feat(types): define resolved project, target and rule records

Targets carry sources, includes, flags and uses; rule instances carry resolved
inputs and outputs. This is the shape every later stage consumes.

lib/types.ml

@@ -0,0 +1,81 @@
+type lang = C | Cxx | Asm
+
+type tkind = Lib | Shared | Bin | Test
+
+let kind_name = function Lib -> "lib" | Shared -> "shared" | Bin -> "bin" | Test -> "test"
+
+type target = {
+  name : string;
+  kind : tkind;
+  dir : string;
+  srcs : string list;
+  gen_srcs : string list;
+  includes : string list;
+  uses : string list;
+  cflags : string list;
+  cxxflags : string list;
+  ldflags : string list;
+  defines : string list;
+  pkgs : string list;
+  install : string option;
+  soname : string option;
+  args : string list;
+  span : Span.t;
+}
+
+type rule = {
+  rname : string;
+  rin : string list;
+  routs : string list;
+  rcmd : string list;
+  rdesc : string;
+  rspan : Span.t;
+}
+
+type toolchain = {
+  cc : string;
+  cxx : string;
+  ar : string;
+  ranlib : string;
+  cflags : string list;
+  cxxflags : string list;
+  ldflags : string list;
+  builddir : string;
+}
+
+type install_item = { from : string; dest : string }
+
+type define = { dname : string; dvalue : string option }
+
+type project = {
+  pname : string;
+  tc : toolchain;
+  targets : target list;
+  rules : rule list;
+  defines : define list;
+  config_header : string option;
+  installs : install_item list;
+  prefix : string;
+  platform : string;
+}
+
+let find p name = List.find_opt (fun t -> t.name = name) p.targets
+
+let rec deps_of p t =
+  List.concat_map
+    (fun u -> match find p u with None -> [] | Some x -> deps_of p x @ [ x ])
+    t.uses
+
+let uniq_targets ts =
+  let seen = Hashtbl.create 8 in
+  List.filter (fun t -> if Hashtbl.mem seen t.name then false else (Hashtbl.add seen t.name (); true)) ts
+
+let order p ts = uniq_targets (List.concat_map (fun t -> deps_of p t @ [ t ]) ts)
+
+let lang_of path =
+  match String.lowercase_ascii (Filename.extension path) with
+  | ".cc" | ".cpp" | ".cxx" | ".c++" | ".mm" -> Cxx
+  | ".s" | ".asm" -> Asm
+  | _ -> C
+
+let all_srcs t = t.srcs @ t.gen_srcs