" ==============================================================================
" File: syntaxFolds.vim
" Author: Srinath Avadhanula
" ( srinath@fastmail.fm )
" Last Change: Sun Oct 27 01:00 AM 2002 PST
" Description: Emulation of the syntax folding capability of vim using manual
" folding
"
" This script provides an emulation of the syntax folding of vim using manual
" folding. Just as in syntax folding, the folds are defined by regions. Each
" region is specified by a call to FoldRegions() which accepts 4 parameters:
"
" call FoldRegions(startpat, endpat, startoff, endoff)
"
" startpat: a line matching this pattern defines the beginning of a fold.
" endpat : a line matching this pattern defines the end of a fold.
" startoff: this is the offset from the starting line at which folding will
" actually start
" endoff : like startoff, but gives the offset of the actual fold end from
" the line satisfying endpat.
" startoff and endoff are necessary when the folding region does
" not have a specific end pattern corresponding to a start
" pattern. for example in latex,
" \begin{section}
" defines the beginning of a section, but its not necessary to
" have a corresponding
" \end{section}
" the section is assumed to end 1 line _before_ another section
" starts.
" startskip: a pattern which defines the beginning of a "skipped" region.
"
" For example, suppose we define a \itemize fold as follows:
" startpat = '^\s*\\item',
" endpat = '^\s*\\item\|^\s*\\end{\(enumerate\|itemize\|description\)}',
" startoff = 0,
" endoff = -1
"
" This defines a fold which starts with a line beginning with an
" \item and ending one line before a line beginning with an
" \item or \end{enumerate} etc.
"
" Then, as long as \item's are not nested things are fine.
" However, once items begin to nest, the fold started by one
" \item can end because of an \item in an \itemize
" environment within this \item. i.e, the following can happen:
"
" \begin{itemize}
" \item Some text <------- fold will start here
" This item will contain a nested item
" \begin{itemize} <----- fold will end here because next line contains \item...
" \item Hello
" \end{itemize} <----- ... instead of here.
" \item Next item of the parent itemize
" \end{itemize}
"
" Therefore, in order to completely define a folding item which
" allows nesting, we need to also define a "skip" pattern.
" startskip and end skip do that.
" Leave '' when there is no nesting.
" endskip: the pattern which defines the end of the "skip" pattern for
" nested folds.
"
" Example:
" 1. A syntax fold region for a latex section is
" startpat = "\\section{"
" endpat = "\\section{"
" startoff = 0
" endoff = -1
" startskip = ''
" endskip = ''
" Note that the start and end patterns are thus the same and endoff has a
" negative value to capture the effect of a section ending one line before
" the next starts.
" 2. A syntax fold region for the \itemize environment is:
" startpat = '^\s*\\item',
" endpat = '^\s*\\item\|^\s*\\end{\(enumerate\|itemize\|description\)}',
" startoff = 0,
" endoff = -1,
" startskip = '^\s*\\begin{\(enumerate\|itemize\|description\)}',
" endskip = '^\s*\\end{\(enumerate\|itemize\|description\)}'
" Note the use of startskip and endskip to allow nesting.
"
"
" Each time a call is made to FoldRegions(), all the regions (which might be
" disjoint, but not nested) are folded up.
" Nested folds can be created by successive calls to FoldRegions(). The first
" call defines the region which is deepest in the folding. See MakeTexFolds()
" for an idea of how this works for latex files.
" Function: AddSyntaxFoldItem (start, end, startoff, endoff [, skipStart, skipEnd]) {{{
function! AddSyntaxFoldItem(start, end, startoff, endoff, ...)
if a:0 > 0
let skipStart = a:1
let skipEnd = a:2
else
let skipStart = ''
let skipEnd = ''
end
if !exists('b:numFoldItems')
let b:numFoldItems = 0
end
let b:numFoldItems = b:numFoldItems + 1
exe 'let b:startPat_'.b:numFoldItems.' = a:start'
exe 'let b:endPat_'.b:numFoldItems.' = a:end'
exe 'let b:startOff_'.b:numFoldItems.' = a:startoff'
exe 'let b:endOff_'.b:numFoldItems.' = a:endoff'
exe 'let b:skipStartPat_'.b:numFoldItems.' = skipStart'
exe 'let b:skipEndPat_'.b:numFoldItems.' = skipEnd'
endfunction
" }}}
" Function: MakeSyntaxFolds (force) {{{
" Description: This function calls FoldRegions() several times with the
" parameters specifying various regions resulting in a nested fold
" structure for the file.
function! MakeSyntaxFolds(force, ...)
if exists('b:doneFolding') && a:force == 0
return
end
let skipEndPattern = ''
if a:0 > 0
let line1 = a:1
let skipEndPattern = '\|'.a:2
else
let line1 = 1
let r = line('.')
let c = virtcol('.')
setlocal fdm=manual
normal! zE
end
if !exists('b:numFoldItems')
b:numFoldItems = 1000000
end
let i = 1
let maxline = line('.')
while exists('b:startPat_'.i) && i <= b:numFoldItems
exe 'let startPat = b:startPat_'.i
exe 'let endPat = b:endPat_'.i
exe 'let startOff = b:startOff_'.i
exe 'let endOff = b:endOff_'.i
let skipStart = ''
let skipEnd = ''
if exists('b:skipStartPat_'.i)
exe 'let skipStart = b:skipStartPat_'.i
exe 'let skipEnd = b:skipEndPat_'.i
end
exe line1
let lastLoc = line1
if skipStart != ''
call InitStack('BeginSkipArray')
call FoldRegionsWithSkip(startPat, endPat, startOff, endOff, skipStart, skipEnd, 1, line('$'))
" call PrintError('done folding ['.startPat.']')
else
call FoldRegionsWithNoSkip(startPat, endPat, startOff, endOff, 1, line('$'), '')
end
let i = i + 1
endwhile
exe maxline
if a:0 == 0
exe r
exe "normal! ".c."|"
if foldlevel(r) > 1
exe "normal! ".(foldlevel(r) - 1)."zo"
end
let b:doneFolding = 0
end
endfunction
" }}}
" FoldRegionsWithSkip: folding things such as \item's which can be nested. {{{
function! FoldRegionsWithSkip(startpat, endpat, startoff, endoff, startskip, endskip, line1, line2)
exe a:line1
" count the regions which have been skipped as we go along. do not want to
" create a fold which with a beginning or end line in one of the skipped
" regions.
let skippedRegions = ''
" start searching for either the starting pattern or the end pattern.
while search(a:startskip.'\|'.a:endskip, 'W')
if getline('.') =~ a:endskip
let lastBegin = Pop('BeginSkipArray')
" call PrintError('popping '.lastBegin.' from stack and folding till '.line('.'))
call FoldRegionsWithNoSkip(a:startpat, a:endpat, a:startoff, a:endoff, lastBegin, line('.'), skippedRegions)
let skippedRegions = skippedRegions.lastBegin.','.line('.').'|'
" if this is the beginning of a skip region, then, push this line as
" the beginning of a skipped region.
elseif getline('.') =~ a:startskip
" call PrintError('pushing '.line('.').' ['.getline('.').'] into stack')
call Push('BeginSkipArray', line('.'))
end
endwhile
" call PrintError('with skip starting at '.a:line1.' returning at line# '.line('.'))
endfunction
" }}}
" FoldRegionsWithNoSkip: folding things such as \sections which do not nest. {{{
function! FoldRegionsWithNoSkip(startpat, endpat, startoff, endoff, line1, line2, skippedRegions)
exe a:line1
" call PrintError('line1 = '.a:line1.', searching from '.line('.').'... for ['.a:startpat.'')
let lineBegin = s:MySearch(a:startpat, 'in')
" call PrintError('... and finding it at '.lineBegin)
while lineBegin <= a:line2
if IsInSkippedRegion(lineBegin, a:skippedRegions)
let lineBegin = s:MySearch(a:startpat, 'out')
" call PrintError(lineBegin.' is being skipped')
continue
end
let lineEnd = s:MySearch(a:endpat, 'out')
while IsInSkippedRegion(lineEnd, a:skippedRegions) && lineEnd <= a:line2
let lineEnd = s:MySearch(a:endpat, 'out')
endwhile
if lineEnd > a:line2
exe (lineBegin + a:startoff).','.a:line2.' fold'
break
else
" call PrintError ('for ['.a:startpat.'] '.(lineBegin + a:startoff).','.(lineEnd + a:endoff).' fold')
exe (lineBegin + a:startoff).','.(lineEnd + a:endoff).' fold'
end
" call PrintError('line1 = '.a:line1.', searching from '.line('.').'... for ['.a:startpat.'')
let lineBegin = s:MySearch(a:startpat, 'in')
" call PrintError('... and finding it at '.lineBegin)
endwhile
exe a:line2
return
endfunction
" }}}
" InitStack: initialize a stack {{{
function! InitStack(name)
exe 'let s:'.a:name.'_numElems = 0'
endfunction
" }}}
" Push: push element into stack {{{
function! Push(name, elem)
exe 'let numElems = s:'.a:name.'_numElems'
let numElems = numElems + 1
exe 'let s:'.a:name.'_Element_'.numElems.' = a:elem'
exe 'let s:'.a:name.'_numElems = numElems'
endfunction
" }}}
" Pop: pops element off stack {{{
function! Pop(name)
exe 'let numElems = s:'.a:name.'_numElems'
if numElems == 0
return ''
else
exe 'let ret = s:'.a:name.'_Element_'.numElems
let numElems = numElems - 1
exe 'let s:'.a:name.'_numElems = numElems'
return ret
end
endfunction
" }}}
" MySearch: just like search(), but returns large number on failure {{{
function! <SID>MySearch(pat, opt)
if a:opt == 'in'
if getline('.') =~ a:pat
let ret = line('.')
else
let ret = search(a:pat, 'W')
end
else
normal! $
let ret = search(a:pat, 'W')
end
if ret == 0
let ret = line('$') + 1
end
return ret
endfunction
" }}}
" Function: IsInSkippedRegion (lnum, regions) {{{
" Description: finds whether a given line number is within one of the regions
" skipped.
function! IsInSkippedRegion(lnum, regions)
let i = 1
let subset = s:Strntok(a:regions, '|', i)
while subset != ''
let n1 = s:Strntok(subset, ',', 1)
let n2 = s:Strntok(subset, ',', 2)
if a:lnum >= n1 && a:lnum <= n2
return 1
end
let subset = s:Strntok(a:regions, '|', i)
let i = i + 1
endwhile
return 0
endfunction " }}}
" Function: Strntok (string, tok, n) {{{
" extract the n^th token from s seperated by tok.
" example: Strntok('1,23,3', ',', 2) = 23
fun! <SID>Strntok(s, tok, n)
return matchstr( a:s.a:tok[0], '\v(\zs([^'.a:tok.']*)\ze['.a:tok.']){'.a:n.'}')
endfun " }}}
" vim600:fdm=marker
