org.apache.oro.text
Interface PatternCache
- GenericPatternCache, PatternCacheFIFO, PatternCacheFIFO2, PatternCacheLRU, PatternCacheRandom
public interface PatternCache
An interface defining the basic functions of a regular expression
cache.
A PatternCache is an object that takes care of compiling, storing, and
retrieving regular expressions so that the programmer does not have to
explicitly manage these operation himself. The main benefit derived
is the ease of use from only having to express regular expressions
by their String representations.
Pattern | addPattern(String expression) - Adds a pattern to the cache and returns the compiled pattern.
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Pattern | addPattern(String expression, int options) - Adds a pattern to the cache and returns the compiled pattern.
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int | capacity() - Returns the maximum number of patterns that can be cached at one time.
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Pattern | getPattern(String expression) - This method fetches a pattern from the cache.
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Pattern | getPattern(String expression, int options) - This method fetches a pattern from the cache.
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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.
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addPattern
public Pattern addPattern(String expression)
throws MalformedPatternException
Adds a pattern to the cache and returns the compiled pattern. This
method is in principle almost identical to
getPattern(String)
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 a 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.
expression
- The regular expression to add to the cache.
- The Pattern corresponding to the String representation of the
regular expression.
addPattern
public Pattern addPattern(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(String)
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.
expression
- The regular expression to add to the cache.options
- The compilation options to use when compiling the
expression.
- The Pattern corresponding to the String representation of the
regular expression.
capacity
public int capacity()
Returns the maximum number of patterns that can be cached at one time.
- The maximum number of patterns that can be cached at one time.
getPattern
public Pattern getPattern(String expression)
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, the implementation must
throw an exception derived from 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.
expression
- The regular expression to fetch from the cache in
compiled form.
- The Pattern corresponding to the String representation of the
regular expression.
getPattern
public Pattern getPattern(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.
expression
- The regular expression to fetch from the cache in
compiled form.options
- The compilation options to use when compiling the
expression.
- The Pattern corresponding to the String representation of the
regular expression.
size
public 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.
- The current size of the cache (i.e., the number of elements
currently cached).
Copyright B) 2000-2003 Apache Software Foundation. All Rights Reserved.