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|
extern crate proc_macro;
use dhall_core::context::Context;
use dhall_core::*;
use proc_macro2::TokenStream;
use quote::quote;
use std::collections::BTreeMap;
pub fn expr(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
let input_str = input.to_string();
let expr: SubExpr<X, Import> = parse_expr(&input_str).unwrap();
let no_import =
|_: &Import| -> X { panic!("Don't use import in dhall::expr!()") };
let expr = expr.as_ref().map_embed(&no_import);
let output = quote_expr(&expr, &Context::new());
output.into()
}
pub fn subexpr(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
let input_str = input.to_string();
let expr: SubExpr<X, Import> = parse_expr(&input_str).unwrap();
let no_import =
|_: &Import| -> X { panic!("Don't use import in dhall::subexpr!()") };
let expr = expr.as_ref().map_embed(&no_import);
let output = quote_subexpr(&rc(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, Label, X, X>) -> TokenStream
where
TS: quote::ToTokens + std::fmt::Debug,
{
let quote_map = |m: BTreeMap<Label, TS>| -> TokenStream {
let entries = m.into_iter().map(|(k, v)| {
let k = quote_label(&k);
quote!(m.insert(#k, #v);)
});
quote! { {
use std::collections::BTreeMap;
let mut m = BTreeMap::new();
#( #entries )*
m
} }
};
let quote_vec = |e: Vec<TS>| -> TokenStream {
quote! { vec![ #(#e),* ] }
};
use dhall_core::ExprF::*;
match expr {
Var(_) => unreachable!(),
Pi(x, t, b) => {
let x = quote_label(&x);
quote! { dhall_core::ExprF::Pi(#x, #t, #b) }
}
Lam(x, t, b) => {
let x = quote_label(&x);
quote! { dhall_core::ExprF::Lam(#x, #t, #b) }
}
App(f, a) => {
let a = quote_vec(a);
quote! { dhall_core::ExprF::App(#f, #a) }
}
Const(c) => {
let c = quote_const(c);
quote! { dhall_core::ExprF::Const(#c) }
}
Builtin(b) => {
let b = quote_builtin(b);
quote! { dhall_core::ExprF::Builtin(#b) }
}
BinOp(o, a, b) => {
let o = quote_binop(o);
quote! { dhall_core::ExprF::BinOp(#o, #a, #b) }
}
NaturalLit(n) => {
quote! { dhall_core::ExprF::NaturalLit(#n) }
}
BoolLit(b) => {
quote! { dhall_core::ExprF::BoolLit(#b) }
}
EmptyOptionalLit(x) => {
quote! { dhall_core::ExprF::EmptyOptionalLit(#x) }
}
NEOptionalLit(x) => {
quote! { dhall_core::ExprF::NEOptionalLit(#x) }
}
EmptyListLit(t) => {
quote! { dhall_core::ExprF::EmptyListLit(#t) }
}
NEListLit(es) => {
let es = quote_vec(es);
quote! { dhall_core::ExprF::NEListLit(#es) }
}
RecordType(m) => {
let m = quote_map(m);
quote! { dhall_core::ExprF::RecordType(#m) }
}
RecordLit(m) => {
let m = quote_map(m);
quote! { dhall_core::ExprF::RecordLit(#m) }
}
UnionType(m) => {
let m = quote_map(m);
quote! { dhall_core::ExprF::UnionType(#m) }
}
e => unimplemented!("{:?}", e),
}
}
// Returns an expression of type SubExpr<_, _>. Expects interpolated variables
// to be of type SubExpr<_, _>.
fn quote_subexpr(
expr: &SubExpr<X, X>,
ctx: &Context<Label, ()>,
) -> TokenStream {
use dhall_core::ExprF::*;
match expr.as_ref().map_ref(
|e| quote_subexpr(e, ctx),
|l, e| quote_subexpr(e, &ctx.insert(l.clone(), ())),
|_| unreachable!(),
|_| unreachable!(),
|l| l.clone(),
) {
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_core::V(#s.into(), #n) };
bx(quote! { dhall_core::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_core::SubExpr<_, _> = #v.clone();
x
} }
}
}
}
e => bx(quote_exprf(e)),
}
}
// Returns an expression of type Expr<_, _>. Expects interpolated variables
// to be of type SubExpr<_, _>.
fn quote_expr(expr: &Expr<X, X>, ctx: &Context<Label, ()>) -> TokenStream {
use dhall_core::ExprF::*;
match expr.map_ref(
|e| quote_subexpr(e, ctx),
|l, e| quote_subexpr(e, &ctx.insert(l.clone(), ())),
|_| unreachable!(),
|_| unreachable!(),
|l| l.clone(),
) {
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_core::V(#s.into(), #n) };
quote! { dhall_core::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_core::SubExpr<_, _> = #v.clone();
x.unroll()
} }
}
}
}
e => quote_exprf(e),
}
}
fn quote_builtin(b: Builtin) -> TokenStream {
format!("dhall_core::Builtin::{:?}", b).parse().unwrap()
}
fn quote_const(c: Const) -> TokenStream {
format!("dhall_core::Const::{:?}", c).parse().unwrap()
}
fn quote_binop(b: BinOp) -> TokenStream {
format!("dhall_core::BinOp::{:?}", b).parse().unwrap()
}
fn quote_label(l: &Label) -> TokenStream {
let l = String::from(l);
quote! { dhall_core::Label::from(#l) }
}
fn bx(x: TokenStream) -> TokenStream {
quote! { dhall_core::bx(#x) }
}
|
