[ruby/error_highlight] Experimentally support a custom formatter

f40a1de20e

lib/error_highlight/formatter.rb

@@ -0,0 +1,24 @@
+module ErrorHighlight
+  class DefaultFormatter
+    def message_for(spot)
+      # currently only a one-line code snippet is supported
+      if spot[:first_lineno] == spot[:last_lineno]
+        marker = " " * spot[:first_column] + "^" * (spot[:last_column] - spot[:first_column])
+
+        "\n\n#{ spot[:snippet] }#{ marker }"
+      else
+        ""
+      end
+    end
+  end
+
+  def self.formatter
+    @@formatter
+  end
+
+  def self.formatter=(formatter)
+    @@formatter = formatter
+  end
+
+  self.formatter = DefaultFormatter.new
+end