Class GenericPatternCache

  • All Implemented Interfaces:
    PatternCache
    Direct Known Subclasses:
    PatternCacheLRU

    public abstract class GenericPatternCache
    extends java.lang.Object
    implements PatternCache
    This is the base class for all cache implementations provided in the org.apache.oro.text package. Although 4 subclasses of GenericPatternCache are provided with this package, users may not derive subclasses from this class. Rather, users should create their own implmentations of the PatternCache interface.
    Since:
    1.0
    See Also:
    PatternCache, PatternCacheLRU
    • Field Summary

      Fields 
      Modifier and Type Field Description
      (package private) Cache _cache  
      (package private) PatternCompiler _compiler  
      static int DEFAULT_CAPACITY
      The default capacity to be used by the GenericPatternCache subclasses provided with this package.
    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      (package private) Pattern addPattern​(java.lang.String expression)
      Same as calling
      Pattern addPattern​(java.lang.String expression, int options)
      Adds a pattern to the cache and returns the compiled pattern.
      int capacity()
      Returns the maximum number of patterns that can be cached at one time.
      Pattern getPattern​(java.lang.String expression)
      Same as calling
      Pattern getPattern​(java.lang.String expression, int options)
      This method fetches a pattern from the cache.
      int size()
      Returns the number of elements in the cache, not to be confused with the capacity() which returns the number of elements that can be held in the cache at one time.
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    • Field Detail

      • DEFAULT_CAPACITY

        public static final int DEFAULT_CAPACITY
        The default capacity to be used by the GenericPatternCache subclasses provided with this package. Its value is 20.
        See Also:
        Constant Field Values
    • Constructor Detail

      • GenericPatternCache

        GenericPatternCache​(Cache cache,
                            PatternCompiler compiler)
        The primary constructor for GenericPatternCache. It has default access so it will only be used within the package. It initializes _cache and _compiler to the arguments provided.

        Parameters:
        cache - The cache with which to store patterns.
        compiler - The PatternCompiler that should be used to compile patterns.
    • Method Detail

      • addPattern

        public final Pattern addPattern​(java.lang.String expression,
                                        int options)
                                 throws MalformedPatternException
        Adds a pattern to the cache and returns the compiled pattern. This method is in principle almost identical to getPattern() except for the fact that it throws a MalformedPatternException if an expression cannot be compiled.

        addPattern() is meant to be used when you expressly intend to add an expression to the cache and is useful for front-loading a cache with expressions before use. If the expression added does not already exist in the cache, it is compiled, added to the cache, and returned. If the compiled expression is already in the cache, it is simply returned.

        The expected behavior of this method should be to start replacing patterns in the cache only after the cache has been filled to capacity.

        Specified by:
        addPattern in interface PatternCache
        Parameters:
        expression - The regular expression to add to the cache.
        options - The compilation options to use when compiling the expression.
        Returns:
        The Pattern corresponding to the String representation of the regular expression.
        Throws:
        MalformedPatternException - If there is an error in compiling the regular expression.
      • getPattern

        public final Pattern getPattern​(java.lang.String expression,
                                        int options)
                                 throws MalformedCachePatternException
        This method fetches a pattern from the cache. It is nearly identical to addPattern() except that it doesn't throw a MalformedPatternException. If the pattern is not in the cache, it is compiled, placed in the cache, and returned. If the pattern cannot be compiled successfully, it throws a MalformedCachePatternException. Note that this exception is derived from RuntimeException, which means you are NOT forced to catch it by the compiler. Please refer to MalformedCachePatternException for a discussion of when you should and shouldn't catch this exception.

        Specified by:
        getPattern in interface PatternCache
        Parameters:
        expression - The regular expression to fetch from the cache in compiled form.
        options - The compilation options to use when compiling the expression.
        Returns:
        The Pattern corresponding to the String representation of the regular expression.
        Throws:
        MalformedCachePatternException - If there is an error in compiling the regular expression.
      • getPattern

        public final Pattern getPattern​(java.lang.String expression)
                                 throws MalformedCachePatternException
        Same as calling
         getPattern(expression, 0)
         
        Specified by:
        getPattern in interface PatternCache
        Parameters:
        expression - The regular expression to fetch from the cache in compiled form.
        Returns:
        The Pattern corresponding to the String representation of the regular expression.
        Throws:
        MalformedCachePatternException - If there is an error in compiling the regular expression.
      • size

        public final int size()
        Returns the number of elements in the cache, not to be confused with the capacity() which returns the number of elements that can be held in the cache at one time.

        Returns:
        The current size of the cache (i.e., the number of elements currently cached).
      • capacity

        public final int capacity()
        Returns the maximum number of patterns that can be cached at one time.

        Specified by:
        capacity in interface PatternCache
        Returns:
        The maximum number of patterns that can be cached at one time.