org.apache.drill.exec.expr

Class CodeGenerator<T>

java.lang.Object

org.apache.drill.exec.expr.CodeGenerator<T>

Type Parameters:

T - The interface that results from compiling and merging the runtime code that is generated.

public class CodeGenerator<T>
extends Object

A code generator is responsible for generating the Java source code required to complete the implementation of an abstract template. A code generator can contain one or more ClassGenerators that implement outer and inner classes associated with a particular runtime generated instance.

Drill supports two ways to generate and compile the code from a code generator: via byte-code manipulations or as "plain Java."

When using byte-code transformations, the code generator is used with a class transformer to merge precompiled template code with runtime generated and compiled query specific code to create a runtime instance.

The code generator can optionally be marked as "plain Java" capable. This means that the generated code can be compiled directly as a Java class without the normal byte-code manipulations. Plain Java allows the option to persist, and debug, the generated code when building new generated classes or otherwise working with generated code. To turn on debugging, see the explanation in ClassBuilder.

Method Summary

Modifier and Type	Method and Description
boolean	equals(Object obj)
void	generate()
String	generateAndGet()
static <T> CodeGenerator<T>	get(MappingSet mappingSet, TemplateClassDefinition<T> definition, OptionSet optionManager)
static <T> CodeGenerator<T>	get(TemplateClassDefinition<T> definition)
static <T> CodeGenerator<T>	get(TemplateClassDefinition<T> definition, OptionSet optionManager)
String	getClassName()
TemplateClassDefinition<T>	getDefinition()
String	getGeneratedCode()
String	getMaterializedClassName()
ClassGenerator<T>	getRoot()
static <T> ClassGenerator<T>	getRoot(MappingSet mappingSet, TemplateClassDefinition<T> definition, OptionSet optionManager)
static <T> ClassGenerator<T>	getRoot(TemplateClassDefinition<T> definition, OptionSet optionManager)
int	hashCode()
boolean	isCodeToBeSaved()
boolean	isPlainJava()
void	plainJavaCapable(boolean flag) Indicates that the code for this class can be generated using the "Plain Java" mechanism based on inheritance.
void	preferPlainJava(boolean flag) Identifies that this generated class should be generated via the plain Java mechanism.
void	saveCodeForDebugging(boolean persist) Debug-time option to persist the code for the generated class to permit debugging.
boolean	supportsPlainJava()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Method Detail

plainJavaCapable

public void plainJavaCapable(boolean flag)

Indicates that the code for this class can be generated using the "Plain Java" mechanism based on inheritance. The byte-code method is more lenient, so some code is missing some features such as proper exception labeling, etc. Set this option to true once the generation mechanism for a class has been cleaned up to work via the plain Java mechanism.

Parameters:

flag - true if the code generated from this instance is ready to be compiled as a plain Java class

preferPlainJava

public void preferPlainJava(boolean flag)

Identifies that this generated class should be generated via the plain Java mechanism. This flag only has meaning if the generated class is capable of plain Java generation.

Parameters:

flag - true if the class should be generated and compiled as a plain Java class (rather than via byte-code manipulations)

supportsPlainJava

public boolean supportsPlainJava()

isPlainJava

public boolean isPlainJava()

saveCodeForDebugging

public void saveCodeForDebugging(boolean persist)

Debug-time option to persist the code for the generated class to permit debugging. Has effect only when code is generated using the plain Java option. Code is written to the code directory specified in ClassBuilder. To debug code, set this option, then point your IDE to the code directory when the IDE prompts you for the source code location.

Parameters:

persist - true to write the code to disk, false (the default) to keep code only in memory.

isCodeToBeSaved

public boolean isCodeToBeSaved()

getRoot

public ClassGenerator<T> getRoot()

generate

public void generate()

generateAndGet

public String generateAndGet()
                      throws IOException

Throws:

IOException

getGeneratedCode

public String getGeneratedCode()

getDefinition

public TemplateClassDefinition<T> getDefinition()

getMaterializedClassName

public String getMaterializedClassName()

getClassName

public String getClassName()

get

public static <T> CodeGenerator<T> get(TemplateClassDefinition<T> definition)

get

public static <T> CodeGenerator<T> get(TemplateClassDefinition<T> definition,
                                       OptionSet optionManager)

getRoot

public static <T> ClassGenerator<T> getRoot(TemplateClassDefinition<T> definition,
                                            OptionSet optionManager)

getRoot

public static <T> ClassGenerator<T> getRoot(MappingSet mappingSet,
                                            TemplateClassDefinition<T> definition,
                                            OptionSet optionManager)

get

public static <T> CodeGenerator<T> get(MappingSet mappingSet,
                                       TemplateClassDefinition<T> definition,
                                       OptionSet optionManager)

hashCode

public int hashCode()

Overrides:

hashCode in class Object

equals

public boolean equals(Object obj)

Overrides:

equals in class Object