Remove redundant parentheses in if expressions

+ `elsif` -> `case`

src/ameba/ast/util.cr

@@ -162,11 +162,11 @@ module Ameba::AST::Util
   # Returns the exp code of a control expression.
   # Wraps implicit tuple literal with curly brackets (e.g. multi-return).
   def control_exp_code(node : Crystal::ControlExpression, code_lines)
-    return unless (exp = node.exp)
-    return unless (exp_code = node_source(exp, code_lines))
+    return unless exp = node.exp
+    return unless exp_code = node_source(exp, code_lines)
     return exp_code unless exp.is_a?(Crystal::TupleLiteral) && exp_code[0] != '{'
-    return unless (exp_start = exp.elements.first.location)
-    return unless (exp_end = exp.end_location)
+    return unless exp_start = exp.elements.first.location
+    return unless exp_end = exp.end_location
 
     "{#{source_between(exp_start, exp_end, code_lines)}}"
   end

src/ameba/ast/visitors/scope_visitor.cr

@@ -114,11 +114,12 @@ module Ameba::AST
     def visit(node : Crystal::Var)
       variable = @current_scope.find_variable node.name
 
-      if @current_scope.arg?(node) # node is an argument
+      case
+      when @current_scope.arg?(node) # node is an argument
         @current_scope.add_argument(node)
-      elsif variable.nil? && @current_assign # node is a variable
+      when variable.nil? && @current_assign # node is a variable
         @current_scope.add_variable(node)
-      elsif variable # node is a reference
+      when variable # node is a reference
         reference = variable.reference node, @current_scope
         if @current_assign.is_a?(Crystal::OpAssign) || !reference.target_of?(@current_assign)
           variable.reference_assignments!

src/ameba/formatter/explain_formatter.cr

@@ -38,7 +38,7 @@ module Ameba::Formatter
     private def explain(source, issue)
       rule = issue.rule
 
-      return unless (location = issue.location)
+      return unless location = issue.location
 
       output_title "ISSUE INFO"
       output_paragraph [

src/ameba/formatter/util.cr

@@ -41,7 +41,7 @@ module Ameba::Formatter
     end
 
     def affected_code(issue : Issue, context_lines = 0, max_length = 120, ellipsis = " ...", prompt = "> ")
-      return unless (location = issue.location)
+      return unless location = issue.location
 
       affected_code(issue.code, location, issue.end_location, context_lines, max_length, ellipsis, prompt)
     end

src/ameba/rule/style/is_a_filter.cr

@@ -59,8 +59,8 @@ module Ameba::Rule::Style
 
     def test(source, node : Crystal::Call)
       return unless node.name.in?(filter_names)
-      return unless (filter_location = node.name_location)
-      return unless (block = node.block)
+      return unless filter_location = node.name_location
+      return unless block = node.block
       return unless (body = block.body).is_a?(Crystal::IsA)
       return unless (path = body.const).is_a?(Crystal::Path)
       return unless body.obj.is_a?(Crystal::Var)

src/ameba/rule/style/redundant_next.cr

@@ -116,7 +116,7 @@ module Ameba::Rule::Style
       return if allow_multi_next && node.exp.is_a?(Crystal::TupleLiteral)
       return if allow_empty_next && (node.exp.nil? || node.exp.try(&.nop?))
 
-      if (exp_code = control_exp_code(node, source.lines))
+      if exp_code = control_exp_code(node, source.lines)
         issue_for node, MSG do |corrector|
           corrector.replace(node, exp_code)
         end

src/ameba/rule/style/redundant_return.cr

@@ -113,7 +113,7 @@ module Ameba::Rule::Style
       return if allow_multi_return && node.exp.is_a?(Crystal::TupleLiteral)
       return if allow_empty_return && (node.exp.nil? || node.exp.try(&.nop?))
 
-      if (exp_code = control_exp_code(node, source.lines))
+      if exp_code = control_exp_code(node, source.lines)
         issue_for node, MSG do |corrector|
           corrector.replace(node, exp_code)
         end

src/ameba/rule/style/variable_names.cr

@@ -59,7 +59,7 @@ module Ameba::Rule::Style
       end
 
       def visit(node : Crystal::InstanceVar | Crystal::ClassVar)
-        if (location = node.location)
+        if location = node.location
           var_locations << location
         end
         super

src/ameba/rule/style/while_true.cr

@@ -34,8 +34,8 @@ module Ameba::Rule::Style
 
     def test(source, node : Crystal::While)
       return unless node.cond.true_literal?
-      return unless (location = node.location)
-      return unless (end_location = node.cond.end_location)
+      return unless location = node.location
+      return unless end_location = node.cond.end_location
 
       issue_for node, MSG do |corrector|
         corrector.replace(location, end_location, "loop do")

src/ameba/spec/annotated_source.cr

@@ -17,12 +17,13 @@ class Ameba::Spec::AnnotatedSource
     annotations = [] of {Int32, String, String}
     code_lines = annotated_code.split('\n') # must preserve trailing newline
     code_lines.each do |code_line|
-      if (annotation_match = ANNOTATION_PATTERN_1.match(code_line))
+      case
+      when annotation_match = ANNOTATION_PATTERN_1.match(code_line)
         message_index = annotation_match.end
         prefix = code_line[0...message_index]
         message = code_line[message_index...]
         annotations << {lines.size, prefix, message}
-      elsif (annotation_index = code_line.index(ANNOTATION_PATTERN_2))
+      when annotation_index = code_line.index(ANNOTATION_PATTERN_2)
         lines << code_line[...annotation_index]
         message_index = annotation_index + ANNOTATION_PATTERN_2.size
         message = code_line[message_index...]