From a4926058496c1c24c00ac07e42d45048dac7c487 Mon Sep 17 00:00:00 2001
From: Dmitriy Ivanov <dimitry@google.com>
Date: Tue, 2 Sep 2014 09:45:40 -0700
Subject: [PATCH] Implement LinkedList::visit()

Change-Id: Ibd9d133dddf1f2e6e65660e3cd2dacafcc0c84d9
---
 linker/linked_list.h              | 15 ++++++++--
 linker/tests/linked_list_test.cpp | 50 ++++++++++++++++++++++++++-----
 2 files changed, 56 insertions(+), 9 deletions(-)

diff --git a/linker/linked_list.h b/linker/linked_list.h
index 14fe1e58d..5fbdc8ffb 100644
--- a/linker/linked_list.h
+++ b/linker/linked_list.h
@@ -86,10 +86,21 @@ class LinkedList {
   }
 
   template<typename F>
-  void for_each(F&& action) {
+  void for_each(F action) {
+    visit([&] (T* si) {
+      action(si);
+      return true;
+    });
+  }
+
+  template<typename F>
+  bool visit(F action) {
     for (LinkedListEntry<T>* e = head_; e != nullptr; e = e->next) {
-      action(e->element);
+      if (!action(e->element)) {
+        return false;
+      }
     }
+    return true;
   }
 
   template<typename F>
diff --git a/linker/tests/linked_list_test.cpp b/linker/tests/linked_list_test.cpp
index 0483b8412..a555edb33 100644
--- a/linker/tests/linked_list_test.cpp
+++ b/linker/tests/linked_list_test.cpp
@@ -151,15 +151,15 @@ TEST(linked_list, copy_to_array) {
   memset(buf, 0, sizeof(buf));
   ASSERT_EQ(4U, list.size());
   ASSERT_EQ(2U, list.copy_to_array(buf, 2));
-  ASSERT_EQ('a', *buf[0]);
-  ASSERT_EQ('b', *buf[1]);
+  ASSERT_STREQ("a", buf[0]);
+  ASSERT_STREQ("b", buf[1]);
   ASSERT_EQ(nullptr, buf[2]);
 
   ASSERT_EQ(4U, list.copy_to_array(buf, max_size));
-  ASSERT_EQ('a', *buf[0]);
-  ASSERT_EQ('b', *buf[1]);
-  ASSERT_EQ('c', *buf[2]);
-  ASSERT_EQ('d', *buf[3]);
+  ASSERT_STREQ("a", buf[0]);
+  ASSERT_STREQ("b", buf[1]);
+  ASSERT_STREQ("c", buf[2]);
+  ASSERT_STREQ("d", buf[3]);
   ASSERT_EQ(nullptr, buf[4]);
 
   memset(buf, 0, sizeof(buf));
@@ -168,7 +168,7 @@ TEST(linked_list, copy_to_array) {
   });
   ASSERT_EQ(1U, list.size());
   ASSERT_EQ(1U, list.copy_to_array(buf, max_size));
-  ASSERT_EQ('c', *buf[0]);
+  ASSERT_STREQ("c", buf[0]);
   ASSERT_EQ(nullptr, buf[1]);
 
   memset(buf, 0, sizeof(buf));
@@ -182,3 +182,39 @@ TEST(linked_list, copy_to_array) {
   ASSERT_EQ(nullptr, buf[0]);
 }
 
+TEST(linked_list, test_visit) {
+  test_list_t list;
+  list.push_back("a");
+  list.push_back("b");
+  list.push_back("c");
+  list.push_back("d");
+
+  int visits = 0;
+  std::stringstream ss;
+  bool result = list.visit([&](const char* c) {
+    ++visits;
+    ss << c;
+    return true;
+  });
+
+  ASSERT_TRUE(result);
+  ASSERT_EQ(4, visits);
+  ASSERT_EQ("abcd", ss.str());
+
+  visits = 0;
+  ss.str(std::string());
+
+  result = list.visit([&](const char* c) {
+    if (++visits == 3) {
+      return false;
+    }
+
+    ss << c;
+    return true;
+  });
+
+  ASSERT_TRUE(!result);
+  ASSERT_EQ(3, visits);
+  ASSERT_EQ("ab", ss.str());
+}
+