From 59498f7fc14ce2f4e9f67d725834ff348e7d289b Mon Sep 17 00:00:00 2001
From: Moritz Bunkus <moritz@bunkus.org>
Date: Sun, 1 Dec 2013 14:45:32 +0100
Subject: [PATCH] common: add function for finding an EbmlElement in an
 EbmlMaster recursively

Returns both the master and the index at which it was found inside
that master.
---
 src/common/ebml.cpp | 25 +++++++++++++++++++++++++
 src/common/ebml.h   |  1 +
 2 files changed, 26 insertions(+)

diff --git a/src/common/ebml.cpp b/src/common/ebml.cpp
index 2cb291d9c..5fe9ba265 100644
--- a/src/common/ebml.cpp
+++ b/src/common/ebml.cpp
@@ -494,6 +494,31 @@ find_ebml_element_by_id(EbmlMaster *master,
   return nullptr;
 }
 
+std::pair<EbmlMaster *, size_t>
+find_element_in_master(EbmlMaster *master,
+                       EbmlElement *element_to_find) {
+  if (!master || !element_to_find)
+    return std::make_pair<EbmlMaster *, size_t>(nullptr, 0);
+
+  auto &elements = master->GetElementList();
+  auto itr       = brng::find(elements, element_to_find);
+
+  if (itr != elements.end())
+    return std::make_pair(master, std::distance(elements.begin(), itr));
+
+  for (auto &sub_element : elements) {
+    auto sub_master = dynamic_cast<EbmlMaster *>(sub_element);
+    if (!sub_master)
+      continue;
+
+    auto result = find_element_in_master(sub_master, element_to_find);
+    if (result.first)
+      return result;
+  }
+
+  return std::make_pair<EbmlMaster *, size_t>(nullptr, 0);
+}
+
 void
 fix_mandatory_elements(EbmlElement *master) {
   if (dynamic_cast<KaxInfo *>(master))
diff --git a/src/common/ebml.h b/src/common/ebml.h
index 31e20c1c1..73544f391 100644
--- a/src/common/ebml.h
+++ b/src/common/ebml.h
@@ -322,6 +322,7 @@ const EbmlCallbacks *find_ebml_parent_callbacks(const EbmlCallbacks &base, const
 const EbmlSemantic *find_ebml_semantic(const EbmlCallbacks &base, const EbmlId &id);
 
 EbmlElement *find_ebml_element_by_id(EbmlMaster *master, const EbmlId &id);
+std::pair<EbmlMaster *, size_t> find_element_in_master(EbmlMaster *master, EbmlElement *element_to_find);
 
 void fix_mandatory_elements(EbmlElement *master);