override fun visitAssignmentStatement()

in src/org/jetbrains/r/inspections/UnusedVariableInspection.kt [36:88]
48 lines of code
14 McCabe index (conditional complexity)

    override fun visitAssignmentStatement(element: RAssignmentStatement) {
      val assignee = element.assignee ?: return

      if (RPsiUtil.isReturnValue(element)) {
        return
      }
      if (isInplaceAssignment(assignee)) {
        return
      }
      // not supported
      if (element.isClosureAssignment) {
        return
      }

      val function = PsiTreeUtil.getParentOfType(element, RFunctionExpression::class.java) ?: return
      val name = assignee.name
      val localVariableInfo = function.getLocalVariableInfo(element)
      val variableDefinition = localVariableInfo?.variables?.get(name) ?: return
      val controlFlow = function.controlFlow
      var found = false
      var rewritten = false

      ControlFlowUtil.iterate(controlFlow.getInstructionByElement(element)?.num()!!, controlFlow.instructions, { instruction ->
        val currentElement = instruction.element ?: return@iterate ControlFlowUtil.Operation.NEXT
        if (currentElement == element) {
          return@iterate ControlFlowUtil.Operation.NEXT
        }
        if (variableDefinition.variableDescription.reads.contains(currentElement)) {
          found = true
          return@iterate ControlFlowUtil.Operation.BREAK
        }
        val writes = variableDefinition.variableDescription.writes
        if (writes.contains(currentElement) && currentElement.parent is RForStatement ||
            currentElement is RAssignmentStatement && currentElement.assignee?.let { writes.contains(it) } == true ) {
          rewritten = true
          return@iterate ControlFlowUtil.Operation.CONTINUE
        }
        if (currentElement is RFunctionExpression &&
            currentElement.localAnalysisResult.closure.contains(variableDefinition.variableDescription)) {
          found = true
          return@iterate ControlFlowUtil.Operation.BREAK
        }
        return@iterate ControlFlowUtil.Operation.NEXT
      }, false)

      if (!found) {
        val message = if (!rewritten) RBundle.message("inspection.message.variable.is.never.used", assignee.text)
                                 else RBundle.message("inspection.message.variable.is.never.used.but.assigned", assignee.text)
        myProblemHolder.registerProblem(assignee,
                                        message,
                                        ProblemHighlightType.LIKE_UNUSED_SYMBOL)
      }
    }