+" Function interface phylosophy:
+"
+" - functions take arbitrary line numbers as parameters.
+" Current cursor line is only a suitable default parameter.
+"
+" - only functions that bind directly to user actions:
+"
+" - print error messages.
+" All intermediate functions limit themselves return `0` to indicate an error.
+"
+" - move the cursor. All other functions do not move the cursor.
+"
+" This is how you should view headers:
+"
+" |BUFFER
+" |
+" |Outside any header
+" |
+" a-+# a
+" |
+" |Inside a
+" |
+" a-+
+" b-+## b
+" |
+" |inside b
+" |
+" b-+
+" c-+### c
+" |
+" |Inside c
+" |
+" c-+
+" d-|# d
+" |
+" |Inside d
+" |
+" d-+
+" e-|e
+" |====
+" |
+" |Inside e
+" |
+" e-+
+
+" For each level, contains the regexp that matches at that level only.
+let s:levelRegexpDict = {
+ \ 1: '\v^(\s*#[^#]|.+\n\=+$)',
+ \ 2: '\v^(\s*##[^#]|.+\n-+$)',
+ \ 3: '\v^\s*###[^#]',
+ \ 4: '\v^\s*####[^#]',
+ \ 5: '\v^\s*#####[^#]',
+ \ 6: '\v^\s*######[^#]'
+\ }
+
+" Maches any header level of any type.
+"
+" This could be deduced from `s:levelRegexpDict`, but it is more
+" efficient to have a single regexp for this.
+"
+let s:headersRegexp = '\v^(\s*#|.+\n(\=+|-+)$)'
+
+" Returns the line number of the first header before `line`, called the
+" current header.
+"
+" If there is no current header, return `0`.
+"
+" @param a:1 The line to look the header of. Default value: `getpos('.')`.
+"
+function! b:Markdown_GetHeaderLineNum(...)
+ if a:0 == 0
+ let l:l = line('.')
+ else
+ let l:l = a:1
+ endif
+ while(l:l > 0)
+ if join(getline(l:l, l:l + 1), "\n") =~ s:headersRegexp
+ return l:l
+ endif
+ let l:l -= 1
+ endwhile
+ return 0
+endfunction
+
+" - if inside a header goes to it.
+" Return its line number.
+"
+" - if on top level outside any headers,
+" print a warning
+" Return `0`.
+"
+function! b:Markdown_MoveToCurHeader()
+ let l:lineNum = b:Markdown_GetHeaderLineNum()
+ if l:lineNum != 0
+ call cursor(l:lineNum, 1)
+ else
+ echo 'outside any header'
+ "normal! gg
+ endif
+ return l:lineNum
+endfunction
+
+" Move cursor to next header of any level.
+"
+" If there are no more headers, print a warning.
+"
+function! b:Markdown_MoveToNextHeader()
+ if search(s:headersRegexp, 'W') == 0
+ "normal! G
+ echo 'no next header'
+ endif
+endfunction
+
+" Move cursor to previous header (before current) of any level.
+"
+" If it does not exist, print a warning.
+"
+function! b:Markdown_MoveToPreviousHeader()
+ let l:curHeaderLineNumber = b:Markdown_GetHeaderLineNum()
+ let l:noPreviousHeader = 0
+ if l:curHeaderLineNumber <= 1
+ let l:noPreviousHeader = 1
+ else
+ let l:previousHeaderLineNumber = b:Markdown_GetHeaderLineNum(l:curHeaderLineNumber - 1)
+ if l:previousHeaderLineNumber == 0
+ let l:noPreviousHeader = 1
+ else
+ call cursor(l:previousHeaderLineNumber, 1)
+ endif
+ endif
+ if l:noPreviousHeader
+ echo 'no previous header'
+ endif
+endfunction
+
+" - if line is inside a header, return the header level (h1 -> 1, h2 -> 2, etc.).
+"
+" - if line is at top level outside any headers, return `0`.
+"
+function! b:Markdown_GetHeaderLevel(...)
+ if a:0 == 0
+ let l:line = line('.')
+ else
+ let l:line = a:1
+ endif
+ let l:linenum = b:Markdown_GetHeaderLineNum(l:line)
+ if l:linenum != 0
+ return b:Markdown_GetLevelOfHeaderAtLine(l:linenum)
+ else
+ return 0
+ endif
+endfunction
+
+" Returns the level of the header at the given line.
+"
+" If there is no header at the given line, returns `0`.
+"
+function! b:Markdown_GetLevelOfHeaderAtLine(linenum)
+ let l:lines = join(getline(a:linenum, a:linenum + 1), "\n")
+ for l:key in keys(s:levelRegexpDict)
+ if l:lines =~ get(s:levelRegexpDict, l:key)
+ return l:key
+ endif
+ endfor
+ return 0
+endfunction
+
+" Move cursor to parent header of the current header.
+"
+" If it does not exit, print a warning and do nothing.
+"
+function! b:Markdown_MoveToParentHeader()
+ let l:linenum = b:Markdown_GetParentHeaderLineNumber()
+ if l:linenum != 0
+ call cursor(l:linenum, 1)
+ else
+ echo 'no parent header'
+ endif
+endfunction
+
+" Return the line number of the parent header of line `line`.
+"
+" If it has no parent, return `0`.
+"
+function! b:Markdown_GetParentHeaderLineNumber(...)
+ if a:0 == 0
+ let l:line = line('.')
+ else
+ let l:line = a:1
+ endif
+ let l:level = b:Markdown_GetHeaderLevel(l:line)
+ if l:level > 1
+ let l:linenum = b:Markdown_GetPreviousHeaderLineNumberAtLevel(l:level - 1, l:line)
+ return l:linenum
+ endif
+ return 0
+endfunction
+
+" Return the line number of the previous header of given level.
+" in relation to line `a:1`. If not given, `a:1 = getline()`
+"
+" `a:1` line is included, and this may return the current header.
+"
+" If none return 0.
+"
+function! b:Markdown_GetNextHeaderLineNumberAtLevel(level, ...)
+ if a:0 < 1
+ let l:line = line('.')
+ else
+ let l:line = a:1
+ endif
+ let l:l = l:line
+ while(l:l <= line('$'))
+ if join(getline(l:l, l:l + 1), "\n") =~ get(s:levelRegexpDict, a:level)
+ return l:l
+ endif
+ let l:l += 1
+ endwhile
+ return 0
+endfunction
+
+" Return the line number of the previous header of given level.
+" in relation to line `a:1`. If not given, `a:1 = getline()`
+"
+" `a:1` line is included, and this may return the current header.
+"
+" If none return 0.
+"
+function! b:Markdown_GetPreviousHeaderLineNumberAtLevel(level, ...)
+ if a:0 == 0
+ let l:line = line('.')
+ else
+ let l:line = a:1
+ endif
+ let l:l = l:line
+ while(l:l > 0)
+ if join(getline(l:l, l:l + 1), "\n") =~ get(s:levelRegexpDict, a:level)
+ return l:l
+ endif
+ let l:l -= 1
+ endwhile
+ return 0
+endfunction
+
+" Move cursor to next sibling header.
+"
+" If there is no next siblings, print a warning and don't move.
+"
+function! b:Markdown_MoveToNextSiblingHeader()
+ let l:curHeaderLineNumber = b:Markdown_GetHeaderLineNum()
+ let l:curHeaderLevel = b:Markdown_GetLevelOfHeaderAtLine(l:curHeaderLineNumber)
+ let l:curHeaderParentLineNumber = b:Markdown_GetParentHeaderLineNumber()
+ let l:nextHeaderSameLevelLineNumber = b:Markdown_GetNextHeaderLineNumberAtLevel(l:curHeaderLevel, l:curHeaderLineNumber + 1)
+ let l:noNextSibling = 0
+ if l:nextHeaderSameLevelLineNumber == 0
+ let l:noNextSibling = 1
+ else
+ let l:nextHeaderSameLevelParentLineNumber = b:Markdown_GetParentHeaderLineNumber(l:nextHeaderSameLevelLineNumber)
+ if l:curHeaderParentLineNumber == l:nextHeaderSameLevelParentLineNumber
+ call cursor(l:nextHeaderSameLevelLineNumber, 1)
+ else
+ let l:noNextSibling = 1
+ endif
+ endif
+ if l:noNextSibling
+ echo 'no next sibling header'
+ endif
+endfunction
+
+" Move cursor to previous sibling header.
+"
+" If there is no previous siblings, print a warning and do nothing.
+"
+function! b:Markdown_MoveToPreviousSiblingHeader()
+ let l:curHeaderLineNumber = b:Markdown_GetHeaderLineNum()
+ let l:curHeaderLevel = b:Markdown_GetLevelOfHeaderAtLine(l:curHeaderLineNumber)
+ let l:curHeaderParentLineNumber = b:Markdown_GetParentHeaderLineNumber()
+ let l:previousHeaderSameLevelLineNumber = b:Markdown_GetPreviousHeaderLineNumberAtLevel(l:curHeaderLevel, l:curHeaderLineNumber - 1)
+ let l:noPreviousSibling = 0
+ if l:previousHeaderSameLevelLineNumber == 0
+ let l:noPreviousSibling = 1
+ else
+ let l:previousHeaderSameLevelParentLineNumber = b:Markdown_GetParentHeaderLineNumber(l:previousHeaderSameLevelLineNumber)
+ if l:curHeaderParentLineNumber == l:previousHeaderSameLevelParentLineNumber
+ call cursor(l:previousHeaderSameLevelLineNumber, 1)
+ else
+ let l:noPreviousSibling = 1
+ endif
+ endif
+ if l:noPreviousSibling
+ echo 'no previous sibling header'
+ endif
+endfunction
+
+" Wrapper to do move commands in visual mode.
+"
+function! s:VisMove(f)
+ norm! gv
+ call function(a:f)()
+endfunction
+
+" Map in both normal and visual modes.
+"
+function! s:MapNormVis(rhs,lhs)
+ execute 'nn <buffer><silent> ' . a:rhs . ' :call ' . a:lhs . '()<cr>'
+ execute 'vn <buffer><silent> ' . a:rhs . ' <esc>:call <sid>VisMove(''' . a:lhs . ''')<cr>'
+endfunction
+
+
+call <sid>MapNormVis('<Plug>(Markdown_MoveToNextHeader)', 'b:Markdown_MoveToNextHeader')
+call <sid>MapNormVis('<Plug>(Markdown_MoveToPreviousHeader)', 'b:Markdown_MoveToPreviousHeader')
+call <sid>MapNormVis('<Plug>(Markdown_MoveToNextSiblingHeader)', 'b:Markdown_MoveToNextSiblingHeader')
+call <sid>MapNormVis('<Plug>(Markdown_MoveToPreviousSiblingHeader)', 'b:Markdown_MoveToPreviousSiblingHeader')
+" Menmonic: Up
+call <sid>MapNormVis('<Plug>(Markdown_MoveToParentHeader)', 'b:Markdown_MoveToParentHeader')
+" Menmonic: Current
+call <sid>MapNormVis('<Plug>(Markdown_MoveToCurHeader)', 'b:Markdown_MoveToCurHeader')
+
+if ! exists('g:markdown_no_default_key_mappings')
+\ || !g:markdown_no_default_key_mappings
+ nmap ]] <Plug>(Markdown_MoveToNextHeader)
+ nmap [[ <Plug>(Markdown_MoveToPreviousHeader)
+ nmap ][ <Plug>(Markdown_MoveToNextSiblingHeader)
+ nmap [] <Plug>(Markdown_MoveToPreviousSiblingHeader)
+ nmap ]u <Plug>(Markdown_MoveToParentHeader)
+ nmap ]c <Plug>(Markdown_MoveToCurHeader)