commons-compiler 3.1.12 · org.codehaus.commons.compiler.IScriptEvaluator

An engine that executes a script in JVM bytecode.

The syntax of the script to compile is a sequence of import declarations (not allowed if you compile many scripts at a time, see below) followed by a sequence of statements, as defined in the Java Language Specification, Java SE 7 Edition, sections 7.5 and 14.

An implementation may or may not implement the concept of "local methods", i.e. method declarations being freely intermixed with statements.

Example:

  import java.text.*;

  System.out.println("HELLO");
  System.out.println(new DecimalFormat("####,###.##").format(a));

(Notice that this expression refers to a parameter "a", as explained below.)

The script may complete abnormally, e.g. through a RETURN statement:

  if (a == null) {
      System.out.println("Oops!");
      return;
  }

Optionally, the script may be declared with a non-void return type. In this case, the last statement of the script must be a RETURN statement (or a THROW statement), and all RETURN statements in the script must return a value with the given type.

The script evaluator is implemented by creating and compiling a temporary compilation unit defining one class with one method the body of which consists of the statements of the script.

To set up a IScriptEvaluator object, proceed as follows:

Create an IScriptEvaluator-implementing class.
Configure the IScriptEvaluator by calling any of the following methods:
Call any of the org.codehaus.commons.compiler.Cookable#cook(Reader) methods to scan, parse, compile and load the script into the JVM.

After the IScriptEvaluator object is created, the script can be executed as often with different parameter values (see evaluate(Object[])). This execution is very fast, compared to the compilation.

Less common methods exist that allow for the specification of the name of the generated class, the class it extends, the interfaces it implements, the name of the method that executes the script, the exceptions that this method (i.e. the script) is allowed to throw, and the ClassLoader that is used to define the generated class and to load classes referenced by the script.

If you want to compile many scripts at the same time, you have the option to cook an array of scripts in one IScriptEvaluator by using the following methods:

Notice that these methods have array parameters in contrast to their one-script brethren.

Field Summary

Modifier and Type	Field and Description
public static final String	DEFAULT_METHOD_NAME The name of the generated method(s), if no custom method name is configured with `setMethodNames(String[])`.
public static final Class<?>	DEFAULT_RETURN_TYPE The return type for any script for which no return type is explicitly configured.

Method Summary

Modifier and Type	Method and Description
public void	cook(Reader... readers) Redeclares org.codehaus.commons.compiler.IMultiCookable.cook. Same as `cook(Reader)`, but for multiple scripts.
public void	cook(String[] fileNames, Reader[] readers) Redeclares org.codehaus.commons.compiler.IMultiCookable.cook. Same as `cook(String, Reader)`, but cooks a set of scripts into one class.
public void	cook(String[] strings) Redeclares org.codehaus.commons.compiler.IMultiCookable.cook. Same as `cook(String)`, but for multiple scripts.
public void	cook(String[] fileNames, String[] strings) Redeclares org.codehaus.commons.compiler.IMultiCookable.cook. Same as `cook(String, String)`, but for multiple scripts.
public <T> T	createFastEvaluator(String Contains the sequence of script tokens script, Class<T> interfaceToImplement, String[] parameterNames)
public <T> T	Returns: An object that implements the given interface createFastEvaluator(Reader Produces the stream of script tokens reader, Class<T> Must declare exactly one method interfaceToImplement, String[] The names of the parameters of that method parameterNames) If the parameter and return types of the expression are known at compile time, then a "fast" script evaluator can be instantiated through this method.
public Object	evaluate() Shorthand for `evaluate(new Object[0])`.
public Object	evaluate(Object[] The actual parameter values arguments) Calls the script with concrete parameter values.
public Object	evaluate(int idx, Object[] arguments) Same as `evaluate(Object[])`, but for multiple scripts.
public Class<?>	getClazz()
public String[]	getDefaultImports()
public Class<?>	Returns: The default return type that was previously configured with `setDefaultReturnType(Class)`, or `DEFAULT_RETURN_TYPE` getDefaultReturnType()
public Method	Returns: The generated and loaded `java.lang.reflect.Method` getMethod()
public Method	getMethod(int idx) Same as `getMethod()`, but for multiple scripts.
public Method[]	Returns: The generated and loaded methods that implement the cooked scripts getResult()
public void	setClassName(String className)
public void	setCompileErrorHandler(ErrorHandler `null` to restore the default behavior (throwing a `CompileException`) compileErrorHandler) Installs an `ErrorHandler` which is invoked during compilation on each error.
public void	setDebuggingInformation(boolean debugSource, boolean debugLines, boolean debugVars) Determines what kind of debugging information is included in the generates classes.
public void	setDefaultImports(String... defaultImports)
public void	setDefaultReturnType(Class<?> defaultReturnType) When this `IScriptEvaluator` is coooked, then the `defaultReturnType` applies to all scripts for which no explicit return type was configured.
public void	setExtendedClass(Class<?> extendedClass)
public void	setImplementedInterfaces(Class<?>[] implementedInterfaces)
public void	setMethodName(String `null` means reset to default name methodName) Defines the name of the generated method.
public void	setMethodNames(String[] methodNames) Same as `setMethodName(String)`, but for multiple scripts.
public void	setOverrideMethod(boolean overrideMethod) Defines whether the generated method overrides a methods declared in a supertype.
public void	setOverrideMethod(boolean[] overrideMethod) Same as `setOverrideMethod(boolean)`, but for multiple scripts.
public void	setParameters(String[] names, Class<?>[] types) Defines the names and types of the parameters of the generated method.
public void	setParameters(String[][] names, Class<?>[][] types) Same as `setParameters(String[], Class[])`, but for multiple scripts.
public void	setParentClassLoader(ClassLoader parentClassLoader) The "parent class loader" is used to load referenced classes.
public void	setReturnType(Class<?> returnType) Defines the return type of the generated method.
public void	setReturnTypes(Class<?>[] The methods' return types; `null` elements mean "use the default return type" returnTypes) Configures the return types of the generated methods.
public void	setStaticMethod(boolean staticMethod) Defines whether the generated method should be STATIC or not.
public void	setStaticMethod(boolean[] staticMethod) Same as `setStaticMethod(boolean)`, but for multiple scripts.
public void	setThrownExceptions(Class<?>[] thrownExceptions) Defines the exceptions that the generated method may throw.
public void	setThrownExceptions(Class<?>[][] thrownExceptions) Same as `setThrownExceptions(Class[])`, but for multiple scripts.
public void	setWarningHandler(WarningHandler `null` to indicate that no warnings be issued warningHandler) By default, warnings are discarded, but an application my install a custom `WarningHandler`.

Field Detail

DEFAULT_METHOD_NAME back to summary

DEFAULT_METHOD_NAME	back to summary
public static final String DEFAULT_METHOD_NAME The name of the generated method(s), if no custom method name is configured with `setMethodNames(String[])`. The `'*'` in this string is replaced with the method index, starting at 0.

public static final String DEFAULT_METHOD_NAME

The name of the generated method(s), if no custom method name is configured with setMethodNames(String[]).

The '*' in this string is replaced with the method index, starting at 0.

DEFAULT_RETURN_TYPE	back to summary
public static final Class<?> DEFAULT_RETURN_TYPE The return type for any script for which no return type is explicitly configured.

Method Detail

cook back to summary

cook	back to summary
public void cook(Reader... readers) throws CompileException, IOException Redeclares org.codehaus.commons.compiler.IMultiCookable.cook. Same as `cook(Reader)`, but for multiple scripts. Annotations @Override

public void cook(Reader... readers) throws CompileException, IOException

Redeclares org.codehaus.commons.compiler.IMultiCookable.cook.

Same as cook(Reader), but for multiple scripts.

Annotations

@Override

cook back to summary

cook	back to summary
public void cook(String[] fileNames, Reader[] readers) throws CompileException, IOException Redeclares org.codehaus.commons.compiler.IMultiCookable.cook. Same as `cook(String, Reader)`, but cooks a set of scripts into one class. Notice that if any of the scripts causes trouble, the entire compilation will fail. If you need to report which of the scripts causes the exception, you may want to use the `fileNames` parameter to distinguish between the individual token sources. Iff the number of scanners is one, then that single script may contain leading IMPORT directives. s Annotations @Override Exceptions IllegalStateException: if any of the preceding `set...()` had an array size different from that of `scanners`

public void cook(String[] fileNames, Reader[] readers) throws CompileException, IOException

Redeclares org.codehaus.commons.compiler.IMultiCookable.cook.

Same as cook(String, Reader), but cooks a set of scripts into one class. Notice that if any of the scripts causes trouble, the entire compilation will fail. If you need to report which of the scripts causes the exception, you may want to use the fileNames parameter to distinguish between the individual token sources.

Iff the number of scanners is one, then that single script may contain leading IMPORT directives.

Annotations

@Override

Exceptions

IllegalStateException:: if any of the preceding set...() had an array size different from that of scanners

cook back to summary

cook	back to summary
public void cook(String[] strings) throws CompileException Redeclares org.codehaus.commons.compiler.IMultiCookable.cook. Same as `cook(String)`, but for multiple scripts. Annotations @Override

public void cook(String[] strings) throws CompileException

Redeclares org.codehaus.commons.compiler.IMultiCookable.cook.

Same as cook(String), but for multiple scripts.

Annotations

@Override

cook back to summary

cook	back to summary
public void cook(String[] fileNames, String[] strings) throws CompileException Redeclares org.codehaus.commons.compiler.IMultiCookable.cook. Same as `cook(String, String)`, but for multiple scripts. Annotations @Override

public void cook(String[] fileNames, String[] strings) throws CompileException

Redeclares org.codehaus.commons.compiler.IMultiCookable.cook.

Same as cook(String, String), but for multiple scripts.

Annotations

@Override

createFastEvaluator	back to summary
public <T> T createFastEvaluator(String script, Class<T> interfaceToImplement, String[] parameterNames) throws CompileException Parameters script:String Contains the sequence of script tokens See Also `createFastEvaluator(Reader, Class, String[])`

createFastEvaluator back to summary

createFastEvaluator	back to summary
public <T> T createFastEvaluator(Reader reader, Class<T> interfaceToImplement, String[] parameterNames) throws CompileException, IOException If the parameter and return types of the expression are known at compile time, then a "fast" script evaluator can be instantiated through this method. Script evaluation is faster than through `evaluate(Object[])`, because it is not done through reflection but through direct method invocation. Example: public interface Foo { int bar(int a, int b); } ... IScriptEvaluator se = `CompilerFactoryFactory`.`getDefaultCompilerFactory`().`newScriptEvaluator`(); // Optionally configure the SE her: se.`setClassName`("Bar"); se.`setDefaultImports`(new String[] { "java.util.*" }); se.`setExtendedClass`(SomeOtherClass.class); se.`setParentClassLoader`(someClassLoader); Foo f = (Foo) se.`createFastScriptEvaluator`( "return a - b;", Foo.class, new String[] { "a", "b" } ); System.out.println("1 - 2 = " + f.bar(1, 2)); All other configuration (implemented type, static method, return type, method name, parameter names and types, thrown exceptions) are predetermined by the `interfaceToImplement`. Notice: The `interfaceToImplement` must either be declared `public`, or with package scope in the same package as the generated class (see `setClassName(String)`). s Parameters reader:Reader Produces the stream of script tokens interfaceToImplement:Class<T> Must declare exactly one method parameterNames:String[] The names of the parameters of that method Returns:T An object that implements the given interface

public <T> T createFastEvaluator(Reader reader, Class<T> interfaceToImplement, String[] parameterNames) throws CompileException, IOException

If the parameter and return types of the expression are known at compile time, then a "fast" script evaluator can be instantiated through this method.

Script evaluation is faster than through evaluate(Object[]), because it is not done through reflection but through direct method invocation.

Example:

public interface Foo {
    int bar(int a, int b);
}
...
IScriptEvaluator se = CompilerFactoryFactory.getDefaultCompilerFactory().newScriptEvaluator();

// Optionally configure the SE her:
se.setClassName("Bar");
se.setDefaultImports(new String[] { "java.util.*" });
se.setExtendedClass(SomeOtherClass.class);
se.setParentClassLoader(someClassLoader);

Foo f = (Foo) se.createFastScriptEvaluator(
    "return a - b;",
    Foo.class,
    new String[] { "a", "b" }
);
System.out.println("1 - 2 = " + f.bar(1, 2));

All other configuration (implemented type, static method, return type, method name, parameter names and types, thrown exceptions) are predetermined by the interfaceToImplement.

Notice: The interfaceToImplement must either be declared public, or with package scope in the same package as the generated class (see setClassName(String)).

Parameters

reader:Reader: Produces the stream of script tokens
interfaceToImplement:Class<T>: Must declare exactly one method
parameterNames:String[]: The names of the parameters of that method

Returns:T

An object that implements the given interface

evaluate back to summary

evaluate	back to summary
public Object evaluate() throws InvocationTargetException Shorthand for `evaluate(new Object[0])`. Annotations @Nullable

public Object evaluate() throws InvocationTargetException

Shorthand for evaluate(new Object[0]).

Annotations

@Nullable

evaluate back to summary

evaluate	back to summary
public Object evaluate(Object[] arguments) throws InvocationTargetException Calls the script with concrete parameter values. Each argument must have the same type as specified through the `parameterTypes` parameter of `setParameters(String[], Class[])`. Arguments of primitive type must passed with their wrapper class objects. The object returned has the class as specified through `setReturnType(Class)`. This method is thread-safe. Notice: In version 3.1.8, the `arguments` parameter was changed from `Object[]` to `Object...`, which turned out to be a really bad decision because it caused a very ugly invocation ambiguity with `evaluate(int, Object[])`. Thus, with version 3.1.10, the parameter was changed back to `Object[]`. Parameters arguments:Object[] The actual parameter values Annotations @Nullable Exceptions IllegalStateException: This IScriptEvaluator is not yet cooked

public Object evaluate(Object[] arguments) throws InvocationTargetException

Calls the script with concrete parameter values.

Each argument must have the same type as specified through the parameterTypes parameter of setParameters(String[], Class[]).

Arguments of primitive type must passed with their wrapper class objects.

The object returned has the class as specified through setReturnType(Class).

This method is thread-safe.

Notice: In version 3.1.8, the arguments parameter was changed from Object[] to Object..., which turned out to be a really bad decision because it caused a very ugly invocation ambiguity with evaluate(int, Object[]). Thus, with version 3.1.10, the parameter was changed back to Object[].

Parameters

arguments:Object[]: The actual parameter values

Annotations

@Nullable

Exceptions

IllegalStateException:: This IScriptEvaluator is not yet cooked

evaluate back to summary

evaluate	back to summary
public Object evaluate(int idx, Object[] arguments) throws InvocationTargetException Same as `evaluate(Object[])`, but for multiple scripts. Annotations @Nullable

public Object evaluate(int idx, Object[] arguments) throws InvocationTargetException

Same as evaluate(Object[]), but for multiple scripts.

Annotations

@Nullable

getClazz	back to summary
public Class<?> getClazz() See Also `IClassBodyEvaluator#getClazz()`

getDefaultImports	back to summary
public String[] getDefaultImports() See Also `IClassBodyEvaluator#getDefaultImports()`

getDefaultReturnType	back to summary
public Class<?> getDefaultReturnType() Returns:Class<?> The default return type that was previously configured with `setDefaultReturnType(Class)`, or `DEFAULT_RETURN_TYPE`

getMethod	back to summary
public Method getMethod() Returns:Method The generated and loaded `java.lang.reflect.Method` Exceptions IllegalStateException: This IScriptEvaluator is not yet cooked

getMethod	back to summary
public Method getMethod(int idx) Same as `getMethod()`, but for multiple scripts.

getResult	back to summary
public Method[] getResult() Returns:Method[] The generated and loaded methods that implement the cooked scripts Exceptions IllegalStateException: This `IScriptEvaluator` is not yet cooked

setClassName	back to summary
public void setClassName(String className) See Also `IClassBodyEvaluator#setClassName(String)`

setCompileErrorHandler back to summary

setCompileErrorHandler	back to summary
public void setCompileErrorHandler(ErrorHandler compileErrorHandler) Installs an `ErrorHandler` which is invoked during compilation on each error. (By default, the compilation throws a `CompileException` on the first error and terminates.) If the given `ErrorHandler` throws a `CompileException`, then the compilation terminates and the exception is propagated. If the given `ErrorHandler` does not throw a `CompileException` but completes normally, then the compilation may or may not continue, depending on the error. Iff the compilation completes normally but errors were reported, then it will throw a `CompileException` indicating the number of errors. In other words: The `ErrorHandler` may throw a `CompileException` or not, but the compilation will definitely throw a `CompileException` if one or more compile errors have occurred. Parameters compileErrorHandler:ErrorHandler `null` to restore the default behavior (throwing a `CompileException`)

public void setCompileErrorHandler(ErrorHandler compileErrorHandler)

Installs an ErrorHandler which is invoked during compilation on each error. (By default, the compilation throws a CompileException on the first error and terminates.)

If the given ErrorHandler throws a CompileException, then the compilation terminates and the exception is propagated.

If the given ErrorHandler does not throw a CompileException but completes normally, then the compilation may or may not continue, depending on the error. Iff the compilation completes normally but errors were reported, then it will throw a CompileException indicating the number of errors.

In other words: The ErrorHandler may throw a CompileException or not, but the compilation will definitely throw a CompileException if one or more compile errors have occurred.

Parameters

compileErrorHandler:ErrorHandler: null to restore the default behavior (throwing a CompileException)

setDebuggingInformation	back to summary
public void setDebuggingInformation(boolean debugSource, boolean debugLines, boolean debugVars) Determines what kind of debugging information is included in the generates classes. The default is typically "`-g:none`".

setDefaultImports	back to summary
public void setDefaultImports(String... defaultImports) See Also `IClassBodyEvaluator#setDefaultImports(String...)`

setDefaultReturnType back to summary

setDefaultReturnType	back to summary
public void setDefaultReturnType(Class<?> defaultReturnType) When this `IScriptEvaluator` is coooked, then the `defaultReturnType` applies to all scripts for which no explicit return type was configured. The initial default return type (if you want, the "default-default" return type) is `void.class`. See Also `setReturnType(Class)`, `setReturnTypes(Class[])`

public void setDefaultReturnType(Class<?> defaultReturnType)

When this IScriptEvaluator is coooked, then the defaultReturnType applies to all scripts for which no explicit return type was configured.

The initial default return type (if you want, the "default-default" return type) is void.class.

See Also: setReturnType(Class), setReturnTypes(Class[])

setExtendedClass	back to summary
public void setExtendedClass(Class<?> extendedClass) See Also `IClassBodyEvaluator#setExtendedClass(Class)`

setImplementedInterfaces	back to summary
public void setImplementedInterfaces(Class<?>[] implementedInterfaces) See Also `IClassBodyEvaluator#setImplementedInterfaces(Class[])`

setMethodName back to summary

setMethodName	back to summary
public void setMethodName(String methodName) Defines the name of the generated method. Initially, the method name is eval*. Parameters methodName:String `null` means reset to default name See Also `IScriptEvaluator#DEFAULT_METHOD_NAME`

public void setMethodName(String methodName)

Defines the name of the generated method. Initially, the method name is eval*.

Parameters

methodName:String: null means reset to default name

See Also

IScriptEvaluator#DEFAULT_METHOD_NAME

setMethodNames back to summary

setMethodNames	back to summary
public void setMethodNames(String[] methodNames) Same as `setMethodName(String)`, but for multiple scripts. Define the names of the generated methods. By default the methods have distinct and implementation-specific names. If two scripts have the same name, then they must have different parameter types (see `setParameters(String[][], Class[][])`).

public void setMethodNames(String[] methodNames)

Same as setMethodName(String), but for multiple scripts.

Define the names of the generated methods. By default the methods have distinct and implementation-specific names.

If two scripts have the same name, then they must have different parameter types (see setParameters(String[][], Class[][])).

setOverrideMethod	back to summary
public void setOverrideMethod(boolean overrideMethod) Defines whether the generated method overrides a methods declared in a supertype.

setOverrideMethod	back to summary
public void setOverrideMethod(boolean[] overrideMethod) Same as `setOverrideMethod(boolean)`, but for multiple scripts.

setParameters back to summary

setParameters	back to summary
public void setParameters(String[] names, Class<?>[] types) Defines the names and types of the parameters of the generated method. `names.length` and `types.length` must be equal. This invariant may be checked immediately, or later when the script is cooked. The parameters can be of primitive type, e.g. `double.class`. The default is to have zero parameters.

public void setParameters(String[] names, Class<?>[] types)

Defines the names and types of the parameters of the generated method.

names.length and types.length must be equal. This invariant may be checked immediately, or later when the script is cooked.

The parameters can be of primitive type, e.g. double.class.

The default is to have zero parameters.

setParameters	back to summary
public void setParameters(String[][] names, Class<?>[][] types) Same as `setParameters(String[], Class[])`, but for multiple scripts.

setParentClassLoader back to summary

public void setParentClassLoader(ClassLoader parentClassLoader)

The "parent class loader" is used to load referenced classes. Useful values are:

`System.getSystemClassLoader()`	The running JVM's class path
`Thread.currentThread().getContextClassLoader()` or `null`	The class loader effective for the invoking thread
`ClassLoaders#BOOTCLASSPATH_CLASS_LOADER`	The running JVM's boot class path

The parent class loader defaults to the current thread's context class loader.

setReturnType back to summary

setReturnType	back to summary
public void setReturnType(Class<?> returnType) Defines the return type of the generated method. Value `null` means "use the default return type". See Also `setDefaultReturnType(Class)`

public void setReturnType(Class<?> returnType)

Defines the return type of the generated method. Value null means "use the default return type".

See Also: setDefaultReturnType(Class)

setReturnTypes back to summary

setReturnTypes	back to summary
public void setReturnTypes(Class<?>[] returnTypes) Configures the return types of the generated methods. If an element of the array is `null`, then use the "default return type" for that script. Parameters returnTypes:Class<?>[] The methods' return types; `null` elements mean "use the default return type" See Also `setDefaultReturnType(Class)`, `getDefaultReturnType()`

public void setReturnTypes(Class<?>[] returnTypes)

Configures the return types of the generated methods. If an element of the array is null, then use the "default return type" for that script.

Parameters

returnTypes:Class<?>[]: The methods' return types; null elements mean "use the default return type"

setStaticMethod	back to summary
public void setStaticMethod(boolean staticMethod) Defines whether the generated method should be STATIC or not. Defaults to `true`.

setStaticMethod	back to summary
public void setStaticMethod(boolean[] staticMethod) Same as `setStaticMethod(boolean)`, but for multiple scripts.

setThrownExceptions	back to summary
public void setThrownExceptions(Class<?>[] thrownExceptions) Defines the exceptions that the generated method may throw.

setThrownExceptions	back to summary
public void setThrownExceptions(Class<?>[][] thrownExceptions) Same as `setThrownExceptions(Class[])`, but for multiple scripts.

setWarningHandler back to summary

setWarningHandler	back to summary
public void setWarningHandler(WarningHandler warningHandler) By default, warnings are discarded, but an application my install a custom `WarningHandler`. Parameters warningHandler:WarningHandler `null` to indicate that no warnings be issued

public void setWarningHandler(WarningHandler warningHandler)

By default, warnings are discarded, but an application my install a custom WarningHandler.

Parameters

warningHandler:WarningHandler: null to indicate that no warnings be issued

public Interface IScriptEvaluator

Field Summary

Method Summary

Field Detail

Method Detail