| package org.apache.maven.plugin.coreit; |
| |
| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you 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. |
| */ |
| |
| import java.lang.reflect.Array; |
| import java.lang.reflect.Field; |
| import java.lang.reflect.Method; |
| import java.util.Arrays; |
| import java.util.Collection; |
| import java.util.Collections; |
| import java.util.Iterator; |
| import java.util.LinkedHashMap; |
| import java.util.List; |
| import java.util.Map; |
| |
| /** |
| * Assists in evaluating expressions. |
| * |
| * @author Benjamin Bentmann |
| * |
| */ |
| class ExpressionUtil |
| { |
| |
| private static final Object[] NO_ARGS = {}; |
| |
| private static final Class[] NO_PARAMS = {}; |
| |
| private static final Class[] OBJECT_PARAM = { Object.class }; |
| |
| private static final Class[] STRING_PARAM = { String.class }; |
| |
| /** |
| * Evaluates the specified expression. Expressions are composed of segments which are separated by a forward slash |
| * ('/'). Each segment specifies a (public) bean property of the current object and drives the evaluation further |
| * down the object graph. For lists, arrays and maps segments can additionally specify the index/key of an element. |
| * The initial segment denotes the root object and the parameter <code>contexts</code> is used to specify which root |
| * objects are available. For instance, if <code>contexts</code> maps the token "project" to a Maven project |
| * instance, the expression "project/build/resources/0/directory" specifies the first resource directory of the |
| * project. |
| * |
| * @param expression The expression to evaluate, may be <code>null</code>. |
| * @param context The object to start expression evaluation at, must not be <code>null</code>. |
| * @return The values of the evaluation, indexed by expression, or an empty map if the segments could not be |
| * evaluated. |
| */ |
| public static Map evaluate( String expression, Object context ) |
| { |
| Map values = Collections.EMPTY_MAP; |
| |
| if ( expression != null && expression.length() > 0 ) |
| { |
| List segments = Arrays.asList( expression.split( "/", 0 ) ); |
| values = evaluate( "", segments, context ); |
| } |
| |
| return values; |
| } |
| |
| /** |
| * Evaluates the given expression segments against the specified object. |
| * |
| * @param prefix The expression prefix that led to the current context, must not be <code>null</code>. |
| * @param segments The expression segments to evaluate, must not be <code>null</code>. |
| * @param context The object to evaluate the segments against, may be <code>null</code>. |
| * @return The values of the evaluation, indexed by expression, or an empty map if the segments could not be |
| * evaluated. |
| */ |
| private static Map evaluate( String prefix, List segments, Object context ) |
| { |
| Map values = Collections.EMPTY_MAP; |
| |
| if ( segments.isEmpty() ) |
| { |
| values = Collections.singletonMap( prefix, context ); |
| } |
| else if ( context != null ) |
| { |
| Map targets = Collections.EMPTY_MAP; |
| String segment = (String) segments.get( 0 ); |
| if ( context.getClass().isArray() && Character.isDigit( segment.charAt( 0 ) ) ) |
| { |
| try |
| { |
| int index = Integer.parseInt( segment ); |
| targets = Collections.singletonMap( segment, Array.get( context, index ) ); |
| } |
| catch ( RuntimeException e ) |
| { |
| // invalid index, just ignore |
| } |
| } |
| else if ( ( context instanceof List ) && Character.isDigit( segment.charAt( 0 ) ) ) |
| { |
| try |
| { |
| int index = Integer.parseInt( segment ); |
| targets = Collections.singletonMap( segment, ( (List) context ).get( index ) ); |
| } |
| catch ( RuntimeException e ) |
| { |
| // invalid index, just ignore |
| } |
| } |
| else if ( ( context instanceof Collection ) && "*".equals( segment ) ) |
| { |
| targets = new LinkedHashMap(); |
| int index = 0; |
| for ( Iterator it = ( (Collection) context ).iterator(); it.hasNext(); index++ ) |
| { |
| targets.put( Integer.toString( index ), it.next() ); |
| } |
| } |
| else if ( context.getClass().isArray() && "*".equals( segment ) ) |
| { |
| targets = new LinkedHashMap(); |
| for ( int index = 0, n = Array.getLength( context ); index < n; index++ ) |
| { |
| targets.put( Integer.toString( index ), Array.get( context, index ) ); |
| } |
| } |
| else |
| { |
| targets = Collections.singletonMap( segment, getProperty( context, segment ) ); |
| } |
| |
| values = new LinkedHashMap(); |
| for ( Object key : targets.keySet() ) |
| { |
| Object target = targets.get( key ); |
| values.putAll( |
| evaluate( concat( prefix, String.valueOf( key ) ), segments.subList( 1, segments.size() ), |
| target ) ); |
| } |
| } |
| |
| return values; |
| } |
| |
| private static String concat( String prefix, String segment ) |
| { |
| return ( prefix == null || prefix.length() <= 0 ) ? segment : ( prefix + '/' + segment ); |
| } |
| |
| /** |
| * Gets the value of a (public) bean property from the specified object. |
| * |
| * @param context The object whose bean property should be retrieved, must not be <code>null</code>. |
| * @param property The name of the bean property, must not be <code>null</code>. |
| * @return The value of the bean property or <code>null</code> if the property does not exist. |
| */ |
| static Object getProperty( Object context, String property ) |
| { |
| Object value; |
| |
| Class type = context.getClass(); |
| if ( context instanceof Collection ) |
| { |
| type = Collection.class; |
| } |
| else if ( context instanceof Map ) |
| { |
| type = Map.class; |
| } |
| |
| try |
| { |
| try |
| { |
| Method method = type.getMethod( property, NO_PARAMS ); |
| method.setAccessible( true ); |
| value = method.invoke( context, NO_ARGS ); |
| } |
| catch ( NoSuchMethodException e ) |
| { |
| try |
| { |
| String name = "get" + Character.toUpperCase( property.charAt( 0 ) ) + property.substring( 1 ); |
| Method method = type.getMethod( name, NO_PARAMS ); |
| method.setAccessible( true ); |
| value = method.invoke( context, NO_ARGS ); |
| } |
| catch ( NoSuchMethodException e1 ) |
| { |
| try |
| { |
| String name = "is" + Character.toUpperCase( property.charAt( 0 ) ) + property.substring( 1 ); |
| Method method = type.getMethod( name, NO_PARAMS ); |
| method.setAccessible( true ); |
| value = method.invoke( context, NO_ARGS ); |
| } |
| catch ( NoSuchMethodException e2 ) |
| { |
| try |
| { |
| Method method; |
| try |
| { |
| method = type.getMethod( "get", STRING_PARAM ); |
| } |
| catch ( NoSuchMethodException e3 ) |
| { |
| method = type.getMethod( "get", OBJECT_PARAM ); |
| } |
| method.setAccessible( true ); |
| value = method.invoke( context, new Object[]{ property } ); |
| } |
| catch ( NoSuchMethodException e3 ) |
| { |
| try |
| { |
| Field field = type.getField( property ); |
| field.setAccessible( true ); |
| value = field.get( context ); |
| } |
| catch ( NoSuchFieldException e4 ) |
| { |
| if ( "length".equals( property ) && type.isArray() ) |
| { |
| value = Array.getLength( context ); |
| } |
| else |
| { |
| throw e4; |
| } |
| } |
| } |
| } |
| } |
| } |
| } |
| catch ( Exception e ) |
| { |
| value = null; |
| } |
| return value; |
| } |
| |
| } |