Initial commit

sys/apis/history.lua

@@ -0,0 +1,47 @@
+local Util = require('util')
+
+local History = { }
+
+function History.load(filename, limit)
+
+  local entries = Util.readLines(filename) or { }
+  local pos = #entries + 1
+
+  return {
+    entries = entries,
+
+    add = function(line)
+      local last = entries[pos] or entries[pos - 1]
+      if not last or line ~= last then
+        table.insert(entries, line)
+        if limit then
+          while #entries > limit do
+            table.remove(entries, 1)
+          end
+        end
+        Util.writeLines(filename, entries)
+        pos = #entries + 1
+      end
+    end,
+
+    setPosition = function(p)
+      pos = p
+    end,
+
+    back = function()
+      if pos > 1 then
+        pos = pos - 1
+        return entries[pos]
+      end
+    end,
+
+    forward = function()
+      if pos <= #entries then
+        pos = pos + 1
+        return entries[pos]
+      end
+    end,
+  }
+end
+
+return History