Files
scryer-prolog/src/prolog/machine/heap.rs

144 lines
3.8 KiB
Rust

use prolog_parser::ast::*;
use crate::prolog::machine::machine_indices::*;
use std::mem;
use std::ops::{Index, IndexMut};
pub struct Heap {
heap: Vec<HeapCellValue>,
pub h: usize,
}
impl Heap {
pub fn with_capacity(cap: usize) -> Self {
Heap {
heap: Vec::with_capacity(cap),
h: 0,
}
}
#[inline]
pub fn push(&mut self, val: HeapCellValue) {
self.heap.push(val);
self.h += 1;
}
#[inline]
pub(crate) fn take(&mut self) -> Self {
let h = self.h;
self.h = 0;
Heap {
heap: mem::replace(&mut self.heap, vec![]),
h,
}
}
#[inline]
pub fn truncate(&mut self, h: usize) {
self.h = h;
self.heap.truncate(h);
}
#[inline]
pub fn last(&self) -> Option<&HeapCellValue> {
self.heap.last()
}
#[inline]
pub fn len(&self) -> usize {
self.heap.len()
}
pub fn append(&mut self, vals: Vec<HeapCellValue>) {
let n = vals.len();
self.heap.extend(vals.into_iter());
self.h += n;
}
pub fn clear(&mut self) {
self.heap.clear();
self.h = 0;
}
pub fn to_list<Iter: Iterator<Item = Addr>>(&mut self, values: Iter) -> usize {
let head_addr = self.h;
for value in values {
let h = self.h;
self.push(HeapCellValue::Addr(Addr::Lis(h + 1)));
self.push(HeapCellValue::Addr(value));
}
self.push(HeapCellValue::Addr(Addr::Con(Constant::EmptyList)));
head_addr
}
pub fn extend<Iter: Iterator<Item = HeapCellValue>>(&mut self, iter: Iter) {
for hcv in iter {
self.push(hcv);
}
}
pub fn to_local_code_ptr(&self, addr: &Addr) -> Option<LocalCodePtr> {
let extract_integer = |s: usize| -> Option<usize> {
match self.heap[s].as_addr(s) {
Addr::Con(Constant::Integer(n)) => n.to_usize(),
_ => None
}
};
match addr {
Addr::Str(s) => {
match &self.heap[*s] {
HeapCellValue::NamedStr(arity, ref name, _) => {
match (name.as_str(), *arity) {
("dir_entry", 1) => {
extract_integer(s+1).map(LocalCodePtr::DirEntry)
}
("in_situ_dir_entry", 1) => {
extract_integer(s+1).map(LocalCodePtr::InSituDirEntry)
}
("top_level", 2) => {
if let Some(chunk_num) = extract_integer(s+1) {
if let Some(p) = extract_integer(s+2) {
return Some(LocalCodePtr::TopLevel(chunk_num, p));
}
}
None
}
("user_goal_expansion", 1) => {
extract_integer(s+1).map(LocalCodePtr::UserGoalExpansion)
}
("user_term_expansion", 1) => {
extract_integer(s+1).map(LocalCodePtr::UserTermExpansion)
}
_ => None
}
}
_ => unreachable!()
}
}
_ => None
}
}
}
impl Index<usize> for Heap {
type Output = HeapCellValue;
fn index(&self, index: usize) -> &Self::Output {
&self.heap[index]
}
}
impl IndexMut<usize> for Heap {
fn index_mut(&mut self, index: usize) -> &mut Self::Output {
&mut self.heap[index]
}
}