Add fennel support, closes #514

1 files changed, 330 insertions, 0 deletions

diff --git a/indent/fennel.vim b/indent/fennel.vim
new file mode 100644
index 00000000..c4516135
--- /dev/null
+++ b/indent/fennel.vim
@@ -0,0 +1,330 @@
+if !exists('g:polyglot_disabled') || index(g:polyglot_disabled, 'fennel') == -1
+
+" Vim filetype plugin file
+" Language: FENNEL
+" Maintainer: Calvin Rose
+"
+" Modified from vim-clojure-static
+" https://github.com/guns/vim-clojure-static/blob/master/indent/clojure.vim
+" This should eventually be replaced by a more standard and performant
+" indenter.
+
+if exists("b:did_indent")
+	finish
+endif
+let b:did_indent = 1
+
+let s:save_cpo = &cpo
+set cpo&vim
+
+setlocal noautoindent nosmartindent
+setlocal softtabstop=2 shiftwidth=2 expandtab
+setlocal indentkeys=!,o,O
+
+if exists("*searchpairpos")
+
+	if !exists('g:fennel_maxlines')
+		let g:fennel_maxlines = 100
+	endif
+
+	if !exists('g:fennel_fuzzy_indent')
+		let g:fennel_fuzzy_indent = 1
+	endif
+
+	if !exists('g:fennel_fuzzy_indent_patterns')
+		let g:fennel_fuzzy_indent_patterns = ['^def', '^let', '^while', '^if', '^fn$', '^var$', '^case$', '^for$', '^each$', '^local$', '^global$', '^match$', '^macro', '^lambda$']
+	endif
+
+	if !exists('g:fennel_fuzzy_indent_blacklist')
+		let g:fennel_fuzzy_indent_blacklist = []
+	endif
+
+	if !exists('g:fennel_special_indent_words')
+		let g:fennel_special_indent_words = ''
+	endif
+
+	if !exists('g:fennel_align_multiline_strings')
+		let g:fennel_align_multiline_strings = 0
+	endif
+
+	if !exists('g:fennel_align_subforms')
+		let g:fennel_align_subforms = 0
+	endif
+
+	function! s:syn_id_name()
+		return synIDattr(synID(line("."), col("."), 0), "name")
+	endfunction
+
+	function! s:ignored_region()
+		return s:syn_id_name() =~? '\vstring|comment|character'
+	endfunction
+
+	function! s:current_char()
+		return getline('.')[col('.')-1]
+	endfunction
+
+	function! s:current_word()
+		return getline('.')[col('.')-1 : searchpos('\v>', 'n', line('.'))[1]-2]
+	endfunction
+
+	function! s:is_paren()
+		return s:current_char() =~# '\v[\(\)\[\]\{\}]' && !s:ignored_region()
+	endfunction
+
+	" Returns 1 if string matches a pattern in 'patterns', which may be a
+	" list of patterns, or a comma-delimited string of implicitly anchored
+	" patterns.
+	function! s:match_one(patterns, string)
+		let list = type(a:patterns) == type([])
+		           \ ? a:patterns
+		           \ : map(split(a:patterns, ','), '"^" . v:val . "$"')
+		for pat in list
+			if a:string =~# pat | return 1 | endif
+		endfor
+	endfunction
+
+	function! s:match_pairs(open, close, stopat)
+		" Stop only on vector and map [ resp. {. Ignore the ones in strings and
+		" comments.
+		if a:stopat == 0 && g:fennel_maxlines > 0
+			let stopat = max([line(".") - g:fennel_maxlines, 0])
+		else
+			let stopat = a:stopat
+		endif
+
+		let pos = searchpairpos(a:open, '', a:close, 'bWn', "!s:is_paren()", stopat)
+		return [pos[0], col(pos)]
+	endfunction
+
+	function! s:fennel_check_for_string_worker()
+		" Check whether there is the last character of the previous line is
+		" highlighted as a string. If so, we check whether it's a ". In this
+		" case we have to check also the previous character. The " might be the
+		" closing one. In case the we are still in the string, we search for the
+		" opening ". If this is not found we take the indent of the line.
+		let nb = prevnonblank(v:lnum - 1)
+
+		if nb == 0
+			return -1
+		endif
+
+		call cursor(nb, 0)
+		call cursor(0, col("$") - 1)
+		if s:syn_id_name() !~? "string"
+			return -1
+		endif
+
+		" This will not work for a " in the first column...
+		if s:current_char() == '"' || s:current_char() == '`'
+			call cursor(0, col("$") - 2)
+			if s:syn_id_name() !~? "string"
+				return -1
+			endif
+			if s:current_char() != '\'
+				return -1
+			endif
+			call cursor(0, col("$") - 1)
+		endif
+
+		let p = searchpos('\(^\|[^\\]\)\zs"\`', 'bW')
+
+		if p != [0, 0]
+			return p[1] - 1
+		endif
+
+		return indent(".")
+	endfunction
+
+	function! s:check_for_string()
+		let pos = getpos('.')
+		try
+			let val = s:fennel_check_for_string_worker()
+		finally
+			call setpos('.', pos)
+		endtry
+		return val
+	endfunction
+
+	" Returns 1 for opening brackets, -1 for _anything else_.
+	function! s:bracket_type(char)
+		return stridx('([{', a:char) > -1 ? 1 : -1
+	endfunction
+
+	" Returns: [opening-bracket-lnum, indent]
+	function! s:fennel_indent_pos()
+		" Get rid of special case.
+		if line(".") == 1
+			return [0, 0]
+		endif
+
+		" We have to apply some heuristics here to figure out, whether to use
+		" normal lisp indenting or not.
+		let i = s:check_for_string()
+		if i > -1
+			return [0, i + !!g:fennel_align_multiline_strings]
+		endif
+
+		call cursor(0, 1)
+
+		" Find the next enclosing [ or {. We can limit the second search
+		" to the line, where the [ was found. If no [ was there this is
+		" zero and we search for an enclosing {.
+		let paren = s:match_pairs('(', ')', 0)
+		let bracket = s:match_pairs('\[', '\]', paren[0])
+		let curly = s:match_pairs('{', '}', bracket[0])
+
+		" In case the curly brace is on a line later then the [ or - in
+		" case they are on the same line - in a higher column, we take the
+		" curly indent.
+		if curly[0] > bracket[0] || curly[1] > bracket[1]
+			if curly[0] > paren[0] || curly[1] > paren[1]
+				return curly
+			endif
+		endif
+
+		" If the curly was not chosen, we take the bracket indent - if
+		" there was one.
+		if bracket[0] > paren[0] || bracket[1] > paren[1]
+			return bracket
+		endif
+
+		" There are neither { nor [ nor (, ie. we are at the toplevel.
+		if paren == [0, 0]
+			return paren
+		endif
+
+		" Now we have to reimplement lispindent. This is surprisingly easy, as
+		" soon as one has access to syntax items.
+		"
+		" - Check whether we are in a special position after a word in
+		"   g:fennel_special_indent_words. These are special cases.
+		" - Get the next keyword after the (.
+		" - If its first character is also a (, we have another sexp and align
+		"   one column to the right of the unmatched (.
+		" - In case it is in lispwords, we indent the next line to the column of
+		"   the ( + sw.
+		" - If not, we check whether it is last word in the line. In that case
+		"   we again use ( + sw for indent.
+		" - In any other case we use the column of the end of the word + 2.
+		call cursor(paren)
+
+		" In case we are at the last character, we use the paren position.
+		if col("$") - 1 == paren[1]
+			return paren
+		endif
+
+		" In case after the paren is a whitespace, we search for the next word.
+		call cursor(0, col('.') + 1)
+		if s:current_char() == ' '
+			call search('\v\S', 'W')
+		endif
+
+		" If we moved to another line, there is no word after the (. We
+		" use the ( position for indent.
+		if line(".") > paren[0]
+			return paren
+		endif
+
+		" We still have to check, whether the keyword starts with a (, [ or {.
+		" In that case we use the ( position for indent.
+		let w = s:current_word()
+		if s:bracket_type(w[0]) == 1
+			return paren
+		endif
+
+		let ww = w
+
+		if &lispwords =~# '\V\<' . ww . '\>'
+			return [paren[0], paren[1] + &shiftwidth - 1]
+		endif
+
+		if g:fennel_fuzzy_indent
+			\ && !s:match_one(g:fennel_fuzzy_indent_blacklist, ww)
+			\ && s:match_one(g:fennel_fuzzy_indent_patterns, ww)
+			return [paren[0], paren[1] + &shiftwidth - 1]
+		endif
+
+		call search('\v\_s', 'cW')
+		call search('\v\S', 'W')
+		if paren[0] < line(".")
+			return [paren[0], paren[1] + (g:fennel_align_subforms ? 0 : &shiftwidth - 1)]
+		endif
+
+		call search('\v\S', 'bW')
+		return [line('.'), col('.') + 1]
+	endfunction
+
+	function! GetFennelIndent()
+		let lnum = line('.')
+		let orig_lnum = lnum
+		let orig_col = col('.')
+		let [opening_lnum, indent] = s:fennel_indent_pos()
+
+		" Account for multibyte characters
+		if opening_lnum > 0
+			let indent -= indent - virtcol([opening_lnum, indent])
+		endif
+
+		" Return if there are no previous lines to inherit from
+		if opening_lnum < 1 || opening_lnum >= lnum - 1
+			call cursor(orig_lnum, orig_col)
+			return indent
+		endif
+
+		let bracket_count = 0
+
+		" Take the indent of the first previous non-white line that is
+		" at the same sexp level. cf. src/misc1.c:get_lisp_indent()
+		while 1
+			let lnum = prevnonblank(lnum - 1)
+			let col = 1
+
+			if lnum <= opening_lnum
+				break
+			endif
+
+			call cursor(lnum, col)
+
+			" Handle bracket counting edge case
+			if s:is_paren()
+				let bracket_count += s:bracket_type(s:current_char())
+			endif
+
+			while 1
+				if search('\v[(\[{}\])]', '', lnum) < 1
+					break
+				elseif !s:ignored_region()
+					let bracket_count += s:bracket_type(s:current_char())
+				endif
+			endwhile
+
+			if bracket_count == 0
+				" Check if this is part of a multiline string
+				call cursor(lnum, 1)
+				if s:syn_id_name() !~? '\vString|Buffer'
+					call cursor(orig_lnum, orig_col)
+					return indent(lnum)
+				endif
+			endif
+		endwhile
+
+		call cursor(orig_lnum, orig_col)
+		return indent
+	endfunction
+
+	setlocal indentexpr=GetFennelIndent()
+
+else
+
+	" In case we have searchpairpos not available we fall back to
+	" normal lisp indenting.
+	setlocal indentexpr=
+	setlocal lisp
+	let b:undo_indent .= '| setlocal lisp<'
+
+endif
+
+let &cpo = s:save_cpo
+unlet! s:save_cpo
+
+endif