001: /*
002: * $Id: PatternCache.java,v 1.7 2003/11/07 20:16:24 dfs Exp $
003: *
004: * ====================================================================
005: * The Apache Software License, Version 1.1
006: *
007: * Copyright (c) 2000 The Apache Software Foundation. All rights
008: * reserved.
009: *
010: * Redistribution and use in source and binary forms, with or without
011: * modification, are permitted provided that the following conditions
012: * are met:
013: *
014: * 1. Redistributions of source code must retain the above copyright
015: * notice, this list of conditions and the following disclaimer.
016: *
017: * 2. Redistributions in binary form must reproduce the above copyright
018: * notice, this list of conditions and the following disclaimer in
019: * the documentation and/or other materials provided with the
020: * distribution.
021: *
022: * 3. The end-user documentation included with the redistribution,
023: * if any, must include the following acknowledgment:
024: * "This product includes software developed by the
025: * Apache Software Foundation (http://www.apache.org/)."
026: * Alternately, this acknowledgment may appear in the software itself,
027: * if and wherever such third-party acknowledgments normally appear.
028: *
029: * 4. The names "Apache" and "Apache Software Foundation", "Jakarta-Oro"
030: * must not be used to endorse or promote products derived from this
031: * software without prior written permission. For written
032: * permission, please contact apache@apache.org.
033: *
034: * 5. Products derived from this software may not be called "Apache"
035: * or "Jakarta-Oro", nor may "Apache" or "Jakarta-Oro" appear in their
036: * name, without prior written permission of the Apache Software Foundation.
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040: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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051: *
052: * This software consists of voluntary contributions made by many
053: * individuals on behalf of the Apache Software Foundation. For more
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056: */
057:
058: package org.apache.oro.text;
059:
060: import org.apache.oro.text.regex.*;
061:
062: /**
063: * An interface defining the basic functions of a regular expression
064: * cache.
065: * <p>
066: * A PatternCache is an object that takes care of compiling, storing, and
067: * retrieving regular expressions so that the programmer does not have to
068: * explicitly manage these operation himself. The main benefit derived
069: * is the ease of use from only having to express regular expressions
070: * by their String representations.
071: *
072: * @version @version@
073: * @since 1.0
074: * @see MalformedCachePatternException
075: */
076:
077: public interface PatternCache {
078:
079: /**
080: * Adds a pattern to the cache and returns the compiled pattern. This
081: * method is in principle almost identical to
082: * {@link #getPattern(String)} except for the fact that
083: * it throws a MalformedPatternException if an expression cannot be
084: * compiled.
085: * <p>
086: * addPattern() is meant to be used when you expressly intend to add
087: * an expression to a cache and is useful for front-loading a cache
088: * with expressions before use. If the expression added does not
089: * already exist in the cache, it is compiled, added to the cache,
090: * and returned. If the compiled expression is already in the cache, it
091: * is simply returned.
092: * <p>
093: * The expected behavior of this method should be to start replacing
094: * patterns in the cache only after the cache has been filled to capacity.
095: * <p>
096: * @param expression The regular expression to add to the cache.
097: * @return The Pattern corresponding to the String representation of the
098: * regular expression.
099: * @exception MalformedPatternException If there is an error in compiling
100: * the regular expression.
101: */
102: public Pattern addPattern(String expression)
103: throws MalformedPatternException;
104:
105: /**
106: * Adds a pattern to the cache and returns the compiled pattern. This
107: * method is in principle almost identical to
108: * {@link #getPattern(String)} except for the fact that
109: * it throws a MalformedPatternException if an expression cannot be
110: * compiled.
111: * <p>
112: * addPattern() is meant to be used when you expressly intend to add
113: * an expression to the cache and is useful for front-loading a cache
114: * with expressions before use. If the expression added does not
115: * already exist in the cache, it is compiled, added to the cache,
116: * and returned. If the compiled expression is already in the cache, it
117: * is simply returned.
118: * <p>
119: * The expected behavior of this method should be to start replacing
120: * patterns in the cache only after the cache has been filled to capacity.
121: * <p>
122: * @param expression The regular expression to add to the cache.
123: * @param options The compilation options to use when compiling the
124: * expression.
125: * @return The Pattern corresponding to the String representation of the
126: * regular expression.
127: * @exception MalformedPatternException If there is an error in compiling
128: * the regular expression.
129: */
130: public Pattern addPattern(String expression, int options)
131: throws MalformedPatternException;
132:
133: /**
134: * This method fetches a pattern from the cache. It is nearly identical
135: * to {@link #addPattern addPattern()} except that it doesn't
136: * throw a MalformedPatternException. If the pattern is not in the
137: * cache, it is compiled, placed in the cache, and returned. If
138: * the pattern cannot be compiled successfully, the implementation must
139: * throw an exception derived from MalformedCachePatternException.
140: * Note that this exception is derived from RuntimeException, which means
141: * you are NOT forced to catch it by the compiler. Please refer to
142: * {@link MalformedCachePatternException} for a discussion of when you
143: * should and shouldn't catch this exception.
144: * <p>
145: * @param expression The regular expression to fetch from the cache in
146: * compiled form.
147: * @return The Pattern corresponding to the String representation of the
148: * regular expression.
149: * @exception MalformedCachePatternException If there is an error in
150: * compiling the regular expression.
151: */
152: public Pattern getPattern(String expression)
153: throws MalformedCachePatternException;
154:
155: /**
156: * This method fetches a pattern from the cache. It is nearly identical
157: * to {@link #addPattern addPattern()} except that it doesn't
158: * throw a MalformedPatternException. If the pattern is not in the
159: * cache, it is compiled, placed in the cache, and returned. If
160: * the pattern cannot be compiled successfully, it
161: * throws a MalformedCachePatternException.
162: * Note that this exception is derived from RuntimeException, which means
163: * you are NOT forced to catch it by the compiler. Please refer to
164: * {@link MalformedCachePatternException} for a discussion of when you
165: * should and shouldn't catch this exception.
166: * <p>
167: * @param expression The regular expression to fetch from the cache in
168: * compiled form.
169: * @param options The compilation options to use when compiling the
170: * expression.
171: * @return The Pattern corresponding to the String representation of the
172: * regular expression.
173: * @exception MalformedCachePatternException If there is an error in
174: * compiling the regular expression.
175: */
176: public Pattern getPattern(String expression, int options)
177: throws MalformedCachePatternException;
178:
179: /**
180: * Returns the number of elements in the cache, not to be confused with
181: * the {@link #capacity()} which returns the number
182: * of elements that can be held in the cache at one time.
183: * <p>
184: * @return The current size of the cache (i.e., the number of elements
185: * currently cached).
186: */
187: public int size();
188:
189: /**
190: * Returns the maximum number of patterns that can be cached at one time.
191: * <p>
192: * @return The maximum number of patterns that can be cached at one time.
193: */
194: public int capacity();
195: }
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