From 7eee81a7284bea5294d1dbe059eaae1507d3f530 Mon Sep 17 00:00:00 2001
From: Evan Silberman <evan@jklol.net>
Date: Wed, 6 Mar 2024 19:42:35 -0800
Subject: [PATCH] Don't print out excessive ANSI codes
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

The ANSI renderer was printing out astonishing quantities of SGR 0s,
which don't hurt anything but has bad code aesthetics. Fix it to only
print out font requests when the font changes.

before:

```
♪ pandoc$ cabal exec -- pandoc -t ansi doc/customizing-pandoc.md  | wc -c
   17986
```

after:

```
♪ pandoc$ cabal exec -- pandoc -t ansi doc/customizing-pandoc.md  | wc -c
    5297
```
---
 src/Text/DocLayout.hs | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/src/Text/DocLayout.hs b/src/Text/DocLayout.hs
index 895808e..64a7b2f 100644
--- a/src/Text/DocLayout.hs
+++ b/src/Text/DocLayout.hs
@@ -289,8 +289,8 @@ render :: HasChars a => Maybe Int -> Doc a -> a
 render = renderPlain
 
 renderANSI :: HasChars a => Maybe Int -> Doc a -> a
-renderANSI n d = go $ prerender n d where
-  go (Attributed s) = foldMap attrRender s
+renderANSI n d = snd $ go $ prerender n d where
+  go (Attributed s) = foldl attrRender (baseFont, "") s
 
 renderPlain :: HasChars a => Maybe Int -> Doc a -> a
 renderPlain n d = go $ prerender n d where
@@ -300,10 +300,11 @@ attrStrip :: HasChars a => Attr a -> a
 attrStrip (Attr _ y) | isNull y = ""
                      | otherwise = y
 
-attrRender :: HasChars a => Attr a -> a
-attrRender a = go a <> renderFont baseFont where
-  go (Attr f y) | isNull y = ""
-                | otherwise = renderFont f <> y
+attrRender :: HasChars a => (Font, a) -> Attr a -> (Font, a)
+attrRender (f, acc) (Attr g y)
+  | isNull y = (f, acc)
+  | f == g = (f, acc <> y)
+  | otherwise = (g, acc <> renderFont g <> y)
 
 prerender :: HasChars a => Maybe Int -> Doc a -> Attributed a
 prerender linelen doc = fromList . reverse . output $