" MetaPost indent file
" Language: MetaPost
" Maintainer: Nicola Vitacolonna <nvitacolonna@gmail.com>
" Former Maintainers: Eugene Minkovskii <emin@mccme.ru>
" Last Change: 2016 Oct 2, 4:13pm
" Version: 0.2
if exists("b:did_indent")
finish
endif
let b:did_indent = 1
setlocal indentexpr=GetMetaPostIndent()
setlocal indentkeys+==end,=else,=fi,=fill,0),0]
let b:undo_indent = "setl indentkeys< indentexpr<"
" Only define the function once.
if exists("*GetMetaPostIndent")
finish
endif
let s:keepcpo= &cpo
set cpo&vim
function GetMetaPostIndent()
let ignorecase_save = &ignorecase
try
let &ignorecase = 0
return GetMetaPostIndentIntern()
finally
let &ignorecase = ignorecase_save
endtry
endfunc
" Regexps {{{
" Note: the next three variables are made global so that a user may add
" further keywords.
"
" Example:
"
" Put these in ~/.vim/after/indent/mp.vim
"
" let g:mp_open_tag .= '\|\<begintest\>'
" let g:mp_close_tag .= '\|\<endtest\>'
" Expressions starting indented blocks
let g:mp_open_tag = ''
\ . '\<if\>'
\ . '\|\<else\%[if]\>'
\ . '\|\<for\%(\|ever\|suffixes\)\>'
\ . '\|\<begingroup\>'
\ . '\|\<\%(\|var\|primary\|secondary\|tertiary\)def\>'
\ . '\|^\s*\<begin\%(fig\|graph\|glyph\|char\|logochar\)\>'
\ . '\|[([{]'
" Expressions ending indented blocks
let g:mp_close_tag = ''
\ . '\<fi\>'
\ . '\|\<else\%[if]\>'
\ . '\|\<end\%(\|for\|group\|def\|fig\|char\|glyph\|graph\)\>'
\ . '\|[)\]}]'
" Statements that may span multiple lines and are ended by a semicolon. To
" keep this list short, statements that are unlikely to be very long or are
" not very common (e.g., keywords like `interim` or `showtoken`) are not
" included.
"
" The regex for assignments and equations (the last branch) is tricky, because
" it must not match things like `for i :=`, `if a=b`, `def...=`, etc... It is
" not perfect, but it works reasonably well.
let g:mp_statement = ''
\ . '\<\%(\|un\|cut\)draw\>'
\ . '\|\<\%(\|un\)fill\%[draw]\>'
\ . '\|\<draw\%(dbl\)\=arrow\>'
\ . '\|\<clip\>'
\ . '\|\<addto\>'
\ . '\|\<save\>'
\ . '\|\<setbounds\>'
\ . '\|\<message\>'
\ . '\|\<errmessage\>'
\ . '\|\<errhelp\>'
\ . '\|\<fontmapline\>'
\ . '\|\<pickup\>'
\ . '\|\<show\>'
\ . '\|\<special\>'
\ . '\|\<write\>'
\ . '\|\%(^\|;\)\%([^;=]*\%('.g:mp_open_tag.'\)\)\@!.\{-}:\=='
" A line ends with zero or more spaces, possibly followed by a comment.
let s:eol = '\s*\%($\|%\)'
" }}}
" Auxiliary functions {{{
" Returns 1 if (0-based) position immediately preceding `pos` in `line` is
" inside a string or a comment; returns 0 otherwise.
" This is the function that is called more often when indenting, so it is
" critical that it is efficient. The method we use is significantly faster
" than using syntax attributes, and more general (it does not require
" syntax_items). It is also faster than using a single regex matching an even
" number of quotes. It helps that MetaPost strings cannot span more than one
" line and cannot contain escaped quotes.
function! s:CommentOrString(line, pos)
let in_string = 0
let q = stridx(a:line, '"')
let c = stridx(a:line, '%')
while q >= 0 && q < a:pos
if c >= 0 && c < q
if in_string " Find next percent symbol
let c = stridx(a:line, '%', q + 1)
else " Inside comment
return 1
endif
endif
let in_string = 1 - in_string
let q = stridx(a:line, '"', q + 1) " Find next quote
endwhile
return in_string || (c >= 0 && c <= a:pos)
endfunction
" Find the first non-comment non-blank line before the current line.
function! s:PrevNonBlankNonComment(lnum)
let l:lnum = prevnonblank(a:lnum - 1)
while getline(l:lnum) =~# '^\s*%'
let l:lnum = prevnonblank(l:lnum - 1)
endwhile
return l:lnum
endfunction
" Returns true if the last tag appearing in the line is an open tag; returns
" false otherwise.
function! s:LastTagIsOpen(line)
let o = s:LastValidMatchEnd(a:line, g:mp_open_tag, 0)
if o == - 1 | return v:false | endif
return s:LastValidMatchEnd(a:line, g:mp_close_tag, o) < 0
endfunction
" A simple, efficient and quite effective heuristics is used to test whether
" a line should cause the next line to be indented: count the "opening tags"
" (if, for, def, ...) in the line, count the "closing tags" (endif, endfor,
" ...) in the line, and compute the difference. We call the result the
" "weight" of the line. If the weight is positive, then the next line should
" most likely be indented. Note that `else` and `elseif` are both opening and
" closing tags, so they "cancel out" in almost all cases, the only exception
" being a leading `else[if]`, which is counted as an opening tag, but not as
" a closing tag (so that, for instance, a line containing a single `else:`
" will have weight equal to one, not zero). We do not treat a trailing
" `else[if]` in any special way, because lines ending with an open tag are
" dealt with separately before this function is called (see
" GetMetaPostIndentIntern()).
"
" Example:
"
" forsuffixes $=a,b: if x.$ = y.$ : draw else: fill fi
" % This line will be indented because |{forsuffixes,if,else}| > |{else,fi}| (3 > 2)
" endfor
function! s:Weight(line)
let [o, i] = [0, s:ValidMatchEnd(a:line, g:mp_open_tag, 0)]
while i > 0
let o += 1
let i = s:ValidMatchEnd(a:line, g:mp_open_tag, i)
endwhile
let [c, i] = [0, matchend(a:line, '^\s*\<else\%[if]\>')] " Skip a leading else[if]
let i = s:ValidMatchEnd(a:line, g:mp_close_tag, i)
while i > 0
let c += 1
let i = s:ValidMatchEnd(a:line, g:mp_close_tag, i)
endwhile
return o - c
endfunction
" Similar to matchend(), but skips strings and comments.
" line: a String
function! s:ValidMatchEnd(line, pat, start)
let i = matchend(a:line, a:pat, a:start)
while i > 0 && s:CommentOrString(a:line, i)
let i = matchend(a:line, a:pat, i)
endwhile
return i
endfunction
" Like s:ValidMatchEnd(), but returns the end position of the last (i.e.,
" rightmost) match.
function! s:LastValidMatchEnd(line, pat, start)
let last_found = -1
let i = matchend(a:line, a:pat, a:start)
while i > 0
if !s:CommentOrString(a:line, i)
let last_found = i
endif
let i = matchend(a:line, a:pat, i)
endwhile
return last_found
endfunction
function! s:DecreaseIndentOnClosingTag(curr_indent)
let cur_text = getline(v:lnum)
if cur_text =~# '^\s*\%('.g:mp_close_tag.'\)'
return max([a:curr_indent - shiftwidth(), 0])
endif
return a:curr_indent
endfunction
" }}}
" Main function {{{
"
" Note: Every rule of indentation in MetaPost is very subjective. We might get
" creative, but things get murky very soon (there are too many corner cases).
" So, we provide a means for the user to decide what to do when this script
" doesn't get it. We use a simple idea: use '%>', '%<' and '%=' to explicitly
" control indentation. The '<' and '>' symbols may be repeated many times
" (e.g., '%>>' will cause the next line to be indented twice).
"
" By using '%>...', '%<...' and '%=', the indentation the user wants is
" preserved by commands like gg=G, even if it does not follow the rules of
" this script.
"
" Example:
"
" def foo =
" makepen(
" subpath(T-n,t) of r %>
" shifted .5down %>
" --subpath(t,T) of r shifted .5up -- cycle %<<<
" )
" withcolor black
" enddef
"
" The default indentation of the previous example would be:
"
" def foo =
" makepen(
" subpath(T-n,t) of r
" shifted .5down
" --subpath(t,T) of r shifted .5up -- cycle
" )
" withcolor black
" enddef
"
" Personally, I prefer the latter, but anyway...
function! GetMetaPostIndentIntern()
" Do not touch indentation inside verbatimtex/btex.. etex blocks.
if synIDattr(synID(v:lnum, 1, 1), "name") =~# '^mpTeXinsert$\|^tex\|^Delimiter'
return -1
endif
" This is the reference line relative to which the current line is indented
" (but see below).
let lnum = s:PrevNonBlankNonComment(v:lnum)
" At the start of the file use zero indent.
if lnum == 0
return 0
endif
let prev_text = getline(lnum)
" User-defined overrides take precedence over anything else.
" See above for an example.
let j = match(prev_text, '%[<>=]')
if j > 0
let i = strlen(matchstr(prev_text, '%>\+', j)) - 1
if i > 0
return indent(lnum) + i * shiftwidth()
endif
let i = strlen(matchstr(prev_text, '%<\+', j)) - 1
if i > 0
return max([indent(lnum) - i * shiftwidth(), 0])
endif
if match(prev_text, '%=', j)
return indent(lnum)
endif
endif
" If the reference line ends with an open tag, indent.
"
" Example:
"
" if c:
" 0
" else:
" 1
" fi if c2: % Note that this line has weight equal to zero.
" ... % This line will be indented
if s:LastTagIsOpen(prev_text)
return s:DecreaseIndentOnClosingTag(indent(lnum) + shiftwidth())
endif
" Lines with a positive weight are unbalanced and should likely be indented.
"
" Example:
"
" def f = enddef for i = 1 upto 5: if x[i] > 0: 1 else: 2 fi
" ... % This line will be indented (because of the unterminated `for`)
if s:Weight(prev_text) > 0
return s:DecreaseIndentOnClosingTag(indent(lnum) + shiftwidth())
endif
" Unterminated statements cause indentation to kick in.
"
" Example:
"
" draw unitsquare
" withcolor black; % This line is indented because of `draw`.
" x := a + b + c
" + d + e; % This line is indented because of `:=`.
"
let i = s:LastValidMatchEnd(prev_text, g:mp_statement, 0)
if i >= 0 " Does the line contain a statement?
if s:ValidMatchEnd(prev_text, ';', i) < 0 " Is the statement unterminated?
return indent(lnum) + shiftwidth()
else
return s:DecreaseIndentOnClosingTag(indent(lnum))
endif
endif
" Deal with the special case of a statement spanning multiple lines. If the
" current reference line L ends with a semicolon, search backwards for
" another semicolon or a statement keyword. If the latter is found first,
" its line is used as the reference line for indenting the current line
" instead of L.
"
" Example:
"
" if cond:
" draw if a: z0 else: z1 fi
" shifted S
" scaled T; % L
"
" for i = 1 upto 3: % <-- Current line: this gets the same indent as `draw ...`
"
" NOTE: we get here only if L does not contain a statement (among those
" listed in g:mp_statement).
if s:ValidMatchEnd(prev_text, ';'.s:eol, 0) >= 0 " L ends with a semicolon
let stm_lnum = s:PrevNonBlankNonComment(lnum)
while stm_lnum > 0
let prev_text = getline(stm_lnum)
let sc_pos = s:LastValidMatchEnd(prev_text, ';', 0)
let stm_pos = s:ValidMatchEnd(prev_text, g:mp_statement, sc_pos)
if stm_pos > sc_pos
let lnum = stm_lnum
break
elseif sc_pos > stm_pos
break
endif
let stm_lnum = s:PrevNonBlankNonComment(stm_lnum)
endwhile
endif
return s:DecreaseIndentOnClosingTag(indent(lnum))
endfunction
" }}}
let &cpo = s:keepcpo
unlet s:keepcpo
" vim:sw=2:fdm=marker
