1 files changed, 105 insertions, 0 deletions
diff --git a/etc/todo/scanners/yaml.rb b/etc/todo/scanners/yaml.rb
new file mode 100644
index 0000000..53b052d
--- /dev/null
+++ b/etc/todo/scanners/yaml.rb
@@ -0,0 +1,105 @@
+require 'syntax'
+
+module Syntax
+
+  # A simple implementation of an YAML lexer. It handles most cases. It is
+  # not a validating lexer.
+  class YAML < Tokenizer
+
+    # Step through a single iteration of the tokenization process. This will
+    # yield (potentially) many tokens, and possibly zero tokens.
+    def step
+      if bol?
+        case
+          when scan(/---(\s*.+)?$/)
+            start_group :document, matched
+          when scan(/(\s*)([a-zA-Z][-\w]*)(\s*):/)
+            start_group :normal, subgroup(1)
+            start_group :key, subgroup(2)
+            start_group :normal, subgroup(3)
+            start_group :punct, ":"
+          when scan(/(\s*)-/)
+            start_group :normal, subgroup(1)
+            start_group :punct, "-"
+          when scan(/\s*$/)
+            start_group :normal, matched
+          when scan(/#.*$/)
+            start_group :comment, matched
+          else
+            append getch
+        end
+      else
+        case
+          when scan(/[\n\r]+/)
+            start_group :normal, matched
+          when scan(/[ \t]+/)
+            start_group :normal, matched
+          when scan(/!+(.*?^)?\S+/)
+            start_group :type, matched
+          when scan(/&\S+/)
+            start_group :anchor, matched
+          when scan(/\*\S+/)
+            start_group :ref, matched
+          when scan(/\d\d:\d\d:\d\d/)
+            start_group :time, matched
+          when scan(/\d\d\d\d-\d\d-\d\d\s\d\d:\d\d:\d\d(\.\d+)? [-+]\d\d:\d\d/)
+            start_group :date, matched
+          when scan(/['"]/)
+            start_group :punct, matched
+            scan_string matched
+          when scan(/:\w+/)
+            start_group :symbol, matched
+          when scan(/[:]/)
+            start_group :punct, matched
+          when scan(/#.*$/)
+            start_group :comment, matched
+          when scan(/>-?/)
+            start_group :punct, matched
+            start_group :normal, scan(/.*$/)
+            append getch until eos? || bol?
+            return if eos?
+            indent = check(/ */)
+            start_group :string
+            loop do
+              line = check_until(/[\n\r]|\Z/)
+              break if line.nil?
+              if line.chomp.length > 0
+                this_indent = line.chomp.match( /^\s*/ )[0]
+                break if this_indent.length < indent.length
+              end
+              append scan_until(/[\n\r]|\Z/)
+            end
+          else
+            start_group :normal, scan_until(/(?=$|#)/)
+        end
+      end
+    end
+
+    private
+
+      def scan_string( delim )
+        regex = /(?=[#{delim=="'" ? "" : "\\\\"}#{delim}])/
+        loop do
+          text = scan_until( regex )
+          if text.nil?
+            start_group :string, scan_until( /\Z/ )
+            break
+          else
+            start_group :string, text unless text.empty?
+          end
+
+          case peek(1)
+            when "\\"
+              start_group :expr, scan(/../)
+            else
+              start_group :punct, getch
+              break
+          end
+        end
+      end
+
+  end
+
+  SYNTAX["yaml"] = YAML
+
+end