From 5812a53cc9241703bd35586da0036dc170ab3721 Mon Sep 17 00:00:00 2001
From: Nadrieril
Date: Sat, 20 Apr 2019 23:07:00 +0200
Subject: Implement more normalization simplifications

---
 dhall_core/src/text.rs | 51 ++++++++++++++++++++++++--------------------------
 1 file changed, 24 insertions(+), 27 deletions(-)

(limited to 'dhall_core')

diff --git a/dhall_core/src/text.rs b/dhall_core/src/text.rs
index ff5c441..83643d9 100644
--- a/dhall_core/src/text.rs
+++ b/dhall_core/src/text.rs
@@ -1,5 +1,4 @@
 use std::iter::FromIterator;
-use std::ops::Add;
 
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct InterpolatedText<SubExpr> {
@@ -33,6 +32,16 @@ pub enum InterpolatedTextContents<SubExpr> {
     Expr(SubExpr),
 }
 
+impl<SubExpr> InterpolatedTextContents<SubExpr> {
+    pub fn is_empty(&self) -> bool {
+        use InterpolatedTextContents::{Expr, Text};
+        match self {
+            Expr(_) => false,
+            Text(s) => s.is_empty(),
+        }
+    }
+}
+
 impl<SubExpr> InterpolatedText<SubExpr> {
     pub fn traverse_ref<'a, SubExpr2, E, F>(
         &'a self,
@@ -51,13 +60,6 @@ impl<SubExpr> InterpolatedText<SubExpr> {
         })
     }
 
-    pub fn as_ref(&self) -> InterpolatedText<&SubExpr> {
-        InterpolatedText {
-            head: self.head.clone(),
-            tail: self.tail.iter().map(|(e, s)| (e, s.clone())).collect(),
-        }
-    }
-
     pub fn iter<'a>(
         &'a self,
     ) -> impl Iterator<Item = InterpolatedTextContents<SubExpr>> + 'a
@@ -65,24 +67,26 @@ impl<SubExpr> InterpolatedText<SubExpr> {
         SubExpr: Clone,
     {
         use std::iter::once;
-        once(InterpolatedTextContents::Text(self.head.clone())).chain(
-            self.tail.iter().flat_map(|(e, s)| {
-                once(InterpolatedTextContents::Expr(SubExpr::clone(e)))
-                    .chain(once(InterpolatedTextContents::Text(s.clone())))
-            }),
-        )
+        use InterpolatedTextContents::{Expr, Text};
+        once(Text(self.head.clone()))
+            .chain(self.tail.iter().flat_map(|(e, s)| {
+                once(Expr(SubExpr::clone(e))).chain(once(Text(s.clone())))
+            }))
+            .filter(|c| !c.is_empty())
     }
 
     pub fn into_iter(
         self,
     ) -> impl Iterator<Item = InterpolatedTextContents<SubExpr>> {
         use std::iter::once;
-        once(InterpolatedTextContents::Text(self.head)).chain(
-            self.tail.into_iter().flat_map(|(e, s)| {
-                once(InterpolatedTextContents::Expr(e))
-                    .chain(once(InterpolatedTextContents::Text(s)))
-            }),
-        )
+        use InterpolatedTextContents::{Expr, Text};
+        once(Text(self.head))
+            .chain(
+                self.tail
+                    .into_iter()
+                    .flat_map(|(e, s)| once(Expr(e)).chain(once(Text(s)))),
+            )
+            .filter(|c| !c.is_empty())
     }
 }
 
@@ -110,10 +114,3 @@ impl<SubExpr> FromIterator<InterpolatedTextContents<SubExpr>>
         res
     }
 }
-
-impl<SubExpr: Clone> Add for &InterpolatedText<SubExpr> {
-    type Output = InterpolatedText<SubExpr>;
-    fn add(self, rhs: &InterpolatedText<SubExpr>) -> Self::Output {
-        self.iter().chain(rhs.iter()).collect()
-    }
-}
-- 
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