org.codehaus.janino
Class ExpressionEvaluator

  org.codehaus.commons.compiler.Cookable
      org.codehaus.janino.SimpleCompiler
          org.codehaus.janino.ClassBodyEvaluator
              org.codehaus.janino.ScriptEvaluator
                  org.codehaus.janino.ExpressionEvaluator

All Implemented Interfaces:

IClassBodyEvaluator, ICookable, IExpressionEvaluator, IScriptEvaluator, ISimpleCompiler

public class ExpressionEvaluator
extends ScriptEvaluator
implements IExpressionEvaluator

This IExpressionEvaluator is implemented by creating and compiling a temporary compilation unit defining one class with one static method with one RETURN statement.

A number of "convenience constructors" exist that execute the set-up steps described for IExpressionEvaluator instantly.

If the parameter and return types of the expression are known at compile time, then a "fast" expression evaluator can be instantiated through createFastExpressionEvaluator(String, Class, String[], ClassLoader). Expression evaluation is faster than through ScriptEvaluator.evaluate(Object[]), because it is not done through reflection but through direct method invocation.

Example:

 public interface Foo {
     int bar(int a, int b);
 }
 ...
 Foo f = (Foo) ExpressionEvaluator.createFastExpressionEvaluator(
     "a + b",                    // expression to evaluate
     Foo.class,                  // interface that describes the expression's signature
     new String[] { "a", "b" },  // the parameters' names
     (ClassLoader) null          // Use current thread's context class loader
 );
 System.out.println("1 + 2 = " + f.bar(1, 2)); // Evaluate the expression
 

Notice: The interfaceToImplement must either be declared public, or with package scope in the root package (i.e. "no" package).

On my system (Intel P4, 2 GHz, MS Windows XP, JDK 1.4.1), expression "x + 1" evaluates as follows:

	Server JVM	Client JVM
Normal EE	23.7 ns	64.0 ns
Fast EE	31.2 ns	42.2 ns

(How can it be that interface method invocation is slower than reflection for the server JVM?)

Field Summary

Fields inherited from class org.codehaus.janino.ScriptEvaluator

optionalOverrideMethod, optionalReturnTypes, optionalStaticMethod

Fields inherited from interface org.codehaus.commons.compiler.IExpressionEvaluator

ANY_TYPE

Fields inherited from interface org.codehaus.commons.compiler.IClassBodyEvaluator

DEFAULT_CLASS_NAME

Fields inherited from interface org.codehaus.commons.compiler.ICookable

BOOT_CLASS_LOADER, SYSTEM_PROPERTY_SOURCE_DEBUGGING_DIR, SYSTEM_PROPERTY_SOURCE_DEBUGGING_ENABLE

Constructor Summary

ExpressionEvaluator()

ExpressionEvaluator(Scanner scanner, className, optionalExtendedType, [] implementedTypes, boolean staticMethod, expressionType, methodName, [] parameterNames, [] parameterTypes, [] thrownExceptions, optionalParentClassLoader)
Equivalent to ExpressionEvaluator ee = new ExpressionEvaluator(); ee.setClassName(className); ee.setExtendedType(optionalExtendedType); ee.setImplementedTypes(implementedTypes); ee.setStaticMethod(staticMethod); ee.setExpressionType(expressionType); ee.setMethodName(methodName); ee.setParameters(parameterNames, parameterTypes); ee.setThrownExceptions(thrownExceptions); ee.setParentClassLoader(optionalParentClassLoader); ee.cook(scanner);

ExpressionEvaluator( expression, expressionType, [] parameterNames, [] parameterTypes)
Equivalent to ExpressionEvaluator ee = new ExpressionEvaluator(); ee.setExpressionType(expressionType); ee.setParameters(parameterNames, parameterTypes); ee.cook(expression);

ExpressionEvaluator( expression, expressionType, [] parameterNames, [] parameterTypes, [] thrownExceptions, optionalExtendedType, [] implementedTypes, optionalParentClassLoader)
Equivalent to ExpressionEvaluator ee = new ExpressionEvaluator(); ee.setExpressionType(expressionType); ee.setParameters(parameterNames, parameterTypes); ee.setThrownExceptions(thrownExceptions); ee.setExtendedType(optionalExtendedType); ee.setImplementedTypes(implementedTypes); ee.setParentClassLoader(optionalParentClassLoader); ee.cook(expression);

ExpressionEvaluator( expression, expressionType, [] parameterNames, [] parameterTypes, [] thrownExceptions, optionalParentClassLoader)
Equivalent to ExpressionEvaluator ee = new ExpressionEvaluator(); ee.setExpressionType(expressionType); ee.setParameters(parameterNames, parameterTypes); ee.setThrownExceptions(thrownExceptions); ee.setParentClassLoader(optionalParentClassLoader); ee.cook(expression);

Method Summary

static	createFastExpressionEvaluator(Scanner scanner, [] optionalDefaultImports, className, optionalExtendedType, interfaceToImplement, [] parameterNames, optionalParentClassLoader) Deprecated. Use ScriptEvaluator.createFastEvaluator(Reader, Class, String[]) instead
static	createFastExpressionEvaluator(Scanner scanner, className, optionalExtendedType, interfaceToImplement, [] parameterNames, optionalParentClassLoader) Deprecated. Use ScriptEvaluator.createFastEvaluator(Reader, Class, String[]) instead
static	createFastExpressionEvaluator( expression, interfaceToImplement, [] parameterNames, optionalParentClassLoader) Deprecated. Use ScriptEvaluator.createFastEvaluator(String, Class, String[]) instead:
protected	getDefaultReturnType()
static []	guessParameterNames(Scanner scanner) Guess the names of the parameters used in the given expression.
protected <Java.BlockStatement>	makeStatements(int idx, Parser parser) Fills the given block by parsing statements until EOF and adding them to the block.
void	setExpressionType( expressionType) Define the type of the expression.
void	setExpressionTypes([] expressionTypes) Same as IExpressionEvaluator.setExpressionType(Class), but for multiple expressions.
void	setReturnType( returnType) Deprecated. setExpressionType(Class) should be called instead.
void	setReturnTypes([] returnTypes) Deprecated. setExpressionTypes(Class[]) should be called instead.

Methods inherited from class org.codehaus.janino.ScriptEvaluator

cook, cook, cook, cook, cook, cook, cook, createFastEvaluator, createFastEvaluator, createFastEvaluator, createFastScriptEvaluator, createFastScriptEvaluator, createFastScriptEvaluator, createFastScriptEvaluator, createInstance, evaluate, evaluate, getMethod, getMethod, makeMethodDeclaration, setMethodName, setMethodNames, setOverrideMethod, setOverrideMethod, setParameters, setParameters, setStaticMethod, setStaticMethod, setThrownExceptions, setThrownExceptions

Methods inherited from class org.codehaus.janino.ClassBodyEvaluator

addPackageMemberClassDeclaration, compileToClass, createFastClassBodyEvaluator, createFastClassBodyEvaluator, getClazz, makeCompilationUnit, setClassName, setDefaultImports, setExtendedClass, setExtendedType, setImplementedInterfaces, setImplementedTypes

Methods inherited from class org.codehaus.janino.SimpleCompiler

assertNotCooked, classesToTypes, classToType, compileToClassLoader, cook, cook, equals, getClassLoader, hashCode, main, setCompileErrorHandler, setDebuggingInformation, setParentClassLoader, setWarningHandler

Methods inherited from class org.codehaus.commons.compiler.Cookable

cook, cook, cook, cook, cook, cook, cook, cookFile, cookFile, cookFile, cookFile, readString

Methods inherited from class java.lang.

, , , , , , , ,

Methods inherited from interface org.codehaus.commons.compiler.IExpressionEvaluator

createFastEvaluator, createFastEvaluator, evaluate

Methods inherited from interface org.codehaus.commons.compiler.IScriptEvaluator

cook, cook, cook, cook, evaluate, getMethod, getMethod, setMethodName, setMethodNames, setOverrideMethod, setOverrideMethod, setParameters, setParameters, setStaticMethod, setStaticMethod, setThrownExceptions, setThrownExceptions

Methods inherited from interface org.codehaus.commons.compiler.IClassBodyEvaluator

createInstance, getClazz, setClassName, setDefaultImports, setExtendedClass, setExtendedType, setImplementedInterfaces, setImplementedTypes

Methods inherited from interface org.codehaus.commons.compiler.ICookable

cook, cook, cook, cook, cook, cook, cook, cook, cookFile, cookFile, cookFile, cookFile, setCompileErrorHandler, setDebuggingInformation, setParentClassLoader, setWarningHandler

Constructor Detail

ExpressionEvaluator

public ExpressionEvaluator( expression,
                            expressionType,
                           [] parameterNames,
                           [] parameterTypes)
                    throws CompileException

Equivalent to

 ExpressionEvaluator ee = new ExpressionEvaluator();
 ee.setExpressionType(expressionType);
 ee.setParameters(parameterNames, parameterTypes);
 ee.cook(expression);

Throws:

CompileException

See Also:

ExpressionEvaluator(), setExpressionType(Class), ScriptEvaluator.setParameters(String[], Class[]), Cookable.cook(String)

ExpressionEvaluator

public ExpressionEvaluator( expression,
                            expressionType,
                           [] parameterNames,
                           [] parameterTypes,
                           [] thrownExceptions,
                            optionalParentClassLoader)
                    throws CompileException

Equivalent to

 ExpressionEvaluator ee = new ExpressionEvaluator();
 ee.setExpressionType(expressionType);
 ee.setParameters(parameterNames, parameterTypes);
 ee.setThrownExceptions(thrownExceptions);
 ee.setParentClassLoader(optionalParentClassLoader);
 ee.cook(expression);

Throws:

CompileException

See Also:

ExpressionEvaluator(), setExpressionType(Class), ScriptEvaluator.setParameters(String[], Class[]), ScriptEvaluator.setThrownExceptions(Class[]), SimpleCompiler.setParentClassLoader(ClassLoader), Cookable.cook(String)

ExpressionEvaluator

public ExpressionEvaluator( expression,
                            expressionType,
                           [] parameterNames,
                           [] parameterTypes,
                           [] thrownExceptions,
                            optionalExtendedType,
                           [] implementedTypes,
                            optionalParentClassLoader)
                    throws CompileException

Equivalent to

 ExpressionEvaluator ee = new ExpressionEvaluator();
 ee.setExpressionType(expressionType);
 ee.setParameters(parameterNames, parameterTypes);
 ee.setThrownExceptions(thrownExceptions);
 ee.setExtendedType(optionalExtendedType);
 ee.setImplementedTypes(implementedTypes);
 ee.setParentClassLoader(optionalParentClassLoader);
 ee.cook(expression);

Throws:

CompileException

See Also:

ExpressionEvaluator(), setExpressionType(Class), ScriptEvaluator.setParameters(String[], Class[]), ScriptEvaluator.setThrownExceptions(Class[]), ClassBodyEvaluator.setExtendedClass(Class), ClassBodyEvaluator.setImplementedInterfaces(Class[]), SimpleCompiler.setParentClassLoader(ClassLoader), Cookable.cook(String)

ExpressionEvaluator

public ExpressionEvaluator(Scanner scanner,
                            className,
                            optionalExtendedType,
                           [] implementedTypes,
                           boolean staticMethod,
                            expressionType,
                            methodName,
                           [] parameterNames,
                           [] parameterTypes,
                           [] thrownExceptions,
                            optionalParentClassLoader)
                    throws CompileException,
                           

Equivalent to

 ExpressionEvaluator ee = new ExpressionEvaluator();
 ee.setClassName(className);
 ee.setExtendedType(optionalExtendedType);
 ee.setImplementedTypes(implementedTypes);
 ee.setStaticMethod(staticMethod);
 ee.setExpressionType(expressionType);
 ee.setMethodName(methodName);
 ee.setParameters(parameterNames, parameterTypes);
 ee.setThrownExceptions(thrownExceptions);
 ee.setParentClassLoader(optionalParentClassLoader);
 ee.cook(scanner);



Throws:
CompileException
See Also:
IExpressionEvaluator, 
IClassBodyEvaluator.setClassName(String), 
IClassBodyEvaluator.setExtendedClass(Class), 
IClassBodyEvaluator.setImplementedInterfaces(Class[]), 
IScriptEvaluator.setStaticMethod(boolean), 
IExpressionEvaluator.setExpressionType(Class), 
IScriptEvaluator.setMethodName(String), 
IScriptEvaluator.setParameters(String[], Class[]), 
IScriptEvaluator.setThrownExceptions(Class[]), 
ICookable.setParentClassLoader(ClassLoader), 
ICookable.cook(Reader)

ExpressionEvaluator

public ExpressionEvaluator()

Method Detail

setExpressionType

public void setExpressionType( expressionType)

Description copied from interface: IExpressionEvaluator

Define the type of the expression. The special type IExpressionEvaluator.ANY_TYPE allows the expression to return any type (primitive or reference).

If expressionType is , then the expression must be an invocation of a void method.

Defaults to IExpressionEvaluator.ANY_TYPE.

Specified by:

setExpressionType in interface IExpressionEvaluator

setExpressionTypes

public void setExpressionTypes([] expressionTypes)

Description copied from interface: IExpressionEvaluator

Same as IExpressionEvaluator.setExpressionType(Class), but for multiple expressions.

Specified by:

setExpressionTypes in interface IExpressionEvaluator

setReturnType

public final void setReturnType( returnType)

Deprecated. setExpressionType(Class) should be called instead.

Description copied from class: ScriptEvaluator

Defines the return types of the generated methods.

Specified by:

setReturnType in interface IExpressionEvaluator

Specified by:

setReturnType in interface IScriptEvaluator

Overrides:

setReturnType in class ScriptEvaluator

Parameters:

returnType - The method's return type; null means the "default return type", which is the type returned by ScriptEvaluator.getDefaultReturnType() (void.class for ScriptEvaluator and Object.class for ExpressionEvaluator)

See Also:

ScriptEvaluator.getDefaultReturnType(), getDefaultReturnType()

setReturnTypes

public final void setReturnTypes([] returnTypes)

Deprecated. setExpressionTypes(Class[]) should be called instead.

Description copied from class: ScriptEvaluator

Defines the return types of the generated methods.

Specified by:

setReturnTypes in interface IExpressionEvaluator

Specified by:

setReturnTypes in interface IScriptEvaluator

Overrides:

setReturnTypes in class ScriptEvaluator

Parameters:

returnTypes - The methods' return types; null elements mean the "default return type", which is the type returned by ScriptEvaluator.getDefaultReturnType() (void.class for ScriptEvaluator and Object.class for ExpressionEvaluator)

See Also:

ScriptEvaluator.getDefaultReturnType(), getDefaultReturnType()

getDefaultReturnType

protected  getDefaultReturnType()

Overrides:

getDefaultReturnType in class ScriptEvaluator

Returns:

void.class

See Also:

ScriptEvaluator.setReturnTypes(Class[])

makeStatements

protected <Java.BlockStatement> makeStatements(int idx,
                                                   Parser parser)
                                            throws CompileException,
                                                   

Description copied from class: ScriptEvaluator

Fills the given block by parsing statements until EOF and adding them to the block.

Overrides:

makeStatements in class ScriptEvaluator

Throws:

CompileException

createFastExpressionEvaluator

public static  createFastExpressionEvaluator( expression,
                                                               interfaceToImplement,
                                                              [] parameterNames,
                                                               optionalParentClassLoader)
                                            throws CompileException

Deprecated. Use ScriptEvaluator.createFastEvaluator(String, Class, String[]) instead:

 IExpressionEvaluator ee = CompilerFactoryFactory.getDefaultCompilerFactory().newExpressionEvaluator();
 ee.setParentClassLoader(optionalParentClassLoader);
 return ee.createFastEvaluator(expression, interfaceToImplement, parameterNames);
 

Throws:

CompileException

createFastExpressionEvaluator

public static  createFastExpressionEvaluator(Scanner scanner,
                                                               className,
                                                               optionalExtendedType,
                                                               interfaceToImplement,
                                                              [] parameterNames,
                                                               optionalParentClassLoader)
                                            throws CompileException,
                                                   

Deprecated. Use ScriptEvaluator.createFastEvaluator(Reader, Class, String[]) instead

Notice: This method is not declared in IExpressionEvaluator, and is hence only available in this implementation of org.codehaus.commons.compiler. To be independent from this particular implementation, try to switch to ScriptEvaluator.createFastEvaluator(Reader, Class, String[]).

Throws:

CompileException

createFastExpressionEvaluator

public static  createFastExpressionEvaluator(Scanner scanner,
                                                              [] optionalDefaultImports,
                                                               className,
                                                               optionalExtendedType,
                                                               interfaceToImplement,
                                                              [] parameterNames,
                                                               optionalParentClassLoader)
                                            throws CompileException,
                                                   

Deprecated. Use ScriptEvaluator.createFastEvaluator(Reader, Class, String[]) instead

Notice: This method is not declared in IExpressionEvaluator, and is hence only available in this implementation of org.codehaus.commons.compiler. To be independent from this particular implementation, try to switch to ScriptEvaluator.createFastEvaluator(Reader, Class, String[]).

Throws:

CompileException

guessParameterNames

public static [] guessParameterNames(Scanner scanner)
                                    throws CompileException,
                                           

Guess the names of the parameters used in the given expression. The strategy is to look at all "ambiguous names" in the expression (e.g. in "a.b.c.d()", the ambiguous name is "a.b.c"), and then at the first components of the ambiguous name.

• If any component starts with an upper-case letter, then ambiguous name is assumed to be a type name.
• Otherwise, it is assumed to be a parameter name.

Throws:

CompileException

See Also:

Scanner.Scanner(String, Reader)