AST to replace `==` with `equals` method invocation

[Paolo Di Tommaso]

Dear all, 

I'm trying to implement an AST transformation to replace any `==` binary expression with a equals method call invocation as suggested here.

My understanding is that it's required to override each the visitor for each node where a binary expression can appear ie. if statement, while statement, assignment, for loop, method call, etc. 

That looks a bit overkill. I was wondering if there's a better way to replace globally all `==` binary expressions with `equals` method invocations. 

Cheers,
Paolo

[MG]

Hi Paolo,

I have not used it myself, but have you had a look at the new Groovy 2.5 "abstract syntax tree search and replace"-feature (http://groovy-lang.org/releasenotes/groovy-2.5.html & search for "AST matching") ?

Cheers,
mg

On 10.06.2018 16:55, Paolo Di Tommaso wrote:

Dear all, 

I'm trying to implement an AST transformation to replace any `==` binary expression with a equals method call invocation as suggested here.

My understanding is that it's required to override each the visitor for each node where a binary expression can appear ie. if statement, while statement, assignment, for loop, method call, etc. 

That looks a bit overkill. I was wondering if there's a better way to replace globally all `==` binary expressions with `equals` method invocations. 

Cheers,
Paolo

[Mario Garcia]

Hi Paolo:

A couple of years ago I created Asteroid (https://github.com/grooviter/asteroid) a library to deal with AST transformations. I needed to create a minor release so I've taken the oportunity to solve this problem and I think is pretty easy. 

• Create a Transformer. A transformer is just a class transforming a specific type of node, and it uses a criteria to filter nodes.
• Create a Global transformation that includes the previous transformer to apply it to the whole codebase
• Test that the AST generated has changed from a BinaryExpression to a MethodCallExpression
• Profit :)

You can find the source code here:  

• Transformer: https://github.com/grooviter/asteroid/blob/master/asteroid-test/src/main/groovy/asteroid/global/samples/ChangeEqualsTransformer.groovy 
• Transformation: https://github.com/grooviter/asteroid/blob/master/asteroid-test/src/main/groovy/asteroid/global/samples/ChangeEqualsTransformation.groovy
• Test: https://github.com/grooviter/asteroid/blob/master/asteroid-test/src/test/groovy/asteroid/global/samples/ChangeEqualsTransformationSpec.groovy

You can find also some documentation at: http://grooviter.github.io/asteroid/

Of course any feedback on the library is appreciated :)

I hope this helps

Mario

2018-06-10 21:27 GMT+02:00 MG <[hidden email]>:

Hi Paolo,

I have not used it myself, but have you had a look at the new Groovy 2.5 "abstract syntax tree search and replace"-feature (http://groovy-lang.org/releasenotes/groovy-2.5.html & search for "AST matching") ?

Cheers,
mg

On 10.06.2018 16:55, Paolo Di Tommaso wrote:

Dear all, 

I'm trying to implement an AST transformation to replace any `==` binary expression with a equals method call invocation as suggested here.

My understanding is that it's required to override each the visitor for each node where a binary expression can appear ie. if statement, while statement, assignment, for loop, method call, etc. 

That looks a bit overkill. I was wondering if there's a better way to replace globally all `==` binary expressions with `equals` method invocations. 

Cheers,
Paolo

[Paolo Di Tommaso]

Thanks Mario, 

Looking at Asteroid code put me in the right direction. In a nutshell it is not possible to mix ClassCodeVisitorSupport logic with class ClassCodeExpressionTransformer one. I need to use two different classes. 

p

On Wed, Jun 13, 2018 at 9:52 AM, Mario Garcia <[hidden email]> wrote:

Hi Paolo:

A couple of years ago I created Asteroid (https://github.com/grooviter/asteroid) a library to deal with AST transformations. I needed to create a minor release so I've taken the oportunity to solve this problem and I think is pretty easy. 

• Create a Transformer. A transformer is just a class transforming a specific type of node, and it uses a criteria to filter nodes.
• Create a Global transformation that includes the previous transformer to apply it to the whole codebase
• Test that the AST generated has changed from a BinaryExpression to a MethodCallExpression
• Profit :)

You can find the source code here:  

• Transformer: https://github.com/grooviter/asteroid/blob/master/asteroid-test/src/main/groovy/asteroid/global/samples/ChangeEqualsTransformer.groovy 
• Transformation: https://github.com/grooviter/asteroid/blob/master/asteroid-test/src/main/groovy/asteroid/global/samples/ChangeEqualsTransformation.groovy
• Test: https://github.com/grooviter/asteroid/blob/master/asteroid-test/src/test/groovy/asteroid/global/samples/ChangeEqualsTransformationSpec.groovy

You can find also some documentation at: http://grooviter.github.io/asteroid/

Of course any feedback on the library is appreciated :)

I hope this helps

Mario

2018-06-10 21:27 GMT+02:00 MG <[hidden email]>:

Hi Paolo,

I have not used it myself, but have you had a look at the new Groovy 2.5 "abstract syntax tree search and replace"-feature (http://groovy-lang.org/releasenotes/groovy-2.5.html & search for "AST matching") ?

Cheers,
mg

On 10.06.2018 16:55, Paolo Di Tommaso wrote:

Dear all, 

I'm trying to implement an AST transformation to replace any `==` binary expression with a equals method call invocation as suggested here.

My understanding is that it's required to override each the visitor for each node where a binary expression can appear ie. if statement, while statement, assignment, for loop, method call, etc. 

That looks a bit overkill. I was wondering if there's a better way to replace globally all `==` binary expressions with `equals` method invocations. 

Cheers,
Paolo