From 80a4e666221a10ba41bd1d00bf2e9c77794b3064 Mon Sep 17 00:00:00 2001
From: Alex Chapman <alex@farfromthere.net>
Date: Wed, 30 Oct 2019 10:22:12 +1100
Subject: [PATCH] Add syntax support for the Dhall configuration language.

---
 rc/filetype/dhall.kak | 90 +++++++++++++++++++++++++++++++++++++++++++
 rc/tools/comment.kak  |  2 +-
 2 files changed, 91 insertions(+), 1 deletion(-)
 create mode 100644 rc/filetype/dhall.kak

diff --git a/rc/filetype/dhall.kak b/rc/filetype/dhall.kak
new file mode 100644
index 00000000..0dcd8d28
--- /dev/null
+++ b/rc/filetype/dhall.kak
@@ -0,0 +1,90 @@
+# https://dhall-lang.org
+#                       
+
+# Detection
+# ‾‾‾‾‾‾‾‾‾
+
+hook global BufCreate .*[.](dhall) %{
+    set-option buffer filetype dhall
+}
+
+# Initialization
+# ‾‾‾‾‾‾‾‾‾‾‾‾‾‾
+
+hook global WinSetOption filetype=dhall %{
+    require-module dhall
+
+    hook window ModeChange insert:.* -group dhall-trim-indent  dhall-trim-indent
+    hook window InsertChar \n -group dhall-indent dhall-indent-on-new-line
+
+    hook -once -always window WinSetOption filetype=.* %{ remove-hooks window dhall-.+ }
+}
+
+hook -group dhall-highlight global WinSetOption filetype=dhall %{
+    add-highlighter window/dhall ref dhall
+    hook -once -always window WinSetOption filetype=.* %{ remove-highlighter window/dhall }
+}
+
+
+provide-module dhall %[
+    
+# Highlighters
+# ‾‾‾‾‾‾‾‾‾‾‾‾
+
+add-highlighter shared/dhall regions
+add-highlighter shared/dhall/code default-region group
+add-highlighter shared/dhall/string  region          '"'          (?<!\\)(\\\\)*" fill string
+add-highlighter shared/dhall/comment region -recurse \{- \{-      -\}             fill comment
+add-highlighter shared/dhall/line_comment region -- $ fill comment
+
+# Matches built-in types
+add-highlighter shared/dhall/code/ regex \b(Location|Sort|Kind|Type|Text|Bool|Natural|Integer|Double|List|Optional)\b 0:type
+
+# Matches built-in keywords
+add-highlighter shared/dhall/code/ regex \b(if|then|else|let|in|using|missing|as|merge|toMap)\b 0:keyword
+
+# Matches bulit-in values
+add-highlighter shared/dhall/code/ regex \b(True|False|Some|None|-?Infinity||NaN)\b 0:value 
+
+# Matches built-in operators
+add-highlighter shared/dhall/code/ regex (,|:|\|\||&&|==|!=|=|\+|\*|\+\+|#|⩓|//\\\\|→|->|\?|λ|\\|\^|⫽|//|\[|\]|\{|\}) 0:operator
+
+# Matches built-in functions
+add-highlighter shared/dhall/code/ regex \b(Natural-fold|Natural-build|Natural-isZero|Natural-even|Natural-odd|Natural-toInteger|Natural-show|Integer-toDouble|Integer-show|Natural-subtract|Double-show|List-build|List-fold|List-length|List-head|List-last|List-indexed|List-reverse|Optional-fold|Optional-build|Text-show)\b 0:keyword
+
+# Matches http[s] imports
+add-highlighter shared/dhall/code/ regex \b(http[s]://\S+)\b(\s+sha256:[a-f0-9]{64}\b)? 0:meta
+
+# Matches local imports
+add-highlighter shared/dhall/code/ regex (~|\.|\.\.|/)\S+ 0:meta
+
+# Matches number (natural, integer, double) literals
+add-highlighter shared/dhall/code/ regex \b(\+|-)?\d+(\.\d+)?(e(\+|-)?\d+)?\b 0:value
+
+# Matches union syntax
+add-highlighter shared/dhall/union region -recurse < < > group
+add-highlighter shared/dhall/union/sep regex (<|\|)\s*((?:_|[A-Z])(?:[a-zA-Z0-9-/_]*))\s*(?:(:)([^|>]*))? 1:operator 2:attribute 3:operator 4:type
+add-highlighter shared/dhall/union/end regex > 0:operator
+
+# Commands
+# ‾‾‾‾‾‾‾‾
+
+define-command -hidden dhall-trim-indent %{
+    # remove trailing white spaces
+    try %{ execute-keys -draft -itersel <a-x> s \h+$ <ret> d }
+}
+
+define-command -hidden dhall-indent-on-new-line %{
+    evaluate-commands -draft -itersel %{
+        # copy -- comments prefix and following white spaces
+        try %{ execute-keys -draft k <a-x> s ^\h*\K--\h* <ret> y gh j P }
+        # preserve previous line indent
+        try %{ execute-keys -draft \; K <a-&> }
+        # filter previous line
+        try %{ execute-keys -draft k : dhall-trim-indent <ret> }
+        # indent after lines ending with let, : or =
+        try %{ execute-keys -draft \; k x <a-k> (let|:|=)$ <ret> j <a-gt> }
+    }
+}
+
+]
diff --git a/rc/tools/comment.kak b/rc/tools/comment.kak
index 586b516b..39d62501 100644
--- a/rc/tools/comment.kak
+++ b/rc/tools/comment.kak
@@ -20,7 +20,7 @@ hook global BufSetOption filetype=(c|cpp|dart|go|java|javascript|objc|php|rust|s
     set-option buffer comment_block_end '*/'
 }
 
-hook global BufSetOption filetype=(cabal|haskell|moon|idris|elm) %{
+hook global BufSetOption filetype=(cabal|haskell|moon|idris|elm|dhall) %{
     set-option buffer comment_line '--'
     set-option buffer comment_block_begin '{-'
     set-option buffer comment_block_end '-}'