Merge pull request #199 from inhabitedtype/consumed-fail

make consumed fail if p commits
inhabitedtype · May 8, 2020 · 6dcdbe3 · 6dcdbe3
2 parents 1ba2998 + 4b4ec9b
commit 6dcdbe3
Show file tree

Hide file tree

Showing 2 changed files with 9 additions and 3 deletions.
diff --git a/lib/angstrom.ml b/lib/angstrom.ml
@@ -556,10 +556,14 @@ let scan_string state f =
 let consume_with p f =
   { run = fun input pos more fail succ ->
     let start = pos in
+    let parser_committed_bytes = Input.parser_committed_bytes input  in
     let succ' input' pos' more' _ =
-      let len = pos' - start in
-      let consumed = Input.apply input' start len ~f in
-      succ input' pos' more' consumed
+      if parser_committed_bytes <> Input.parser_committed_bytes input'
+      then fail input' pos' more' [] "consumed: parser committed"
+      else (
+        let len = pos' - start in
+        let consumed = Input.apply input' start len ~f in
+        succ input' pos' more' consumed)
     in
     p.run input pos more fail succ'
   }

diff --git a/lib_test/test_angstrom.ml b/lib_test/test_angstrom.ml
@@ -311,6 +311,8 @@ let combinators =
         ["abc"] "ab";
       check_s ~msg:"with more input" (consumed (string "abc"))
         ["a"; "bc"] "abc";
+      check_fail ~msg:"with commit" (consumed (char 'a' *> commit *> char 'b'))
+        ["a"; "b"];
       let integer =
         option '+' (char '-') *> take_while (function '0'..'9' -> true | _ -> false)
       in