add missing file

I18n/I18next/Read.lean

@@ -0,0 +1,41 @@
+import I18n.EnvExtension
+-- import DateTime
+
+
+open Lean System
+namespace I18n
+
+open Elab.Command in
+
+def POFile.ofJson (json : Json) : Except String POFile :=
+  match json with
+  | .obj <| x =>
+    let entries : Array POEntry := x.toArray.filterMap (fun ⟨key, val⟩ =>
+      match val with
+      | .str val =>
+        some {msgId := key, msgStr := val}
+      | _ =>
+        -- TODO: This silently drops anything that is not a string.
+        none)
+    .ok {
+      header := {
+        -- Todo: is the header used for anything?
+        projectIdVersion := "",
+        reportMsgidBugsTo := "",
+        potCreationDate := "",
+        language := "" },
+      entries := entries }
+  | _ => throw "Invalid Json!"
+
+def POFile.readFromJson (path : FilePath) : IO POFile := do
+  if ¬ (← FilePath.pathExists path) then
+    panic "File does not exist!"
+  let content ← IO.FS.readFile path
+  match Json.parse content with
+  | .ok f =>
+    match POFile.ofJson f with
+    | .ok f => return f
+    | .error err =>
+      panic! s!"Failed to turn Json into PO file: {err}"
+  | .error err =>
+    panic! s!"Failed to parse Json file: {err}"