runtime(kdl): include syntax, indent and ftplugin files

closes: #14956

Co-authored-by: Aram Drevekenin <aram@poor.dev>
Signed-off-by: inzuo Jiang <jiangyinzuo@foxmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/.github/MAINTAINERS b/.github/MAINTAINERS
index 7433062..926dc07 100644
--- a/.github/MAINTAINERS
+++ b/.github/MAINTAINERS
@@ -175,6 +175,7 @@
 runtime/ftplugin/julia.vim		@carlobaldassi
 runtime/ftplugin/jq.vim	    	        @vito-c
 runtime/ftplugin/kconfig.vim		@chrisbra
+runtime/ftplugin/kdl.vim		@imsnif @jiangyinzuo
 runtime/ftplugin/kotlin.vim		@udalov
 runtime/ftplugin/less.vim		@genoma
 runtime/ftplugin/liquid.vim		@tpope
@@ -292,6 +293,7 @@
 runtime/indent/json.vim			@elzr
 runtime/indent/jsonc.vim		@izhakjakov
 runtime/indent/julia.vim		@carlobaldassi
+runtime/indent/kdl.vim			@imsnif @jiangyinzuo
 runtime/indent/kotlin.vim		@udalov
 runtime/indent/krl.vim			@KnoP-01
 runtime/indent/ld.vim			@dkearns
@@ -434,6 +436,7 @@
 runtime/syntax/jq.vim		        @vito-c
 runtime/syntax/kconfig.vim		@chrisbra
 runtime/syntax/kotlin.vim		@udalov
+runtime/syntax/kdl.vim			@imsnif @jiangyinzuo
 runtime/syntax/krl.vim			@KnoP-01
 runtime/syntax/less.vim			@genoma
 runtime/syntax/liquid.vim		@tpope
diff --git a/runtime/ftplugin/kdl.vim b/runtime/ftplugin/kdl.vim
new file mode 100644
index 0000000..c9a1d8b
--- /dev/null
+++ b/runtime/ftplugin/kdl.vim
@@ -0,0 +1,17 @@
+" Vim filetype plugin
+" Language:         KDL
+" Author:           Aram Drevekenin <aram@poor.dev>
+" Maintainer:       Yinzuo Jiang <jiangyinzuo@foxmail.com>
+" Last Change:      2024-06-10
+
+if exists("b:did_ftplugin")
+  finish
+endif
+
+let b:did_ftplugin = 1
+
+setlocal comments=://
+setlocal commentstring=//\ %s
+setlocal formatoptions-=t
+
+let b:undo_ftplugin = 'setlocal comments< commentstring< formatoptions<'
diff --git a/runtime/indent/kdl.vim b/runtime/indent/kdl.vim
new file mode 100644
index 0000000..2d24f18
--- /dev/null
+++ b/runtime/indent/kdl.vim
@@ -0,0 +1,26 @@
+" Vim indent file
+" Language:         KDL
+" Author:           Aram Drevekenin <aram@poor.dev>
+" Maintainer:       Yinzuo Jiang <jiangyinzuo@foxmail.com>
+" Last Change:      2024-06-10
+
+" Only load this indent file when no other was loaded.
+if exists("b:did_indent")
+    finish
+endif
+let b:did_indent = 1
+
+setlocal indentexpr=KdlIndent()
+let b:undo_indent = "setlocal indentexpr<"
+
+function! KdlIndent(...)
+  let line = getline(v:lnum)
+  let previousNum = prevnonblank(v:lnum - 1)
+  let previous = getline(previousNum)
+
+  if previous =~ "{" && previous !~ "}" && line !~ "}" && line !~ ":$"
+    return indent(previousNum) + &tabstop
+  else
+    return indent(previousNum)
+  endif
+endfunction
diff --git a/runtime/syntax/kdl.vim b/runtime/syntax/kdl.vim
new file mode 100644
index 0000000..a36bb9e
--- /dev/null
+++ b/runtime/syntax/kdl.vim
@@ -0,0 +1,45 @@
+" Vim syntax file
+" Language: KDL
+" Maintainer: Aram Drevekenin <aram@poor.dev>
+" Maintainer: Yinzuo Jiang <jiangyinzuo@foxmail.com>
+" Latest Revision: 2024-06-10
+
+" quit when a syntax file was already loaded
+if exists("b:current_syntax")
+  finish
+endif
+
+syn match kdlNode '\v(\w|-|\=)' display
+syn match kdlBool '\v(true|false)' display
+
+syn keyword kdlTodo contained TODO FIXME XXX NOTE
+syn match kdlComment "//.*$" contains=kdlTodo
+
+" Regular int like number with - + or nothing in front
+syn match kdlNumber '\d\+'
+syn match kdlNumber '[-+]\d\+'
+
+" Floating point number with decimal no E or e (+,-)
+syn match kdlNumber '\d\+\.\d*' contained display
+syn match kdlNumber '[-+]\d\+\.\d*' contained display
+ 
+" Floating point like number with E and no decimal point (+,-)
+syn match kdlNumber '[-+]\=\d[[:digit:]]*[eE][\-+]\=\d\+' contained display
+syn match kdlNumber '\d[[:digit:]]*[eE][\-+]\=\d\+' contained display
+ 
+" Floating point like number with E and decimal point (+,-)
+syn match kdlNumber '[-+]\=\d[[:digit:]]*\.\d*[eE][\-+]\=\d\+' contained display
+syn match kdlNumber '\d[[:digit:]]*\.\d*[eE][\-+]\=\d\+' contained display
+
+syn region kdlString start='"' end='"' skip='\\\\\|\\"' display
+ 
+syn region kdlChildren start="{" end="}" contains=kdlString,kdlNumber,kdlNode,kdlBool,kdlComment
+
+hi def link kdlTodo        Todo
+hi def link kdlComment     Comment
+hi def link kdlNode        Statement
+hi def link kdlBool        Boolean
+hi def link kdlString      String
+hi def link kdlNumber      Number
+
+let b:current_syntax = "kdl"