Setup basic piece table like data structure.

2026-07-28 00:31:58 +01:00
parent 27e8494fc8
commit 737c6c1d20
7 changed files with 228 additions and 5 deletions
@@ -0,0 +1,69 @@
+#pragma once
+
+#include "pch.h"
+
+struct Shard {
+  enum struct ShardKind {
+    Branch,
+    Petal
+  } kind;
+
+  uint32_t length;
+  uint32_t lines;
+
+  std::atomic_uint32_t refs;
+
+  Shard(ShardKind kind, uint32_t length, uint32_t lines)
+      : kind(kind), length(length), lines(lines) {};
+};
+
+struct ShardPtr {
+  Shard *ptr;
+
+  ShardPtr(const ShardPtr &other) : ptr(other.ptr) {
+    if (ptr)
+      ptr->refs++;
+  }
+
+  ShardPtr &operator=(const ShardPtr &other) {
+    if (ptr == other.ptr)
+      return *this;
+    if (ptr && --ptr->refs == 0)
+      delete ptr;
+    ptr = other.ptr;
+    if (ptr)
+      ptr->refs++;
+    return *this;
+  }
+
+  ShardPtr(Shard *p = nullptr) : ptr(p) {
+    if (ptr)
+      ptr->refs++;
+  }
+
+  ~ShardPtr() {
+    if (ptr && --ptr->refs == 0)
+      delete ptr;
+  }
+};
+
+struct Branch : Shard {
+  ShardPtr left;
+  ShardPtr right;
+
+  Branch(Shard *l, Shard *r)
+      : Shard(ShardKind::Branch, l->length + r->length, l->lines + r->lines),
+        left(ShardPtr(l)), right(ShardPtr(r)) {};
+};
+
+struct Petal : Shard {
+  enum struct Kind {
+    Original,
+    Append
+  } source;
+
+  uint32_t pos;
+
+  Petal(uint32_t length, uint32_t lines, Kind source, uint32_t pos)
+      : Shard(ShardKind::Petal, length, lines), source(source), pos(pos) {};
+};