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| -rw-r--r-- | runtime/indent/mp.vim | 320 |
1 files changed, 320 insertions, 0 deletions
diff --git a/runtime/indent/mp.vim b/runtime/indent/mp.vim new file mode 100644 index 0000000..07873e1 --- /dev/null +++ b/runtime/indent/mp.vim @@ -0,0 +1,320 @@ +vim9script + +# MetaPost indent file +# Language: MetaPost +# Maintainer: Nicola Vitacolonna <nvitacolonna@gmail.com> +# Former Maintainers: Eugene Minkovskii <emin@mccme.ru> +# Latest Revision: 2022 Aug 12 + +if exists("b:did_indent") + finish +endif + +b:did_indent = 1 + +setlocal indentexpr=g:MetaPostIndent() +setlocal indentkeys+==end,=else,=fi,=fill,0),0] +setlocal nolisp +setlocal nosmartindent + +b:undo_indent = "setl indentexpr< indentkeys< lisp< smartindent<" + +# Regexps {{{ +# Expressions starting indented blocks +const MP_OPEN_TAG = [ + '\<if\>', + '\<else\%[if]\>', + '\<for\%(\|ever\|suffixes\)\>', + '\<begingroup\>', + '\<\%(\|var\|primary\|secondary\|tertiary\)def\>', + '^\s*\<begin\%(fig\|graph\|glyph\|char\|logochar\)\>', + '[([{]', + ]->extend(get(g:, "mp_open_tag", []))->join('\|') + +# Expressions ending indented blocks +const MP_CLOSE_TAG = [ + '\<fi\>', + '\<else\%[if]\>', + '\<end\%(\|for\|group\|def\|fig\|char\|glyph\|graph\)\>', + '[)\]}]' + ]->extend(get(g:, "mp_close_tag", []))->join('\|') + +# 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. +const MP_STATEMENT = [ + '\<\%(\|un\|cut\)draw\%(dot\)\=\>', + '\<\%(\|un\)fill\%[draw]\>', + '\<draw\%(dbl\)\=arrow\>', + '\<clip\>', + '\<addto\>', + '\<save\>', + '\<setbounds\>', + '\<message\>', + '\<errmessage\>', + '\<errhelp\>', + '\<fontmapline\>', + '\<pickup\>', + '\<show\>', + '\<special\>', + '\<write\>', + '\%(^\|;\)\%([^;=]*\%(' .. MP_OPEN_TAG .. '\)\)\@!.\{-}:\==', + ]->join('\|') + +# A line ends with zero or more spaces, possibly followed by a comment. +const EOL = '\s*\%($\|%\)' +# }}} + +# Auxiliary functions {{{ +# Returns true if (0-based) position immediately preceding `pos` in `line` is +# inside a string or a comment; returns false 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. +def IsCommentOrString(line: string, pos: number): bool + var in_string = 0 + var q = stridx(line, '"') + var c = stridx(line, '%') + + while q >= 0 && q < pos + if c >= 0 && c < q + if in_string # Find next percent symbol + c = stridx(line, '%', q + 1) + else # Inside comment + return true + endif + endif + in_string = 1 - in_string + q = stridx(line, '"', q + 1) # Find next quote + endwhile + + return in_string || (c >= 0 && c <= pos) +enddef + +# Find the first non-comment non-blank line before the given line. +def PrevNonBlankNonComment(lnum: number): number + var nr = prevnonblank(lnum - 1) + while getline(nr) =~# '^\s*%' + nr = prevnonblank(nr - 1) + endwhile + return nr +enddef + +# Returns true if the last tag appearing in the line is an open tag; returns +# false otherwise. +def LastTagIsOpen(line: string): bool + var o = LastValidMatchEnd(line, MP_OPEN_TAG, 0) + if o == - 1 + return false + endif + return LastValidMatchEnd(line, MP_CLOSE_TAG, o) < 0 +enddef + +# 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 MetaPostIndent()). +# +# 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 +def Weight(line: string): number + var o = 0 + var i = ValidMatchEnd(line, MP_OPEN_TAG, 0) + while i > 0 + o += 1 + i = ValidMatchEnd(line, MP_OPEN_TAG, i) + endwhile + var c = 0 + i = matchend(line, '^\s*\<else\%[if]\>') # Skip a leading else[if] + i = ValidMatchEnd(line, MP_CLOSE_TAG, i) + while i > 0 + c += 1 + i = ValidMatchEnd(line, MP_CLOSE_TAG, i) + endwhile + return o - c +enddef + +# Similar to matchend(), but skips strings and comments. +# line: a String +def ValidMatchEnd(line: string, pat: string, start: number): number + var i = matchend(line, pat, start) + while i > 0 && IsCommentOrString(line, i) + i = matchend(line, pat, i) + endwhile + return i +enddef + +# Like s:ValidMatchEnd(), but returns the end position of the last (i.e., +# rightmost) match. +def LastValidMatchEnd(line: string, pat: string, start: number): number + var last_found = -1 + var i = matchend(line, pat, start) + while i > 0 + if !IsCommentOrString(line, i) + last_found = i + endif + i = matchend(line, pat, i) + endwhile + return last_found +enddef + +def DecreaseIndentOnClosingTag(curr_indent: number): number + var cur_text = getline(v:lnum) + if cur_text =~# '^\s*\%(' .. MP_CLOSE_TAG .. '\)' + return max([curr_indent - shiftwidth(), 0]) + endif + return curr_indent +enddef +# }}} + +# Main function {{{ +def g:MetaPostIndent(): number + # Do not touch indentation inside verbatimtex/btex.. etex blocks. + if synIDattr(synID(v:lnum, 1, 1), "name") =~# '^mpTeXinsert$\|^tex\|^Delimiter' + return -1 + endif + + # At the start of a MetaPost block inside ConTeXt, do not touch indentation + if synIDattr(synID(prevnonblank(v:lnum - 1), 1, 1), "name") == "contextBlockDelim" + return -1 + endif + + var lnum = PrevNonBlankNonComment(v:lnum) + + # At the start of the file use zero indent. + if lnum == 0 + return 0 + endif + + var prev_text = getline(lnum) + + # 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). + # + # User-defined overrides take precedence over anything else. + var j = match(prev_text, '%[<>=!]') + if j > 0 + var i = strlen(matchstr(prev_text, '%>\+', j)) - 1 + if i > 0 + return indent(lnum) + i * shiftwidth() + endif + + i = strlen(matchstr(prev_text, '%<\+', j)) - 1 + if i > 0 + return max([indent(lnum) - i * shiftwidth(), 0]) + endif + + if match(prev_text, '%=', j) > -1 + return indent(lnum) + endif + + if match(prev_text, '%!', j) > -1 + return -1 + 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 LastTagIsOpen(prev_text) + return 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 Weight(prev_text) > 0 + return 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 `:=`. + # + var i = LastValidMatchEnd(prev_text, MP_STATEMENT, 0) + if i >= 0 # Does the line contain a statement? + if ValidMatchEnd(prev_text, ';', i) < 0 # Is the statement unterminated? + return indent(lnum) + shiftwidth() + else + return 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 ValidMatchEnd(prev_text, ';' .. EOL, 0) >= 0 # L ends with a semicolon + var stm_lnum = PrevNonBlankNonComment(lnum) + while stm_lnum > 0 + prev_text = getline(stm_lnum) + var sc_pos = LastValidMatchEnd(prev_text, ';', 0) + var stm_pos = ValidMatchEnd(prev_text, MP_STATEMENT, sc_pos) + if stm_pos > sc_pos + lnum = stm_lnum + break + elseif sc_pos > stm_pos + break + endif + stm_lnum = PrevNonBlankNonComment(stm_lnum) + endwhile + endif + + return DecreaseIndentOnClosingTag(indent(lnum)) +enddef +# }}} + +# vim: sw=2 fdm=marker |