OCaml: Implement configuration parser, bind lexer tokens with schema

ocaml/lib/parsers/config/parser.ml

@@ -0,0 +1,55 @@
+(* open Utilities.Aliases *)
+open Lexer
+
+type schema = Schema.schema
+type token = Lexer.token
+type config = Schema.main
+
+let default_config: config = Schema.origin.input.configuration.main
+
+(*
+    TODO: The `elog` calls in this module's functions cause cram tests
+    to fail. Separate logging levels can be implemented to solve this.
+*)
+
+let update config key value: config =
+    match key with
+    | Schema.SuCommand ->
+        (* elog $ "[c.parser.update] Setting value '" ^ value ^ "'"; *)
+        { config with Schema.su_command = value }
+    | Unknown ->
+        (* elog $ "[c.parser.update] Dropping value: unknown key"; *)
+        config
+
+let parse tokens =
+    let rec parse_tokens tokens config ready_key =
+        match tokens with
+        | [] -> config
+        | Key key :: tail ->
+            (* elog $ "[c.parser.parse ] Picked key '" ^ *)
+            (*     Schema.string_of_key key ^ "'"; *)
+            parse_tokens tail config (Some key)
+        | Value value :: tail ->
+            (* elog $ "[c.parser.parse ] Picked value '" ^ value ^ "'"; *)
+            (match ready_key with
+                | Some key -> parse_tokens tail (update config key value) None
+                | None -> raise (Malformed_source "Value lacks preceding key"))
+        | Unknown _char :: tail ->
+            (* elog $ "[c.parser.parse ] Dropping unknown token " ^ str_char char; *)
+            parse_tokens tail config ready_key
+        | (Space|Equal|LineBreak|End) :: tail ->
+            parse_tokens tail config ready_key
+
+    in
+    parse_tokens tokens default_config None
+
+let apply (origin: Schema.schema) (config: config): Schema.schema =
+    { origin with input = {
+        origin.input with configuration = {
+            origin.input.configuration with main = config
+        }
+    }}
+
+let string_of_config (config: config): string =
+    "su_command = " ^ config.su_command ^ "\n" ^
+    ""