What is AST

An abstract syntax tree (AST). http://home.a00.itscom.net/hatada/c-tips/ast/ast01.html

AST in the program

Analyze the source code and generate a tree with each node as a leaf.

AST parseable library

JavaPerser https://github.com/javaparser/javaparser/wiki

If you use the library of com.sun.tools.javac.model, you can change the intermediate AST at compile time ...? ??

Note about Java Parser

Perth

In order to parse the source code, parse it with the following code and convert it to the CompilationUnit type. You can specify InputSteream, File, etc. in this argument.

JavaParser.parse([source]);

AST change

Once converted to CompilationUnit, you can get the object that represents each node, so you can modify it from there.

The nodes that could be obtained directly from the Compilation Unit are:

ImportDeclaration
AnnotationDeclaration
PackageDecralation
ClassOrInterfaceDeclaration
EnumDeclaration

Perhaps if you want to process the node in Class (or Interface), get ClassOrInterfaceDeclaration once and modify it.

If you want to get a method

targetclass.getMethodsByName("testMethod1")

Now you can get a list of node MethodDeclarations that represent methods with the name "testMethod1". (If there is the same name, it will be added to the list accordingly)

Modifier refers to private or something like that

Also, if you want to get a Method with arguments.

//You can get a Method with String and int as arguments with the name methodName.
ClassOrInterfaceDeclaration.getMethodsBySignature(String new methodName, new String[] {"String","int"});

Erase the node

If you call remove () as it is, it disappears.

Change the name.

Call setName (String name). You can also assign using a SimpleName object

Change the initialization.

Change the initialization with setInitializer of VariableDeclarator. The argument is of Expression type, which can be created by JavaParser.parseExpression.

VariableDeclarator.setInitializer(JavaParser.parseExpression(content));

Put a variable in Class

Use ClassOrInterfaceDeclaration as before. You can call add *** for this object to get the object that represents that node as it is added.

//private ScanSize[] aaa;To add
FieldDeclaration field = targetclass.addField(ScanSize[].class, "aaa", Modifier.PRIVATE);

If you put the VariableDeclarator created elsewhere in setVariable () of this field object, it will be entered as it is.

Maybe the method can go as well, maybe.

Push variables from your own source into another source

Get your own source and parse

Path selfSource =　Paths.get("[Source Path]");

By doing this, you can get arbitrary declarations etc., so all you have to do is plunge into another file

reference

Detailed article about Java Parser https://qiita.com/opengl-8080/items/50ddee7d635c7baee0ab#%E5%8F%82%E8%80%83

AST conversion in annotation processor --change variable type at compile time with reference to Lombok http://fits.hatenablog.com/entry/2015/01/17/172651

Notes for AST analysis