Toying with event recording to see if it can be used for testing

src/text_editor/buffer.cpp

@@ -227,6 +227,9 @@ void MergeSort(int64_t Count, Edit *First, Edit *Temp) {
 
 void ApplyEdits(Buffer *buffer, Array<Edit> edits) {
     Scratch scratch((Arena *)buffer->allocator.object);
+    Assert(buffer->data[0]);
+    Assert(buffer->allocator.proc);
+    Assert(buffer->lines.len);
 
     // Figure out how much we insert and how much we delete so
     // we can resize buffers properly if necessary
@@ -356,13 +359,22 @@ void ApplyEdits(Buffer *buffer, Array<Edit> edits) {
         }
         buffer->lines.add({base_index, base_index + string.len});
     }
+
+    Assert(buffer->data[0]);
+    Assert(buffer->allocator.proc);
+    Assert(buffer->lines.len);
 }
 
-void InitBuffer(Buffer *buffer) {
-    Scratch     scratch;
-    Array<Edit> edits = {};
-    AddEdit(&edits, {}, "");
-    ApplyEdits(buffer, edits);
+void InitBuffer(Allocator allocator, Buffer *buffer, int64_t _size = 4096) {
+    int64_t size      = AlignUp(_size, 4096);
+    buffer->allocator = allocator;
+    for (int i = 0; i < 2; i += 1) {
+        buffer->data[i] = AllocArray(allocator, char, size);
+        Assert(buffer->data[i]);
+    }
+    buffer->cap             = size;
+    buffer->lines.allocator = allocator;
+    buffer->lines.add({});
 }
 
 String CopyNullTerminated(Allocator allocator, Buffer &buffer, Range range) {
@@ -569,3 +581,29 @@ int64_t Seek(Buffer &buffer, int64_t pos, int64_t direction = ITERATE_FORWARD) {
     }
     return result;
 }
+
+int64_t MoveRight(Buffer &buffer, int64_t pos) {
+    pos = pos + 1;
+    pos = AdjustUTF8Pos(buffer, pos);
+    Assert(pos >= 0 && pos <= buffer.len);
+    return pos;
+}
+
+int64_t MoveLeft(Buffer &buffer, int64_t pos) {
+    pos = pos - 1;
+    pos = AdjustUTF8Pos(buffer, pos, -1);
+    Assert(pos >= 0 && pos <= buffer.len);
+    return pos;
+}
+
+int64_t MoveDown(Buffer &buffer, int64_t pos) {
+    LineAndColumn info    = FindLineAndColumn(buffer, pos);
+    int64_t       new_pos = FindPos(buffer, info.line.number + 1, info.column);
+    return new_pos;
+}
+
+int64_t MoveUp(Buffer &buffer, int64_t pos) {
+    LineAndColumn info    = FindLineAndColumn(buffer, pos);
+    int64_t       new_pos = FindPos(buffer, info.line.number - 1, info.column);
+    return new_pos;
+}