X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=helm%2Fmatita%2FmatitaMisc.ml;h=c3b83fd472f31453181f1598fd786f88d24ff442;hb=ef9ec8cb57d15426a96fe40d056eb07804753bb9;hp=1a55795a5536666d5c0adc993bdb5d1bcc1d7a13;hpb=5ee4e9d9fbff19b7937459c5ad4652542ac1ccb8;p=helm.git

diff --git a/helm/matita/matitaMisc.ml b/helm/matita/matitaMisc.ml
index 1a55795a5..c3b83fd47 100644
--- a/helm/matita/matitaMisc.ml
+++ b/helm/matita/matitaMisc.ml
@@ -49,3 +49,84 @@ let strip_trailing_blanks =
   let rex = Pcre.regexp "\\s*$" in
   fun s -> Pcre.replace ~rex s
 
+let empty_mathml =
+  let doc =
+    Misc.domImpl#createDocument ~namespaceURI:(Some Misc.mathml_ns)
+      ~qualifiedName:(Gdome.domString "math") ~doctype:None
+  in
+  doc#get_documentElement
+
+exception History_failure
+
+type 'a memento = 'a array * int * int * int  (* data, hd, tl, cur *)
+
+class type ['a] history =
+  object
+    method add : 'a -> unit
+    method next : 'a
+    method previous : 'a
+    method load: 'a memento -> unit
+    method save: 'a memento
+  end
+
+class shell_history size =
+  let size = size + 1 in
+  let decr x = let x' = x - 1 in if x' < 0 then size + x' else x' in
+  let incr x = (x + 1) mod size in
+  object (self)
+    val data = Array.create size ""
+    val mutable hd = 0  (* insertion point *)
+    val mutable tl = -1 (* oldest inserted item *)
+    val mutable cur = -1  (* current item for the history *)
+    method add s =
+      data.(hd) <- s;
+      if tl = -1 then tl <- hd;
+      hd <- incr hd;
+      if hd = tl then tl <- incr tl;
+      cur <- hd
+    method previous =
+      if cur = tl then raise History_failure;
+      cur <- decr cur;
+      data.(cur)
+    method next =
+      if cur = hd then raise History_failure;
+      cur <- incr cur;
+      if cur = hd then "" else data.(cur)
+    method load (data', hd', tl', cur') =
+      assert (Array.length data = Array.length data');
+      hd <- hd'; tl <- tl'; cur <- cur';
+      Array.blit data' 0 data 0 (Array.length data')
+    method save = (Array.copy data, hd, tl, cur)
+  end
+
+class ['a] browser_history ?memento size init =
+  object (self)
+    initializer match memento with Some m -> self#load m | _ -> ()
+    val data = Array.create size init
+    val mutable hd = 0
+    val mutable tl = 0
+    val mutable cur = 0
+    method previous =
+      if cur = tl then raise History_failure;
+      cur <- cur - 1;
+      if cur = ~-1 then cur <- size - 1;
+      data.(cur)
+    method next =
+      if cur = hd then raise History_failure;
+      cur <- cur + 1;
+      if cur = size then cur <- 0;
+      data.(cur)
+    method add (e:'a) =
+      cur <- cur + 1;
+      if cur = size then cur <- 0;
+      if cur = tl then tl <- tl + 1;
+      if tl = size then tl <- 0;
+      hd <- cur;
+      data.(cur) <- e
+    method load (data', hd', tl', cur') =
+      assert (Array.length data = Array.length data');
+      hd <- hd'; tl <- tl'; cur <- cur';
+      Array.blit data' 0 data 0 (Array.length data')
+    method save = (Array.copy data, hd, tl, cur)
+  end
+