From d1a8383e64303e94e2e0942b64b420c01b2504d8 Mon Sep 17 00:00:00 2001
From: Doug Hoyte <doug@hcsw.org>
Date: Wed, 8 Mar 2023 16:42:09 -0500
Subject: [PATCH] wip

---
 js/xor.js    | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 src/xor.h    | 16 +++++++--------
 test/xor.cpp |  2 +-
 3 files changed, 65 insertions(+), 9 deletions(-)

diff --git a/js/xor.js b/js/xor.js
index 83da51f..4f86dad 100644
--- a/js/xor.js
+++ b/js/xor.js
@@ -112,6 +112,62 @@ class XorView {
             lastTimestampOut[0] = temp;
             return encodeVarInt(timestamp + 1);
         };
+
+        let appendBoundKey = (key, output) => {
+            output.push(...encodeTimestampOut(key.timestamp));
+            output.push(...encodeVarInt(key.id.length));
+            output.push(...key.id);
+        };
+
+        let appendMinimalBoundKey = (curr, prev) => {
+            output.push(...encodeTimestampOut(curr.timestamp));
+
+            if (curr.timestamp !== prev.timestamp) {
+                output.push(...encodeVarInt(0));
+            } else {
+                let sharedPrefixBytes = 0;
+
+                for (let i = 0; i < this.idSize; i++) {
+                    if (curr.id[i] !== prev.id[i]) break;
+                    sharedPrefixBytes++;
+                }
+
+                output.push(...encodeVarInt(sharedPrefixBytes + 1));
+                output.push(...curr.id.slice(0, sharedPrefixBytes + 1));
+            }
+        };
+
+        // Split our range
+        let numElems = upper - lower;
+        let buckets = 16;
+
+        if (numElems < buckets * 2) {
+            appendBoundKey(lowerKey);
+            appendBoundKey(upperKey);
+
+            output.push(...encodeVarInt(numElems + 8));
+            for (let it = lower; it < upper; ++it) output.push(...this.elems[it].id);
+        } else {
+            let elemsPerBucket = Math.floor(numElems / buckets);
+            let bucketsWithExtra = numElems % buckets;
+            let curr = lower;
+
+            for (let i = 0; i < buckets; i++) {
+                if (i == 0) appendBoundKey(lowerKey);
+                else appendMinimalBoundKey(this.elems[curr], this.elems[curr - 1]);
+
+                let ourXorSet = new Array(this.idSize).fill(0);
+                for (let bucketEnd = curr + elemsPerBucket + (i < bucketsWithExtra ? 1 : 0); curr != bucketEnd; curr++) {
+                    for (let j = 0; j < this.idSize; j++) ourXorSet[j] ^= this.elems[curr][j];
+                }
+
+                if (i === buckets - 1) appendBoundKey(upperKey);
+                else appendMinimalBoundKey(this.elems[curr], this.elems[curr - 1]);
+
+                output.push(...encodeVarInt(0)); // mode = 0
+                output.push(...ourXorSet.id);
+            }
+        }
     }
 }
 
diff --git a/src/xor.h b/src/xor.h
index b5c35fa..0380392 100644
--- a/src/xor.h
+++ b/src/xor.h
@@ -157,13 +157,13 @@ struct XorView {
             return encodeVarInt(timestamp + 1);
         };
 
-        auto appendBoundKey = [&](uint64_t t, std::string k, std::string &output) {
+        auto appendBoundKey = [&](uint64_t t, std::string k) {
             output += encodeTimestampOut(t);
             output += encodeVarInt(k.size());
             output += k;
         };
 
-        auto appendMinimalBoundKey = [&](const XorElem &curr, const XorElem &prev, std::string &output) {
+        auto appendMinimalBoundKey = [&](const XorElem &curr, const XorElem &prev) {
             output += encodeTimestampOut(curr.timestamp);
 
             if (curr.timestamp != prev.timestamp) {
@@ -188,8 +188,8 @@ struct XorView {
         const uint64_t buckets = 16;
 
         if (numElems < buckets * 2) {
-            appendBoundKey(lowerTimestamp, lowerKey, output);
-            appendBoundKey(upperTimestamp, upperKey, output);
+            appendBoundKey(lowerTimestamp, lowerKey);
+            appendBoundKey(upperTimestamp, upperKey);
 
             output += encodeVarInt(numElems + 8);
             for (auto it = lower; it < upper; ++it) output += it->getId(idSize);
@@ -199,16 +199,16 @@ struct XorView {
             auto curr = lower;
 
             for (uint64_t i = 0; i < buckets; i++) {
-                if (i == 0) appendBoundKey(lowerTimestamp, lowerKey, output);
-                else appendMinimalBoundKey(*curr, *std::prev(curr), output);
+                if (i == 0) appendBoundKey(lowerTimestamp, lowerKey);
+                else appendMinimalBoundKey(*curr, *std::prev(curr));
 
                 XorElem ourXorSet;
                 for (auto bucketEnd = curr + elemsPerBucket + (i < bucketsWithExtra ? 1 : 0); curr != bucketEnd; curr++) {
                     ourXorSet ^= *curr;
                 }
 
-                if (i == buckets - 1) appendBoundKey(upperTimestamp, upperKey, output);
-                else appendMinimalBoundKey(*curr, *std::prev(curr), output);
+                if (i == buckets - 1) appendBoundKey(upperTimestamp, upperKey);
+                else appendMinimalBoundKey(*curr, *std::prev(curr));
 
                 output += encodeVarInt(0); // mode = 0
                 output += ourXorSet.getId(idSize);
diff --git a/test/xor.cpp b/test/xor.cpp
index 8e757ec..7d05e57 100644
--- a/test/xor.cpp
+++ b/test/xor.cpp
@@ -55,7 +55,7 @@ int main() {
     x1.finalise();
     x2.finalise();
 
-    std::string q = x1.initialQuery();
+    std::string q = x1.initial();
 
     uint64_t round = 0;