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|
extern crate proc_macro;
use dhall_syntax::context::Context;
use dhall_syntax::*;
use proc_macro2::TokenStream;
use quote::quote;
pub fn expr(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
let input_str = input.to_string();
let expr: SubExpr<_, Import> = parse_expr(&input_str).unwrap();
let no_import =
|_: &Import| -> X { panic!("Don't use import in dhall::expr!()") };
let expr = expr.map_embed(no_import);
let output = quote_expr(expr.as_ref(), &Context::new());
output.into()
}
pub fn subexpr(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
let input_str = input.to_string();
let expr: SubExpr<_, Import> = parse_expr(&input_str).unwrap();
let no_import =
|_: &Import| -> X { panic!("Don't use import in dhall::subexpr!()") };
let expr = expr.map_embed(no_import);
let output = quote_subexpr(&expr, &Context::new());
output.into()
}
// Returns an expression of type ExprF<T, _>, where T is the
// type of the subexpressions after interpolation.
pub fn quote_exprf<TS>(expr: ExprF<TS, X>) -> TokenStream
where
TS: quote::ToTokens + std::fmt::Debug,
{
use dhall_syntax::ExprF::*;
match expr {
Var(_) => unreachable!(),
Pi(x, t, b) => {
let x = quote_label(&x);
quote! { dhall_syntax::ExprF::Pi(#x, #t, #b) }
}
Lam(x, t, b) => {
let x = quote_label(&x);
quote! { dhall_syntax::ExprF::Lam(#x, #t, #b) }
}
App(f, a) => {
quote! { dhall_syntax::ExprF::App(#f, #a) }
}
Annot(x, t) => {
quote! { dhall_syntax::ExprF::Annot(#x, #t) }
}
Const(c) => {
let c = quote_const(c);
quote! { dhall_syntax::ExprF::Const(#c) }
}
Builtin(b) => {
let b = quote_builtin(b);
quote! { dhall_syntax::ExprF::Builtin(#b) }
}
BinOp(o, a, b) => {
let o = quote_binop(o);
quote! { dhall_syntax::ExprF::BinOp(#o, #a, #b) }
}
NaturalLit(n) => {
quote! { dhall_syntax::ExprF::NaturalLit(#n) }
}
BoolLit(b) => {
quote! { dhall_syntax::ExprF::BoolLit(#b) }
}
SomeLit(x) => {
quote! { dhall_syntax::ExprF::SomeLit(#x) }
}
EmptyListLit(t) => {
quote! { dhall_syntax::ExprF::EmptyListLit(#t) }
}
NEListLit(es) => {
let es = quote_vec(es);
quote! { dhall_syntax::ExprF::NEListLit(#es) }
}
RecordType(m) => {
let m = quote_map(m);
quote! { dhall_syntax::ExprF::RecordType(#m) }
}
RecordLit(m) => {
let m = quote_map(m);
quote! { dhall_syntax::ExprF::RecordLit(#m) }
}
UnionType(m) => {
let m = quote_opt_map(m);
quote! { dhall_syntax::ExprF::UnionType(#m) }
}
e => unimplemented!("{:?}", e),
}
}
// Returns an expression of type SubExpr<_, _>. Expects interpolated variables
// to be of type SubExpr<_, _>.
fn quote_subexpr<N>(
expr: &SubExpr<N, X>,
ctx: &Context<Label, ()>,
) -> TokenStream {
use dhall_syntax::ExprF::*;
match expr.as_ref().map_ref_with_special_handling_of_binders(
|e| quote_subexpr(e, ctx),
|l, e| quote_subexpr(e, &ctx.insert(l.clone(), ())),
|_| unreachable!(),
) {
Var(V(ref s, n)) => {
match ctx.lookup(s, n) {
// Non-free variable; interpolates as itself
Some(()) => {
let s: String = s.into();
let var = quote! { dhall_syntax::V(#s.into(), #n) };
rc(quote! { dhall_syntax::ExprF::Var(#var) })
}
// Free variable; interpolates as a rust variable
None => {
let s: String = s.into();
// TODO: insert appropriate shifts ?
let v: TokenStream = s.parse().unwrap();
quote! { {
let x: dhall_syntax::SubExpr<_, _> = #v.clone();
x
} }
}
}
}
e => rc(quote_exprf(e)),
}
}
// Returns an expression of type Expr<_, _>. Expects interpolated variables
// to be of type SubExpr<_, _>.
fn quote_expr<N>(expr: &Expr<N, X>, ctx: &Context<Label, ()>) -> TokenStream {
use dhall_syntax::ExprF::*;
match expr.map_ref_with_special_handling_of_binders(
|e| quote_subexpr(e, ctx),
|l, e| quote_subexpr(e, &ctx.insert(l.clone(), ())),
|_| unreachable!(),
) {
Var(V(ref s, n)) => {
match ctx.lookup(s, n) {
// Non-free variable; interpolates as itself
Some(()) => {
let s: String = s.into();
let var = quote! { dhall_syntax::V(#s.into(), #n) };
quote! { dhall_syntax::ExprF::Var(#var) }
}
// Free variable; interpolates as a rust variable
None => {
let s: String = s.into();
// TODO: insert appropriate shifts ?
let v: TokenStream = s.parse().unwrap();
quote! { {
let x: dhall_syntax::SubExpr<_, _> = #v.clone();
x.unroll()
} }
}
}
}
e => quote_exprf(e),
}
}
fn quote_builtin(b: Builtin) -> TokenStream {
format!("dhall_syntax::Builtin::{:?}", b).parse().unwrap()
}
fn quote_const(c: Const) -> TokenStream {
format!("dhall_syntax::Const::{:?}", c).parse().unwrap()
}
fn quote_binop(b: BinOp) -> TokenStream {
format!("dhall_syntax::BinOp::{:?}", b).parse().unwrap()
}
fn quote_label(l: &Label) -> TokenStream {
let l = String::from(l);
quote! { dhall_syntax::Label::from(#l) }
}
fn rc(x: TokenStream) -> TokenStream {
quote! { dhall_syntax::rc(#x) }
}
fn quote_opt<TS>(x: Option<TS>) -> TokenStream
where
TS: quote::ToTokens + std::fmt::Debug,
{
match x {
Some(x) => quote!(Some(#x)),
None => quote!(None),
}
}
fn quote_vec<TS>(e: Vec<TS>) -> TokenStream
where
TS: quote::ToTokens + std::fmt::Debug,
{
quote! { vec![ #(#e),* ] }
}
fn quote_map<TS>(m: impl IntoIterator<Item = (Label, TS)>) -> TokenStream
where
TS: quote::ToTokens + std::fmt::Debug,
{
let entries = m.into_iter().map(|(k, v)| {
let k = quote_label(&k);
quote!(m.push((#k, #v));)
});
quote! { {
use std::vec::Vec;
let mut m = Vec::new();
#( #entries )*
m
} }
}
fn quote_opt_map<TS>(
m: impl IntoIterator<Item = (Label, Option<TS>)>,
) -> TokenStream
where
TS: quote::ToTokens + std::fmt::Debug,
{
quote_map(m.into_iter().map(|(k, v)| (k, quote_opt(v))))
}
|
