1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.jexl3;
18
19 import java.util.Collections;
20 import java.util.Map;
21 import org.apache.commons.jexl3.annotations.NoJexl;
22
23 /**
24 * A JEXL evaluation environment wrapping variables, namespace and options.
25 */
26 public class JexlEvalContext implements
27 JexlContext,
28 JexlContext.NamespaceResolver,
29 JexlContext.OptionsHandle {
30 /** The marker for the empty vars. */
31 private static final Map<String,Object> EMPTY_MAP = Collections.<String,Object>emptyMap();
32 /** The variables.*/
33 private final JexlContext vars;
34 /** The namespace. */
35 private final JexlContext.NamespaceResolver ns;
36 /** The options. */
37 private final JexlOptions options = new JexlOptions();
38
39 /**
40 * Default constructor.
41 */
42 @NoJexl
43 public JexlEvalContext() {
44 this(EMPTY_MAP);
45 }
46
47 /**
48 * Creates an evaluation environment wrapping an existing user provided vars.
49 * <p>The supplied vars should be null only in derived classes that override the get/set/has methods.
50 * For a default vars context with a code supplied vars, use the default no-parameter contructor.</p>
51 * @param map the variables map
52 */
53 @NoJexl
54 public JexlEvalContext(final Map<String, Object> map) {
55 this.vars = map == EMPTY_MAP ? new MapContext() : new MapContext(map);
56 this.ns = null;
57 }
58
59 /**
60 * Creates an evaluation environment from a context.
61 * @param context the context (may be null, implies readonly)
62 */
63 @NoJexl
64 public JexlEvalContext(final JexlContext context) {
65 this(context, context instanceof JexlContext.NamespaceResolver? (JexlContext.NamespaceResolver) context : null);
66 }
67
68 /**
69 * Creates an evaluation environment from a context and a namespace.
70 * @param context the context (may be null, implies readonly)
71 * @param namespace the namespace (may be null, implies empty namespace)
72 */
73 @NoJexl
74 public JexlEvalContext(final JexlContext context, final JexlContext.NamespaceResolver namespace) {
75 this.vars = context != null? context : JexlEngine.EMPTY_CONTEXT;
76 this.ns = namespace != null? namespace : JexlEngine.EMPTY_NS;
77 }
78
79 @Override
80 @NoJexl
81 public boolean has(final String name) {
82 return vars.has(name);
83 }
84
85 @Override
86 @NoJexl
87 public Object get(final String name) {
88 return vars.get(name);
89 }
90
91 @Override
92 @NoJexl
93 public void set(final String name, final Object value) {
94 vars.set(name, value);
95 }
96
97 @Override
98 @NoJexl
99 public Object resolveNamespace(final String name) {
100 return ns != null? ns.resolveNamespace(name) : null;
101 }
102
103 @Override
104 @NoJexl
105 public JexlOptions getEngineOptions() {
106 return options;
107 }
108
109 }