From e27adcdce55dc15c97bb0ac6d5bc0b082d2232c2 Mon Sep 17 00:00:00 2001
From: Nadrieril
Date: Sat, 9 Mar 2019 14:32:07 +0100
Subject: Use new Label type instead of &str in parser

---
 dhall/src/imports.rs           |   2 +-
 dhall/src/main.rs              |   4 +-
 dhall_core/src/core.rs         |  57 +++++++++++++++++++---
 dhall_core/src/grammar_util.rs |   4 --
 dhall_core/src/lib.rs          |   1 -
 dhall_core/src/parser.rs       | 104 +++++++++++++++++++++--------------------
 dhall_generator/src/lib.rs     |   4 +-
 7 files changed, 110 insertions(+), 66 deletions(-)
 delete mode 100644 dhall_core/src/grammar_util.rs

diff --git a/dhall/src/imports.rs b/dhall/src/imports.rs
index 9ae66a7..d9f0b33 100644
--- a/dhall/src/imports.rs
+++ b/dhall/src/imports.rs
@@ -75,7 +75,7 @@ pub fn load_dhall_file(
     let mut buffer = String::new();
     File::open(f)?.read_to_string(&mut buffer)?;
     let expr = parser::parse_expr(&*buffer)?;
-    let expr = expr.take_ownership_of_labels();
+    let expr = expr.map_label(&|l| String::from(l.clone()));
     let expr = if resolve_imports {
         let root = ImportRoot::LocalDir(f.parent().unwrap().to_owned());
         let resolve = |import: &Import| -> Expr<String, X, X> {
diff --git a/dhall/src/main.rs b/dhall/src/main.rs
index d072fe7..db69a46 100644
--- a/dhall/src/main.rs
+++ b/dhall/src/main.rs
@@ -65,8 +65,8 @@ fn main() {
         }
     };
 
-    let expr: Expr<String, _, _> =
-        imports::panic_imports(&expr.take_ownership_of_labels());
+    let expr: Expr<Label, _, _> =
+        imports::panic_imports(&expr);
 
     let type_expr = match typecheck::type_of(&expr) {
         Err(e) => {
diff --git a/dhall_core/src/core.rs b/dhall_core/src/core.rs
index eed9e0c..7bd1318 100644
--- a/dhall_core/src/core.rs
+++ b/dhall_core/src/core.rs
@@ -68,6 +68,41 @@ pub struct Import {
     pub hash: Option<()>,
 }
 
+// The type for labels throughout the AST
+// It owns the data because otherwise lifetimes would make recursive imports impossible
+#[derive(Debug, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
+pub struct Label(String);
+
+impl From<String> for Label {
+    fn from(s: String) -> Self {
+        Label(s)
+    }
+}
+
+impl From<&'static str> for Label {
+    fn from(s: &'static str) -> Self {
+        Label(s.to_owned())
+    }
+}
+
+impl From<Label> for String {
+    fn from(x: Label) -> String {
+        x.0
+    }
+}
+
+impl Display for Label {
+    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+        self.0.fmt(f)
+    }
+}
+
+impl Label {
+    pub fn from_str<'a>(s: &'a str) -> Label {
+        s.to_owned().into()
+    }
+}
+
 /// Label for a bound variable
 ///
 /// The `String` field is the variable's name (i.e. \"`x`\").
@@ -268,7 +303,6 @@ pub trait StringLike:
     + Hash
     + Ord
     + Eq
-    + Default
     + Into<String>
     + From<String>
     + From<&'static str>
@@ -282,7 +316,6 @@ impl<T> StringLike for T where
         + Hash
         + Ord
         + Eq
-        + Default
         + Into<String>
         + From<String>
         + From<&'static str>
@@ -340,6 +373,18 @@ impl<Label: StringLike, S, A> Expr<Label, S, A> {
         self.map_shallow(recurse, |x| x.clone(), map_embed, |x| x.clone())
     }
 
+    pub fn map_label<L2: StringLike, F>(&self, map_label: &F) -> Expr<L2, S, A>
+    where
+        A: Clone,
+        S: Clone,
+        F: Fn(&Label) -> L2,
+    {
+        let recurse = |e: &Expr<Label, S, A>| -> Expr<L2, S, A> {
+            e.map_label(map_label)
+        };
+        self.map_shallow(recurse, |x| x.clone(), |x| x.clone(), map_label)
+    }
+
     pub fn bool_lit(&self) -> Option<bool> {
         match *self {
             Expr::BoolLit(v) => Some(v),
@@ -362,11 +407,11 @@ impl<Label: StringLike, S, A> Expr<Label, S, A> {
     }
 }
 
-impl<'i, S: Clone, A: Clone> Expr<&'i str, S, A> {
-    pub fn take_ownership_of_labels<L: StringLike + From<String>>(
+impl<S: Clone, A: Clone> Expr<&'static str, S, A> {
+    pub fn take_ownership_of_labels<L: StringLike>(
         &self,
     ) -> Expr<L, S, A> {
-        let recurse = |e: &Expr<&'i str, S, A>| -> Expr<L, S, A> {
+        let recurse = |e: &Expr<&'static str, S, A>| -> Expr<L, S, A> {
             e.take_ownership_of_labels()
         };
         map_shallow(
@@ -787,7 +832,7 @@ where
     S: Clone,
     T: Clone,
     Label1:
-        Display + fmt::Debug + Clone + Hash + Ord + Eq + Into<String> + Default,
+        Display + fmt::Debug + Clone + Hash + Ord + Eq + Into<String>,
     Label2: StringLike,
     F1: Fn(&Expr<Label1, S, A>) -> Expr<Label2, T, B>,
     F2: FnOnce(&S) -> T,
diff --git a/dhall_core/src/grammar_util.rs b/dhall_core/src/grammar_util.rs
deleted file mode 100644
index 2547e94..0000000
--- a/dhall_core/src/grammar_util.rs
+++ /dev/null
@@ -1,4 +0,0 @@
-use crate::core::{Expr, Import, X};
-
-pub type ParsedExpr<'i> = Expr<&'i str, X, Import>;
-pub type BoxExpr<'i> = Box<ParsedExpr<'i>>;
diff --git a/dhall_core/src/lib.rs b/dhall_core/src/lib.rs
index bd53603..386d6bc 100644
--- a/dhall_core/src/lib.rs
+++ b/dhall_core/src/lib.rs
@@ -4,5 +4,4 @@
 pub mod core;
 pub use crate::core::*;
 pub mod context;
-mod grammar_util;
 pub mod parser;
diff --git a/dhall_core/src/parser.rs b/dhall_core/src/parser.rs
index 0ba1586..7073a93 100644
--- a/dhall_core/src/parser.rs
+++ b/dhall_core/src/parser.rs
@@ -7,7 +7,9 @@ use dhall_parser::{DhallParser, Rule};
 
 use crate::core;
 use crate::core::*;
-use crate::grammar_util::{BoxExpr, ParsedExpr};
+
+pub type ParsedExpr = Expr<Label, X, Import>;
+pub type BoxExpr = Box<ParsedExpr>;
 
 pub type ParseError = pest::error::Error<Rule>;
 
@@ -418,6 +420,8 @@ named!(str<&'a str>; captured_str!(s) => s.trim());
 
 named!(raw_str<&'a str>; captured_str!(s) => s);
 
+named!(label<Label>; captured_str!(s) => Label::from(s.trim().to_owned()));
+
 // TODO: parse escapes and interpolation
 rule!(double_quote_literal<String>;
     children!(strs*: raw_str) => {
@@ -537,7 +541,7 @@ rule!(import_hashed_raw<(ImportLocation, Option<()>)>;
     }
 );
 
-rule!(import_raw<BoxExpr<'a>>;
+rule!(import_raw<BoxExpr>;
     // TODO: handle "as Text"
     children!(import: import_hashed_raw) => {
         let (location, hash) = import;
@@ -549,7 +553,7 @@ rule!(import_raw<BoxExpr<'a>>;
     }
 );
 
-rule_group!(expression<BoxExpr<'a>>;
+rule_group!(expression<BoxExpr>;
     identifier_raw,
     lambda_expression,
     ifthenelse_expression,
@@ -586,47 +590,47 @@ rule_group!(expression<BoxExpr<'a>>;
     final_expression
 );
 
-rule!(lambda_expression<BoxExpr<'a>>;
-    children!(label: str, typ: expression, body: expression) => {
-        bx(Expr::Lam(label, typ, body))
+rule!(lambda_expression<BoxExpr>;
+    children!(l: label, typ: expression, body: expression) => {
+        bx(Expr::Lam(l, typ, body))
     }
 );
 
-rule!(ifthenelse_expression<BoxExpr<'a>>;
+rule!(ifthenelse_expression<BoxExpr>;
     children!(cond: expression, left: expression, right: expression) => {
         bx(Expr::BoolIf(cond, left, right))
     }
 );
 
-rule!(let_expression<BoxExpr<'a>>;
+rule!(let_expression<BoxExpr>;
     children!(bindings*: let_binding, final_expr: expression) => {
         bindings.fold(final_expr, |acc, x| bx(Expr::Let(x.0, x.1, x.2, acc)))
     }
 );
 
-rule!(let_binding<(&'a str, Option<BoxExpr<'a>>, BoxExpr<'a>)>;
-    children!(name: str, annot?: expression, expr: expression) => (name, annot, expr)
+rule!(let_binding<(Label, Option<BoxExpr>, BoxExpr)>;
+    children!(name: label, annot?: expression, expr: expression) => (name, annot, expr)
 );
 
-rule!(forall_expression<BoxExpr<'a>>;
-    children!(label: str, typ: expression, body: expression) => {
-        bx(Expr::Pi(label, typ, body))
+rule!(forall_expression<BoxExpr>;
+    children!(l: label, typ: expression, body: expression) => {
+        bx(Expr::Pi(l, typ, body))
     }
 );
 
-rule!(arrow_expression<BoxExpr<'a>>;
+rule!(arrow_expression<BoxExpr>;
     children!(typ: expression, body: expression) => {
-        bx(Expr::Pi("_", typ, body))
+        bx(Expr::Pi("_".into(), typ, body))
     }
 );
 
-rule!(merge_expression<BoxExpr<'a>>;
+rule!(merge_expression<BoxExpr>;
     children!(x: expression, y: expression, z?: expression) => {
         bx(Expr::Merge(x, y, z))
     }
 );
 
-rule!(empty_collection<BoxExpr<'a>>;
+rule!(empty_collection<BoxExpr>;
     children!(x: str, y: expression) => {
        match x {
           "Optional" => bx(Expr::OptionalLit(Some(y), vec![])),
@@ -636,7 +640,7 @@ rule!(empty_collection<BoxExpr<'a>>;
     }
 );
 
-rule!(non_empty_optional<BoxExpr<'a>>;
+rule!(non_empty_optional<BoxExpr>;
     children!(x: expression, _y: str, z: expression) => {
         bx(Expr::OptionalLit(Some(z), vec![*x]))
     }
@@ -644,7 +648,7 @@ rule!(non_empty_optional<BoxExpr<'a>>;
 
 macro_rules! binop {
     ($rule:ident, $op:ident) => {
-        rule!($rule<BoxExpr<'a>>;
+        rule!($rule<BoxExpr>;
             children!(first: expression, rest*: expression) => {
                 rest.fold(first, |acc, e| bx(Expr::BinOp(BinOp::$op, acc, e)))
             }
@@ -652,7 +656,7 @@ macro_rules! binop {
     };
 }
 
-rule!(annotated_expression<BoxExpr<'a>>;
+rule!(annotated_expression<BoxExpr>;
     children!(e: expression, annot: expression) => {
         bx(Expr::Annot(e, annot))
     },
@@ -672,19 +676,19 @@ binop!(times_expression, NaturalTimes);
 binop!(equal_expression, BoolEQ);
 binop!(not_equal_expression, BoolNE);
 
-rule!(application_expression<BoxExpr<'a>>;
+rule!(application_expression<BoxExpr>;
     children!(first: expression, rest*: expression) => {
         rest.fold(first, |acc, e| bx(Expr::App(acc, e)))
     }
 );
 
-rule!(selector_expression_raw<BoxExpr<'a>>;
-    children!(first: expression, rest*: str) => {
+rule!(selector_expression_raw<BoxExpr>;
+    children!(first: expression, rest*: label) => {
         rest.fold(first, |acc, e| bx(Expr::Field(acc, e)))
     }
 );
 
-rule!(literal_expression_raw<BoxExpr<'a>>;
+rule!(literal_expression_raw<BoxExpr>;
     children!(n: double_literal_raw) => bx(Expr::DoubleLit(n)),
     children!(n: minus_infinity_literal) => bx(Expr::DoubleLit(std::f64::NEG_INFINITY)),
     children!(n: plus_infinity_literal) => bx(Expr::DoubleLit(std::f64::INFINITY)),
@@ -696,7 +700,7 @@ rule!(literal_expression_raw<BoxExpr<'a>>;
     children!(e: expression) => e,
 );
 
-rule!(identifier_raw<BoxExpr<'a>>;
+rule!(identifier_raw<BoxExpr>;
     children!(name: str, idx?: natural_literal_raw) => {
         match Builtin::parse(name) {
             Some(b) => bx(Expr::Builtin(b)),
@@ -705,40 +709,40 @@ rule!(identifier_raw<BoxExpr<'a>>;
                 "False" => bx(Expr::BoolLit(false)),
                 "Type" => bx(Expr::Const(Const::Type)),
                 "Kind" => bx(Expr::Const(Const::Kind)),
-                name => bx(Expr::Var(V(name, idx.unwrap_or(0)))),
+                name => bx(Expr::Var(V(Label::from(name.to_owned()), idx.unwrap_or(0)))),
             }
         }
     }
 );
 
-rule!(empty_record_literal<BoxExpr<'a>>;
+rule!(empty_record_literal<BoxExpr>;
     children!() => bx(Expr::RecordLit(BTreeMap::new()))
 );
 
-rule!(empty_record_type<BoxExpr<'a>>;
+rule!(empty_record_type<BoxExpr>;
     children!() => bx(Expr::Record(BTreeMap::new()))
 );
 
-rule!(non_empty_record_type_or_literal<BoxExpr<'a>>;
-    children!(first_label: str, rest: non_empty_record_type) => {
+rule!(non_empty_record_type_or_literal<BoxExpr>;
+    children!(first_label: label, rest: non_empty_record_type) => {
         let (first_expr, mut map) = rest;
         map.insert(first_label, *first_expr);
         bx(Expr::Record(map))
     },
-    children!(first_label: str, rest: non_empty_record_literal) => {
+    children!(first_label: label, rest: non_empty_record_literal) => {
         let (first_expr, mut map) = rest;
         map.insert(first_label, *first_expr);
         bx(Expr::RecordLit(map))
     },
 );
 
-rule!(non_empty_record_type<(BoxExpr<'a>, BTreeMap<&'a str, ParsedExpr<'a>>)>;
+rule!(non_empty_record_type<(BoxExpr, BTreeMap<Label, ParsedExpr>)>;
     self!(x: partial_record_entries) => x
 );
 
-named!(partial_record_entries<(BoxExpr<'a>, BTreeMap<&'a str, ParsedExpr<'a>>)>;
+named!(partial_record_entries<(BoxExpr, BTreeMap<Label, ParsedExpr>)>;
     children!(expr: expression, entries*: record_entry) => {
-        let mut map: BTreeMap<&str, ParsedExpr> = BTreeMap::new();
+        let mut map: BTreeMap<Label, ParsedExpr> = BTreeMap::new();
         for (n, e) in entries {
             map.insert(n, *e);
         }
@@ -746,15 +750,15 @@ named!(partial_record_entries<(BoxExpr<'a>, BTreeMap<&'a str, ParsedExpr<'a>>)>;
     }
 );
 
-named!(record_entry<(&'a str, BoxExpr<'a>)>;
-    children!(name: str, expr: expression) => (name, expr)
+named!(record_entry<(Label, BoxExpr)>;
+    children!(name: label, expr: expression) => (name, expr)
 );
 
-rule!(non_empty_record_literal<(BoxExpr<'a>, BTreeMap<&'a str, ParsedExpr<'a>>)>;
+rule!(non_empty_record_literal<(BoxExpr, BTreeMap<Label, ParsedExpr>)>;
     self!(x: partial_record_entries) => x
 );
 
-rule!(union_type_or_literal<BoxExpr<'a>>;
+rule!(union_type_or_literal<BoxExpr>;
     children!(_e: empty_union_type) => {
         bx(Expr::Union(BTreeMap::new()))
     },
@@ -769,25 +773,25 @@ rule!(union_type_or_literal<BoxExpr<'a>>;
 rule!(empty_union_type<()>; children!() => ());
 
 rule!(non_empty_union_type_or_literal
-      <(Option<(&'a str, BoxExpr<'a>)>, BTreeMap<&'a str, ParsedExpr<'a>>)>;
-    children!(label: str, e: expression, entries: union_type_entries) => {
-        (Some((label, e)), entries)
+      <(Option<(Label, BoxExpr)>, BTreeMap<Label, ParsedExpr>)>;
+    children!(l: label, e: expression, entries: union_type_entries) => {
+        (Some((l, e)), entries)
     },
-    children!(l: str, e: expression, rest: non_empty_union_type_or_literal) => {
+    children!(l: label, e: expression, rest: non_empty_union_type_or_literal) => {
         let (x, mut entries) = rest;
         entries.insert(l, *e);
         (x, entries)
     },
-    children!(l: str, e: expression) => {
+    children!(l: label, e: expression) => {
         let mut entries = BTreeMap::new();
         entries.insert(l, *e);
         (None, entries)
     },
 );
 
-rule!(union_type_entries<BTreeMap<&'a str, ParsedExpr<'a>>>;
+rule!(union_type_entries<BTreeMap<Label, ParsedExpr>>;
     children!(entries*: union_type_entry) => {
-        let mut map: BTreeMap<&str, ParsedExpr> = BTreeMap::new();
+        let mut map: BTreeMap<Label, ParsedExpr> = BTreeMap::new();
         for (n, e) in entries {
             map.insert(n, *e);
         }
@@ -795,21 +799,21 @@ rule!(union_type_entries<BTreeMap<&'a str, ParsedExpr<'a>>>;
     }
 );
 
-rule!(union_type_entry<(&'a str, BoxExpr<'a>)>;
-    children!(name: str, expr: expression) => (name, expr)
+rule!(union_type_entry<(Label, BoxExpr)>;
+    children!(name: label, expr: expression) => (name, expr)
 );
 
-rule!(non_empty_list_literal_raw<BoxExpr<'a>>;
+rule!(non_empty_list_literal_raw<BoxExpr>;
     children!(items*: expression) => {
         bx(Expr::ListLit(None, items.map(|x| *x).collect()))
     }
 );
 
-rule!(final_expression<BoxExpr<'a>>;
+rule!(final_expression<BoxExpr>;
     children!(e: expression, _eoi: EOI) => e
 );
 
-pub fn parse_expr<'i>(s: &'i str) -> ParseResult<BoxExpr<'i>> {
+pub fn parse_expr<'i>(s: &'i str) -> ParseResult<BoxExpr> {
     let pairs = DhallParser::parse(Rule::final_expression, s)?;
     // Match the only item in the pairs iterator
     match_iter!(@panic; pairs; (p) => expression(p))
diff --git a/dhall_generator/src/lib.rs b/dhall_generator/src/lib.rs
index d1a8bdf..e66ab2c 100644
--- a/dhall_generator/src/lib.rs
+++ b/dhall_generator/src/lib.rs
@@ -11,8 +11,8 @@ pub fn dhall_expr(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
     let expr: Box<Expr<_, X, Import>> = parser::parse_expr(&input_str).unwrap();
     let no_import =
         |_: &Import| -> X { panic!("Don't use import in dhall!()") };
-    let expr = expr.take_ownership_of_labels().map_embed(&no_import);
-    let output = dhall_to_tokenstream::<String>(&expr, &Context::new());
+    let expr = expr.map_embed(&no_import);
+    let output = dhall_to_tokenstream::<Label>(&expr, &Context::new());
     output.into()
 }
 
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