Add a new example of topological sort

examples/topological_sort/tsort.ml

@@ -0,0 +1,63 @@
+(** Example: topological sort *)
+
+#use "list.ml"
+
+let tsort vs es =
+  let is_leaf es v =
+    list_for_all (fun e -> match e with (_, v2) -> v <> v2) es
+  in
+  let partition_leaves vs es =
+    list_partition (fun e -> match e with (v, _) -> list_mem v vs) es
+  in
+  let rec aux acc vs es =
+    match list_partition (is_leaf es) vs with
+    | (vs1, []) -> list_flatten (list_rev (vs1 :: acc))
+    | (vs1, vs2) ->
+      match partition_leaves vs1 es with (_, es2) -> aux (vs1 :: acc) vs2 es2
+  in
+  aux [] vs es
+
+(*  +----> [2] --> [5] <-- [7]
+    |               ^       ^
+    |               |       |
+   [1] <-- [3] -----+       |
+    ^       ^               |
+    |       |               |
+    +----- [4] <---------- [6] *)
+let vertices = [1; 2; 3; 4; 5; 6; 7]
+let edges = [ (1, 2); (* (vertex_begin, vertex_end) *)
+              (2, 5);
+              (3, 1);
+              (3, 5);
+              (4, 1);
+              (4, 3);
+              (6, 4);
+              (6, 7);
+              (7, 5) ]
+
+(* Result: 6, 4, 7, 3, 1, 2, 5 *)
+let xs = tsort vertices edges
+let x0 = list_nth xs 0
+let x1 = list_nth xs 1
+let x2 = list_nth xs 2
+let x3 = list_nth xs 3
+let x4 = list_nth xs 4
+let x5 = list_nth xs 5
+let x6 = list_nth xs 6
+
+(*!
+// This is C++ code.
+
+#include <cstdio>
+
+int main () { // We use printf in order to output readable assembly code.
+  std::printf("%d  ", x0::val);
+  std::printf("%d  ", x1::val);
+  std::printf("%d  ", x2::val);
+  std::printf("%d  ", x3::val);
+  std::printf("%d  ", x4::val);
+  std::printf("%d  ", x5::val);
+  std::printf("%d\n", x6::val);
+  return 0;
+}
+*)

gen_files.ml

@@ -42,6 +42,7 @@ let make_ml in_file out_file =
 let () =
   make_ml "examples/fib/fib.ml" "src/example_fib.ml";
   make_ml "examples/quicksort/qsort.ml" "src/example_qsort.ml";
+  make_ml "examples/topological_sort/tsort.ml" "src/example_tsort.ml";
   make_ml "examples/dijkstra/dijkstra.ml" "src/example_dijkstra.ml";
   make_ml "include/evilml.hpp" "src/evilml_hpp.ml";
   let in_mls = Sys.readdir "include"

html/index.html

@@ -75,6 +75,7 @@ <h1>Evil ML: ML to C++ template language</h1>
       Examples:
       <input type="button" value="Fibonacci" id="btn_ex_fib">
       <input type="button" value="Quick sort" id="btn_ex_qsort">
+      <input type="button" value="Topological sort" id="btn_ex_tsort">
       <input type="button" value="Dijkstra's algoritm" id="btn_ex_dijkstra">
     </div>
     <hr>