nar 0.0.8

Narc, a dependently-typed programming language with dependent pattern matching
Documentation 
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use std::collections::BTreeMap;

use voile_util::{
    meta::MI,
    uid::{GI, UID},
};

use crate::syntax::abs::{desugar::DesugarErr, AbsDecl};

/// Desugar Monad.
pub type DesugarM<State = DesugarState> = Result<State, DesugarErr>;

#[derive(Debug, Clone, Default)]
pub struct DesugarState {
    pub decls: Vec<AbsDecl>,
    pub local: BTreeMap<String, UID>,
    /// TODO: make it per-definition.
    pub meta_count: MI,
}

impl DesugarState {
    pub fn with_capacity(decl_possible_size: usize) -> Self {
        Self {
            meta_count: Default::default(),
            local: Default::default(),
            decls: Vec::with_capacity(decl_possible_size),
        }
    }

    pub fn decl_len(&self) -> GI {
        GI(self.decls.len())
    }

    pub fn lookup_decls(&self, filter: impl Fn(&AbsDecl) -> bool) -> Option<(GI, &AbsDecl)> {
        let mut iter = self.decls.iter().enumerate();
        iter.find(|(_, x)| filter(*x)).map(|(ix, d)| (GI(ix), d))
    }

    pub fn ensure_local_emptiness(&self) {
        debug_assert!(self.local.is_empty())
    }

    pub fn lookup_local(&self, name: &str) -> Option<UID> {
        self.local.get(name).copied()
    }

    pub fn lookup_by_name(&self, name: &str) -> Option<(GI, &AbsDecl)> {
        self.lookup_decls(|decl| name == decl.decl_name().text)
    }

    pub fn fresh_meta(&mut self) -> MI {
        let ret = self.meta_count;
        self.meta_count += 1;
        ret
    }
}