add TrailRef type for trail

2019-01-26 20:06:27 -07:00
parent 91b85db90c
commit 6e735bc2d4
3 changed files with 49 additions and 23 deletions
--- a/src/prolog/machine/machine_state.rs
+++ b/src/prolog/machine/machine_state.rs
@@ -212,7 +212,7 @@ pub struct MachineState {
    pub(crate) and_stack: AndStack,
    pub(super) or_stack: OrStack,
    pub(super) registers: Registers,
-    pub(super) trail: Vec<Ref>,
+    pub(super) trail: Vec<TrailRef>,
    pub(super) pstr_trail: Vec<(usize, StringList, usize)>, // b, String, trunc_pt
    pub(super) pstr_tr: usize,
    pub(super) tr: usize,