From 0bdfaae3f79d23c0fd560b18578043330167a2d3 Mon Sep 17 00:00:00 2001
From: Daniil Baturin <daniil@baturin.org>
Date: Sun, 1 Mar 2015 00:45:42 +0600
Subject: Add get_child and some tests for it.

---
 src/vytree/vytree.ml     | 18 ++++++++++++++++++
 test/vyconf_tree_test.ml | 19 +++++++++++++++++++
 2 files changed, 37 insertions(+)

diff --git a/src/vytree/vytree.ml b/src/vytree/vytree.ml
index 6a97211..7ee3e65 100644
--- a/src/vytree/vytree.ml
+++ b/src/vytree/vytree.ml
@@ -78,3 +78,21 @@ let rec delete_child node path =
         | Some next_child' -> 
             let new_node = delete_child next_child' names in
             replace_child node new_node
+
+let rec get_child node path =
+    match path with
+    | [] -> raise Empty_path
+    | [name] ->
+        begin
+            let child = find_child node name in
+            match child with
+            | None -> raise Nonexistent_path
+            | Some child' -> child'
+        end
+    | name :: names ->
+        begin
+            let next_child = find_child node name in
+            match next_child with
+            | None -> raise Nonexistent_path
+            | Some child' -> get_child child' names
+        end
diff --git a/test/vyconf_tree_test.ml b/test/vyconf_tree_test.ml
index 69efcfc..2bf40be 100644
--- a/test/vyconf_tree_test.ml
+++ b/test/vyconf_tree_test.ml
@@ -73,6 +73,23 @@ let test_delete_nonexistent test_ctxt =
     let node = make "root" () in
     assert_raises Nonexistent_path (fun () -> delete_child node ["foo"; "bar"])
 
+(* get_child works with immediate children *)
+let test_get_immediate_child test_ctxt =
+    let node = make "root" () in
+    let node' = insert_child () node ["foo"] () in
+    assert_equal (name_of_node (get_child node' ["foo"])) "foo"
+
+(* get_child works with multi-level paths *)
+let test_get_child_multilevel test_ctxt =
+    let node = make "root" () in
+    let node' = insert_child () node ["foo"; "bar"] () in
+    assert_equal (name_of_node (get_child node' ["foo"; "bar"])) "bar"
+
+(* get_child raises Nonexistent_path for non-existent paths *)
+let test_get_child_nonexistent test_ctxt =
+    let node = make "root" () in
+    assert_raises Nonexistent_path (fun () -> get_child node ["foo"; "bar"])
+
 let suite =
     "VyConf tree tests" >::: [
         "test_make_node" >:: test_make_node;
@@ -84,6 +101,8 @@ let suite =
         "test_delete_immediate_child" >:: test_delete_immediate_child;
         "test_delete_multi_level" >:: test_delete_multi_level;
         "test_delete_nonexistent" >:: test_delete_nonexistent;
+        "test_get_immediate_child" >:: test_get_immediate_child;
+        "test_get_child_multilevel" >:: test_get_child_multilevel;
     ]
 
 let () =
-- 
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