From fd44eeba080fc1551f6ae1bf6817530de8de563f Mon Sep 17 00:00:00 2001
From: Sijawusz Pur Rahnama <sija@sija.pl>
Date: Thu, 9 Nov 2023 06:46:51 +0100
Subject: [PATCH] Add `Naming/AsciiIdentifiers` rule

---
 .../rule/naming/ascii_identifiers_spec.cr     | 94 +++++++++++++++++++
 src/ameba/rule/naming/ascii_identifiers.cr    | 80 ++++++++++++++++
 2 files changed, 174 insertions(+)
 create mode 100644 spec/ameba/rule/naming/ascii_identifiers_spec.cr
 create mode 100644 src/ameba/rule/naming/ascii_identifiers.cr

diff --git a/spec/ameba/rule/naming/ascii_identifiers_spec.cr b/spec/ameba/rule/naming/ascii_identifiers_spec.cr
new file mode 100644
index 00000000..ca4df7a3
--- /dev/null
+++ b/spec/ameba/rule/naming/ascii_identifiers_spec.cr
@@ -0,0 +1,94 @@
+require "../../../spec_helper"
+
+module Ameba::Rule::Naming
+  subject = AsciiIdentifiers.new
+
+  describe AsciiIdentifiers do
+    it "reports classes with names containing non-ascii characters" do
+      expect_issue subject, <<-CRYSTAL
+        class BigAwesome🐺
+            # ^^^^^^^^^^^ error: Identifier contains non-ascii characters
+          @🐺_name : String
+        # ^^^^^^^ error: Identifier contains non-ascii characters
+        end
+        CRYSTAL
+    end
+
+    it "reports modules with names containing non-ascii characters" do
+      expect_issue subject, <<-CRYSTAL
+        module Bąk
+             # ^^^ error: Identifier contains non-ascii characters
+          @@bąk_name : String
+        # ^^^^^^^^^^ error: Identifier contains non-ascii characters
+        end
+        CRYSTAL
+    end
+
+    it "reports enums with names containing non-ascii characters" do
+      expect_issue subject, <<-CRYSTAL
+        enum TypeOf🔥
+           # ^^^^^^^ error: Identifier contains non-ascii characters
+        end
+        CRYSTAL
+    end
+
+    it "reports defs with names containing non-ascii characters" do
+      expect_issue subject, <<-CRYSTAL
+        def łódź
+          # ^^^^ error: Identifier contains non-ascii characters
+        end
+        CRYSTAL
+    end
+
+    it "reports defs with parameter names containing non-ascii characters" do
+      expect_issue subject, <<-CRYSTAL
+        def forest_adventure(include_🐺 = true, include_🐿 = true)
+                           # ^ error: Identifier contains non-ascii characters
+                                             # ^ error: Identifier contains non-ascii characters
+        end
+        CRYSTAL
+    end
+
+    it "reports argument names containing non-ascii characters" do
+      expect_issue subject, <<-CRYSTAL
+        %w[wensleydale cheddar brie].each { |🧀| nil }
+                                           # ^ error: Identifier contains non-ascii characters
+        CRYSTAL
+    end
+
+    it "reports aliases with names containing non-ascii characters" do
+      expect_issue subject, <<-CRYSTAL
+        alias JSON🧀 = JSON::Any
+            # ^^^^^ error: Identifier contains non-ascii characters
+        CRYSTAL
+    end
+
+    it "reports constants with names containing non-ascii characters" do
+      expect_issue subject, <<-CRYSTAL
+        I_LOVE_🍣 = true
+        # ^^^^^^ error: Identifier contains non-ascii characters
+        CRYSTAL
+    end
+
+    it "reports assignments with variable names containing non-ascii characters" do
+      expect_issue subject, <<-CRYSTAL
+        space_👾 = true
+        # ^^^^^ error: Identifier contains non-ascii characters
+        CRYSTAL
+    end
+
+    it "reports multiple assignments with variable names containing non-ascii characters" do
+      expect_issue subject, <<-CRYSTAL
+        foo, space_👾 = true, true
+           # ^^^^^^^ error: Identifier contains non-ascii characters
+        CRYSTAL
+    end
+
+    it "passes for strings with non-ascii characters" do
+      expect_no_issues subject, <<-CRYSTAL
+        space = "👾"
+        space = :invader # 👾
+        CRYSTAL
+    end
+  end
+end
diff --git a/src/ameba/rule/naming/ascii_identifiers.cr b/src/ameba/rule/naming/ascii_identifiers.cr
new file mode 100644
index 00000000..4ee4f2c7
--- /dev/null
+++ b/src/ameba/rule/naming/ascii_identifiers.cr
@@ -0,0 +1,80 @@
+module Ameba::Rule::Naming
+  # A rule that reports non-ascii characters in identifiers.
+  #
+  # Favour this:
+  #
+  # ```
+  # class BigAwesomeWolf
+  # end
+  # ```
+  #
+  # Over this:
+  #
+  # ```
+  # class BigAwesome🐺
+  # end
+  # ```
+  #
+  # YAML configuration example:
+  #
+  # ```
+  # Naming/AsciiIdentifiers:
+  #   Enabled: true
+  # ```
+  class AsciiIdentifiers < Base
+    include AST::Util
+
+    properties do
+      description "Disallows non-ascii characters in identifiers"
+    end
+
+    MSG = "Identifier contains non-ascii characters"
+
+    def test(source, node : Crystal::Assign)
+      if (target = node.target).is_a?(Crystal::Path)
+        check_issue(source, target, target)
+      end
+    end
+
+    def test(source, node : Crystal::MultiAssign)
+      node.targets.each do |target|
+        check_issue(source, target, target)
+      end
+    end
+
+    def test(source, node : Crystal::Def)
+      check_issue_with_location(source, node)
+
+      node.args.each do |arg|
+        check_issue_with_location(source, arg)
+      end
+    end
+
+    def test(source, node : Crystal::ClassVar | Crystal::InstanceVar | Crystal::Var | Crystal::Alias)
+      check_issue_with_location(source, node)
+    end
+
+    def test(source, node : Crystal::ClassDef | Crystal::ModuleDef | Crystal::EnumDef | Crystal::LibDef)
+      check_issue(source, node.name, node.name)
+    end
+
+    private def check_issue_with_location(source, node)
+      location = name_location(node)
+      end_location = name_end_location(node)
+
+      if location && end_location
+        check_issue(source, location, end_location, node.name)
+      else
+        check_issue(source, node, node.name)
+      end
+    end
+
+    private def check_issue(source, location, end_location, name)
+      issue_for location, end_location, MSG unless name.to_s.ascii_only?
+    end
+
+    private def check_issue(source, node, name)
+      issue_for node, MSG unless name.to_s.ascii_only?
+    end
+  end
+end