001/////////////////////////////////////////////////////////////////////////////////////////////// 002// checkstyle: Checks Java source code and other text files for adherence to a set of rules. 003// Copyright (C) 2001-2024 the original author or authors. 004// 005// This library is free software; you can redistribute it and/or 006// modify it under the terms of the GNU Lesser General Public 007// License as published by the Free Software Foundation; either 008// version 2.1 of the License, or (at your option) any later version. 009// 010// This library is distributed in the hope that it will be useful, 011// but WITHOUT ANY WARRANTY; without even the implied warranty of 012// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 013// Lesser General Public License for more details. 014// 015// You should have received a copy of the GNU Lesser General Public 016// License along with this library; if not, write to the Free Software 017// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 018/////////////////////////////////////////////////////////////////////////////////////////////// 019 020package com.puppycrawl.tools.checkstyle; 021 022import java.util.Map; 023import java.util.Properties; 024import java.util.function.Function; 025import java.util.stream.Collectors; 026 027/** 028 * Resolves external properties from an 029 * underlying {@code Properties} object. 030 * 031 */ 032public final class PropertiesExpander 033 implements PropertyResolver { 034 035 /** The underlying values. */ 036 private final Map<String, String> values; 037 038 /** 039 * Creates a new PropertiesExpander. 040 * 041 * @param properties the underlying properties to use for 042 * property resolution. 043 * @throws IllegalArgumentException when properties argument is null 044 */ 045 public PropertiesExpander(Properties properties) { 046 if (properties == null) { 047 throw new IllegalArgumentException("cannot pass null"); 048 } 049 values = properties.stringPropertyNames() 050 .stream() 051 .collect( 052 Collectors.toUnmodifiableMap(Function.identity(), properties::getProperty)); 053 } 054 055 @Override 056 public String resolve(String name) { 057 return values.get(name); 058 } 059 060}