python: db uprade and downgrade scripts

python/downgrades/47e552c4357a04c5735355fad818630daee4a5ac/py_stmts.ql

@@ -0,0 +1,30 @@
+// First we need to wrap some database types
+class Stmt_ extends @py_stmt {
+  string toString() { result = "Stmt" }
+}
+
+class StmtList_ extends @py_stmt_list {
+  string toString() { result = "StmtList" }
+}
+
+/**
+ * New kinds have been inserted such that
+ * `@py_Exec` which used to have index 7 now has index 8.
+ * Entries with lower indices are unchanged.
+ */
+bindingset[new_index]
+int old_index(int new_index) {
+  if new_index < 7 then result = new_index else result + (8 - 7) = new_index
+}
+
+// The schema for py_stmts is:
+//
+// py_stmts(unique int id : @py_stmt,
+//   int kind: int ref,
+//   int parent : @py_stmt_list ref,
+//   int idx : int ref);
+from Stmt_ expr, int new_kind, StmtList_ parent, int idx, int old_kind
+where
+  py_stmts(expr, new_kind, parent, idx) and
+  old_kind = old_index(new_kind)
+select expr, old_kind, parent, idx

python/downgrades/47e552c4357a04c5735355fad818630daee4a5ac/upgrade.properties

@@ -0,0 +1,3 @@
+description: Add support for `except*`
+compatibility: backwards
+py_stmts.rel: run py_stmts.qlo

python/ql/lib/upgrades/503c0516fba2e5da9570f00eb34ef43025ecb8fb/py_stmts.ql

@@ -0,0 +1,30 @@
+// First we need to wrap some database types
+class Stmt_ extends @py_stmt {
+  string toString() { result = "Stmt" }
+}
+
+class StmtList_ extends @py_stmt_list {
+  string toString() { result = "StmtList" }
+}
+
+/**
+ * New kinds have been inserted such that
+ * `@py_Exec` which used to have index 7 now has index 8.
+ * Entries with lower indices are unchanged.
+ */
+bindingset[old_index]
+int new_index(int old_index) {
+  if old_index < 7 then result = old_index else result = (8 - 7) + old_index
+}
+
+// The schema for py_stmts is:
+//
+// py_stmts(unique int id : @py_stmt,
+//   int kind: int ref,
+//   int parent : @py_stmt_list ref,
+//   int idx : int ref);
+from Stmt_ expr, int old_kind, StmtList_ parent, int idx, int new_kind
+where
+  py_stmts(expr, old_kind, parent, idx) and
+  new_kind = new_index(old_kind)
+select expr, new_kind, parent, idx

python/ql/lib/upgrades/503c0516fba2e5da9570f00eb34ef43025ecb8fb/upgrade.properties

@@ -0,0 +1,3 @@
+description: Add support for `except*`
+compatibility: backwards
+py_stmts.rel: run py_stmts.qlo