Introduce LitKind to factor out common enum nodes

6 files changed, 55 insertions, 40 deletions

diff --git a/dhall/src/syntax/ast/expr.rs b/dhall/src/syntax/ast/expr.rs
index 512010a..18ec9fd 100644
--- a/dhall/src/syntax/ast/expr.rs
+++ b/dhall/src/syntax/ast/expr.rs
@@ -103,6 +103,19 @@ pub struct Expr {
 
 pub type UnspannedExpr = ExprKind<Expr>;
 
+/// Simple literals
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub enum LitKind {
+    ///  `True`
+    Bool(bool),
+    ///  `1`
+    Natural(Natural),
+    ///  `+2`
+    Integer(Integer),
+    ///  `3.24`
+    Double(Double),
+}
+
 /// Syntax tree for expressions
 // Having the recursion out of the enum definition enables writing
 // much more generic code and improves pattern-matching behind
@@ -110,6 +123,7 @@ pub type UnspannedExpr = ExprKind<Expr>;
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub enum ExprKind<SubExpr> {
     Const(Const),
+    Lit(LitKind),
     ///  `x`
     ///  `x@n`
     Var(V),
@@ -131,16 +145,8 @@ pub enum ExprKind<SubExpr> {
     Builtin(Builtin),
     // Binary operations
     BinOp(BinOp, SubExpr, SubExpr),
-    ///  `True`
-    BoolLit(bool),
     ///  `if x then y else z`
     BoolIf(SubExpr, SubExpr, SubExpr),
-    ///  `1`
-    NaturalLit(Natural),
-    ///  `+2`
-    IntegerLit(Integer),
-    ///  `3.24`
-    DoubleLit(Double),
     ///  `"Some ${interpolated} text"`
     TextLit(InterpolatedText<SubExpr>),
     ///  `[] : t`
diff --git a/dhall/src/syntax/ast/visitor.rs b/dhall/src/syntax/ast/visitor.rs
index 39959ac..c361bc1 100644
--- a/dhall/src/syntax/ast/visitor.rs
+++ b/dhall/src/syntax/ast/visitor.rs
@@ -91,10 +91,7 @@ where
         Annot(x, t) => Annot(expr!(x)?, expr!(t)?),
         Const(k) => Const(*k),
         Builtin(v) => Builtin(*v),
-        BoolLit(b) => BoolLit(*b),
-        NaturalLit(n) => NaturalLit(*n),
-        IntegerLit(n) => IntegerLit(*n),
-        DoubleLit(n) => DoubleLit(*n),
+        Lit(l) => Lit(l.clone()),
         TextLit(t) => TextLit(t.traverse_ref(|e| expr!(e))?),
         BinOp(o, x, y) => BinOp(*o, expr!(x)?, expr!(y)?),
         BoolIf(b, t, f) => BoolIf(expr!(b)?, expr!(t)?, expr!(f)?),
diff --git a/dhall/src/syntax/binary/decode.rs b/dhall/src/syntax/binary/decode.rs
index 6fbcc10..2e50d61 100644
--- a/dhall/src/syntax/binary/decode.rs
+++ b/dhall/src/syntax/binary/decode.rs
@@ -6,8 +6,8 @@ use crate::error::DecodeError;
 use crate::syntax;
 use crate::syntax::{
     Expr, ExprKind, FilePath, FilePrefix, Hash, ImportLocation, ImportMode,
-    Integer, InterpolatedText, Label, Natural, Scheme, Span, UnspannedExpr,
-    URL, V,
+    Integer, InterpolatedText, Label, LitKind, Natural, Scheme, Span,
+    UnspannedExpr, URL, V,
 };
 use crate::DecodedExpr;
 
@@ -31,8 +31,8 @@ fn cbor_value_to_dhall(data: &cbor::Value) -> Result<DecodedExpr, DecodeError> {
         String(s) => match Builtin::parse(s) {
             Some(b) => ExprKind::Builtin(b),
             None => match s.as_str() {
-                "True" => BoolLit(true),
-                "False" => BoolLit(false),
+                "True" => Lit(LitKind::Bool(true)),
+                "False" => Lit(LitKind::Bool(false)),
                 "Type" => Const(Const::Type),
                 "Kind" => Const(Const::Kind),
                 "Sort" => Const(Const::Sort),
@@ -40,8 +40,8 @@ fn cbor_value_to_dhall(data: &cbor::Value) -> Result<DecodedExpr, DecodeError> {
             },
         },
         U64(n) => Var(V(Label::from("_"), *n as usize)),
-        F64(x) => DoubleLit((*x).into()),
-        Bool(b) => BoolLit(*b),
+        F64(x) => Lit(LitKind::Double((*x).into())),
+        Bool(b) => Lit(LitKind::Bool(*b)),
         Array(vec) => match vec.as_slice() {
             [String(l), U64(n)] => {
                 if l.as_str() == "_" {
@@ -216,9 +216,9 @@ fn cbor_value_to_dhall(data: &cbor::Value) -> Result<DecodedExpr, DecodeError> {
                 let z = cbor_value_to_dhall(&z)?;
                 BoolIf(x, y, z)
             }
-            [U64(15), U64(x)] => NaturalLit(*x as Natural),
-            [U64(16), U64(x)] => IntegerLit(*x as Integer),
-            [U64(16), I64(x)] => IntegerLit(*x as Integer),
+            [U64(15), U64(x)] => Lit(LitKind::Natural(*x as Natural)),
+            [U64(16), U64(x)] => Lit(LitKind::Integer(*x as Integer)),
+            [U64(16), I64(x)] => Lit(LitKind::Integer(*x as Integer)),
             [U64(18), String(first), rest @ ..] => {
                 TextLit(InterpolatedText::from((
                     first.clone(),
diff --git a/dhall/src/syntax/binary/encode.rs b/dhall/src/syntax/binary/encode.rs
index 686f737..291ac4a 100644
--- a/dhall/src/syntax/binary/encode.rs
+++ b/dhall/src/syntax/binary/encode.rs
@@ -46,6 +46,7 @@ where
     use std::iter::once;
     use syntax::Builtin;
     use syntax::ExprKind::*;
+    use syntax::LitKind::*;
 
     use self::Serialize::{RecordMap, UnionMap};
     fn expr(x: &Expr) -> self::Serialize<'_> {
@@ -60,10 +61,10 @@ where
     match e.as_ref() {
         Const(c) => ser.serialize_str(&c.to_string()),
         Builtin(b) => ser.serialize_str(&b.to_string()),
-        BoolLit(b) => ser.serialize_bool(*b),
-        NaturalLit(n) => ser_seq!(ser; tag(15), U64(*n as u64)),
-        IntegerLit(n) => ser_seq!(ser; tag(16), I64(*n as i64)),
-        DoubleLit(n) => {
+        Lit(Bool(b)) => ser.serialize_bool(*b),
+        Lit(Natural(n)) => ser_seq!(ser; tag(15), U64(*n as u64)),
+        Lit(Integer(n)) => ser_seq!(ser; tag(16), I64(*n as i64)),
+        Lit(Double(n)) => {
             let n: f64 = (*n).into();
             ser.serialize_f64(n)
         }
diff --git a/dhall/src/syntax/text/parser.rs b/dhall/src/syntax/text/parser.rs
index 0ff1363..f3ebd2b 100644
--- a/dhall/src/syntax/text/parser.rs
+++ b/dhall/src/syntax/text/parser.rs
@@ -7,6 +7,7 @@ use pest_consume::{match_nodes, Parser};
 
 use crate::syntax::map::{DupTreeMap, DupTreeSet};
 use crate::syntax::ExprKind::*;
+use crate::syntax::LitKind::*;
 use crate::syntax::{
     Double, Expr, FilePath, FilePrefix, Hash, ImportLocation, ImportMode,
     Integer, InterpolatedText, InterpolatedTextContents, Label, NaiveDouble,
@@ -344,8 +345,8 @@ impl DhallParser {
         let e = match crate::syntax::Builtin::parse(s) {
             Some(b) => Builtin(b),
             None => match s {
-                "True" => BoolLit(true),
-                "False" => BoolLit(false),
+                "True" => Lit(Bool(true)),
+                "False" => Lit(Bool(false)),
                 "Type" => Const(crate::syntax::Const::Type),
                 "Kind" => Const(crate::syntax::Const::Kind),
                 "Sort" => Const(crate::syntax::Const::Sort),
@@ -833,9 +834,9 @@ impl DhallParser {
     #[alias(expression, shortcut = true)]
     fn primitive_expression(input: ParseInput) -> ParseResult<Expr> {
         Ok(match_nodes!(input.children();
-            [double_literal(n)] => spanned(input, DoubleLit(n)),
-            [natural_literal(n)] => spanned(input, NaturalLit(n)),
-            [integer_literal(n)] => spanned(input, IntegerLit(n)),
+            [double_literal(n)] => spanned(input, Lit(Double(n))),
+            [natural_literal(n)] => spanned(input, Lit(Natural(n))),
+            [integer_literal(n)] => spanned(input, Lit(Integer(n))),
             [double_quote_literal(s)] => spanned(input, TextLit(s)),
             [single_quote_literal(s)] => spanned(input, TextLit(s)),
             [record_type_or_literal(e)] => spanned(input, e),
diff --git a/dhall/src/syntax/text/printer.rs b/dhall/src/syntax/text/printer.rs
index d1c9588..8891d41 100644
--- a/dhall/src/syntax/text/printer.rs
+++ b/dhall/src/syntax/text/printer.rs
@@ -196,15 +196,7 @@ impl<SE: Display + Clone> Display for ExprKind<SE> {
             Var(a) => a.fmt(f)?,
             Const(k) => k.fmt(f)?,
             Builtin(v) => v.fmt(f)?,
-            BoolLit(true) => f.write_str("True")?,
-            BoolLit(false) => f.write_str("False")?,
-            NaturalLit(a) => a.fmt(f)?,
-            IntegerLit(a) if *a >= 0 => {
-                f.write_str("+")?;
-                a.fmt(f)?;
-            }
-            IntegerLit(a) => a.fmt(f)?,
-            DoubleLit(a) => a.fmt(f)?,
+            Lit(a) => a.fmt(f)?,
             TextLit(a) => a.fmt(f)?,
             RecordType(a) if a.is_empty() => f.write_str("{}")?,
             RecordType(a) => fmt_list("{ ", ", ", " }", a, f, |(k, t), f| {
@@ -239,7 +231,25 @@ impl<SE: Display + Clone> Display for ExprKind<SE> {
 
 impl Display for Expr {
     fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
-        self.as_ref().fmt_phase(f, PrintPhase::Base)
+        self.kind().fmt_phase(f, PrintPhase::Base)
+    }
+}
+
+impl Display for LitKind {
+    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+        use LitKind::*;
+        match self {
+            Bool(true) => f.write_str("True")?,
+            Bool(false) => f.write_str("False")?,
+            Natural(a) => a.fmt(f)?,
+            Integer(a) if *a >= 0 => {
+                f.write_str("+")?;
+                a.fmt(f)?;
+            }
+            Integer(a) => a.fmt(f)?,
+            Double(a) => a.fmt(f)?,
+        }
+        Ok(())
     }
 }