrides:
        hashCode in class Object
        Returns:
        A hash code
      • dump

        @Deprecated
        public void dump​(PrintStream out)
        Deprecated.
        This API is ICU internal only.
        Dump the contents of the state table and character classes for this break iterator. For debugging only.
      • compileRules

        public static void compileRules​(String rules,
                                        OutputStream ruleBinary)
                                 throws IOException
        Compile a set of source break rules into the binary state tables used by the break iterator engine. Creating a break iterator from precompiled rules is much faster than creating one from source rules. Binary break rules are not guaranteed to be compatible between different versions of ICU.
        Parameters:
        rules - The source form of the break rules
        ruleBinary - An output stream to receive the compiled rules.
        Throws:
        IOException - If there is an error writing the output.
        See Also:
        getInstanceFromCompiledRules(InputStream)
      • first

        public int first()
        Sets the current iteration position to the beginning of the text. (i.e., the CharacterIterator's starting offset).
        Specified by:
        first in class BreakIterator
        Returns:
        The offset of the beginning of the text.
      • last

        public int last()
        Sets the current iteration position to the end of the text. (i.e., the CharacterIterator's ending offset).
        Specified by:
        last in class BreakIterator
        Returns:
        The text's past-the-end offset.
      • next

        public int next​(int n)
        Advances the iterator either forward or backward the specified number of steps. Negative values move backward, and positive values move forward. This is equivalent to repeatedly calling next() or previous().
        Specified by:
        next in class BreakIterator
        Parameters:
        n - The number of steps to move. The sign indicates the direction (negative is backwards, and positive is forwards).
        Returns:
        The character offset of the boundary position n boundaries away from the current one.
      • next

        public int next()
        Advances the iterator to the next boundary position.
        Specified by:
        next in class BreakIterator
        Returns:
        The position of the first boundary after this one.
      • previous

        public int previous()
        Moves the iterator backwards, to the boundary preceding the current one.
        Specified by:
        previous in class BreakIterator
        Returns:
        The position of the boundary position immediately preceding the starting position.
      • following

        public int following​(int startPos)
        Sets the iterator to refer to the first boundary position following the specified position.
        Specified by:
        following in class BreakIterator
        Parameters:
        startPos - The position from which to begin searching for a break position.
        Returns:
        The position of the first break after the current position.
      • preceding

        public int preceding​(int offset)
        Sets the iterator to refer to the last boundary position before the specified position.
        Overrides:
        preceding in class BreakIterator
        Parameters:
        offset - The position to begin searching for a break from.
        Returns:
        The position of the last boundary before the starting position.
      • checkOffset

        protected static final void checkOffset​(int offset,
                                                CharacterIterator text)
        Throw IllegalArgumentException unless begin <= offset < end.
      • isBoundary

        public boolean isBoundary​(int offset)
        Returns true if the specified position is a boundary position. As a side effect, leaves the iterator pointing to the first boundary position at or after "offset".
        Overrides:
        isBoundary in class BreakIterator
        Parameters:
        offset - the offset to check.
        Returns:
        True if "offset" is a boundary position.
      • current

        public int current()
        Returns the current iteration position. Note that DONE is never returned from this function; if iteration has run to the end of a string, current() will return the length of the string while next() will return BreakIterator.DONE).
        Specified by:
        current in class BreakIterator
        Returns:
        The current iteration position.
      • getRuleStatus

        public int getRuleStatus()
        Return the status tag from the break rule that determined the boundary at the current iteration position. The values appear in the rule source within brackets, {123}, for example. For rules that do not specify a status, a default value of 0 is returned. If more than one rule applies, the numerically largest of the possible status values is returned.

        Of the standard types of ICU break iterators, only the word and line break iterator provides status values. The values are defined in class RuleBasedBreakIterator, and allow distinguishing between words that contain alphabetic letters, "words" that appear to be numbers, punctuation and spaces, words containing ideographic characters, and more. Call getRuleStatus after obtaining a boundary position from next(), previous(), or any other break iterator functions that returns a boundary position.

        Note that getRuleStatus() returns the value corresponding to current() index even after next() has returned DONE.

        Overrides:
        getRuleStatus in class BreakIterator
        Returns:
        the status from the break rule that determined the boundary at the current iteration position.
      • getRuleStatusVec

        public int getRuleStatusVec​(int[] fillInArray)
        Get the status (tag) values from the break rule(s) that determined the boundary at the current iteration position. The values appear in the rule source within brackets, {123}, for example. The default status value for rules that do not explicitly provide one is zero.

        The status values used by the standard ICU break rules are defined as public constants in class RuleBasedBreakIterator.

        If the size of the output array is insufficient to hold the data, the output will be truncated to the available length. No exception will be thrown.

        Overrides:
        getRuleStatusVec in class BreakIterator
        Parameters:
        fillInArray - an array to be filled in with the status values.
        Returns:
        The number of rule status values from the rules that determined the boundary at the current iteration position. In the event that the array is too small, the return value is the total number of status values that were available, not the reduced number that were actually returned.
      • getText

        public CharacterIterator getText()
        Return a CharacterIterator over the text being analyzed. This version of this method returns the actual CharacterIterator we're using internally. Changing the state of this iterator can have undefined consequences. If you need to change it, clone it first.
        Specified by:
        getText in class BreakIterator
        Returns:
        An iterator over the text being analyzed.
      • setText

        public void setText​(CharacterIterator newText)
        Set the iterator to analyze a new piece of text. This function resets the current iteration position to the beginning of the text.
        Specified by:
        setText in class BreakIterator
        Parameters:
        newText - An iterator over the text to analyze.