From 5f3313a3bf927829df8cdebc9b434d2c4510135c Mon Sep 17 00:00:00 2001
From: Andrew Noyes <anoyes34@gmail.com>
Date: Thu, 18 Jan 2024 16:57:23 -0800
Subject: [PATCH] Use runInterleaved in lastLeqMulti

---
 ConflictSet.cpp | 110 ++++++++++++++++++++++--------------------------
 1 file changed, 50 insertions(+), 60 deletions(-)

diff --git a/ConflictSet.cpp b/ConflictSet.cpp
index ae44e47..4049c1b 100644
--- a/ConflictSet.cpp
+++ b/ConflictSet.cpp
@@ -106,6 +106,43 @@ struct Iterator {
   int cmp;
 };
 
+// Call Stepwise::step for each element of remaining until it returns true.
+// Applies a permutation to remaining as a side effect.
+template <class Stepwise>
+void runInterleaved(std::span<Stepwise> remaining, int stepLimit = -1) {
+  while (remaining.size() > 0) {
+    for (int i = 0; i < int(remaining.size());) {
+      if (stepLimit-- == 0) {
+        return;
+      }
+      bool done = remaining[i].step();
+      if (done) {
+        if (i != int(remaining.size()) - 1) {
+          using std::swap;
+          swap(remaining[i], remaining.back());
+        }
+        remaining = remaining.subspan(0, remaining.size() - 1);
+      } else {
+        ++i;
+      }
+    }
+  }
+};
+
+template <class Stepwise>
+void runSequential(std::span<Stepwise> remaining, int stepLimit = -1) {
+  for (auto &r : remaining) {
+    if (stepLimit-- == 0) {
+      return;
+    }
+    while (!r.step()) {
+      if (stepLimit-- == 0) {
+        return;
+      }
+    }
+  }
+}
+
 struct StepwiseLastLeq {
   Node *current;
   Node *result;
@@ -147,17 +184,16 @@ void lastLeqMulti(Node *root, std::span<Key> keys, Iterator *results) {
   // Descend until queries for front and back diverge
   Node *current = root;
   Node *resultP = nullptr;
-  auto stepwiseLastLeqBegin =
-      StepwiseLastLeq(current, resultP, keys.front(), -1);
-  auto stepwiseLastLeqEnd = StepwiseLastLeq(current, resultP, keys.back(), -1);
+  auto stepwiseFront = StepwiseLastLeq(current, resultP, keys.front(), -1);
+  auto stepwiseBack = StepwiseLastLeq(current, resultP, keys.back(), -1);
   for (;;) {
-    bool done1 = stepwiseLastLeqBegin.step();
-    bool done2 = stepwiseLastLeqEnd.step();
-    if (!done1 && !done2 && stepwiseLastLeqBegin.c == stepwiseLastLeqEnd.c) {
-      assert(stepwiseLastLeqBegin.current == stepwiseLastLeqEnd.current);
-      assert(stepwiseLastLeqBegin.result == stepwiseLastLeqEnd.result);
-      current = stepwiseLastLeqBegin.current;
-      resultP = stepwiseLastLeqBegin.result;
+    bool done1 = stepwiseFront.step();
+    bool done2 = stepwiseBack.step();
+    if (!done1 && !done2 && stepwiseFront.c == stepwiseBack.c) {
+      assert(stepwiseFront.current == stepwiseBack.current);
+      assert(stepwiseFront.result == stepwiseBack.result);
+      current = stepwiseFront.current;
+      resultP = stepwiseFront.result;
     } else {
       break;
     }
@@ -170,22 +206,11 @@ void lastLeqMulti(Node *root, std::span<Key> keys, Iterator *results) {
       *iter++ = StepwiseLastLeq(current, resultP, k, index++);
     }
   }
-  auto remaining =
+  auto stepwiseSpan =
       std::span<StepwiseLastLeq>(stepwiseLastLeqs.get(), keys.size());
-  while (remaining.size() > 0) {
-    for (int i = 0; i < int(remaining.size());) {
-      bool done = remaining[i].step();
-      if (done) {
-        const auto &c = remaining[i];
-        results[c.index] = Iterator{c.result, c.resultC};
-        if (i != int(remaining.size()) - 1) {
-          remaining[i] = remaining.back();
-        }
-        remaining = remaining.subspan(0, remaining.size() - 1);
-      } else {
-        ++i;
-      }
-    }
+  runInterleaved(stepwiseSpan);
+  for (const auto &stepwise : stepwiseSpan) {
+    results[stepwise.index] = Iterator{stepwise.result, stepwise.resultC};
   }
 }
 
@@ -401,41 +426,6 @@ bool checkInvariants(Node *node) {
   return success;
 }
 
-template <class Stepwise>
-void runInterleaved(std::span<Stepwise> remaining, int stepLimit = -1) {
-  while (remaining.size() > 0) {
-    for (int i = 0; i < int(remaining.size());) {
-      if (stepLimit-- == 0) {
-        return;
-      }
-      bool done = remaining[i].step();
-      if (done) {
-        if (i != int(remaining.size()) - 1) {
-          using std::swap;
-          swap(remaining[i], remaining.back());
-        }
-        remaining = remaining.subspan(0, remaining.size() - 1);
-      } else {
-        ++i;
-      }
-    }
-  }
-};
-
-template <class Stepwise>
-void runSequential(std::span<Stepwise> remaining, int stepLimit = -1) {
-  for (auto &r : remaining) {
-    if (stepLimit-- == 0) {
-      return;
-    }
-    while (!r.step()) {
-      if (stepLimit-- == 0) {
-        return;
-      }
-    }
-  }
-}
-
 } // namespace
 
 struct ConflictSet::Impl {