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enable backtracking on partial strings

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This commit is contained in:
Mark Thom
2018-09-24 22:24:23 -06:00
parent 23eed192e9
commit 58ed374363
6 changed files with 205 additions and 64 deletions
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45
src/prolog/machine/machine_state.rs
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@@ -249,7 +249,8 @@ pub struct MachineState {
pub(super) or_stack: OrStack,
pub(super) registers: Registers,
pub(super) trail: Vec<Ref>,
pub(super) partial_string_trail: Vec<(StringList, usize)>,
pub(super) pstr_trail: Vec<(usize, StringList, usize)>, // b, String, trunc_pt
pub(super) pstr_tr: usize,
pub(super) tr: usize,
pub(super) hb: usize,
pub(super) block: usize, // an offset into the OR stack.
@@ -298,6 +299,15 @@ pub(crate) trait CallPolicy: Any {
machine_st.tr = machine_st.or_stack[b].tr;
machine_st.trail.truncate(machine_st.tr);
let old_pstr_tr = machine_st.or_stack[b].pstr_tr;
let curr_pstr_tr = machine_st.pstr_tr;
machine_st.unwind_pstr_trail(old_pstr_tr, curr_pstr_tr);
machine_st.pstr_tr = machine_st.or_stack[b].pstr_tr;
machine_st.pstr_trail.truncate(machine_st.pstr_tr);
machine_st.heap.truncate(machine_st.or_stack[b].h);
machine_st.hb = machine_st.heap.h;
@@ -324,9 +334,18 @@ pub(crate) trait CallPolicy: Any {
let curr_tr = machine_st.tr;
machine_st.unwind_trail(old_tr, curr_tr);
machine_st.tr = machine_st.or_stack[b].tr;
machine_st.tr = machine_st.or_stack[b].tr;
machine_st.trail.truncate(machine_st.tr);
let old_pstr_tr = machine_st.or_stack[b].pstr_tr;
let curr_pstr_tr = machine_st.pstr_tr;
machine_st.unwind_pstr_trail(old_pstr_tr, curr_pstr_tr);
machine_st.pstr_tr = machine_st.or_stack[b].pstr_tr;
machine_st.pstr_trail.truncate(machine_st.pstr_tr);
machine_st.heap.truncate(machine_st.or_stack[b].h);
machine_st.hb = machine_st.heap.h;
@@ -351,10 +370,18 @@ pub(crate) trait CallPolicy: Any {
let curr_tr = machine_st.tr;
machine_st.unwind_trail(old_tr, curr_tr);
machine_st.tr = machine_st.or_stack[b].tr;
machine_st.trail.truncate(machine_st.tr);
let old_pstr_tr = machine_st.or_stack[b].pstr_tr;
let curr_pstr_tr = machine_st.pstr_tr;
machine_st.unwind_pstr_trail(old_pstr_tr, curr_pstr_tr);
machine_st.pstr_tr = machine_st.or_stack[b].pstr_tr;
machine_st.pstr_trail.truncate(machine_st.pstr_tr);
machine_st.heap.truncate(machine_st.or_stack[b].h);
machine_st.b = machine_st.or_stack[b].b;
@@ -382,10 +409,18 @@ pub(crate) trait CallPolicy: Any {
let curr_tr = machine_st.tr;
machine_st.unwind_trail(old_tr, curr_tr);
machine_st.tr = machine_st.or_stack[b].tr;
machine_st.trail.truncate(machine_st.tr);
let old_pstr_tr = machine_st.or_stack[b].pstr_tr;
let curr_pstr_tr = machine_st.pstr_tr;
machine_st.unwind_pstr_trail(old_pstr_tr, curr_pstr_tr);
machine_st.pstr_tr = machine_st.or_stack[b].pstr_tr;
machine_st.pstr_trail.truncate(machine_st.pstr_tr);
machine_st.heap.truncate(machine_st.or_stack[b].h);
machine_st.b = machine_st.or_stack[b].b;
@@ -842,6 +877,7 @@ fn cut_body(machine_st: &mut MachineState, addr: Addr) -> bool {
if b > b0 {
machine_st.b = b0;
machine_st.tidy_trail();
machine_st.tidy_pstr_trail();
machine_st.or_stack.truncate(machine_st.b);
}
} else {
@@ -923,6 +959,7 @@ impl CutPolicy for SCCCutPolicy {
if b > b0 {
machine_st.b = b0;
machine_st.tidy_trail();
machine_st.tidy_pstr_trail();
machine_st.or_stack.truncate(machine_st.b);
}
} else {