Merge pull request #197 from crystal-ameba/feature/any-instead-of-empty

Add Performance/AnyInsteadOfEmpty rule

spec/ameba/ast/scope_spec.cr

@@ -51,7 +51,7 @@ module Ameba::AST
     it "adds a new variable to the scope" do
       scope = Scope.new as_node("")
       scope.add_variable(Crystal::Var.new "foo")
-      scope.variables.any?.should be_true
+      scope.variables.empty?.should be_false
     end
   end
 

spec/ameba/ast/variabling/variable_spec.cr

@@ -48,7 +48,7 @@ module Ameba::AST
       it "assigns the variable (creates a new assignment)" do
         variable = Variable.new(var_node, scope)
         variable.assign(assign_node, scope)
-        variable.assignments.any?.should be_true
+        variable.assignments.empty?.should be_false
       end
 
       it "can create multiple assignments" do
@@ -64,7 +64,7 @@ module Ameba::AST
         variable = Variable.new(var_node, scope)
         variable.assign(as_node("foo=1"), scope)
         variable.reference(var_node, scope)
-        variable.references.any?.should be_true
+        variable.references.empty?.should be_false
       end
 
       it "adds a reference to the scope" do

spec/ameba/rule/performance/any_instead_of_empty_spec.cr

@@ -0,0 +1,46 @@
+require "../../../spec_helper"
+
+module Ameba::Rule::Performance
+  subject = AnyInsteadOfEmpty.new
+
+  describe AnyInsteadOfEmpty do
+    it "passes if there is no potential performance improvements" do
+      source = Source.new %(
+        [1, 2, 3].any?(&.zero?)
+        [1, 2, 3].any?(String)
+        [1, 2, 3].any?(1..3)
+        [1, 2, 3].any? { |e| e > 1 }
+      )
+      subject.catch(source).should be_valid
+    end
+
+    it "reports if there is any? call without a block nor argument" do
+      source = Source.new %(
+        [1, 2, 3].any?
+      )
+      subject.catch(source).should_not be_valid
+    end
+
+    context "macro" do
+      it "reports in macro scope" do
+        source = Source.new %(
+          {{ [1, 2, 3].any? }}
+        )
+        subject.catch(source).should_not be_valid
+      end
+    end
+
+    it "reports rule, pos and message" do
+      source = Source.new path: "source.cr", code: %(
+        [1, 2, 3].any?
+      )
+      subject.catch(source).should_not be_valid
+      issue = source.issues.first
+
+      issue.rule.should_not be_nil
+      issue.location.to_s.should eq "source.cr:1:11"
+      issue.end_location.to_s.should eq "source.cr:1:15"
+      issue.message.should eq "Use `!{...}.empty?` instead of `{...}.any?`"
+    end
+  end
+end

src/ameba/ast/variabling/variable.cr

@@ -58,7 +58,7 @@ module Ameba::AST
     # variable.referenced? # => true
     # ```
     def referenced?
-      references.any?
+      !references.empty?
     end
 
     # Creates a reference to this variable in some scope.

src/ameba/ast/visitors/flow_expression_visitor.cr

@@ -60,7 +60,7 @@ module Ameba::AST
     end
 
     private def in_loop?
-      @loop_stack.any?
+      !@loop_stack.empty?
     end
   end
 end

src/ameba/cli/cmd.cr

@@ -61,7 +61,7 @@ module Ameba::Cli
         if f.size == 1 && f.first =~ /.+:\d+:\d+/
           configure_explain_opts(f.first, opts)
         else
-          opts.globs = f if f.any?
+          opts.globs = f unless f.empty?
         end
       end
 

src/ameba/rule/lint/unneeded_disable_directive.cr

@@ -36,7 +36,7 @@ module Ameba::Rule::Lint
         next unless token.type == :COMMENT
         next unless directive = source.parse_inline_directive(token.value.to_s)
         next unless names = unneeded_disables(source, directive, token.location)
-        next unless names.any?
+        next if names.empty?
 
         issue_for token, MSG % names.join(", ")
       end

src/ameba/rule/performance/any_instead_of_empty.cr

@@ -0,0 +1,44 @@
+module Ameba::Rule::Performance
+  # This rule is used to identify usage of arg-less `Enumerable#any?` calls.
+  #
+  # Using `Enumerable#any?` instead of `Enumerable#empty?` might lead to an
+  # unexpected results (like `[nil, false].any? # => false`). In some cases
+  # it also might be less efficient, since it iterates until the block will
+  # return a _truthy_ value, instead of just checking if there's at least
+  # one value present.
+  #
+  # For example, this is considered invalid:
+  #
+  # ```
+  # [1, 2, 3].any?
+  # ```
+  #
+  # And it should be written as this:
+  #
+  # ```
+  # ![1, 2, 3].empty?
+  # ```
+  #
+  # YAML configuration example:
+  #
+  # ```
+  # Performance/AnyInsteadOfEmpty:
+  #   Enabled: true
+  # ```
+  class AnyInsteadOfEmpty < Base
+    properties do
+      description "Identifies usage of arg-less `any?` calls."
+    end
+
+    ANY_NAME = "any?"
+    MSG      = "Use `!{...}.empty?` instead of `{...}.any?`"
+
+    def test(source, node : Crystal::Call)
+      return unless node.name == ANY_NAME
+      return unless node.block.nil? && node.args.empty?
+      return unless node.obj
+
+      issue_for node.name_location, node.name_end_location, MSG
+    end
+  end
+end

src/ameba/rule/performance/first_last_after_filter.cr

@@ -45,7 +45,7 @@ module Ameba::Rule::Performance
     def test(source, node : Crystal::Call)
       return unless node.name.in?(CALL_NAMES) && (obj = node.obj)
       return unless obj.is_a?(Crystal::Call) && obj.block
-      return if !node.block.nil? || node.args.any?
+      return unless node.block.nil? && node.args.empty?
       return unless obj.name.in?(filter_names)
 
       message = node.name.includes?(CALL_NAMES.first) ? MSG : MSG_REVERSE