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1
17
18 package org.apache.el.lang;
19
20 import java.io.StringReader  ;
21 import java.lang.ref.SoftReference ;
22 import java.lang.reflect.Method ;
23 import java.util.Map ;
24 import java.util.WeakHashMap ;
25 import java.util.concurrent.ConcurrentHashMap ;
26 import java.util.concurrent.ConcurrentMap ;
27
28 import javax.el.ELContext;
29 import javax.el.ELException;
30 import javax.el.FunctionMapper;
31 import javax.el.MethodExpression;
32 import javax.el.ValueExpression;
33 import javax.el.VariableMapper;
34
35 import org.apache.el.MethodExpressionImpl;
36 import org.apache.el.MethodExpressionLiteral;
37 import org.apache.el.ValueExpressionImpl;
38 import org.apache.el.parser.AstCompositeExpression;
39 import org.apache.el.parser.AstDeferredExpression;
40 import org.apache.el.parser.AstDynamicExpression;
41 import org.apache.el.parser.AstFunction;
42 import org.apache.el.parser.AstIdentifier;
43 import org.apache.el.parser.AstLiteralExpression;
44 import org.apache.el.parser.AstValue;
45 import org.apache.el.parser.ELParser;
46 import org.apache.el.parser.Node;
47 import org.apache.el.parser.NodeVisitor;
48 import org.apache.el.parser.ParseException;
49 import org.apache.el.util.ConcurrentCache;
50 import org.apache.el.util.MessageFactory;
51
52
56 public final class ExpressionBuilder implements NodeVisitor {
57
58 private static final ConcurrentCache cache = new ConcurrentCache(5000);
59
60 private FunctionMapper fnMapper;
61
62 private VariableMapper varMapper;
63
64 private String expression;
65
66
69 public ExpressionBuilder(String expression, ELContext ctx)
70 throws ELException {
71 this.expression = expression;
72
73 FunctionMapper ctxFn = ctx.getFunctionMapper();
74 VariableMapper ctxVar = ctx.getVariableMapper();
75
76 if (ctxFn != null) {
77 this.fnMapper = new FunctionMapperFactory(ctxFn);
78 }
79 if (ctxVar != null) {
80 this.varMapper = new VariableMapperFactory(ctxVar);
81 }
82 }
83
84 public final static Node createNode(String expr) throws ELException {
85 Node n = createNodeInternal(expr);
86 return n;
87 }
88
89 private final static Node createNodeInternal(String expr)
90 throws ELException {
91 if (expr == null) {
92 throw new ELException(MessageFactory.get("error.null"));
93 }
94
95 Node n = (Node) cache.get(expr);
96 if (n == null) {
97 try {
98 n = (new ELParser(new StringReader (expr)))
99 .CompositeExpression();
100
101 if (n instanceof AstCompositeExpression) {
103 int numChildren = n.jjtGetNumChildren();
104 if (numChildren == 1) {
105 n = n.jjtGetChild(0);
106 } else {
107 Class type = null;
108 Node child = null;
109 for (int i = 0; i < numChildren; i++) {
110 child = n.jjtGetChild(i);
111 if (child instanceof AstLiteralExpression)
112 continue;
113 if (type == null)
114 type = child.getClass();
115 else {
116 if (!type.equals(child.getClass())) {
117 throw new ELException(MessageFactory.get(
118 "error.mixed", expr));
119 }
120 }
121 }
122 }
123 }
124 if (n instanceof AstDeferredExpression
125 || n instanceof AstDynamicExpression) {
126 n = n.jjtGetChild(0);
127 }
128 cache.put(expr, n);
129 } catch (ParseException pe) {
130 throw new ELException("Error Parsing: " + expr, pe);
131 }
132 }
133 return n;
134 }
135
136 private void prepare(Node node) throws ELException {
137 try {
138 node.accept(this);
139 } catch (Exception e) {
140 throw (ELException) e;
141 }
142 if (this.fnMapper instanceof FunctionMapperFactory) {
143 this.fnMapper = ((FunctionMapperFactory) this.fnMapper).create();
144 }
145 if (this.varMapper instanceof VariableMapperFactory) {
146 this.varMapper = ((VariableMapperFactory) this.varMapper).create();
147 }
148 }
149
150 private Node build() throws ELException {
151 Node n = createNodeInternal(this.expression);
152 this.prepare(n);
153 if (n instanceof AstDeferredExpression
154 || n instanceof AstDynamicExpression) {
155 n = n.jjtGetChild(0);
156 }
157 return n;
158 }
159
160
165 public void visit(Node node) throws ELException {
166 if (node instanceof AstFunction) {
167
168 AstFunction funcNode = (AstFunction) node;
169
170 if (this.fnMapper == null) {
171 throw new ELException(MessageFactory.get("error.fnMapper.null"));
172 }
173 Method m = fnMapper.resolveFunction(funcNode.getPrefix(), funcNode
174 .getLocalName());
175 if (m == null) {
176 throw new ELException(MessageFactory.get(
177 "error.fnMapper.method", funcNode.getOutputName()));
178 }
179 int pcnt = m.getParameterTypes().length;
180 if (node.jjtGetNumChildren() != pcnt) {
181 throw new ELException(MessageFactory.get(
182 "error.fnMapper.paramcount", funcNode.getOutputName(),
183 "" + pcnt, "" + node.jjtGetNumChildren()));
184 }
185 } else if (node instanceof AstIdentifier && this.varMapper != null) {
186 String variable = ((AstIdentifier) node).getImage();
187
188 this.varMapper.resolveVariable(variable);
190 }
191 }
192
193 public ValueExpression createValueExpression(Class expectedType)
194 throws ELException {
195 Node n = this.build();
196 return new ValueExpressionImpl(this.expression, n, this.fnMapper,
197 this.varMapper, expectedType);
198 }
199
200 public MethodExpression createMethodExpression(Class expectedReturnType,
201 Class [] expectedParamTypes) throws ELException {
202 Node n = this.build();
203 if (n instanceof AstValue || n instanceof AstIdentifier) {
204 return new MethodExpressionImpl(expression, n, this.fnMapper,
205 this.varMapper, expectedReturnType, expectedParamTypes);
206 } else if (n instanceof AstLiteralExpression) {
207 return new MethodExpressionLiteral(expression, expectedReturnType,
208 expectedParamTypes);
209 } else {
210 throw new ELException("Not a Valid Method Expression: "
211 + expression);
212 }
213 }
214 }
215 |
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