Files
scryer-prolog/src/indexing.rs

367 lines
12 KiB
Rust

use crate::prolog_parser::ast::*;
use crate::prolog_parser::tabled_rc::*;
use crate::instructions::*;
use crate::rug::Integer;
use crate::indexmap::IndexMap;
use std::collections::VecDeque;
use std::convert::TryFrom;
use std::hash::Hash;
use std::rc::Rc;
#[derive(Debug, Clone, Copy)]
enum IntIndex {
External(usize),
Fail,
Internal(usize),
}
#[derive(Debug)]
pub struct CodeOffsets {
atom_tbl: TabledData<Atom>,
pub constants: IndexMap<Constant, ThirdLevelIndex>,
pub lists: ThirdLevelIndex,
pub structures: IndexMap<(ClauseName, usize), ThirdLevelIndex>,
}
impl CodeOffsets {
pub fn new() -> Self {
CodeOffsets {
atom_tbl: TabledData::new(Rc::new("_index".to_string())),
constants: IndexMap::new(),
lists: Vec::new(),
structures: IndexMap::new(),
}
}
fn cap_choice_seq_with_trust(prelude: &mut ThirdLevelIndex) {
prelude.last_mut().map(|instr| {
match instr {
&mut IndexedChoiceInstruction::Retry(i) => {
*instr = IndexedChoiceInstruction::Trust(i)
}
_ => {}
};
});
}
fn add_index(is_first_index: bool, index: usize) -> IndexedChoiceInstruction {
if is_first_index {
IndexedChoiceInstruction::Try(index)
} else {
IndexedChoiceInstruction::Retry(index)
}
}
fn intercept_overlapping_constant(&mut self, constant: &Constant, index: usize) {
match constant {
&Constant::Atom(ref name, ref op) if name.is_char() => {
let c = name.as_str().chars().next().unwrap();
let code = self.constants
.entry(Constant::Char(c))
.or_insert(vec![]);
code.push(Self::add_index(code.is_empty(), index));
if op.is_some() {
let code = self.constants
.entry(Constant::Atom(name.clone(), None))
.or_insert(vec![]);
code.push(Self::add_index(false, index));
}
}
&Constant::Atom(ref name, Some(_)) => {
let code = self.constants
.entry(Constant::Atom(name.clone(), None))
.or_insert(vec![]);
code.push(Self::add_index(code.is_empty(), index));
}
&Constant::Char(c) => {
let atom = clause_name!(c.to_string(), self.atom_tbl.clone());
let code = self.constants
.entry(Constant::Atom(atom, None))
.or_insert(vec![]);
code.push(Self::add_index(code.is_empty(), index));
}
&Constant::Fixnum(n) => {
let code = self.constants
.entry(Constant::Integer(Rc::new(Integer::from(n))))
.or_insert(vec![]);
code.push(Self::add_index(code.is_empty(), index));
if n >= 0 {
if let Ok(n) = usize::try_from(n) {
let code = self.constants
.entry(Constant::Usize(n))
.or_insert(vec![]);
code.push(Self::add_index(code.is_empty(), index));
}
}
}
&Constant::Integer(ref n) => {
if let Some(n) = n.to_isize() {
let code = self.constants
.entry(Constant::Fixnum(n))
.or_insert(vec![]);
code.push(Self::add_index(code.is_empty(), index));
}
if let Some(n) = n.to_usize() {
let code = self.constants
.entry(Constant::Usize(n))
.or_insert(vec![]);
code.push(Self::add_index(code.is_empty(), index));
}
}
&Constant::Usize(n) => {
let code = self.constants
.entry(Constant::Integer(Rc::new(Integer::from(n))))
.or_insert(vec![]);
code.push(Self::add_index(code.is_empty(), index));
if let Ok(n) = isize::try_from(n) {
let code = self.constants
.entry(Constant::Fixnum(n))
.or_insert(vec![]);
code.push(Self::add_index(code.is_empty(), index));
}
}
_ => {
}
}
}
pub fn index_term(&mut self, first_arg: &Term, index: usize) {
match first_arg {
&Term::Clause(_, ref name, ref terms, _) => {
let code = self
.structures
.entry((name.clone(), terms.len()))
.or_insert(Vec::new());
let is_initial_index = code.is_empty();
code.push(Self::add_index(is_initial_index, index));
}
&Term::Cons(..) | &Term::Constant(_, Constant::String(_)) => {
let is_initial_index = self.lists.is_empty();
self.lists.push(Self::add_index(is_initial_index, index));
}
&Term::Constant(_, ref constant) => {
self.intercept_overlapping_constant(constant, index);
let code = self.constants
.entry(constant.clone())
.or_insert(vec![]);
let is_initial_index = code.is_empty();
code.push(Self::add_index(is_initial_index, index));
}
_ => {
}
};
}
fn second_level_index<Index>(
indices: IndexMap<Index, ThirdLevelIndex>,
prelude: &mut CodeDeque,
) -> IndexMap<Index, IntIndex>
where
Index: Eq + Hash,
{
let mut index_locs = IndexMap::new();
for (key, mut code) in indices.into_iter() {
if code.len() > 1 {
index_locs.insert(key, IntIndex::Internal(prelude.len()));
Self::cap_choice_seq_with_trust(&mut code);
prelude.extend(code.into_iter().map(|code| Line::from(code)));
} else {
code.first().map(|i| {
index_locs.insert(key, IntIndex::External(i.offset()));
});
}
}
index_locs
}
fn no_indices(&self) -> bool {
let no_constants = self.constants.is_empty();
let no_structures = self.structures.is_empty();
let no_lists = self.lists.is_empty();
no_constants && no_structures && no_lists
}
fn flatten_index<Index>(index: IndexMap<Index, IntIndex>, len: usize) -> IndexMap<Index, usize>
where
Index: Eq + Hash,
{
let mut flattened_index = IndexMap::new();
for (key, int_index) in index.into_iter() {
match int_index {
IntIndex::External(offset) => {
flattened_index.insert(key, offset + len + 1);
}
IntIndex::Internal(offset) => {
flattened_index.insert(key, offset + 1);
}
_ => {}
};
}
flattened_index
}
fn adjust_internal_index(index: IntIndex) -> IntIndex {
match index {
IntIndex::Internal(o) => IntIndex::Internal(o + 1),
IntIndex::External(o) => IntIndex::External(o),
_ => IntIndex::Fail,
}
}
fn switch_on_constant(
con_ind: IndexMap<Constant, ThirdLevelIndex>,
prelude: &mut CodeDeque,
) -> IntIndex {
let con_ind = Self::second_level_index(con_ind, prelude);
if con_ind.len() > 1 {
let index = Self::flatten_index(con_ind, prelude.len());
let instr = IndexingInstruction::SwitchOnConstant(index.len(), index);
prelude.push_front(Line::from(instr));
IntIndex::Internal(1)
} else {
con_ind
.values()
.next()
.map(|index| Self::adjust_internal_index(*index))
.unwrap_or(IntIndex::Fail)
}
}
fn switch_on_structure(
str_ind: IndexMap<(ClauseName, usize), ThirdLevelIndex>,
prelude: &mut CodeDeque,
) -> IntIndex {
let str_ind = Self::second_level_index(str_ind, prelude);
if str_ind.len() > 1 {
let index = Self::flatten_index(str_ind, prelude.len());
let instr = IndexingInstruction::SwitchOnStructure(index.len(), index);
prelude.push_front(Line::from(instr));
IntIndex::Internal(1)
} else {
str_ind
.values()
.next()
.map(|index| Self::adjust_internal_index(*index))
.unwrap_or(IntIndex::Fail)
}
}
fn switch_on_list(mut lists: ThirdLevelIndex, prelude: &mut CodeDeque) -> IntIndex {
if lists.len() > 1 {
Self::cap_choice_seq_with_trust(&mut lists);
prelude.extend(lists.into_iter().map(|i| Line::from(i)));
IntIndex::Internal(0)
} else {
lists
.first()
.map(|i| IntIndex::External(i.offset()))
.unwrap_or(IntIndex::Fail)
}
}
fn switch_on_str_offset_from(
str_loc: IntIndex,
prelude_len: usize,
con_loc: IntIndex,
) -> usize {
match str_loc {
IntIndex::External(o) => o + prelude_len + 1,
IntIndex::Fail => 0,
IntIndex::Internal(_) => match con_loc {
IntIndex::Internal(_) => 2,
_ => 1,
},
}
}
fn switch_on_con_offset_from(con_loc: IntIndex, prelude_len: usize) -> usize {
match con_loc {
IntIndex::External(offset) => offset + prelude_len + 1,
IntIndex::Fail => 0,
IntIndex::Internal(offset) => offset,
}
}
fn switch_on_lst_offset_from(
lst_loc: IntIndex,
prelude_len: usize,
) -> usize {
match lst_loc {
IntIndex::External(o) => o + prelude_len + 1,
IntIndex::Fail => 0,
IntIndex::Internal(_) => 1, // this internal is always 0.
}
}
pub fn add_indices(self, code: &mut Code, mut code_body: Code) {
if self.no_indices() {
*code = code_body;
return;
}
let mut prelude = VecDeque::new();
let lst_loc = Self::switch_on_list(self.lists, &mut prelude);
let str_loc = Self::switch_on_structure(self.structures, &mut prelude);
let con_loc = Self::switch_on_constant(self.constants, &mut prelude);
let prelude_length = prelude.len();
for (index, line) in prelude.iter_mut().enumerate() {
match line {
&mut Line::IndexedChoice(IndexedChoiceInstruction::Try(ref mut i)) |
&mut Line::IndexedChoice(IndexedChoiceInstruction::Retry(ref mut i)) |
&mut Line::IndexedChoice(IndexedChoiceInstruction::Trust(ref mut i)) => {
*i += prelude_length - index;
}
_ => {
}
}
}
let str_loc = Self::switch_on_str_offset_from(str_loc, prelude.len(), con_loc);
let con_loc = Self::switch_on_con_offset_from(con_loc, prelude.len());
let lst_loc = Self::switch_on_lst_offset_from(lst_loc, prelude.len());
let switch_instr =
IndexingInstruction::SwitchOnTerm(prelude.len() + 1, con_loc, lst_loc, str_loc);
prelude.push_front(Line::from(switch_instr));
*code = Vec::from(prelude);
code.append(&mut code_body);
}
}