1 files changed, 128 insertions, 0 deletions
diff --git a/indent/svelte.vim b/indent/svelte.vim
new file mode 100644
index 00000000..0b3c732f
--- /dev/null
+++ b/indent/svelte.vim
@@ -0,0 +1,128 @@
+if exists('g:polyglot_disabled') && index(g:polyglot_disabled, 'svelte') != -1
+  finish
+endif
+
+" Vim indent file
+" Language:   Svelte 3 (HTML/JavaScript)
+" Author:     Evan Lecklider <evan@lecklider.com>
+" Maintainer: Evan Lecklide <evan@lecklider.com>
+" URL:        https://github.com/evanleck/vim-svelte
+
+if exists("b:did_indent")
+  finish
+endif
+
+runtime! indent/html.vim
+unlet! b:did_indent
+
+let s:html_indent = &l:indentexpr
+let b:did_indent = 1
+
+setlocal indentexpr=GetSvelteIndent()
+setlocal indentkeys=o,O,*<Return>,<>>,{,},0),0],!^F,;,=:else,=:then,=:catch,=/if,=/each,=/await
+
+" Only define the function once.
+if exists('*GetSvelteIndent')
+  finish
+endif
+
+function! GetSvelteIndent()
+  let current_line_number = v:lnum
+
+  if current_line_number == 0
+    return 0
+  endif
+
+  let current_line = getline(current_line_number)
+
+  " Opening script and style tags should be all the way outdented.
+  if current_line =~ '^\s*</\?\(script\|style\)'
+    return 0
+  endif
+
+  let previous_line_number = prevnonblank(current_line_number - 1)
+  let previous_line = getline(previous_line_number)
+  let previous_line_indent = indent(previous_line_number)
+
+  " The inside of scripts an styles should be indented.
+  if previous_line =~ '^<\(script\|style\)'
+    return shiftwidth()
+  endif
+
+  execute "let indent = " . s:html_indent
+
+  " For some reason, the HTML CSS indentation keeps indenting the next line over
+  " and over after each style declaration.
+  if searchpair('<style>', '', '</style>', 'bW') && previous_line =~ ';$' && current_line !~ '}'
+    return previous_line_indent
+  endif
+
+  " "#if" or "#each"
+  if previous_line =~ '^\s*{\s*#\(if\|each\|await\)'
+    return previous_line_indent + shiftwidth()
+  endif
+
+  " ":else" or ":then"
+  if previous_line =~ '^\s*{\s*:\(else\|catch\|then\)'
+    return previous_line_indent + shiftwidth()
+  endif
+
+  " Custom element juggling for abnormal self-closing tags (<Widget />),
+  " capitalized component tags (<Widget></Widget>), and custom svelte tags
+  " (<svelte:head></svelte:head>).
+  if synID(previous_line_number, match(previous_line, '\S') + 1, 0) == hlID('htmlTag')
+        \ && synID(current_line_number, match(current_line, '\S') + 1, 0) != hlID('htmlEndTag')
+    let indents_match = indent == previous_line_indent
+    let previous_closes = previous_line =~ '/>$'
+
+    if indents_match && !previous_closes && previous_line =~ '<\(\u\|\l\+:\l\+\)'
+      return previous_line_indent + shiftwidth()
+    elseif !indents_match && previous_closes
+      return previous_line_indent
+    endif
+  endif
+
+  " "/await" or ":catch" or ":then"
+  if current_line =~ '^\s*{\s*\/await' || current_line =~ '^\s*{\s*:\(catch\|then\)'
+    let await_start = searchpair('{\s*#await\>', '', '{\s*\/await\>', 'bW')
+
+    if await_start
+      return indent(await_start)
+    endif
+  endif
+
+  " "/each"
+  if current_line =~ '^\s*{\s*\/each'
+    let each_start = searchpair('{\s*#each\>', '', '{\s*\/each\>', 'bW')
+
+    if each_start
+      return indent(each_start)
+    endif
+  endif
+
+  " "/if"
+  if current_line =~ '^\s*{\s*\/if'
+    let if_start = searchpair('{\s*#if\>', '', '{\s*\/if\>', 'bW')
+
+    if if_start
+      return indent(if_start)
+    endif
+  endif
+
+  " ":else" is tricky because it can match an opening "#each" _or_ an opening
+  " "#if", so we try to be smart and look for the closest of the two.
+  if current_line =~ '^\s*{\s*:else'
+    let if_start = searchpair('{\s*#if\>', '', '{\s*\/if\>', 'bW')
+
+    " If it's an "else if" then we know to look for an "#if"
+    if current_line =~ '^\s*{\s*:else if' && if_start
+      return indent(if_start)
+    else
+      " The greater line number will be closer to the cursor position because
+      " we're searching backward.
+      return indent(max([if_start, searchpair('{\s*#each\>', '', '{\s*\/each\>', 'bW')]))
+    endif
+  endif
+
+  return indent
+endfunction