Files
scryer-prolog/src/machine/lib_machine.rs
2024-12-08 20:18:06 -03:00

837 lines
26 KiB
Rust

use std::collections::BTreeMap;
use crate::machine::machine_indices::VarKey;
use crate::machine::mock_wam::CompositeOpDir;
use crate::machine::{BREAK_FROM_DISPATCH_LOOP_LOC, LIB_QUERY_SUCCESS};
use crate::parser::ast::{Var, VarPtr};
use crate::parser::parser::{Parser, Tokens};
use crate::read::{write_term_to_heap, TermWriteResult};
use crate::{atom_table, StreamConfig};
use indexmap::IndexMap;
use super::{
streams::Stream, Atom, AtomCell, HeapCellValue, HeapCellValueTag, LeafAnswer, Machine,
MachineConfig, PrologTerm,
};
/// An iterator though the leaf answers of a query.
pub struct QueryState<'a> {
machine: &'a mut Machine,
term: TermWriteResult,
stub_b: usize,
var_names: IndexMap<HeapCellValue, VarPtr>,
called: bool,
}
impl Drop for QueryState<'_> {
fn drop(&mut self) {
// This may be wrong if the iterator is not fully consumend, but from testing it seems
// fine.
self.machine.trust_me();
}
}
impl Iterator for QueryState<'_> {
type Item = Result<LeafAnswer, String>;
fn next(&mut self) -> Option<Self::Item> {
let var_names = &mut self.var_names;
let term_write_result = &self.term;
let machine = &mut self.machine;
// No more choicepoints, end iteration
if self.called && machine.machine_st.b <= self.stub_b {
return None;
}
machine.dispatch_loop();
self.called = true;
if !machine.machine_st.ball.stub.is_empty() {
// NOTE: this means an exception was thrown, at which
// point we backtracked to the stub choice point.
// this should halt the search for solutions as it
// does in the Scryer top-level. the exception term is
// contained in self.machine_st.ball.
let error_string = self
.machine
.machine_st
.ball
.stub
.iter()
.filter(|h| {
matches!(
h.get_tag(),
HeapCellValueTag::Atom | HeapCellValueTag::Fixnum
)
})
.map(|h| match h.get_tag() {
HeapCellValueTag::Atom => {
let (name, _) = cell_as_atom_cell!(h).get_name_and_arity();
name.as_str().to_string()
}
HeapCellValueTag::Fixnum => h.get_value().clone().to_string(),
_ => unreachable!(),
})
.collect::<Vec<String>>()
.join(" ");
return Some(Err(error_string));
}
if machine.machine_st.p == LIB_QUERY_SUCCESS {
if term_write_result.var_dict.is_empty() {
self.machine.machine_st.backtrack();
return Some(Ok(LeafAnswer::True));
}
} else if machine.machine_st.p == BREAK_FROM_DISPATCH_LOOP_LOC {
return Some(Ok(LeafAnswer::False));
}
let mut bindings: BTreeMap<String, PrologTerm> = BTreeMap::new();
let var_dict = &term_write_result.var_dict;
for (var_key, term_to_be_printed) in var_dict.iter() {
let mut var_name = var_key.to_string();
if var_name.starts_with('_') {
let should_print = var_names.values().any(|x| match x.borrow().clone() {
Var::Named(v) => v == var_name,
_ => false,
});
if !should_print {
continue;
}
}
let mut term =
PrologTerm::from_heapcell(machine, *term_to_be_printed, &mut var_names.clone());
if let PrologTerm::Var(ref term_str) = term {
if *term_str == var_name {
continue;
}
// Var dict is in the order things appear in the query. If var_name appears
// after term in the query, switch their places.
let var_name_idx = var_dict
.get_index_of(&VarKey::VarPtr(Var::Named(var_name.clone()).into()))
.unwrap();
let term_idx =
var_dict.get_index_of(&VarKey::VarPtr(Var::Named(term_str.clone()).into()));
if let Some(idx) = term_idx {
if idx < var_name_idx {
let new_term = PrologTerm::Var(var_name);
let new_var_name = term_str.into();
term = new_term;
var_name = new_var_name;
}
}
}
bindings.insert(var_name, term);
}
// NOTE: there are outstanding choicepoints, backtrack
// through them for further solutions. if
// self.machine_st.b == stub_b we've backtracked to the stub
// choice point, so we should break.
self.machine.machine_st.backtrack();
Some(Ok(LeafAnswer::LeafAnswer {
bindings: bindings,
residual_goals: vec![],
}))
}
}
impl Machine {
/// Creates a new [`Machine`] configured for use as a library.
pub fn new_lib() -> Self {
Machine::new(MachineConfig::default().with_streams(StreamConfig::in_memory()))
}
/// Loads a module into the [`Machine`] from a string.
pub fn load_module_string(&mut self, module_name: &str, program: impl Into<String>) {
let stream = Stream::from_owned_string(program.into(), &mut self.machine_st.arena);
self.load_file(module_name, stream);
}
/// Consults a module into the [`Machine`] from a string.
pub fn consult_module_string(&mut self, module_name: &str, program: impl Into<String>) {
let stream = Stream::from_owned_string(program.into(), &mut self.machine_st.arena);
self.machine_st.registers[1] = stream_as_cell!(stream);
self.machine_st.registers[2] = atom_as_cell!(&atom_table::AtomTable::build_with(
&self.machine_st.atom_tbl,
module_name
));
self.run_module_predicate(atom!("loader"), (atom!("consult_stream"), 2));
}
fn allocate_stub_choice_point(&mut self) {
// NOTE: create a choice point to terminate the dispatch_loop
// if an exception is thrown.
let stub_b = self.machine_st.stack.allocate_or_frame(0);
let or_frame = self.machine_st.stack.index_or_frame_mut(stub_b);
or_frame.prelude.num_cells = 0;
or_frame.prelude.e = 0;
or_frame.prelude.cp = 0;
or_frame.prelude.b = 0;
or_frame.prelude.bp = BREAK_FROM_DISPATCH_LOOP_LOC;
or_frame.prelude.boip = 0;
or_frame.prelude.biip = 0;
or_frame.prelude.tr = 0;
or_frame.prelude.h = 0;
or_frame.prelude.b0 = 0;
or_frame.prelude.attr_var_queue_len = 0;
self.machine_st.b = stub_b;
self.machine_st.hb = self.machine_st.heap.len();
self.machine_st.block = stub_b;
}
/// Runs a query.
pub fn run_query(&mut self, query: impl Into<String>) -> QueryState {
let mut parser = Parser::new(
Stream::from_owned_string(query.into(), &mut self.machine_st.arena),
&mut self.machine_st,
);
let op_dir = CompositeOpDir::new(&self.indices.op_dir, None);
let term = parser
.read_term(&op_dir, Tokens::Default)
.expect("Failed to parse query");
self.allocate_stub_choice_point();
// Write parsed term to heap
let term_write_result =
write_term_to_heap(&term, &mut self.machine_st.heap, &self.machine_st.atom_tbl)
.expect("couldn't write term to heap");
let var_names: IndexMap<_, _> = term_write_result
.var_dict
.iter()
.map(|(var_key, cell)| match var_key {
// NOTE: not the intention behind Var::InSitu here but
// we can hijack it to store anonymous variables
// without creating problems.
VarKey::AnonVar(h) => (*cell, VarPtr::from(Var::InSitu(*h))),
VarKey::VarPtr(var_ptr) => (*cell, var_ptr.clone()),
})
.collect();
// Write term to heap
self.machine_st.registers[1] = self.machine_st.heap[term_write_result.heap_loc];
self.machine_st.cp = LIB_QUERY_SUCCESS; // BREAK_FROM_DISPATCH_LOOP_LOC;
let call_index_p = self
.indices
.code_dir
.get(&(atom!("call"), 1))
.expect("couldn't get code index")
.local()
.unwrap();
self.machine_st.execute_at_index(1, call_index_p);
let stub_b = self.machine_st.b;
QueryState {
machine: self,
term: term_write_result,
stub_b,
var_names,
called: false,
}
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::machine::{QueryMatch, QueryResolution, Term};
#[test]
#[cfg_attr(miri, ignore = "it takes too long to run")]
fn programatic_query() {
let mut machine = Machine::new_lib();
machine.load_module_string(
"facts",
String::from(
r#"
triple("a", "p1", "b").
triple("a", "p2", "b").
"#,
),
);
let query = String::from(r#"triple("a",P,"b")."#);
let output = machine.run_query(query);
assert_eq!(
output,
Ok(QueryResolution::Matches(vec![
QueryMatch::from(btreemap! {
"P" => Term::from("p1"),
}),
QueryMatch::from(btreemap! {
"P" => Term::from("p2"),
}),
]))
);
assert_eq!(
machine.run_query(String::from(r#"triple("a","p1","b")."#)),
Ok(QueryResolution::True)
);
assert_eq!(
machine.run_query(String::from(r#"triple("x","y","z")."#)),
Ok(QueryResolution::False)
);
}
#[test]
#[cfg_attr(miri, ignore = "it takes too long to run")]
fn failing_query() {
let mut machine = Machine::new_lib();
let query = String::from(r#"triple("a",P,"b")."#);
let output = machine.run_query(query);
assert_eq!(
output,
Err(String::from(
"error existence_error procedure / triple 3 / triple 3"
))
);
}
#[test]
#[cfg_attr(miri, ignore = "it takes too long to run")]
fn complex_results() {
let mut machine = Machine::new_lib();
machine.load_module_string(
"facts",
r#"
:- discontiguous(subject_class/2).
:- discontiguous(constructor/2).
subject_class("Todo", c).
constructor(c, '[{action: "addLink", source: "this", predicate: "todo://state", target: "todo://ready"}]').
subject_class("Recipe", xyz).
constructor(xyz, '[{action: "addLink", source: "this", predicate: "recipe://title", target: "literal://string:Meta%20Muffins"}]').
"#.to_string());
let result = machine.run_query(String::from(
"subject_class(\"Todo\", C), constructor(C, Actions).",
));
assert_eq!(
result,
Ok(QueryResolution::Matches(vec![QueryMatch::from(
btreemap! {
"C" => Term::Atom("c".into()),
"Actions" => Term::Atom("[{action: \"addLink\", source: \"this\", predicate: \"todo://state\", target: \"todo://ready\"}]".into()),
}
),]))
);
let result = machine.run_query(String::from(
"subject_class(\"Recipe\", C), constructor(C, Actions).",
));
assert_eq!(
result,
Ok(QueryResolution::Matches(vec![QueryMatch::from(
btreemap! {
"C" => Term::Atom("xyz".into()),
"Actions" => Term::Atom("[{action: \"addLink\", source: \"this\", predicate: \"recipe://title\", target: \"literal://string:Meta%20Muffins\"}]".into()),
}
),]))
);
let result = machine.run_query(String::from("subject_class(Class, _)."));
assert_eq!(
result,
Ok(QueryResolution::Matches(vec![
QueryMatch::from(btreemap! {
"Class" => Term::String("Todo".into())
}),
QueryMatch::from(btreemap! {
"Class" => Term::String("Recipe".into())
}),
]))
);
}
#[test]
#[cfg_attr(miri, ignore = "it takes too long to run")]
fn empty_predicate() {
let mut machine = Machine::new_lib();
machine.load_module_string(
"facts",
r#"
:- discontiguous(subject_class/2).
"#
.to_string(),
);
let result = machine.run_query(String::from("subject_class(X, _)."));
assert_eq!(result, Ok(QueryResolution::False));
}
#[test]
#[cfg_attr(miri, ignore = "it takes too long to run")]
fn list_results() {
let mut machine = Machine::new_lib();
machine.load_module_string(
"facts",
r#"
list([1,2,3]).
"#
.to_string(),
);
let result = machine.run_query(String::from("list(X)."));
assert_eq!(
result,
Ok(QueryResolution::Matches(vec![QueryMatch::from(
btreemap! {
"X" => Term::List(vec![
Term::Integer(1.into()),
Term::Integer(2.into()),
Term::Integer(3.into()),
]),
}
),]))
);
}
#[test]
#[cfg_attr(miri, ignore = "it takes too long to run")]
fn consult() {
let mut machine = Machine::new_lib();
machine.consult_module_string(
"facts",
String::from(
r#"
triple("a", "p1", "b").
triple("a", "p2", "b").
"#,
),
);
let query = String::from(r#"triple("a",P,"b")."#);
let output = machine.run_query(query);
assert_eq!(
output,
Ok(QueryResolution::Matches(vec![
QueryMatch::from(btreemap! {
"P" => Term::from("p1"),
}),
QueryMatch::from(btreemap! {
"P" => Term::from("p2"),
}),
]))
);
assert_eq!(
machine.run_query(String::from(r#"triple("a","p1","b")."#)),
Ok(QueryResolution::True)
);
assert_eq!(
machine.run_query(String::from(r#"triple("x","y","z")."#)),
Ok(QueryResolution::False)
);
machine.consult_module_string(
"facts",
String::from(
r#"
triple("a", "new", "b").
"#,
),
);
assert_eq!(
machine.run_query(String::from(r#"triple("a","p1","b")."#)),
Ok(QueryResolution::False)
);
assert_eq!(
machine.run_query(String::from(r#"triple("a","new","b")."#)),
Ok(QueryResolution::True)
);
}
#[test]
#[cfg_attr(miri, ignore = "it takes too long to run")]
#[ignore = "uses old flawed interface"]
fn integration_test() {
let mut machine = Machine::new_lib();
// File with test commands, i.e. program code to consult and queries to run
let code = include_str!("./lib_integration_test_commands.txt");
// Split the code into blocks
let blocks = code.split("=====");
let mut i = 0;
let mut last_result: Option<_> = None;
// Iterate over the blocks
for block in blocks {
// Trim the block to remove any leading or trailing whitespace
let block = block.trim();
// Skip empty blocks
if block.is_empty() {
continue;
}
// Check if the block is a query
if let Some(query) = block.strip_prefix("query") {
// Parse and execute the query
let result = machine.run_query(query.to_string());
assert!(result.is_ok());
last_result = Some(result);
} else if let Some(code) = block.strip_prefix("consult") {
// Load the code into the machine
machine.consult_module_string("facts", code.to_string());
} else if let Some(result) = block.strip_prefix("result") {
i += 1;
if let Some(Ok(ref last_result)) = last_result {
println!("\n\n=====Result No. {i}=======\n{last_result}\n===============");
assert_eq!(last_result.to_string(), result.to_string().trim(),)
}
}
}
}
#[test]
#[cfg_attr(miri, ignore = "it takes too long to run")]
fn findall() {
let mut machine = Machine::new_lib();
machine.consult_module_string(
"facts",
String::from(
r#"
triple("a", "p1", "b").
triple("a", "p2", "b").
"#,
),
);
let query =
String::from(r#"findall([Predicate, Target], triple(_,Predicate,Target), Result)."#);
let output = machine.run_query(query);
assert_eq!(
output,
Ok(QueryResolution::Matches(vec![QueryMatch::from(
btreemap! {
"Result" => Term::List(
Vec::from([
Term::List([Term::from("p1"), Term::from("b")].into()),
Term::List([Term::from("p2"), Term::from("b")].into()),
])
),
}
),]))
);
}
#[test]
#[cfg_attr(miri, ignore = "it takes too long to run")]
fn dont_return_partial_matches() {
let mut machine = Machine::new_lib();
machine.consult_module_string(
"facts",
String::from(
r#"
:- discontiguous(property_resolve/2).
subject_class("Todo", c).
"#,
),
);
let query = String::from(r#"property_resolve(C, "isLiked"), subject_class("Todo", C)."#);
let output = machine.run_query(query);
assert_eq!(output, Ok(QueryResolution::False));
let query = String::from(r#"subject_class("Todo", C), property_resolve(C, "isLiked")."#);
let output = machine.run_query(query);
assert_eq!(output, Ok(QueryResolution::False));
}
#[test]
#[cfg_attr(miri, ignore = "it takes too long to run")]
fn dont_return_partial_matches_without_discountiguous() {
let mut machine = Machine::new_lib();
machine.consult_module_string(
"facts",
String::from(
r#"
a("true for a").
b("true for b").
"#,
),
);
let query = String::from(r#"a("true for a")."#);
let output = machine.run_query(query);
assert_eq!(output, Ok(QueryResolution::True));
let query = String::from(r#"a("true for a"), b("true for b")."#);
let output = machine.run_query(query);
assert_eq!(output, Ok(QueryResolution::True));
let query = String::from(r#"a("true for b"), b("true for b")."#);
let output = machine.run_query(query);
assert_eq!(output, Ok(QueryResolution::False));
let query = String::from(r#"a("true for a"), b("true for a")."#);
let output = machine.run_query(query);
assert_eq!(output, Ok(QueryResolution::False));
}
#[test]
#[cfg_attr(miri, ignore = "it takes too long to run")]
fn non_existent_predicate_should_not_cause_panic_when_other_predicates_are_defined() {
let mut machine = Machine::new_lib();
machine.consult_module_string(
"facts",
String::from(
r#"
triple("a", "p1", "b").
triple("a", "p2", "b").
"#,
),
);
let query = String::from("non_existent_predicate(\"a\",\"p1\",\"b\").");
let result = machine.run_query(query);
assert_eq!(
result,
Err(String::from("error existence_error procedure / non_existent_predicate 3 / non_existent_predicate 3"))
);
}
#[test]
#[cfg_attr(miri, ignore)]
fn atom_quoting() {
let mut machine = Machine::new_lib();
let query = "X = '.'.".into();
let result = machine.run_query(query);
assert_eq!(
result,
Ok(QueryResolution::Matches(vec![QueryMatch::from(
btreemap! {
"X" => Term::Atom(".".into()),
}
)]))
);
}
#[test]
#[cfg_attr(miri, ignore)]
fn rational_number() {
use crate::parser::dashu::rational::RBig;
let mut machine = Machine::new_lib();
let query = "X is 1 rdiv 2.".into();
let result = machine.run_query(query);
assert_eq!(
result,
Ok(QueryResolution::Matches(vec![QueryMatch::from(
btreemap! {
"X" => Term::Rational(RBig::from_parts(1.into(), 2u32.into())),
}
)]))
);
}
#[test]
#[cfg_attr(miri, ignore)]
fn big_integer() {
use crate::parser::dashu::integer::IBig;
let mut machine = Machine::new_lib();
let query = "X is 10^100.".into();
let result = machine.run_query(query);
assert_eq!(
result,
Ok(QueryResolution::Matches(vec![QueryMatch::from(
btreemap! {
"X" => Term::Integer(IBig::from(10).pow(100)),
}
)]))
);
}
#[test]
#[cfg_attr(miri, ignore)]
fn complicated_term() {
let mut machine = Machine::new_lib();
let query = "X = a(\"asdf\", [42, 2.54, asdf, a, [a,b|_], Z]).".into();
let result = machine.run_query(query);
let expected = Term::Structure(
// Composite term
"a".into(),
vec![
Term::String("asdf".into()), // String
Term::List(vec![
Term::Integer(42.into()), // Fixnum
Term::Float(2.54.into()), // Float
Term::Atom("asdf".into()), // Atom
Term::Atom("a".into()), // Char
Term::Structure(
// Partial string
".".into(),
vec![
Term::Atom("a".into()),
Term::Structure(
".".into(),
vec![
Term::Atom("b".into()),
Term::Var("_A".into()), // Anonymous variable
],
),
],
),
Term::Var("Z".into()), // Named variable
]),
],
);
assert_eq!(
result,
Ok(QueryResolution::Matches(vec![QueryMatch::from(
btreemap! {
"X" => expected,
}
)]))
);
}
#[test]
#[cfg_attr(miri, ignore = "it takes too long to run")]
fn issue_2341() {
let mut machine = Machine::new_lib();
machine.load_module_string(
"facts",
String::from(
r#"
male(stephen).
parent(albert,edward).
father(F,C):-parent(F,C),male(F).
"#,
),
);
let query = String::from(r#"father(F,C)."#);
let output = machine.run_query(query);
assert_eq!(output, Ok(QueryResolution::False));
}
#[test]
#[cfg_attr(miri, ignore)]
fn query_iterator_determinism() {
let mut machine = Machine::new_lib();
{
let mut iterator = machine.run_query_iter("X = 1.".into());
iterator.next();
assert_eq!(iterator.next(), None);
}
{
let mut iterator = machine.run_query_iter("X = 1 ; false.".into());
iterator.next();
assert_eq!(iterator.next(), Some(Ok(LeafAnswer::False)));
assert_eq!(iterator.next(), None);
}
{
let mut iterator = machine.run_query_iter("false.".into());
assert_eq!(iterator.next(), Some(Ok(LeafAnswer::False)));
assert_eq!(iterator.next(), None);
}
}
#[test]
#[cfg_attr(miri, ignore)]
fn query_iterator_backtracking_when_no_variables() {
let mut machine = Machine::new_lib();
let mut iterator = machine.run_query_iter("true;false.".into());
assert_eq!(iterator.next(), Some(Ok(LeafAnswer::True)));
assert_eq!(iterator.next(), Some(Ok(LeafAnswer::False)));
assert_eq!(iterator.next(), None);
}
#[test]
#[cfg_attr(miri, ignore)]
fn differentiate_anonymous_variables() {
let mut machine = Machine::new_lib();
let result = machine.run_query("A = [_,_], _B = 1 ; B = [_,_].".into());
assert_eq!(
result,
Ok(QueryResolution::Matches(vec![
QueryMatch::from(btreemap! {
"A" => Term::List(vec![Term::Var("_A".into()), Term::Var("_C".into())]),
"_B" => Term::Integer(1.into()),
}),
QueryMatch::from(btreemap! {
"B" => Term::List(vec![Term::Var("_A".into()), Term::Var("_C".into())]),
}),
]))
);
}
#[test]
#[cfg_attr(miri, ignore)]
fn order_of_variables_in_binding() {
let mut machine = Machine::new_lib();
let result = machine.run_query("X = Y, Z = W.".into());
assert_eq!(
result,
Ok(QueryResolution::Matches(vec![QueryMatch::from(
btreemap! {
"X" => Term::Var("Y".into()),
"Z" => Term::Var("W".into()),
}
),]))
);
}
}