1 files changed, 75 insertions, 0 deletions
diff --git a/Master/texmf-dist/scripts/context/ruby/base/state.rb b/Master/texmf-dist/scripts/context/ruby/base/state.rb
new file mode 100644
index 00000000000..f57231592a7
--- /dev/null
+++ b/Master/texmf-dist/scripts/context/ruby/base/state.rb
@@ -0,0 +1,75 @@
+require "md5"
+
+# todo: register omissions per file
+
+class FileState
+
+    def initialize
+        @states = Hash.new
+        @omiter = Hash.new
+    end
+
+    def reset
+        @states.clear
+        @omiter.clear
+    end
+
+    def register(filename,omit=nil)
+        unless @states.key?(filename) then
+            @states[filename] = Array.new
+            @omiter[filename] = omit
+        end
+        @states[filename] << checksum(filename,@omiter[filename])
+    end
+
+    def update(filename=nil)
+        [filename,@states.keys].flatten.compact.uniq.each do |fn|
+            register(fn)
+        end
+    end
+
+    def inspect(filename=nil)
+        result = ''
+        [filename,@states.keys].flatten.compact.uniq.sort.each do |fn|
+            if @states.key?(fn) then
+                result += "#{fn}: #{@states[fn].inspect}\n"
+            end
+        end
+        result
+    end
+
+    def changed?(filename)
+        if @states.key?(filename) then
+            n = @states[filename].length
+            if n>1 then
+                changed = @states[filename][n-1] != @states[filename][n-2]
+            else
+                changed = true
+            end
+        else
+            changed = true
+        end
+        return changed
+    end
+
+    def checksum(filename,omit=nil)
+        sum = ''
+        begin
+            if FileTest.file?(filename) && (data = IO.read(filename)) then
+                data.gsub!(/\n.*?(#{[omit].flatten.join('|')}).*?\n/ms,"\n") if omit
+                sum = MD5.new(data).hexdigest.upcase
+            end
+        rescue
+            sum = ''
+        end
+        return sum
+    end
+
+    def stable?
+        @states.keys.each do |s|
+            return false if changed?(s)
+        end
+        return true
+    end
+
+end