How does Astra work?

Astra uses Eclipse JDT to compile source code into an AST, a construct that provides useful information about the structure and meaning of the code. Astra then allows you to analyse or refactor your source code based on information from the AST.

Here's a sequence diagram explaining how it works:

AstraCore iterates through all the Java source files in the input directory. File-by-file, an AST is compiled - from the source file, plus any additional classpaths supplied. Each individual construct, such as a name, type, expression, statement, or declaration, is represented in this AST by an ASTNode. It also builds an ASTRewriter, to record any changes to be made to the AST.

Astra then visits every ASTNode in the AST, passing every node through a set of ASTOperations. If an operation is applicable to that node, (e.g. is this an invocation of method A?) the ASTOperation records relevant changes in the ASTRewriter (e.g. invoke method B instead)

When all ASTNodes in a source file's AST have been visited, any changes recorded in the ASTRewriter are written back to the original source file. At this stage, Astra will also organise imports in a similar way to an IDE, removing duplicates and unused imports, and sorting.