Desenvolva plugins para o compilador do Java 8

Desenvolva plugins para o compilador do Java 8

• 1.
  Desenvolva plugins parao compilador do Java 8 JustJava 2013
• 2.
  Marcelo de Castro marcelo@castro.eti.br @mcastroinfo
• 3.
  Plugin para ojavac 8 0101010101011111000000000101001110001 1100011100000001111010101010110001110 1001001010000101001010101011010110111
• 4.
  • Por quê,para quê, desenvolver plugins para o compilador do Java? – Adicionar checagem extras em tempo de compilação – Adicionar transformações de código – Customizar análise do código fonte
• 5.
  Este código compila? Teste.java publicclass Teste { public static final int var = 0; public static void main(String[] args) { int i = 0; System.out.println("#JustJava2013"); try{ i++; }catch(Exception Ex){ } } public static void method(int a, int b, int c, int d, int e, int f, int g, int h, int i, int j, int k){ } class inner{} }
• 6.
  Jogo dos 5erros(!?) public class Teste { public static final int var = 0; public static void main(String[] args) { int i = 0; System.out.println("#JustJava2013"); try{ i++; }catch(Exception Ex){ } } public static void method(int a, int b, int c, int d, int e, int f, int g, int h, int i, int j, int k){ } class inner{} } VAR ex Inner vazio Muitos parâmetros
• 7.
  Compilar ou nãocompilar ????? public class Teste { public static final int var = 0; public static void main(String[] args) { int i = 0; System.out.println("#JustJava2013"); try{ i++; }catch(Exception Ex){ } } public static void method(int a, int b, int c, int d, int e, int f, int g, int h, int i, int j, int k){ } class inner{} }
• 8.
  Alterando o comportamento dojavac 1. Usar Java 8 (tools.jar no CLASSPATH) 2. Implementar Plugin(*) 3. Implementar TaskListener 4. Implementar a lógica desejada – (TreePathScanner, TreeScanner, TreeVisitor) – Ex: Não aceitar bloco catch vazio 5. Gerar o jar do Plugin – META-INF/services/ • com.sun.source.util.Plugin – NomeTotalmenteQualificadoDoPlugin(*) 6. Compilar usando o plugin – javac -processorpath CodeCheckPlugin.jar - Xplugin:CodeCheckPlugin Teste.java
• 9.
  API 0101010101011111000000000101001110001 1100011100000001111010101010110001110 1001001010000101001010101011010110111
• 10.
  interfaces com.sun.source.util • Plugin – permitedefinir um plugin para o compilador • SourcePositions – fornece métodos para obter a posição corrente da compilação • TaskListener – fornece um listener para monitorar atividades do javac
• 11.
  interface Plugin public classCodeCheckPlugin implements Plugin { @Override public String getName() { return "CodeCheckPlugin"; } @Override public void init(JavacTask task, String... strings) { System.out.println("Iniciando plugin!"); task.setTaskListener(new CheckTaskListener(task)); } }
• 12.
  interface TaskListener public classCheckTaskListener implements TaskListener{ @Override public void started(TaskEvent taskEvent) { if(taskEvent.getKind().equals(TaskEvent.Kind.ANALYZE)) { CompilationUnitTree compUnit = taskEvent.getCompilationUnit(); TreePathScanner emptyCacthVisitor = new EmptyCacthVisitor(task); emptyCacthVisitor.scan(compUnit, null); } } @Override public void finished(TaskEvent te) { } }
• 13.
  TaskEvent.Kind •PARSE •ENTER •ANNOTATION_PROCESSING •ANNOTATION_PROCESSING_ROUND •ANALYZE •GENERATE Source File Teste.java Byte Code Teste.class
• 14.
  Abstract Syntax Trees Exemploda Gramática da Linguagem Java normalClassDeclaration : 'class' Identifier typeParameters? ('extends' type)? ('implements' typeList)? classBody public class Teste extends TesteBase{ } class TesteBase{} *AST: abstract syntax tree
• 15.
  interface SourcePositions SourcePositions sourcePositions= trees.getSourcePositions(); sourcePositions.getStartPosition (compilationUnitTree, tree); sourcePositions.getEndPosition (compilationUnitTree, tree);
• 16.
  Classes (Syntax Trees) com.sun.source.util com.sun.source.tree •public abstract class Trees • public abstract class DocTrees extends Trees • public interface Tree • public enum Tree.Kind • public interface CompilationUnitTree extends Tree • public interface MethodTree extends Tree • public interface BlockTree extends Tree • public interface CatchTree extends Tree • public interface StatementTree extends Tree • public interface ModifiersTree extends Tree • public interface VariableTree extends Tree • public interface PrimitiveTypeTree extends Tree • + um montão de Tree
• 17.
  DEMO 0101010101011111000000000101001110001 1100011100000001111010101010110001110 1001001010000101001010101011010110111
• 18.
  Referências • OpenJDK 8http://openjdk.java.net/ • Javadoc (javac b74) http://download.java.net/lambda/b74/docs/jdk/api/javac/tree/ • Compiler Grammar http://openjdk.java.net/projects/compiler-grammar/ • Hacking the Java Compiler for Fun and Profit By Raoul-Gabriel Urma • “Java Compiler Plugins”, Oracle Java Magazine January/February 2013, Raoul-Gabriel Urma& Jonathan Gibbons http://www.oraclejavamagazine- digital.com/javamagazine/20130102?sub_id=jFwJyABK25xj#pg56
• 19.
  OBRIGADO Marcelo de Castro marcelo@castro.eti.br @mcastroinfo