todoapp: use local storage properly

examples/todoapp/todoapp.nim

@@ -1,5 +1,5 @@
 
-import vdom, karax, karaxdsl, jstrutils, components
+import vdom, karax, karaxdsl, jstrutils, components, localstorage
 
 type
   Filter = enum
@@ -10,36 +10,35 @@ var
   filter: Filter
   entriesLen: int
 
-proc getItem(key : cstring ): cstring {.importc: "localStorage.getItem"}
-proc setItem(key, value : cstring ) {.importc: "localStorage.setItem"}
-proc clearEntries() {.importc: "localStorage.clear"}
+const
+  contentSuffix = cstring"content"
+  completedSuffix = cstring"completed"
+  lenSuffix = cstring"entriesLen"
 
-proc getEntryCstring(pos: int): cstring =
-  result = getItem(&pos & cstring"cstring")
+proc getEntryContent(pos: int): cstring =
+  result = getItem(&pos & contentSuffix)
   if result == cstring"null":
     result = nil
 
 proc isCompleted(pos: int): bool =
-  var value = getItem(cstring($pos & "bool"))
+  var value = getItem(&pos & completedSuffix)
   result = value == cstring"true"
 
-proc setEntryCstring(pos: int, value: cstring) =
-  setItem(cstring($pos & "cstring"), value)
+proc setEntryContent(pos: int, content: cstring) =
+  setItem(&pos & contentSuffix, content)
 
-proc markAsCompleted(pos: int, value : bool) =
-  var val = cstring"true"
-  if not value:
-    val = cstring"false"
-  setItem(cstring($pos & "bool"), val)
+proc markAsCompleted(pos: int, completed: bool) =
+  setItem(&pos & completedSuffix, &completed)
 
-proc addEntry(str: cstring, bval : bool) =
-  setEntryCstring(entriesLen, str)
-  markAsCompleted(entriesLen, bval)
+proc addEntry(content: cstring, completed: bool) =
+  setEntryContent(entriesLen, content)
+  markAsCompleted(entriesLen, completed)
   inc entriesLen
+  setItem(lenSuffix, &entriesLen)
 
-proc updateEntry(pos: int, str: cstring, bval: bool) =
-  setEntryCstring(pos, str)
-  markAsCompleted(pos, bval)
+proc updateEntry(pos: int, content: cstring, completed: bool) =
+  setEntryContent(pos, content)
+  markAsCompleted(pos, completed)
 
 proc onTodoEnter(ev: Event; n: VNode) =
   addEntry(n.value, false)
@@ -54,7 +53,7 @@ proc editHandler(ev: Event; n: VNode) =
 proc focusLost(ev: Event; n: VNode) = selectedEntry = -1
 
 proc editEntry(ev: Event; n: VNode) =
-  setEntryCstring(n.key, n.value)
+  setEntryContent(n.key, n.value)
   selectedEntry = -1
 
 proc toggleEntry(ev: Event; n: VNode) =
@@ -62,12 +61,12 @@ proc toggleEntry(ev: Event; n: VNode) =
   markAsCompleted(id, not isCompleted(id))
 
 proc onAllDone(ev: Event; n: VNode) =
-  clearEntries()
+  clear()
   selectedEntry = -1
 
 proc clearCompleted(ev: Event, n: VNode) =
   for i in 0..<entriesLen:
-    if isCompleted(i): setEntryCstring(i, nil)
+    if isCompleted(i): setEntryContent(i, nil)
 
 proc toClass(completed: bool): cstring =
   (if completed: cstring"completed" else: cstring(nil))
@@ -132,8 +131,7 @@ proc createDom(): VNode =
         ul(class = "todo-list"):
           #for i, d in pairs(entries):
           for i in 0..entriesLen-1:
-  
-            var d0 = getEntryCstring(i)
+            var d0 = getEntryContent(i)
             var d1 = isCompleted(i)
             if d0 != nil:
               let b = case filter
@@ -151,5 +149,9 @@ setOnHashChange(proc(hash: cstring) =
   elif hash == "#/completed": filter = completed
   elif hash == "#/active": filter = active
 )
-entriesLen = 0
+
+if hasItem(lenSuffix):
+  entriesLen = parseInt getItem(lenSuffix)
+else:
+  entriesLen = 0
 setRenderer createDom

src/jstrutils.nim

@@ -21,3 +21,5 @@ proc isInt*(s: cstring): bool {.asmNoStackFrame.} =
   asm """
     return s.match(/^[0-9]+$/);
   """
+
+proc parseInt*(s: cstring): int {.importcpp: "parseInt(#, 10)", nodecl.}

src/localstorage.nim

@@ -0,0 +1,10 @@
+## Karax -- Single page applications for Nim.
+
+## This module contains wrappers for the HTML 5 local storage.
+
+proc getItem*(key: cstring): cstring {.importc: "localStorage.getItem"}
+proc setItem*(key, value: cstring) {.importc: "localStorage.setItem"}
+proc hasItem*(key: cstring): bool {.importcpp: "(localStorage.getItem(#) !== null)".}
+proc clear*() {.importc: "localStorage.clear"}
+
+proc removeItem*(key: cstring) {.importc: "localStorage.removeItem".}