Move Lookahead list.at() processing to common utilities

BUG=b:271591258
TEST=USE="coverage" FEATURES="test noclean" emerge-brya chromeos-base/gestures

Change-Id: Ief01adbe704e69704efad3af241b7a1b88d3e220
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/gestures/+/4352450
Reviewed-by: Harry Cutts <hcutts@chromium.org>
Auto-Submit: Denis Brockus <dbrockus@chromium.org>
Tested-by: Denis Brockus <dbrockus@chromium.org>
Code-Coverage: Harry Cutts <hcutts@chromium.org>
Commit-Queue: Harry Cutts <hcutts@chromium.org>

3 files changed, 7 insertions, 85 deletions

diff --git a/include/lookahead_filter_interpreter.h b/include/lookahead_filter_interpreter.h
index 890919f..d3d4077 100644
--- a/include/lookahead_filter_interpreter.h
+++ b/include/lookahead_filter_interpreter.h
@@ -15,6 +15,7 @@
 #include "include/gestures.h"
 #include "include/prop_registry.h"
 #include "include/tracer.h"
+#include "include/util.h"
 
 #ifndef GESTURES_LOOKAHEAD_FILTER_INTERPRETER_H_
 #define GESTURES_LOOKAHEAD_FILTER_INTERPRETER_H_
@@ -34,7 +35,6 @@ class LookaheadFilterInterpreter : public FilterInterpreter {
   FRIEND_TEST(LookaheadFilterInterpreterTest, SimpleTest);
   FRIEND_TEST(LookaheadFilterInterpreterTest, SpuriousCallbackTest);
   FRIEND_TEST(LookaheadFilterInterpreterTest, VariableDelayTest);
-  FRIEND_TEST(LookaheadFilterInterpreterTest, QStateListTest);
 
  public:
   LookaheadFilterInterpreter(PropRegistry* prop_reg, Interpreter* next,
@@ -108,15 +108,13 @@ class LookaheadFilterInterpreter : public FilterInterpreter {
 
   stime_t ExtraVariableDelay() const;
 
-  typedef std::optional<
-            std::reference_wrapper<
-              LookaheadFilterInterpreter::QState
-            >
-          > OptionalRefQState;
+  typedef std::list<QState> QStateListType;
+  typedef std::optional<std::reference_wrapper<QState>> OptionalRefQState;
 
-  class QStateList : public std::list<QState> {
-  public:
-    OptionalRefQState at(int offset);
+  struct QStateList : public QStateListType {
+    OptionalRefQState at(int offset) {
+      return ListAt<OptionalRefQState, QStateListType>(*this, offset);
+    }
   } queue_;
 
   // The last id assigned to a contact (part of drumroll suppression)
diff --git a/src/lookahead_filter_interpreter.cc b/src/lookahead_filter_interpreter.cc
index 730becf..69156f5 100644
--- a/src/lookahead_filter_interpreter.cc
+++ b/src/lookahead_filter_interpreter.cc
@@ -587,24 +587,4 @@ void LookaheadFilterInterpreter::QState::set_state(
   state_.msc_timestamp = new_state.msc_timestamp;
 }
 
-LookaheadFilterInterpreter::OptionalRefQState
-LookaheadFilterInterpreter::QStateList::at(int offset) {
-  // Traverse to the appropriate offset
-  if (offset < 0) {
-    // negative offset is from end to begin
-    for (auto iter = rbegin(); iter != rend(); ++iter) {
-      if (++offset == 0)
-        return LookaheadFilterInterpreter::OptionalRefQState{*iter};
-    }
-  } else {
-    // positive offset is from begin to end
-    for (auto iter = begin(); iter != end(); ++iter, --offset) {
-      if (offset == 0)
-        return LookaheadFilterInterpreter::OptionalRefQState{*iter};
-    }
-  }
-  // Invalid offset
-  return std::nullopt;
-}
-
 }  // namespace gestures
diff --git a/src/lookahead_filter_interpreter_unittest.cc b/src/lookahead_filter_interpreter_unittest.cc
index e4d02a9..ee99a0f 100644
--- a/src/lookahead_filter_interpreter_unittest.cc
+++ b/src/lookahead_filter_interpreter_unittest.cc
@@ -1276,60 +1276,4 @@ TEST(LookaheadFilterInterpreterTest, SemiMtNoTrackingIdAssignmentTest) {
   }
 }
 
-TEST(LookaheadFilterInterpreterTest, QStateListTest) {
-  const size_t kMaxQNodes = 4;
-
-  LookaheadFilterInterpreterTestInterpreter* base_interpreter = NULL;
-  std::unique_ptr<LookaheadFilterInterpreter> interpreter;
-
-  HardwareProperties hwprops = {
-    0, 0, 100, 100,  // left, top, right, bottom
-    1,  // x res (pixels/mm)
-    1,  // y res (pixels/mm)
-    25, 25,  // scrn DPI X, Y
-    -1,  // orientation minimum
-    2,   // orientation maximum
-    2, 5,  // max fingers, max_touch
-    1, 1, 0,  // t5r2, semi, button pad
-    0, 0,  // has wheel, vertical wheel is high resolution
-    0,  // haptic pad
-  };
-  TestInterpreterWrapper wrapper(interpreter.get(), &hwprops);
-
-  base_interpreter = new LookaheadFilterInterpreterTestInterpreter;
-  interpreter.reset(new LookaheadFilterInterpreter(
-      NULL, base_interpreter, NULL));
-  wrapper.Reset(interpreter.get());
-
-  auto& queue = interpreter->queue_;
-
-  EXPECT_TRUE(queue.empty());
-  EXPECT_EQ(queue.size(), 0);
-
-  // Use the default constructor one time... just for coverage
-  queue.push_front(LookaheadFilterInterpreter::QState());
-
-  for (size_t i{1}; i < kMaxQNodes; ++i) {
-    queue.push_front(
-      LookaheadFilterInterpreter::QState(hwprops.max_finger_cnt));
-  }
-  EXPECT_EQ(queue.size(), kMaxQNodes);
-  EXPECT_EQ(&(queue.at(-1)->get()), &(queue.at(queue.size() - 1)->get()));
-
-  for (size_t i = 0; i < kMaxQNodes; ++i) {
-    for (size_t j = 0; j < kMaxQNodes; ++j) {
-      if (i == j) {
-        EXPECT_EQ(&(queue.at(i)->get()), &(queue.at(j)->get()));
-      } else {
-        EXPECT_NE(&(queue.at(i)->get()), &(queue.at(j)->get()));
-      }
-    }
-  }
-
-  int qnode_count = queue.size();
-  EXPECT_EQ(queue.at(qnode_count), std::nullopt);
-  EXPECT_NE(queue.at(qnode_count - 1), std::nullopt);
-  EXPECT_EQ(queue.at(-qnode_count - 1), std::nullopt);
-  EXPECT_NE(queue.at(-qnode_count), std::nullopt);
-}
 }  // namespace gestures