feat: use the native crystal highlighter

The chroma highlighter for crystal is not great,
because the pygments one special cases things like
heredocs and that got lost in translation.

Since the crystal compiler comes with a highlighter
why not use it?

src/lexer.cr

@@ -1,6 +1,7 @@
 require "./constants/lexers"
 require "./heuristics"
 require "baked_file_system"
+require "crystal/syntax_highlighter"
 
 module Tartrazine
   class LexerFiles
@@ -26,6 +27,7 @@ module Tartrazine
   end
 
   private def self.lexer_by_name(name : String) : BaseLexer
+    return CrystalLexer.new if name == "crystal"
     lexer_file_name = LEXERS_BY_NAME.fetch(name.downcase, nil)
     return create_delegating_lexer(name) if lexer_file_name.nil? && name.includes? "+"
     raise Exception.new("Unknown lexer: #{name}") if lexer_file_name.nil?
@@ -34,6 +36,10 @@ module Tartrazine
   end
 
   private def self.lexer_by_filename(filename : String) : BaseLexer
+    if filename.ends_with?(".cr")
+      return CrystalLexer.new
+    end
+
     candidates = Set(String).new
     LEXERS_BY_FILENAME.each do |k, v|
       candidates += v.to_set if File.match?(k, File.basename(filename))
@@ -327,4 +333,81 @@ module Tartrazine
       new_state
     end
   end
+
+  class CustomCrystalHighlighter < Crystal::SyntaxHighlighter
+    @tokens = [] of Token
+
+    def render_delimiter(&block)
+      @tokens << {type: "LiteralString", value: block.call.to_s}
+    end
+
+    def render_interpolation(&block)
+      @tokens << {type: "LiteralStringInterpol", value: "\#{"}
+      @tokens << {type: "Text", value: block.call.to_s}
+      @tokens << {type: "LiteralStringInterpol", value: "}"}
+    end
+
+    def render_string_array(&block)
+      @tokens << {type: "LiteralString", value: block.call.to_s}
+    end
+
+    # ameba:disable Metrics/CyclomaticComplexity
+    def render(type : TokenType, value : String)
+      case type
+      when .comment?
+        @tokens << {type: "Comment", value: value}
+      when .number?
+        @tokens << {type: "LiteralNumber", value: value}
+      when .char?
+        @tokens << {type: "LiteralStringChar", value: value}
+      when .symbol?
+        @tokens << {type: "LiteralStringSymbol", value: value}
+      when .const?
+        @tokens << {type: "NameConstant", value: value}
+      when .string?
+        @tokens << {type: "LiteralString", value: value}
+      when .ident?
+        @tokens << {type: "NameVariable", value: value}
+      when .keyword?, .self?
+        @tokens << {type: "NameKeyword", value: value}
+      when .primitive_literal?
+        @tokens << {type: "Literal", value: value}
+      when .operator?
+        @tokens << {type: "Operator", value: value}
+      when Crystal::SyntaxHighlighter::TokenType::DELIMITED_TOKEN, Crystal::SyntaxHighlighter::TokenType::DELIMITER_START, Crystal::SyntaxHighlighter::TokenType::DELIMITER_END
+        @tokens << {type: "LiteralString", value: value}
+      else
+        @tokens << {type: "Text", value: value}
+      end
+    end
+  end
+
+  class CrystalTokenizer < Tartrazine::BaseTokenizer
+    include Iterator(Token)
+    @hl = CustomCrystalHighlighter.new
+    @lexer : BaseLexer
+    @iter : Iterator(Token)
+
+    # delegate next, to: @iter
+
+    def initialize(@lexer : BaseLexer, text : String, secondary = false)
+      # Respect the `ensure_nl` config option
+      if text.size > 0 && text[-1] != '\n' && @lexer.config[:ensure_nl] && !secondary
+        text += "\n"
+      end
+      # Just do the tokenizing
+      @hl.highlight(text)
+      @iter = @hl.@tokens.each
+    end
+
+    def next : Iterator::Stop | Token
+      @iter.next
+    end
+  end
+
+  class CrystalLexer < BaseLexer
+    def tokenizer(text : String, secondary = false) : BaseTokenizer
+      CrystalTokenizer.new(self, text, secondary)
+    end
+  end
 end

src/rules.cr

@@ -17,7 +17,6 @@ module Tartrazine
 
   abstract struct BaseRule
     abstract def match(text : Bytes, pos : Int32, tokenizer : Tokenizer) : Tuple(Bool, Int32, Array(Token))
-    abstract def initialize(node : XML::Node)
 
     @actions : Array(Action) = [] of Action
 
@@ -40,9 +39,6 @@ module Tartrazine
       return true, pos + match[0].size, @actions.flat_map(&.emit(match, tokenizer))
     end
 
-    def initialize(node : XML::Node)
-    end
-
     def initialize(node : XML::Node, multiline, dotall, ignorecase)
       pattern = node["pattern"]
       pattern = "(?m)" + pattern if multiline

src/styles.cr

@@ -84,27 +84,6 @@ module Tartrazine
 
     property styles = {} of String => Style
 
-    # Get the style for a token.
-    def style(token)
-      styles[token] = Style.new unless styles.has_key?(token)
-      s = styles[token]
-
-      # We already got the data from the style hierarchy
-      return s if s.complete?
-
-      # Form the hierarchy of parent styles
-      parents = style_parents(token)
-
-      s = parents.map do |parent|
-        styles[parent]
-      end.reduce(s) do |acc, style|
-        acc + style
-      end
-      s.complete = true
-      styles[token] = s
-      s
-    end
-
     def style_parents(token)
       parents = ["Background"]
       parts = token.underscore.split("_").map(&.capitalize)