ognl.enhance.OgnlExpressionCompiler Maven / Gradle / Ivy
/**
*
*/
package ognl.enhance;
import ognl.Node;
import ognl.OgnlContext;
import java.lang.reflect.Method;
/**
* Core interface implemented by expression compiler instances.
*/
public interface OgnlExpressionCompiler {
/** Static constant used in conjunction with {@link OgnlContext} to store temporary references. */
String ROOT_TYPE = "-ognl-root-type";
/**
* The core method executed to compile a specific expression. It is expected that this expression
* always return a {@link Node} with a non null {@link ognl.Node#getAccessor()} instance - unless an exception
* is thrown by the method or the statement wasn't compilable in this instance because of missing/null objects
* in the expression. These instances may in some cases continue to call this compilation method until the expression
* is resolvable.
*
* @param context
* The context of execution.
* @param expression
* The pre-parsed root expression node to compile.
* @param root
* The root object for the expression - may be null in many instances so some implementations
* may exit
* @throws Exception
* If an error occurs compiling the expression and no strategy has been implemented to handle incremental
* expression compilation for incomplete expression members.
*/
void compileExpression(OgnlContext context, Node expression, Object root)
throws Exception;
/**
* Gets a javassist safe class string for the given class instance. This is especially
* useful for handling array vs. normal class casting strings.
*
* @param clazz
* The class to get a string equivalent javassist compatible string reference for.
*
* @return The string equivalent of the class.
*/
String getClassName(Class clazz);
/**
* Used in places where the preferred {@link #getSuperOrInterfaceClass(java.lang.reflect.Method, Class)} isn't possible
* because the method isn't known for a class. Attempts to upcast the given class to the next available non-private accessible
* class so that compiled expressions can reference the interface class of an instance so as not to be compiled in to overly
* specific statements.
*
* @param clazz
* The class to attempt to find a compatible interface for.
* @return The same class if no higher level interface could be matched against or the interface equivalent class.
*/
Class getInterfaceClass(Class clazz);
/**
* For the given {@link Method} and class finds the highest level interface class this combination can be cast to.
*
* @param m
* The method the class must implement.
* @param clazz
* The current class being worked with.
* @return The highest level interface / class that the referenced {@link Method} is declared in.
*/
Class getSuperOrInterfaceClass(Method m, Class clazz);
/**
* For a given root object type returns the base class type to be used in root referenced expressions. This
* helps in some instances where the root objects themselves are compiled javassist instances that need more generic
* class equivalents to cast to.
*
* @param rootNode
* The root expression node.
* @param context
* The current execution context.
* @return The root expression class type to cast to for this node.
*/
Class getRootExpressionClass(Node rootNode, OgnlContext context);
/**
* Used primarily by AST types like {@link ognl.ASTChain} where foo.bar.id type references
* may need to be cast multiple times in order to properly resolve the members in a compiled statement.
*
*
* This method should be using the various {@link ognl.OgnlContext#getCurrentType()} / {@link ognl.OgnlContext#getCurrentAccessor()} methods
* to inspect the type stack and properly cast to the right classes - but only when necessary.
*
*
* @param context
* The current execution context.
* @param expression
* The node being checked for casting.
* @param body
* The java source string generated by the given node.
* @return The body string parameter plus any additional casting syntax needed to make the expression
* resolvable.
*/
String castExpression(OgnlContext context, Node expression, String body);
/**
* Method is used for expressions where multiple inner parameter method calls in generated java source strings
* cause javassit failures. It is hacky and cumbersome to have to generate expressions this way but it's the only
* current known way to make javassist happy.
*
*
* Takes an expression block generated by a node and creates a new method on the base object being compiled so that
* sufficiently complicated sub expression blocks can be broken out in to distinct methods to be referenced by the core
* accessor / setter methods in the base compiled root object.
*
*
* @param context
* The current execution context.
* @param expression
* The java source expression to dump in to a seperate method reference.
* @param type
* The return type that should be specified for the new method.
* @return The method name that will be used to reference the sub expression in place of the actual sub expression
* itself.
*/
String createLocalReference(OgnlContext context, String expression, Class type);
}