feat(pycharm): add related class provider for Python #358

- Implement PythonRelatedClassProvider to find related classes/functions for a given Python element
- Register the provider in the plugin XML configuration

Author: phodal

pycharm/src/main/kotlin/cc/unitmesh/python/provider/PythonRelatedClassProvider.kt

@@ -0,0 +1,38 @@
+package cc.unitmesh.python.provider
+
+import cc.unitmesh.devti.provider.RelatedClassesProvider
+import com.intellij.openapi.project.Project
+import com.intellij.psi.PsiElement
+import com.intellij.psi.PsiFile
+import com.intellij.psi.PsiNamedElement
+import com.jetbrains.python.codeInsight.PyPsiIndexUtil
+
+class PythonRelatedClassProvider : RelatedClassesProvider {
+    override fun lookupIO(element: PsiElement): List<PsiElement> {
+        return emptyList()
+    }
+
+    override fun lookupIO(element: PsiFile): List<PsiElement> {
+        return emptyList()
+    }
+
+    override fun lookupCaller(
+        project: Project,
+        element: PsiElement
+    ): List<PsiNamedElement> {
+        if(element is PsiNamedElement) {
+            val findUsages = PyPsiIndexUtil.findUsages(element, false)
+            return findUsages.mapNotNull { usageInfo ->
+                when (usageInfo.element) {
+                    is PsiNamedElement -> {
+                        return@mapNotNull usageInfo.element as PsiNamedElement
+                    }
+
+                    else -> return@mapNotNull null
+                }
+            }
+        }
+
+        return emptyList()
+    }
+}

pycharm/src/main/resources/cc.unitmesh.pycharm.xml

@@ -27,5 +27,8 @@
 
         <runService implementation="cc.unitmesh.python.provider.PythonRunService"/>
 
+        <relatedClassProvider
+                language="Python"
+                implementationClass="cc.unitmesh.python.provider.PythonRelatedClassProvider"/>
     </extensions>
 </idea-plugin>