com.netflix.spectator.impl.PatternMatcher Maven / Gradle / Ivy
/*
* Copyright 2014-2020 Netflix, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.netflix.spectator.impl;
import com.netflix.spectator.impl.matcher.PatternUtils;
/**
* Efficient alternative to using {@link java.util.regex.Pattern} for use cases that just
* require basic matching. Calling the matches method should be mostly equivalent to calling
* {@link java.util.regex.Matcher#find()}. It supports most common capabilities of the normal
* java regular expressions. Unsupported features are:
*
*
* - Boundary matchers other than {@code ^} and {@code $}
* - Predefined horizontal and veritical whitespace classes
* - java.lang.Character classes
* - Unicode classes
* - Back references
* - Special constructs other than lookahead
*
*
* This class is an internal implementation detail only intended for use within spectator.
* It is subject to change without notice.
*/
public interface PatternMatcher {
/**
* Returns true if the passed in string matches the pattern.
*/
boolean matches(String str);
/**
* Returns a fixed string prefix for the pattern if one is available. This can be used
* with indexed data to help select a subset of values that are possible matches. If the
* pattern does not have a fixed string prefix, then null will be returned.
*/
default String prefix() {
return null;
}
/**
* The minimum possible length of a matching string. This can be used as a quick check
* to see if there is any way a given string could match.
*/
default int minLength() {
return 0;
}
/**
* Returns true if the pattern is anchored to the start of the string.
*/
default boolean isStartAnchored() {
return false;
}
/**
* Returns true if the pattern is anchored to the end of the string.
*/
default boolean isEndAnchored() {
return false;
}
/**
* Returns true if this matcher will match any string. This can be used as a quick check
* to avoid checking for matches.
*/
default boolean alwaysMatches() {
return false;
}
/**
* Returns true if this matcher will not match any string. This can be used as a quick check
* to avoid checking for matches.
*/
default boolean neverMatches() {
return false;
}
/**
* Returns a new matcher that matches the same pattern only ignoring the case of the input
* string. Note, character classes will be matched as is and must explicitly include both
* cases if that is the desired matching criteria.
*/
default PatternMatcher ignoreCase() {
return this;
}
/**
* Returns a pattern that can be used with a SQL LIKE clause or null if this expression
* cannot be expressed as a SQL pattern. Can be used to more optimally map the pattern
* to a SQL data store.
*/
default String toSqlPattern() {
return null;
}
/**
* Compile a pattern string and return a matcher that can be used to check if string values
* match the pattern. Pattern matchers are can be reused many times and are thread safe.
*/
static PatternMatcher compile(String pattern) {
return PatternUtils.compile(pattern);
}
/**
* Helper function to check if a string value matches the provided pattern. Note, if matching
* many values against the same pattern, then it is much more efficient to use
* {@link #compile(String)} to get an instance of a matcher that can be reused.
*
* @param pattern
* Pattern to use for creating the matcher instance.
* @param value
* Value to check against the pattern.
* @return
* True if the pattern matches the value.
*/
static boolean matches(String pattern, String value) {
return compile(pattern).matches(value);
}
}