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Start of a small Clojure reader for indentation w/o syntax highlighting
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Not complete yet, but getting there.
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@axvr
axvr committed Apr 30, 2023
1 parent 51f5dcb commit cc9cda7
Showing 1 changed file with 88 additions and 89 deletions.
177 changes: 88 additions & 89 deletions indent/clojure.vim
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Original file line number Diff line number Diff line change
Expand Up @@ -21,24 +21,86 @@ setlocal noautoindent nosmartindent nolisp
setlocal softtabstop=2 shiftwidth=2 expandtab
setlocal indentkeys=!,o,O

function! s:GetSynIdName(line, col)
return synIDattr(synID(a:line, a:col, 0), 'name')
" Returns true if char_idx is preceded by an odd number of backslashes.
function! s:IsEscaped(line_str, char_idx)
let ln = a:line_str[: a:char_idx - 1]
return (strlen(ln) - strlen(trim(ln, '\', 2))) % 2
endfunction

function! s:SyntaxMatch(pattern, line, col)
return s:GetSynIdName(a:line, a:col) =~? a:pattern
endfunction
let s:pairs = {'(': ')', '[': ']', '{': '}'}

" TODO: Maybe write a Vim9script version of this?
" Repeatedly search for tokens on the given line in reverse order building up
" a list of tokens and their positions. Ignores escaped tokens.
function! s:AnalyseLine(line_num)
let tokens = []
let ln = getline(a:line_num)
while 1
" Due to legacy Vimscript being painfully slow, we literally
" have to move the cursor and perform searches which is
" ironically faster than for looping by character.
let token = searchpos('[()\[\]{};"]', 'bW', a:line_num)

if token == [0, 0] | break | endif
let t_idx = token[1] - 1
if s:IsEscaped(ln, t_idx) | continue | endif
let t_char = ln[t_idx]
if t_char ==# ';'
" Comment found, reset the token list for this line.
tokens = []
elseif t_char =~# '[()\[\]{}"]'
" Add token to the list.
call add(tokens, [t_char, token])
endif
endwhile

function! s:IgnoredRegion()
return s:SyntaxMatch('\%(string\|regex\|comment\|character\)', line('.'), col('.'))
return tokens
endfunction

function! s:NotStringDelimiter()
return ! s:SyntaxMatch('stringdelimiter', line('.'), col('.'))
endfunction
" This should also be capable of figuring out if we're in a multi-line string
" or regex.
function! s:InverseRead(lnum)
let lnum = a:lnum - 1
let tokens = []

while lnum > 0
call cursor(lnum + 1, 1)
let line_tokens = s:AnalyseLine(lnum)

" let should_ignore = empty(a:tokens) ? 0 : (a:tokens[-1][0] ==# '"')

" Reduce "tokens" and "line_tokens".
for t in line_tokens
" TODO: attempt early termination.
if empty(tokens)
call add(tokens, t)
elseif t[0] ==# '"' && tokens[-1][0] ==# '"'
" TODO: track original start and ignore values
" inside strings.
call remove(tokens, -1)
elseif get(s:pairs, t[0], '') ==# tokens[-1][0]
" Matching pair: drop the last item in tokens.
call remove(tokens, -1)
else
" No match: append to token list.
call add(tokens, t)
endif
endfor

" echom 'Pass' lnum tokens

if ! empty(tokens) && has_key(s:pairs, tokens[0][0])
" TODO: on string match, check if string or regex.
" echom 'Match!' tokens[0]
return tokens[0]
endif

let lnum -= 1
endwhile

function! s:NotRegexpDelimiter()
return ! s:SyntaxMatch('regexpdelimiter', line('.'), col('.'))
return ['^', [0, 0]] " Default to top-level.
endfunction

function! s:Conf(opt, default)
Expand All @@ -51,7 +113,7 @@ function! s:EqualsOperatorInEffect()
return v:operator ==# '=' && state('o') ==# 'o'
endfunction

function! s:GetStringIndent(delim_pos, regex)
function! s:GetStringIndent(delim_pos, is_regex)
" Mimic multi-line string indentation behaviour in VS Code and Emacs.
let m = mode()
if m ==# 'i' || (m ==# 'n' && ! s:EqualsOperatorInEffect())
Expand All @@ -62,7 +124,7 @@ function! s:GetStringIndent(delim_pos, regex)
" 1: Indent in alignment with string start delimiter.
if alignment == -1 | return 0
elseif alignment == 1 | return a:delim_pos[1]
else | return a:delim_pos[1] - (a:regex ? 2 : 1)
else | return a:delim_pos[1] - (a:is_regex ? 2 : 1)
endif
else
return -1 " Keep existing indent.
Expand All @@ -71,97 +133,34 @@ endfunction

function! s:GetListIndent(delim_pos)
" TODO Begin analysis and apply rules!
" let lns = getline(delim_pos[0], v:lnum - 1)
let ln1 = getline(delim_pos[0])
let sym = get(split(ln1[delim_pos[1]:], '[[:space:],;()\[\]{}@\\"^~`]', 1), 0, -1)
if sym != -1 && ! empty(sym) && match(sym, '^[0-9:]') == -1
" TODO: align indentation.
" TODO: lookup rules.
return delim_pos[1] + 1 " 2 space indentation
endif

" TODO: switch between 1 vs 2 space indentation.
return delim_pos[1] " 1 space indentation
endfunction

" Wrapper around "searchpairpos" that will automatically set "s:best_match" to
" the closest pair match and optimises the "stopline" value for later
" searches. This results in a significant performance gain by reducing the
" search distance and number of syntax lookups that need to take place.
function! s:CheckPair(name, start, end, SkipFn)
let prevln = s:best_match[1][0]
let pos = searchpairpos(a:start, '', a:end, 'bznW', a:SkipFn, prevln)
if prevln < pos[0] || (prevln == pos[0] && s:best_match[1][1] < pos[1])
let s:best_match = [a:name, pos]
endif
endfunction

function! s:GetCurrentSynName(lnum)
if empty(getline(a:lnum))
" Improves the accuracy of string detection when a newline is
" entered while in insert mode.
let strline = a:lnum - 1
return s:GetSynIdName(strline, strlen(getline(strline)))
else
return s:GetSynIdName(a:lnum, 1)
endif
endfunction

function! s:GetClojureIndent()
" Move cursor to the first column of the line we want to indent.
call cursor(v:lnum, 1)

let s:best_match = ['top', [0, 0]]

let synname = s:GetCurrentSynName(v:lnum)
if synname =~? 'string'
call s:CheckPair('str', '"', '"', function('<SID>NotStringDelimiter'))
" Sometimes, string highlighting does not kick in correctly,
" until after this first "s:CheckPair" call, so we have to
" detect and attempt an automatic correction.
let new_synname = s:GetCurrentSynName(v:lnum)
if new_synname !=# synname
echoerr 'Misdetected string! Retrying...'
let s:best_match = ['top', [0, 0]]
let synname = new_synname
endif
endif

if synname =~? 'string'
" We already checked this above, so pass through this block.
elseif synname =~? 'regex'
call s:CheckPair('rex', '#\zs"', '"', function('<SID>NotRegexpDelimiter'))
else
let IgnoredRegionFn = function('<SID>IgnoredRegion')
if bufname() =~? '\.edn$'
" If EDN file, check list pair last.
call s:CheckPair('map', '{', '}', IgnoredRegionFn)
call s:CheckPair('vec', '\[', '\]', IgnoredRegionFn)
call s:CheckPair('lst', '(', ')', IgnoredRegionFn)
else
" If CLJ file, check list pair first.
call s:CheckPair('lst', '(', ')', IgnoredRegionFn)
call s:CheckPair('map', '{', '}', IgnoredRegionFn)
call s:CheckPair('vec', '\[', '\]', IgnoredRegionFn)
endif
endif

" Calculate and return indent to use based on the matching form.
let [formtype, coord] = s:best_match
if formtype ==# 'top' | return 0 " At top level, no indent.
elseif formtype ==# 'lst' | return s:GetListIndent(coord)
elseif formtype ==# 'vec' | return coord[1] " Vector
elseif formtype ==# 'map' | return coord[1] " Map/set
elseif formtype ==# 'str' | return s:GetStringIndent(coord, 0)
elseif formtype ==# 'rex' | return s:GetStringIndent(coord, 1)
else | return -1 " Keep existing indent.
let [formtype, coord] = s:InverseRead(v:lnum)
if formtype ==# '^' | return 0 " At top-level, no indent.
elseif formtype ==# '(' | return s:GetListIndent(coord)
elseif formtype ==# '[' | return coord[1] " Vector
elseif formtype ==# '{' | return coord[1] " Map/set
elseif formtype ==# '"' | return s:GetStringIndent(coord, 0)
elseif formtype ==# '#"' | return s:GetStringIndent(coord, 1)
else | return -1 " Keep existing indent.
endif
endfunction

if exists("*searchpairpos")
setlocal indentexpr=s:GetClojureIndent()
else
" If "searchpairpos" is not available, fallback to Lisp indenting.
setlocal lisp
endif
" TODO: lispoptions if exists.
setlocal indentexpr=s:GetClojureIndent()

let &cpoptions = s:save_cpo
unlet! s:save_cpo
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