Ruby: Add colored CLI output for the parse and lex commnads (#776)

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<img width="2890" height="1752" alt="CleanShot 2025-11-04 at 00 26
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Author: marcoroth

.rubocop.yml

@@ -80,6 +80,7 @@ Metrics/AbcSize:
     - lib/herb/project.rb
     - lib/herb/engine.rb
     - lib/herb/engine/**/*.rb
+    - lib/herb/token.rb
     - templates/template.rb
     - test/fork_helper.rb
     - test/snapshot_utils.rb

lib/herb.rb

@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 # typed: false
 
+require_relative "herb/colors"
 require_relative "herb/range"
 require_relative "herb/position"
 require_relative "herb/location"

lib/herb/colors.rb

@@ -0,0 +1,82 @@
+# frozen_string_literal: true
+# typed: true
+
+# rbs_inline: enabled
+
+module Herb
+  module Colors
+    module_function
+
+    #: () -> bool
+    def enabled?
+      return false if ENV["NO_COLOR"]
+      return false if defined?(IRB)
+      return false if defined?(Minitest)
+
+      $stdout.tty?
+    end
+
+    #: (String) -> String
+    def white(string)
+      return string unless enabled?
+
+      "\e[37m#{string}\e[0m"
+    end
+
+    #: (String) -> String
+    def yellow(string)
+      return string unless enabled?
+
+      "\e[33m#{string}\e[0m"
+    end
+
+    #: (String) -> String
+    def green(string)
+      return string unless enabled?
+
+      "\e[32m#{string}\e[0m"
+    end
+
+    #: (String) -> String
+    def red(string)
+      return string unless enabled?
+
+      "\e[31m#{string}\e[0m"
+    end
+
+    #: (String) -> String
+    def magenta(string)
+      return string unless enabled?
+
+      "\e[35m#{string}\e[0m"
+    end
+
+    #: (String) -> String
+    def cyan(string)
+      return string unless enabled?
+
+      "\e[36m#{string}\e[0m"
+    end
+
+    #: (String) -> String
+    def bright_magenta(string)
+      return string unless enabled?
+
+      "\e[95m#{string}\e[0m"
+    end
+
+    #: (String) -> String
+    def dimmed(string)
+      return string unless enabled?
+
+      "\e[2m#{string}\e[0m"
+    end
+
+    #: (String) -> String
+    def bold(string)
+      return string unless enabled?
+
+      "\e[1m#{string}\e[0m"
+    end
+  end
+end

lib/herb/location.rb

@@ -40,12 +40,12 @@ def to_json(state = nil)
 
     #: () -> String
     def tree_inspect
-      %((location: #{start.tree_inspect}-#{self.end.tree_inspect}))
+      "#{start.tree_inspect}-#{self.end.tree_inspect}"
     end
 
     #: () -> String
     def inspect
-      %(#<Herb::Location #{tree_inspect}>)
+      %(#<Herb::Location (location: #{tree_inspect})>)
     end
   end
 end

lib/herb/token.rb

@@ -3,6 +3,8 @@
 
 module Herb
   class Token
+    include Colors
+
     attr_reader :value #: String
     attr_reader :range #: Range
     attr_reader :location #: Location
@@ -33,7 +35,7 @@ def to_json(state = nil)
 
     #: () -> String
     def tree_inspect
-      %("#{value.force_encoding("utf-8")}" #{location.tree_inspect})
+      "#{green("\"#{value.force_encoding("utf-8")}\"")} #{dimmed("(location: #{location.tree_inspect})")}"
     end
 
     #: () -> String
@@ -45,9 +47,19 @@ def value_inspect
       end
     end
 
+    #: () -> String
+    def colorize_range
+      white("[") + cyan(range.from.to_s) + white(", ") + cyan(range.to.to_s) + white("]")
+    end
+
+    #: (Position) -> String
+    def colorize_position(position)
+      white("(") + cyan(position.line.to_s) + white(":") + cyan(position.column.to_s) + white(")")
+    end
+
     #: () -> String
     def inspect
-      %(#<Herb::Token type="#{type}" value=#{value_inspect} range=#{range.tree_inspect} start=#{location.start.tree_inspect} end=#{location.end.tree_inspect}>)
+      "#{white("#<")}#{bold(yellow("Herb::Token"))} #{white("type=")}#{bright_magenta("\"#{type}\"")} #{white("value=")}#{green(value_inspect)} #{white("range=")}#{colorize_range} #{white("start=")}#{colorize_position(location.start)} #{white("end=")}#{colorize_position(location.end)}#{white(">")}"
     end
   end
 end