From 781976b1991759bc9daf1afe09cea1415bce04be Mon Sep 17 00:00:00 2001
From: Paul Kulchenko <paul@kulchenko.com>
Date: Tue, 15 Nov 2022 22:08:37 -0800
Subject: [PATCH] Add iterating over changeset to SQLite Lua API

---
 tool/net/lsqlite3.c | 69 +++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 67 insertions(+), 2 deletions(-)

diff --git a/tool/net/lsqlite3.c b/tool/net/lsqlite3.c
index ff7485c6b..7b7e89a9e 100644
--- a/tool/net/lsqlite3.c
+++ b/tool/net/lsqlite3.c
@@ -1827,13 +1827,15 @@ static int db_deserialize(lua_State *L) {
 
 typedef struct {
     sqlite3_changeset_iter *itr;
+    bool collectable;
 } liter;
 
-static liter *lsqlite_makeiter(lua_State *L, sqlite3_changeset_iter *piter) {
+static liter *lsqlite_makeiter(lua_State *L, sqlite3_changeset_iter *piter, bool collectable) {
     liter *litr = (liter*)lua_newuserdata(L, sizeof(liter));
     lua_rawgeti(L, LUA_REGISTRYINDEX, sqlite_itr_meta_ref);
     lua_setmetatable(L, -2);
     litr->itr = piter;
+    litr->collectable = collectable;
     return litr;
 }
 
@@ -1847,6 +1849,26 @@ static liter *lsqlite_checkiter(lua_State *L, int index) {
     return litr;
 }
 
+static int liter_finalize(lua_State *L) {
+    liter *litr = lsqlite_getiter(L, 1);
+    int rc;
+    if (litr->itr) {
+        if (!litr->collectable) {
+            return pusherr(L, SQLITE_CORRUPT);
+        }
+        if ((rc = sqlite3changeset_finalize(litr->itr)) != SQLITE_OK) {
+            return pusherr(L, rc);
+        }
+        litr->itr = NULL;
+    }
+    lua_pushboolean(L, 1);
+    return 1;
+}
+
+static int liter_gc(lua_State *L) {
+    return liter_finalize(L);
+}
+
 static int liter_tostring(lua_State *L) {
     char buff[32];
     liter *litr = lsqlite_getiter(L, 1);
@@ -1896,6 +1918,20 @@ static int liter_conflict(lua_State *L) {
     return liter_table(L, sqlite3changeset_conflict);
 }
 
+static int liter_op(lua_State *L) {
+    const char *zTab;
+    int rc, nCol, Op, bIndirect;
+    liter *litr = lsqlite_checkiter(L, 1);
+
+    if ((rc = sqlite3changeset_op(litr->itr, &zTab, &nCol, &Op, &bIndirect)) != LUA_OK) {
+        return pusherr(L, rc);
+    }
+    lua_pushstring(L, zTab);
+    lua_pushinteger(L, Op);
+    lua_pushboolean(L, bIndirect);
+    return 3;
+}
+
 static int liter_fk_conflicts(lua_State *L) {
     int rc, nOut;
     liter *litr = lsqlite_checkiter(L, 1);
@@ -1906,6 +1942,15 @@ static int liter_fk_conflicts(lua_State *L) {
     return 1;
 }
 
+static int liter_next(lua_State *L) {
+    liter *litr = lsqlite_checkiter(L, 1);
+    if (!litr->collectable) {
+        return pusherr(L, SQLITE_CORRUPT);
+    }
+    lua_pushinteger(L, sqlite3changeset_next(litr->itr));
+    return 1;
+}
+
 static int liter_pk(lua_State *L) {
     const char *zTab;
     int n, rc, nCol;
@@ -2031,7 +2076,7 @@ static int db_changeset_conflict_callback(
     lua_rawgeti(L, LUA_REGISTRYINDEX, changeset_conflict_cb); /* get callback */
     lua_rawgeti(L, LUA_REGISTRYINDEX, changeset_cb_udata); /* get callback user data */
     lua_pushinteger(L, eConflict);
-    (void)lsqlite_makeiter(L, p);
+    (void)lsqlite_makeiter(L, p, 0);
     lua_pushstring(L, zTab);
     lua_pushinteger(L, Op);
     lua_pushboolean(L, bIndirect);
@@ -2241,6 +2286,21 @@ static int db_create_session(lua_State *L) {
     return 1;
 }
 
+static int db_iterate_changeset(lua_State *L) {
+    sqlite3_changeset_iter *p;
+    sdb *db = lsqlite_checkdb(L, 1);
+    const char *cset = luaL_checkstring(L, 2);
+    int nset = lua_rawlen(L, 2);
+    int flags = luaL_optinteger(L, 3, 0);
+    int rc;
+
+    if ((rc = sqlite3changeset_start_v2(&p, nset, cset, flags)) != SQLITE_OK) {
+        return pusherr(L, rc);
+    }
+    (void)lsqlite_makeiter(L, p, 1);
+    return 1;
+}
+
 static int db_invert_changeset(lua_State *L) {
     sdb *db = lsqlite_checkdb(L, 1);
     const char *cset = luaL_checkstring(L, 2);
@@ -2551,6 +2611,7 @@ static const luaL_Reg dblib[] = {
     {"apply_changeset",     db_apply_changeset      },
     {"invert_changeset",    db_invert_changeset     },
     {"concat_changeset",    db_concat_changeset     },
+    {"iterate_changeset",   db_iterate_changeset    },
 #endif
 
     {"__tostring",          db_tostring             },
@@ -2652,13 +2713,17 @@ static const luaL_Reg reblib[] = {
 };
 
 static const luaL_Reg itrlib[] = {
+    {"op",              liter_op                },
     {"pk",              liter_pk                },
     {"new",             liter_new               },
     {"old",             liter_old               },
+    {"next",            liter_next              },
     {"conflict",        liter_conflict          },
+    {"finalize",        liter_finalize          },
     {"fk_conflicts",    liter_fk_conflicts      },
 
     {"__tostring",      liter_tostring          },
+    {"__gc",            liter_gc                },
     {NULL, NULL}
 };