FileDocCategorySizeDatePackage
ExpressionBuilder.javaAPI DocApache Tomcat 6.0.146607Fri Jul 20 04:20:32 BST 2007org.apache.el.lang

ExpressionBuilder

public final class ExpressionBuilder extends Object implements org.apache.el.parser.NodeVisitor
author
Jacob Hookom [jacob@hookom.net]
version
$Change: 181177 $$DateTime: 2001/06/26 08:45:09 $$Author: markt $

Fields Summary
private static final org.apache.el.util.ConcurrentCache
cache
private FunctionMapper
fnMapper
private VariableMapper
varMapper
private String
expression
Constructors Summary
public ExpressionBuilder(String expression, ELContext ctx)


	 	 
	    
			  
		this.expression = expression;

		FunctionMapper ctxFn = ctx.getFunctionMapper();
		VariableMapper ctxVar = ctx.getVariableMapper();

		if (ctxFn != null) {
			this.fnMapper = new FunctionMapperFactory(ctxFn);
		}
		if (ctxVar != null) {
			this.varMapper = new VariableMapperFactory(ctxVar);
		}
Methods Summary
private org.apache.el.parser.Nodebuild()

		Node n = createNodeInternal(this.expression);
		this.prepare(n);
		if (n instanceof AstDeferredExpression
				|| n instanceof AstDynamicExpression) {
			n = n.jjtGetChild(0);
		}
		return n;
public javax.el.MethodExpressioncreateMethodExpression(java.lang.Class expectedReturnType, java.lang.Class[] expectedParamTypes)

		Node n = this.build();
		if (n instanceof AstValue || n instanceof AstIdentifier) {
			return new MethodExpressionImpl(expression, n, this.fnMapper,
					this.varMapper, expectedReturnType, expectedParamTypes);
		} else if (n instanceof AstLiteralExpression) {
			return new MethodExpressionLiteral(expression, expectedReturnType,
					expectedParamTypes);
		} else {
			throw new ELException("Not a Valid Method Expression: "
					+ expression);
		}
public static final org.apache.el.parser.NodecreateNode(java.lang.String expr)

		Node n = createNodeInternal(expr);
		return n;
private static final org.apache.el.parser.NodecreateNodeInternal(java.lang.String expr)

		if (expr == null) {
			throw new ELException(MessageFactory.get("error.null"));
		}

		Node n = (Node) cache.get(expr);
		if (n == null) {
			try {
				n = (new ELParser(new StringReader(expr)))
						.CompositeExpression();

				// validate composite expression
				if (n instanceof AstCompositeExpression) {
					int numChildren = n.jjtGetNumChildren();
					if (numChildren == 1) {
						n = n.jjtGetChild(0);
					} else {
						Class type = null;
						Node child = null;
						for (int i = 0; i < numChildren; i++) {
							child = n.jjtGetChild(i);
							if (child instanceof AstLiteralExpression)
								continue;
							if (type == null)
								type = child.getClass();
							else {
								if (!type.equals(child.getClass())) {
									throw new ELException(MessageFactory.get(
											"error.mixed", expr));
								}
							}
						}
					}
				}
				if (n instanceof AstDeferredExpression
						|| n instanceof AstDynamicExpression) {
					n = n.jjtGetChild(0);
				}
				cache.put(expr, n);
			} catch (ParseException pe) {
				throw new ELException("Error Parsing: " + expr, pe);
			}
		}
		return n;
public javax.el.ValueExpressioncreateValueExpression(java.lang.Class expectedType)

		Node n = this.build();
		return new ValueExpressionImpl(this.expression, n, this.fnMapper,
				this.varMapper, expectedType);
private voidprepare(org.apache.el.parser.Node node)

        try {
            node.accept(this);
        } catch (Exception e) {
            throw (ELException) e;
        }
		if (this.fnMapper instanceof FunctionMapperFactory) {
			this.fnMapper = ((FunctionMapperFactory) this.fnMapper).create();
		}
		if (this.varMapper instanceof VariableMapperFactory) {
			this.varMapper = ((VariableMapperFactory) this.varMapper).create();
		}
public voidvisit(org.apache.el.parser.Node node)

		if (node instanceof AstFunction) {

			AstFunction funcNode = (AstFunction) node;

			if (this.fnMapper == null) {
				throw new ELException(MessageFactory.get("error.fnMapper.null"));
			}
			Method m = fnMapper.resolveFunction(funcNode.getPrefix(), funcNode
					.getLocalName());
			if (m == null) {
				throw new ELException(MessageFactory.get(
						"error.fnMapper.method", funcNode.getOutputName()));
			}
			int pcnt = m.getParameterTypes().length;
			if (node.jjtGetNumChildren() != pcnt) {
				throw new ELException(MessageFactory.get(
						"error.fnMapper.paramcount", funcNode.getOutputName(),
						"" + pcnt, "" + node.jjtGetNumChildren()));
			}
		} else if (node instanceof AstIdentifier && this.varMapper != null) {
			String variable = ((AstIdentifier) node).getImage();

			// simply capture it
			this.varMapper.resolveVariable(variable);
		}