public Interface IExpressionEvaluator

Special value for setExpressionType(Class) that indicates that the expression may have any type.

The fully qualified name of the generated class, iff not reconfigured by setClassName(String).

The type of all expressions that were not reconfigured with setExpressionTypes(Class[]).

If the parameter and return types of the expression are known at compile time, then a "fast" expression evaluator can be instantiated through createFastEvaluator(String, Class, String[]). Expression 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);
}
...
ExpressionEvaluator ee = CompilerFactoryFactory.getDefaultCompilerFactory().newExpressionEvaluator();

// Optionally configure the EE here...
ee.setClassName("Bar");
ee.setDefaultImports(new String[] { "java.util.*" });
ee.setExtendedClass(SomeOtherClass.class);
ee.setParentClassLoader(someClassLoader);

// Optionally configure the EE here...
Foo f = (Foo) ee.createFastEvaluator(
    "a + b",                    // expression to evaluate
    Foo.class,                  // interface that describes the expression's signature
    new String[] { "a", "b" }   // the parameters' names
);
System.out.println("1 + 2 = " + f.bar(1, 2)); // Evaluate the expression

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 be accessible by the compiled class, i.e. either be declared public, or with protected or default access in the package of the compiled class (see setClassName(String).

See Also

createFastEvaluator(String, Class, String[])

Shorthand for evaluate(new Object[0]).

Annotations

@Nullable

Evaluates the expression with concrete parameter values.

Each argument value 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 setExpressionType(Class).

This method is thread-safe.

Null arguments is equivalent with new Object[0].

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

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

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[].

Annotations

@Nullable

Returns:Class<?>

The generated Class

Exceptions

IllegalStateException:

This IClassBodyEvaluator is not yet cooked

Returns:Class<?>

The currently configured "default expression type"

See Also

setDefaultExpressionType(Class)

Returns:String[]

The default imports that were previously configured with setDefaultImports(String...)

Returns:Method

The generated and loaded java.lang.reflect.Method

Exceptions

IllegalStateException:

This IExpressionEvaluator is not yet cooked

Same as getMethod(), but for multiple expressions.

Returns:Method[]

The generated and loaded methods that implement the cooked expressions

Exceptions

IllegalStateException:

This IScriptEvaluator is not yet cooked

Sets the name of the generated class. Defaults to DEFAULT_CLASS_NAME. In most cases, there is no need to set this name, because the generated class is loaded into its own java.lang.ClassLoader where its name cannot collide with classes generated by other evaluators.

One reason to use this function is to have a class name in a non-default package, which can be relevant when types and members with DEFAULT accessibility are accessed.

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)

Determines what kind of debugging information is included in the generates classes. The default is typically "-g:none".

Reconfigures the "default expression type"; if no expression type is configured for an expression, then, when cooking this IExpressionEvaluator, the "default expression type" is used for the expression

"Default imports" add to the system import "java.lang", i.e. the evaluator may refer to classes imported by default imports without having to explicitly declare IMPORT statements.

Notice that JDK 5 "static imports" are also supported, as shown here:

    sc.setDefaultImports(
        "java.util.Map",                          // Single type import
        "java.io.*",                              // Type-import-on-demand
        "static java.util.Collections.EMPTY_MAP", // Single static import
        "static java.util.Collections.*",         // Static-import-on-demand
    );

Defines the type of the expression.

Defaults to Object.class, which, thanks to autoboxing, allows for any expression type (including primitive types).

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

Configures the types of the expressions.

Unless this method is called, all expressions have type Object.class.

If any expression has type void.class, then it must be an invocation of a void method.

Sets a particular superclass that the generated class will extend. If extendedClass is null, the generated class will extend Object.

The usual reason to set a base class for an evaluator is that the generated class can directly access the superclass's (non-private) members.

Configures the interfaces that the generated class implements.

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

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

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

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

Defines whether the generated method overrides a methods declared in a supertype.

Same as setOverrideMethod(boolean), but for multiple expressions.

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 expression is cooked.

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

The default is to have zero parameters.

Same as setParameters(String[], Class[]), but for multiple expressions.

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

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

Annotations

@Deprecated

Defines whether the generated method should be STATIC or not. Defaults to true.

Same as setStaticMethod(boolean), but for multiple expressions.

Defines the exceptions that the generated method may throw.

Same as setThrownExceptions(Class[]), but for multiple expressions.

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

Parameters

warningHandler:WarningHandler

null to indicate that no warnings be issued