A plug-in for the Synthetic migration ViewBinding

Recently, the company planned to transfer the original Synthetic to ViewBinding. It would be painful to change the underline to hump, so I simply wrote a plug-in.

Why migrate

For more on why to migrate, check out this article Kotlin updated version 1.5: Synthetic Crime Analysis

To sum up:

Efficiency issues caused by changes in view cache mechanism after Kotlin upgrade 1.5;
Wide-eyed taking a view using Kotlin Synwide-eyed might cause a null pointer;
Synthetic has expired, according to the inertia from disappear not long (manual dog head);

Implementation using delegate properties

We ultimately chose the implementation of KotlinDelegate internally. For analysis and principles, see the original author’s article:

Android | ViewBinding and Kotlin entrust shuangjian combination

Based on the above wheels, there are two main pieces of code that we will eventually need to migrate:

Implementation of viewBinding:

  private val binding by viewBinding(LayoutTestBinding::bind)
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Change the name of the underline in the original code to the name of the camel:

app_detail -> binding.appDetail

The first implementation of viewBinding is relatively simple, and the most tedious is the modification of the hump. Therefore, the main purpose of this plug-in is to quickly transition the existing code.

The main implementation

From the editor checked r.layout. name, find the corresponding XML and parse all ids in it:

   fun getLayoutFileFromCaret(file: PsiFile, editor: Editor): PsiFile? {
        val offset = editor.caretModel.offset
        val candidateA = file.findElementAt(offset)
        val candidateB = file.findElementAt(offset - 1)
        val layout = findLayoutResource(candidateA)
        returnlayout ? : findLayoutResource(candidateB) }private fun findLayoutResource(element: PsiElement?).: PsiFile? {
        if (element == null) {
            return null // nothing to be used
        }
        vallayout: PsiElement = element.parent.parent.firstChild ? :return null
        if ("R.layout"! = layout.text) {return null // not layout file
        }
        val name = String.format("%s.xml", element.text)
        return resolveLayoutResourceFile(element, name)
    }


    fun resolveLayoutResourceFile(element: PsiElement? , layoutName:String?).: PsiFile? {
        if (element == null || layoutName == null) return null
        val project = element.project
        val module = ModuleUtil.findModuleForPsiElement(element)
        var files: Array<PsiFile>? = null
        if(module ! =null) {
            val moduleScope = module.getModuleWithDependenciesAndLibrariesScope(false)
            files = FilenameIndex.getFilesByName(project, layoutName, moduleScope)
        }
        if (files == null || files.isEmpty()) {
            files = FilenameIndex.getFilesByName(project, layoutName, everythingScope(project))
        }
        return if (files.isEmpty()) {
            null //no matching files
        } else files[0]}Copy the code

Based on the ID set found, replace the original ID with hump by text:

fun doWriteAction(viewIdInfoAsList: List<ViewInfo>) {
    writeCommandAction(mProject).run<Exception> {
        try {
            var classStr = mClass.text
            // Replace in descending order of text length to prevent repeated replacement of child elements
            val viewList = viewIdInfoAsList.sortedByDescending {
                it.id.length
            }
            for (info in viewList) {
                var str = String.format(
                    Constants.COMMON_VIEW,
                    info.id
                )
                if (info.id.contains("_")){
                    str = String.format(
                        Constants.COMMON_VIEW,
                        CaseFormat.UPPER_UNDERSCORE.to(CaseFormat.LOWER_CAMEL, info.id)
                    )
                }

                println("SynthiticReplaceMethod  info.id ${info.id}   str $str")
                classStr = classStr.replace(
                    info.id, str
                )
            }
            mClass = mClass.replace(mFactory.createClass(classStr)) asKtClass mClass.body? .addAfter(mFactory.createProperty(bindingCode), mClass.body? .firstChild) }catch (e: Exception) {
            e.printStackTrace()
        }
    }
}
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Plug-in installation

Take the bag down github.com/MartinHY/Sy…
Idea Local Installation
Delete 0.0 after migration

Plug-in usage

Select the Layout ID in the code and right-click Synthetic2ViewBinding:

Generate the relevant replacement code:

A few problems with plug-ins

ViewBinding is not supported for internal classes. The viewBinding will only be generated at the bottom of the construct.
Because the plugin is replaced by ktClass text globally, it does not check whether it is a method or a variable. It is recommended to check the comparison line by line (RollBackChange is very useful).
Plug-ins are only responsible for solving the efficiency problem of migration, and relevant functions need to be verified by themselves.

A plug-in for the Synthetic migration ViewBinding