From 4e4bb1fd0045571ca710e05127fec3842cd574c3 Mon Sep 17 00:00:00 2001
From: Milan Hauth <milahu@gmail.com>
Date: Sun, 2 Apr 2023 19:36:19 +0200
Subject: [PATCH] Revert "Revert "fixup: lazy db.pages""

This reverts commit 7b697c67a2ac889c4152ce6021065993be5d509b.
---
 database/sqlite3.ksy | 33 ++++++++++++++++++++++-----------
 1 file changed, 22 insertions(+), 11 deletions(-)

diff --git a/database/sqlite3.ksy b/database/sqlite3.ksy
index bce8cc642..b0916eada 100644
--- a/database/sqlite3.ksy
+++ b/database/sqlite3.ksy
@@ -37,17 +37,7 @@ seq:
     type: database_header
 instances:
   pages:
-    type:
-      switch-on: '(_index == header.idx_lock_byte_page ? 0 : _index >= header.idx_first_ptrmap_page and _index <= header.idx_last_ptrmap_page ? 1 : 2)'
-      cases:
-        0: lock_byte_page(_index + 1)
-        1: ptrmap_page(_index + 1)
-        # TODO: Free pages and cell overflow pages are incorrectly interpreted as btree pages
-        # This is unfortunate, but unavoidable since there's no way to recognize these types at
-        # this point in the parser.
-        2: btree_page(_index + 1)
-    pos: 0
-    size: header.page_size
+    type: page(_index + 1, header.page_size * _index)
     repeat: expr
     repeat-expr: header.num_pages
     doc: |
@@ -57,6 +47,27 @@ instances:
       TODO how exactly? add example code
     if: false
 types:
+  page:
+    params:
+      - id: page_number
+        type: s4
+      - id: ofs_body
+        type: s4
+    instances:
+      page_index:
+        value: 'page_number - 1'
+      body:
+        pos: ofs_body
+        size: _root.header.page_size
+        type:
+          switch-on: '(page_index == _root.header.idx_lock_byte_page ? 0 : page_index >= _root.header.idx_first_ptrmap_page and page_index <= _root.header.idx_last_ptrmap_page ? 1 : 2)'
+          cases:
+            0: lock_byte_page(page_number)
+            1: ptrmap_page(page_number)
+            # TODO: Free pages and cell overflow pages are incorrectly interpreted as btree pages
+            # This is unfortunate, but unavoidable since there's no way to recognize these types at
+            # this point in the parser.
+            2: btree_page(page_number)
   database_header:
     seq:
       - id: magic