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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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6
Cargo.lock generated
View File

@@ -86,8 +86,7 @@ dependencies = [
[[package]]
name = "prolog_parser"
version = "0.7.15"
source = "registry+https://github.com/rust-lang/crates.io-index"
version = "0.7.16"
dependencies = [
"num 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
"ordered-float 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -113,7 +112,7 @@ dependencies = [
"downcast 0.9.1 (registry+https://github.com/rust-lang/crates.io-index)",
"num 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
"ordered-float 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)",
"prolog_parser 0.7.15 (registry+https://github.com/rust-lang/crates.io-index)",
"prolog_parser 0.7.16",
"termion 1.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
]
@@ -152,7 +151,6 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
"checksum num-traits 0.1.41 (registry+https://github.com/rust-lang/crates.io-index)" = "cacfcab5eb48250ee7d0c7896b51a2c5eec99c1feea5f32025635f5ae4b00070"
"checksum num-traits 0.2.5 (registry+https://github.com/rust-lang/crates.io-index)" = "630de1ef5cc79d0cdd78b7e33b81f083cbfe90de0f4b2b2f07f905867c70e9fe"
"checksum ordered-float 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)" = "58d25b6c0e47b20d05226d288ff434940296e7e2f8b877975da32f862152241f"
"checksum prolog_parser 0.7.15 (registry+https://github.com/rust-lang/crates.io-index)" = "11f378539616d1cd7b8fc006f309b5a4b483b82cbab76e898a9f1c99318b4dfa"
"checksum redox_syscall 0.1.32 (registry+https://github.com/rust-lang/crates.io-index)" = "ab105df655884ede59d45b7070c8a65002d921461ee813a024558ca16030eea0"
"checksum redox_termios 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "7e891cfe48e9100a70a3b6eb652fef28920c117d366339687bd5576160db0f76"
"checksum termion 1.5.1 (registry+https://github.com/rust-lang/crates.io-index)" = "689a3bdfaab439fd92bc87df5c4c78417d3cbe537487274e9b0b2dce76e92096"

2
Cargo.toml
View File

@@ -10,7 +10,7 @@ license = "BSD-3-Clause"
downcast = "0.9.1"
num = "0.2"
ordered-float = "0.5.0"
prolog_parser = "0.7.15"
prolog_parser = "0.7.16"
[dependencies.termion]
version = "1.4.0"

45
src/prolog/machine/machine_state.rs
View File

@@ -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 {

143
src/prolog/machine/machine_state_impl.rs
View File

@@ -49,7 +49,8 @@ impl MachineState {
or_stack: OrStack::new(),
registers: vec![Addr::HeapCell(0); MAX_ARITY + 1], // self.registers[0] is never used.
trail: vec![],
partial_string_trail: vec![],
pstr_trail: vec![],
pstr_tr: 0,
tr: 0,
hb: 0,
block: 0,
@@ -162,6 +163,51 @@ impl MachineState {
printer.print(addr)
}
pub(super)
fn unify_string(&mut self, pdl: &mut Vec<Addr>, s1: &mut StringList, s2: &mut StringList) -> bool
{
if let Some(c1) = s1.head() {
if let Some(c2) = s2.head() {
if c1 == c2 {
pdl.push(Addr::Con(Constant::String(s1.tail())));
pdl.push(Addr::Con(Constant::String(s2.tail())));
return true;
}
} else if s2.is_expandable() {
self.pstr_trail(s2.clone());
pdl.push(Addr::Con(Constant::String(s2.push_char(c1))));
pdl.push(Addr::Con(Constant::String(s1.tail())));
return true;
}
} else if s1.is_expandable() {
if let Some(c) = s2.head() {
self.pstr_trail(s1.clone());
pdl.push(Addr::Con(Constant::String(s1.push_char(c))));
pdl.push(Addr::Con(Constant::String(s2.tail())));
} else if s2.is_expandable() {
return s1 == s2;
} else {
self.pstr_trail(s1.clone());
s1.set_non_expandable();
}
return true;
} else if s2.head().is_none() {
if s2.is_expandable() {
self.pstr_trail(s2.clone());
}
s2.set_non_expandable();
return true;
}
false
}
pub(super) fn unify(&mut self, a1: Addr, a2: Addr) {
let mut pdl = vec![a1, a2];
@@ -208,6 +254,8 @@ impl MachineState {
continue;
} else if s.is_expandable() {
let prev_s = s.clone();
let mut stepper = |c| {
let new_s = s.push_char(c);
@@ -217,12 +265,14 @@ impl MachineState {
match self.heap[a1].clone() {
HeapCellValue::Addr(Addr::Con(Constant::Char(c))) => {
self.pstr_trail(prev_s);
stepper(c);
continue;
},
HeapCellValue::Addr(Addr::Con(Constant::Atom(ref a, _))) =>
if let Some(c) = a.as_str().chars().next() {
if c.len_utf8() == a.as_str().len() {
self.pstr_trail(prev_s);
stepper(c);
continue;
}
@@ -237,6 +287,7 @@ impl MachineState {
| (Addr::Con(Constant::String(ref s)), Addr::Con(Constant::EmptyList))
if self.flags.double_quotes.is_chars() => {
if s.is_expandable() && s.is_empty() {
self.pstr_trail(s.clone());
s.set_non_expandable();
continue;
}
@@ -251,43 +302,9 @@ impl MachineState {
pdl.push(Addr::HeapCell(a2 + 1));
},
(Addr::Con(Constant::String(ref mut s1)),
Addr::Con(Constant::String(ref mut s2))) => {
let mut stepper = |s1: &mut StringList, s2: &mut StringList| -> bool {
if let Some(c1) = s1.head() {
if let Some(c2) = s2.head() {
if c1 == c2 {
pdl.push(Addr::Con(Constant::String(s1.tail())));
pdl.push(Addr::Con(Constant::String(s2.tail())));
return true;
}
} else if s2.is_expandable() {
pdl.push(Addr::Con(Constant::String(s2.push_char(c1))));
pdl.push(Addr::Con(Constant::String(s1.tail())));
return true;
}
} else if s1.is_expandable() {
if let Some(c) = s2.head() {
pdl.push(Addr::Con(Constant::String(s1.push_char(c))));
pdl.push(Addr::Con(Constant::String(s2.tail())));
} else if s2.is_expandable() {
return s1 == s2;
} else {
s1.set_non_expandable();
}
return true;
} else if s2.head().is_none() {
s2.set_non_expandable();
return true;
}
false
};
self.fail = !(stepper(s1, s2) || stepper(s2, s1));
},
Addr::Con(Constant::String(ref mut s2))) =>
self.fail = !(self.unify_string(&mut pdl, s1, s2)
|| self.unify_string(&mut pdl, s2, s1)),
(Addr::Con(ref c1), Addr::Con(ref c2)) =>
if c1 != c2 {
self.fail = true;
@@ -317,6 +334,19 @@ impl MachineState {
}
}
#[inline]
fn pstr_trail(&mut self, s: StringList) {
if let Some((prev_b, prev_s, _)) = self.pstr_trail.last().cloned() {
if prev_b == self.b && prev_s == s {
return;
}
}
let len = s.len();
self.pstr_trail.push((self.b, s, len));
self.pstr_tr += 1;
}
fn trail(&mut self, r: Ref) {
match r {
Ref::HeapCell(hc) =>
@@ -356,6 +386,35 @@ impl MachineState {
}
}
pub(super) fn unwind_pstr_trail(&mut self, a1: usize, a2: usize) {
for i in a1 .. a2 {
let (_, mut s, end) = self.pstr_trail[i].clone();
s.truncate(end);
}
}
pub(super) fn tidy_pstr_trail(&mut self) {
if self.b == 0 {
return;
}
let b = self.b - 1;
let mut i = self.or_stack[b].pstr_tr;
while i < self.pstr_tr {
let str_b = self.pstr_trail[i].0;
if b < str_b {
let pstr_tr = self.pstr_tr;
let val = self.pstr_trail[pstr_tr - 1].clone();
self.pstr_trail[i] = val;
self.pstr_tr -= 1;
} else {
i += 1;
}
}
}
pub(super) fn tidy_trail(&mut self) {
if self.b == 0 {
return;
@@ -402,6 +461,8 @@ impl MachineState {
#[inline]
fn write_char_to_string(&mut self, s: &mut StringList, c: char) -> bool {
self.pstr_trail(s.clone());
let new_s = s.push_char(c);
self.heap.push(HeapCellValue::Addr(Addr::Con(Constant::String(new_s))));
false
@@ -422,6 +483,7 @@ impl MachineState {
Constant::EmptyList if self.flags.double_quotes.is_chars() =>
!s.is_empty(),
Constant::String(ref s2) if s.is_empty() && s.is_expandable() => {
self.pstr_trail(s.clone());
s.append(s2);
false
},
@@ -2140,6 +2202,7 @@ impl MachineState {
self.b,
self.p.clone() + 1,
self.tr,
self.pstr_tr,
self.heap.h,
self.b0,
self.num_of_args);
@@ -2175,6 +2238,7 @@ impl MachineState {
self.b,
self.p.clone() + offset,
self.tr,
self.pstr_tr,
self.heap.h,
self.b0,
self.num_of_args);
@@ -2246,13 +2310,14 @@ impl MachineState {
self.b0 = 0;
self.s = 0;
self.tr = 0;
self.pstr_tr = 0;
self.p = CodePtr::default();
self.cp = LocalCodePtr::default();
self.num_of_args = 0;
self.fail = false;
self.trail.clear();
self.partial_string_trail.clear();
self.pstr_trail.clear();
self.heap.clear();
self.mode = MachineMode::Write;
self.and_stack.clear();

22
src/prolog/or_stack.rs
View File

@@ -10,6 +10,7 @@ pub struct Frame {
pub b: usize,
pub bp: CodePtr,
pub tr: usize,
pub pstr_tr: usize,
pub h: usize,
pub b0: usize,
args: Vec<Addr>
@@ -22,20 +23,22 @@ impl Frame {
b: usize,
bp: CodePtr,
tr: usize,
pstr_tr: usize,
h: usize,
b0: usize,
n: usize)
-> Self
{
Frame {
global_index: global_index,
e: e,
cp: cp,
b: b,
bp: bp,
tr: tr,
h: h,
b0: b0,
global_index,
e,
cp,
b,
bp,
tr,
pstr_tr,
h,
b0,
args: vec![Addr::HeapCell(0); n]
}
}
@@ -59,11 +62,12 @@ impl OrStack {
b: usize,
bp: CodePtr,
tr: usize,
pstr_tr: usize,
h: usize,
b0: usize,
n: usize)
{
self.0.push(Frame::new(global_index, e, cp, b, bp, tr, h, b0, n));
self.0.push(Frame::new(global_index, e, cp, b, bp, tr, pstr_tr, h, b0, n));
}
pub fn len(&self) -> usize {

51
src/tests.rs
View File

@@ -1488,7 +1488,7 @@ fn test_queries_on_builtins()
[["Term = [[[[_22, _26], _26], _22]]", "X = _2", "Y = _0"]]);
assert_prolog_success!(&mut wam, "?- duplicate_term([X, [Y, [X]]], Term).",
[["Term = [_12, [_16, [_12]]]", "X = _0", "Y = _4"]]);
// test duplicate_term on cyclic terms.
assert_prolog_failure!(&mut wam, "?- X = g(X, Y), Y = f(X), duplicate_term(Y, g(Z)).");
assert_prolog_success!(&mut wam, "?- X = g(X, Y), Y = f(X), duplicate_term(Y, f(Z)).",
@@ -1499,7 +1499,7 @@ fn test_queries_on_builtins()
[["NewTerm = f(_16, _16, [_19, a, [], _16])",
"Term = f(_0, Y, [_6, a, [], Y])",
"X = _6", "Y = _0"]]);
assert_prolog_success!(&mut wam, "?- float(3.14159269).");
assert_prolog_failure!(&mut wam, "?- float(3).");
assert_prolog_failure!(&mut wam, "?- float(\"sdfsa\").");
@@ -1640,12 +1640,12 @@ fn test_queries_on_builtins()
assert_prolog_success!(&mut wam, "?- call_with_inference_limit((setup_call_cleanup(S=1,(G=2;fail),writeq(S+G>B)), B=3, !), 100, R).",
[["G = 2", "B = 3", "R = !", "S = 1"]]);
assert_prolog_success!(&mut wam, "?- call_with_inference_limit((setup_call_cleanup(S=1,(G=2;fail),writeq(S+G>B)), B=3, !), 10, R).",
[["S = _1", "G = _4", "B = _14", "R = inference_limit_exceeded"]]);
[["S = _1", "G = _4", "B = _14", "R = inference_limit_exceeded"]]);
assert_prolog_success!(&mut wam, "?- X = '\\n'.",
[["X = '\\n'"]]);
assert_prolog_success!(&mut wam, "?- X = '\\b'.",
[["X = '\\b'"]]);
[["X = '\\b'"]]);
assert_prolog_success!(&mut wam, "?- X = '\\v'.",
[["X = '\\v'"]]);
assert_prolog_success!(&mut wam, "?- X = '\\a'.",
@@ -1889,7 +1889,7 @@ fn test_queries_on_string_lists()
assert_prolog_success!(&mut wam, "?- X = \"abc\", Y = \"abc\", X =@= Y.");
assert_prolog_success!(&mut wam, "?- partial_string(\"abc\", X), partial_string(\"abc\", Y), X =@= Y.");
submit(&mut wam, "matcher([a,b,c|X], ['d','e','f'|X]).");
assert_prolog_success!(&mut wam, "?- matcher(\"abcdef\", \"defdef\").");
@@ -1973,7 +1973,7 @@ fn test_queries_on_string_lists()
assert_prolog_failure!(&mut wam, "?- partial_string(\"abc\", X), X \\=@= \"abc\".");
assert_prolog_failure!(&mut wam, "?- partial_string(\"abc\", X), X @< \"abc\".");
assert_prolog_success!(&mut wam, "?- partial_string(\"ab\", X), matcher(X, Y), Y = [a,b|V],
assert_prolog_success!(&mut wam, "?- partial_string(\"ab\", X), matcher(X, Y), Y = [a,b|V],
matcher(Y, Z), is_partial_string(Y).",
[["V = [c | _]", "X = [a, b, c, a, b, c | _]", "Y = [a, b, c | _]", "Z = _"]]);
assert_prolog_success!(&mut wam, "?- partial_string(\"a\", X), matcher(X, Y).",
@@ -1982,4 +1982,41 @@ fn test_queries_on_string_lists()
[["X = [a, b, c | _]", "Y = _"]]);
assert_prolog_success!(&mut wam, "?- partial_string(\"a\", X), matcher(X, Y), Y = \"def\".",
[["X = [a, b, c, d, e, f]", "Y = [d, e, f]"]]);
submit(&mut wam, "matcher([a,b,c|X], X).
matcher([a,b,d|X], X).");
assert_prolog_success!(&mut wam, "?- partial_string(\"ab\", X), matcher(X, Y).",
[["X = [a, b, c | _]", "Y = _"],
["X = [a, b, d | _]", "Y = _"]]);
submit(&mut wam, "matcher([a,b,c,d|X], X).
matcher([a,c,d|X], X).");
assert_prolog_success!(&mut wam, "?- partial_string(\"ab\", X), matcher(X, Y).",
[["X = [a, b, c, d | _]", "Y = _"]]);
assert_prolog_success!(&mut wam, "?- partial_string(\"a\", X), matcher(X, Y).",
[["X = [a, b, c, d | _]", "Y = _"],
["X = [a, c, d | _]", "Y = _"]]);
submit(&mut wam, "matcher([a,b,c,d|X], X).
matcher([a,c,d|X], X).
matcher([a,e,f|X], X).");
assert_prolog_success!(&mut wam, "?- partial_string(\"a\", X), matcher(X, Y).",
[["X = [a, b, c, d | _]", "Y = _"],
["X = [a, c, d | _]", "Y = _"],
["X = [a, e, f | _]", "Y = _"]]);
assert_prolog_success!(&mut wam, "?- partial_string(\"a\", X), matcher(X, Y), Y = \" t\".",
[["X = [a, b, c, d, ' ', t]", "Y = [' ', t]"],
["X = [a, c, d, ' ', t]", "Y = [' ', t]"],
["X = [a, e, f, ' ', t]", "Y = [' ', t]"]]);
submit(&mut wam, "matcher([a,b,c|X], X) :- X = [].
matcher([a,b,c|X], X).");
assert_prolog_success!(&mut wam, "?- partial_string(\"abc\", X), matcher(X, Y).",
[["X = [a, b, c]", "Y = []"],
["X = [a, b, c | _]", "Y = _"]]);
}