use std::fmt::Debug;
use proc_macro2::{Punct, Spacing, TokenStream};
use quote::{quote, ToTokens, TokenStreamExt};
use crate::{
quote_option,
sets::{IndexableMap, USizeSet},
};
const ERR_INVALID_PA_ID: &'static str = "Parse actions must have kind 0 / 1 / 2 / 3";
pub const PA_ID_SHIFT: usize = 0;
pub const PA_ID_GOTO: usize = 1;
pub const PA_ID_REDUCE: usize = 2;
pub const PA_ID_INVALID: usize = 3;
type SeedRule = (usize, usize, usize);
#[derive(Clone, Copy)]
pub enum ParseAction {
Shift(usize),
Goto(usize),
Reduce(usize),
Invalid,
}
impl Debug for ParseAction {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
match &self {
ParseAction::Shift(state) => write!(f, "Shift({state})"),
ParseAction::Goto(state) => write!(f, "Goto({state})"),
ParseAction::Reduce(prod) => write!(f, "Reduce({prod})"),
ParseAction::Invalid => write!(f, "Invalid"),
}
}
}
impl ToTokens for ParseAction {
fn to_tokens(&self, tokens: &mut TokenStream) {
let (pa_kind, pa_val) = match self {
ParseAction::Shift(state) => (PA_ID_SHIFT, *state),
ParseAction::Goto(state) => (PA_ID_GOTO, *state),
ParseAction::Reduce(rule) => (PA_ID_REDUCE, *rule),
ParseAction::Invalid => (PA_ID_INVALID, 0),
};
tokens.append_all(quote! { (#pa_kind, #pa_val) });
}
}
#[derive(Debug)]
pub struct ParseTable {
pub actions: Vec<Vec<ParseAction>>,
pub errors: Vec<Option<(usize, usize)>>,
pub reductions: Vec<Vec<bool>>,
pub rule_lens: Vec<(usize, usize)>,
}
pub enum Conflict {
RR(usize, usize, usize),
SR(usize, usize, usize),
}
impl ParseTable {
pub fn from_raw(
actions_raw: Vec<Vec<(usize, usize)>>,
rule_lens: Vec<(usize, usize)>,
errors: Vec<Option<(usize, usize)>>,
reductions: Vec<Vec<bool>>,
) -> Result<Self, &'static str> {
let mut actions = vec![vec![ParseAction::Invalid; actions_raw[0].len()]; actions_raw.len()];
for (i, state_actions) in actions_raw.into_iter().enumerate() {
for (j, (action_type, value)) in state_actions.into_iter().enumerate() {
actions[i][j] = match action_type {
PA_ID_SHIFT => ParseAction::Shift(value),
PA_ID_GOTO => ParseAction::Goto(value),
PA_ID_REDUCE => ParseAction::Reduce(value),
PA_ID_INVALID => ParseAction::Invalid,
_ => return Err(ERR_INVALID_PA_ID),
};
}
}
Ok(Self {
actions,
rule_lens,
errors,
reductions,
})
}
pub fn from_rules(
rules: Vec<Vec<Vec<usize>>>,
error_callbacks: Vec<Option<usize>>,
) -> Result<Self, Vec<Conflict>> {
let dfa = ParseDFA::from_rules(rules);
let mut conflicts = vec![];
#[cfg(not(feature = "lr1"))]
let (state_ids, max_id) = {
let mut found_seeds = std::collections::BTreeMap::<&Vec<SeedRule>, usize>::new();
let mut state_ids = vec![usize::MAX; dfa.states.len()];
for (i, (state, _)) in dfa.states.iter().enumerate() {
state_ids[i] = found_seeds.get(&state.0).map(|i| *i).unwrap_or_else(|| {
found_seeds.insert(&state.0, found_seeds.len());
found_seeds.len() - 1
});
}
(state_ids, found_seeds.len())
};
#[cfg(feature = "lr1")]
let (state_ids, max_id) = ((0..dfa.states.len()).collect::<Vec<_>>(), dfa.states.len());
let mut actions = vec![vec![ParseAction::Invalid; dfa.rules.len()]; max_id];
let mut production_ids = vec![];
let mut rule_lens = vec![];
let mut i = 0;
for (prod, prod_rules) in dfa.rules.iter().enumerate() {
production_ids.push(vec![]);
for rule in prod_rules.iter() {
production_ids.last_mut().unwrap().push(i);
rule_lens.push((rule.len(), prod));
i += 1;
}
}
let mut errors = vec![None; actions.len()];
let mut reductions = vec![vec![false; dfa.rules.len()]; dfa.rules.len()];
for (i, (state, trans)) in dfa.states.iter().enumerate() {
let (seeds, lookaheads) = &**state;
let id = state_ids[i];
for (seed, lookahead) in seeds.into_iter().zip(lookaheads.into_iter()) {
for (item, next) in trans
.iter()
.enumerate()
.filter_map(|(i, tran)| tran.map(move |tran| (i, tran)))
{
if matches!(actions[id][item], ParseAction::Reduce(_)) {
conflicts.push(Conflict::SR(seed.0, seed.1, item));
}
actions[id][item] = if dfa.rules[item].len() == 0 {
ParseAction::Shift(state_ids[next])
} else {
if let Some(error) = error_callbacks[item] {
errors[state_ids[next]] = Some((error, item));
}
ParseAction::Goto(state_ids[next])
};
}
if seed.2 == dfa.rules[seed.0][seed.1].len() {
for item in lookahead.iter() {
let production = production_ids[seed.0][seed.1];
if let ParseAction::Reduce(old_prod) = actions[id][item]
&& old_prod != production
{
conflicts.push(Conflict::RR(seed.0, seed.1, item));
}
reductions[seed.0][item] = true;
actions[id][item] = ParseAction::Reduce(production);
}
}
}
}
conflicts
.is_empty()
.then_some(Self {
actions,
rule_lens,
reductions,
errors,
})
.ok_or(conflicts)
}
}
impl ToTokens for ParseTable {
fn to_tokens(&self, tokens: &mut proc_macro2::TokenStream) {
fn quote_2d<T: ToTokens>(a: &Vec<Vec<T>>) -> TokenStream {
let mut result_inner = TokenStream::new();
result_inner.append_separated(
a.iter().map(|v| {
let mut row_inner = TokenStream::new();
row_inner.append_separated(v.iter(), Punct::new(',', Spacing::Alone));
quote! { vec![#row_inner] }
}),
Punct::new(',', Spacing::Alone),
);
quote! { vec![#result_inner] }
}
fn quote_1d<T, F: Fn(&T) -> TokenStream>(v: &Vec<T>, f: F) -> TokenStream {
let mut result_inner = TokenStream::new();
result_inner.append_separated(v.iter().map(f), Punct::new(',', Spacing::Alone));
quote! { vec![#result_inner] }
}
let actions = quote_2d(&self.actions);
let reductions = quote_2d(&self.reductions);
let quote_pair = |(x, y): &(usize, usize)| quote! { (#x, #y) };
let rule_lens = quote_1d(&self.rule_lens, quote_pair);
let errors = quote_1d(&self.errors, |error| {
quote_option(&error.map(|e| quote_pair(&e)))
});
tokens.append_all(quote! { (#actions, #rule_lens, #errors, #reductions) });
}
}
#[derive(Debug)]
struct ParseDFA {
states: IndexableMap<(Vec<SeedRule>, Vec<USizeSet>), Vec<Option<usize>>>,
rules: Vec<Vec<Vec<usize>>>,
}
fn get_firsts(rules: &Vec<Vec<Vec<usize>>>) -> Vec<USizeSet> {
fn helper(
firsts: &mut Vec<USizeSet>,
vis: &mut Vec<bool>,
rules: &Vec<Vec<Vec<usize>>>,
cur: usize,
) {
vis[cur] = true;
if rules[cur].is_empty() {
firsts[cur].set(cur, true);
return;
}
for dep in rules[cur]
.iter()
.filter_map(|prod| prod.first().map(|x| *x))
.filter(|dep| *dep != cur)
{
if !vis[dep] {
helper(firsts, vis, rules, dep);
}
let [src, dst] = firsts.get_disjoint_mut([cur, dep]).unwrap();
*src |= dst;
}
}
let mut firsts: Vec<USizeSet> = vec![USizeSet::default(); rules.len()];
let mut vis = vec![false; rules.len()];
for node in 0..rules.len() {
if !vis[node] {
helper(&mut firsts, &mut vis, &rules, node);
}
}
firsts
}
fn get_derived_rules(rules: &Vec<Vec<Vec<usize>>>, start: usize) -> Vec<(usize, usize)> {
fn helper(
cur: usize,
result: &mut Vec<(usize, usize)>,
vis: &mut Vec<bool>,
rules: &Vec<Vec<Vec<usize>>>,
) {
vis[cur] = true;
for (i, rule) in rules[cur].iter().enumerate() {
result.push((cur, i));
if !vis[rule[0]] && !rules[rule[0]].is_empty() {
helper(rule[0], result, vis, rules);
}
}
}
let mut result = vec![];
let mut vis = vec![false; rules.len()];
helper(start, &mut result, &mut vis, &rules);
result
}
fn get_derived_lookaheads(
seed: SeedRule,
seed_lookahead: &USizeSet,
firsts: &Vec<USizeSet>,
rules: &Vec<Vec<Vec<usize>>>,
) -> Vec<Option<USizeSet>> {
fn helper(
cur: usize,
cur_lookahead: &USizeSet,
firsts: &Vec<USizeSet>,
result: &mut Vec<Option<USizeSet>>,
rules: &Vec<Vec<Vec<usize>>>,
) {
if let Some(ref mut cur_result) = result[cur] {
*cur_result |= cur_lookahead
} else {
result[cur] = Some(cur_lookahead.clone());
}
for (i, rule) in rules[cur].iter().enumerate() {
let next_lookahead = rule
.get(i + 1)
.map(|n| &firsts[*n])
.unwrap_or(cur_lookahead);
if result[rule[0]]
.as_ref()
.map(|next_result| !next_lookahead.is_subset(next_result))
.unwrap_or(true)
&& rules[rule[0]].len() > 0
{
helper(rule[0], &next_lookahead, firsts, result, rules);
}
}
}
let mut result = vec![None; rules.len()];
let cur_lookahead = rules[seed.0][seed.1]
.get(seed.2 + 1)
.map(|n| &firsts[*n])
.unwrap_or(seed_lookahead);
helper(
rules[seed.0][seed.1][seed.2],
cur_lookahead,
firsts,
&mut result,
rules,
);
result
}
impl ParseDFA {
fn from_rules(rules: Vec<Vec<Vec<usize>>>) -> Self {
let firsts = get_firsts(&rules);
let mut stack = (0..rules.len())
.filter(|i| !rules[*i].is_empty())
.collect::<Vec<_>>();
let states_vec = stack
.iter()
.map(|i| {
(
(
(0..rules[*i].len()).map(|j| (*i, j, 0)).collect::<Vec<_>>(),
vec![firsts.last().unwrap().clone(); rules[*i].len()],
),
vec![],
)
})
.collect::<Vec<_>>();
let mut states = IndexableMap::from(states_vec);
let derived_rules = (0..rules.len())
.map(|i| get_derived_rules(&rules, i))
.collect::<Vec<_>>();
while let Some(cur_state) = stack.pop() {
let iter_state = || {
states[cur_state]
.0
.0
.iter()
.zip(states[cur_state].0 .1.iter())
.filter(|(seed, _)| seed.2 < rules[seed.0][seed.1].len())
};
if iter_state().next().is_none() {
continue;
}
let mut trans = vec![(vec![], vec![]); rules.len()];
for (seed, lookahead) in iter_state() {
let new_seed = (seed.0, seed.1, seed.2 + 1);
let edge = rules[seed.0][seed.1][seed.2];
trans[edge].0.push(new_seed);
trans[edge].1.push(lookahead.clone());
}
let derived_lookaheads = iter_state()
.map(|(seed, lookahead)| get_derived_lookaheads(*seed, &lookahead, &firsts, &rules))
.collect::<Vec<_>>();
for (i, rule) in iter_state().enumerate().flat_map(|(i, (seed, _))| {
derived_rules[rules[seed.0][seed.1][seed.2]]
.iter()
.map(move |rule| (i, rule))
}) {
let new_seed = (rule.0, rule.1, 1);
let edge = rules[rule.0][rule.1][0];
if let Some((tran, _)) = trans[edge]
.0
.iter()
.enumerate()
.filter(|(_, seed)| **seed == new_seed)
.next()
{
trans[edge].1[tran] |= derived_lookaheads[i][rule.0].as_ref().unwrap();
} else {
trans[edge].0.push(new_seed);
trans[edge]
.1
.push(derived_lookaheads[i][rule.0].clone().unwrap());
}
}
let true_tran = trans
.into_iter()
.map(|state| {
(state.0.len() > 0).then(|| {
states.get_ind(&state).unwrap_or_else(|| {
let state_id = states.push(state, vec![]).0;
stack.push(state_id);
state_id
})
})
})
.collect();
states[cur_state].1 = true_tran;
}
Self { rules, states }
}
}