handle variable-length front matter

autoload/denote/notes.vim

@@ -1,3 +1,90 @@
+" Script-local function that retrieves the front-matter of a file.
+function s:getfrontmatter(filename)
+	let l:ext = fnamemodify(a:filename, ':e')
+	if index(g:denote_note_file_extensions, l:ext) == -1
+		return []
+	endif
+	" The following code aims to be as robust as possible. This is achieved by
+	" parsing each file-type (extension) separately. A common signature of the
+	" front matter is the empty line that separates the front matter from the
+	" rest of the text. As fail safe, we assume that the front matter is shorter
+	" than l:max lines.
+	" Markdown:
+	" - The first line is either '---' or '+++'.
+	" - The last line is the same as the first line.
+	" - All entries (apart first and last lines) are of the form '^\w\+:\?'.
+	" - Contains the entry '^identifier'.
+	" Org:
+	" - All lines start with '^#+\w\+:\s*'.
+	" - Contains the entry '^#identifier:
+	" Text:
+	" - The last line is '^-\+$.
+	" - All lines start with '^\w\+:\s*.
+	" - Contains the entry '^identifier:'
+	"
+	" Note: getbufline() returns an empty list if no more lines are available.
+	let l:max = 50
+	call bufload(a:filename)
+	let l:fmt = []
+	let l:lnr = 1
+	let l:identifier_seen = v:false
+	if l:ext == 'md'
+		let l:separator = getbufline(a:filename, l:lnr)[0]
+		if index(['---', '+++'], l:separator) == -1
+			return []
+		endif
+		call add(l:fmt, l:separator)
+		let l:lnr += 1
+		while l:lnr < l:max
+			let l:line = getbufline(a:filename, l:lnr)[0]
+			if l:line == l:separator
+				call add(l:fmt, l:line)
+				return l:identifier_seen && getbufline(a:filename, l:lnr + 1)[0] == '' ? l:fmt : []
+			endif
+			if l:line !~ '^\w\+:\?'
+				return []
+			endif
+			call add(l:fmt, l:line)
+			if l:line =~ '^identifier'
+				let l:identifier_seen = v:true
+			endif
+			let l:lnr += 1
+		endwhile
+	elseif l:ext == 'org'
+		while l:lnr < l:max
+			let l:line = getbufline(a:filename, l:lnr)[0]
+			if l:line == ''
+				return l:identifier_seen ? l:fmt : []
+			endif
+			if l:line !~ '^#+\w\+:'
+				return []
+			endif
+			call add(l:fmt, l:line)
+			if l:line =~ '^#+identifier:'
+				let l:identifier_seen = v:true
+			endif
+			let l:lnr += 1
+		endwhile
+	elseif l:ext == 'txt'
+		while l:lnr < l:max
+			let l:line = getbufline(a:filename, l:lnr)[0]
+			if l:line =~ '^-\+$'
+				call add(l:fmt, l:line)
+				return l:identifier_seen && getbufline(a:filename, l:lnr + 1)[0] == '' ? l:fmt : []
+			endif
+			if l:line !~ '^\w\+:'
+				return []
+			endif
+			call add(l:fmt, l:line)
+			if l:line =~ '^identifier:'
+				let l:identifier_seen = v:true
+			endif
+			let l:lnr += 1
+		endwhile
+	endif
+	return []
+endfunction
+
 " Put all notes of the given tag to the location list. The search argument may be
 " empty. For improving search, white spaces are replaced by the * |wildcard|.
 function denote#notes#list(search)
@@ -35,7 +122,7 @@ function denote#notes#new(title, ext=g:denote_new_ext)
 	call denote#loclist#jumptowindow()
 	" Open file and write front matter
 	exe 'edit ' l:fn
-	call setline(1, libdenote#fm_gen(a:ext, l:identifier, a:title))
+	call setline(1, libdenote#fm_gen(a:ext, l:identifier, a:title, [], g:denote_fm_md_type))
 endfunction
 
 " Function to set the title of the selected entry
@@ -56,11 +143,18 @@ function denote#notes#settitle(linenr, title)
 	if index(g:denote_note_file_extensions, l:ext) >= 0
 		" Handle front matter
 		call bufload(l:filename)
-		let l:frontmatter = getbufline(l:filename,
+		let l:frontmatter = s:getfrontmatter(l:filename)
-					\ 1, 1 + libdenote#fm_len(fnamemodify(l:filename, ':e')))
+		if empty(l:frontmatter)
-		let l:frontmatter = libdenote#fm_alter(l:frontmatter, {'title': a:title})
+			" Write fresh front matter
-		call setbufline(l:filename, 1, l:frontmatter)
+			let l:frontmatter = libdenote#fm_gen(l:ext, l:meta.id, l:meta.title, l:meta.tags, g:denote_fm_md_type)
-		let curl=line('.')
+			call add(l:frontmatter, '')
+			call appendbufline(l:filename, 0, l:frontmatter)
+		else
+			" Modify front matter
+			let l:frontmatter = libdenote#fm_alter(l:frontmatter, {'title': a:title})
+			call setbufline(l:filename, 1, l:frontmatter)
+		endif
+		let curl = line('.')
 		call denote#loclist#jumptowindow()
 		exe 'silent buf ' .. l:bufnr
 		exe 'silent file ' .. l:newfilename
@@ -108,10 +202,18 @@ function denote#notes#tagmod(line1, line2, tag, add)
 		if index(g:denote_note_file_extensions, l:ext) >= 0
 			" Handle front matter
 			call bufload(l:filename)
-			let l:frontmatter = getbufline(l:filename, 1, 1 + libdenote#fm_len(fnamemodify(l:filename, ':e')))
+			let l:frontmatter = s:getfrontmatter(l:filename)
-			let l:frontmatter = libdenote#fm_alter(l:frontmatter, {'tags': l:meta.tags})
+			if empty(l:frontmatter)
-			call setbufline(l:filename, 1, l:frontmatter)
+				" Write fresh front matter
-			let curl=line('.')
+				let l:frontmatter = libdenote#fm_gen(l:ext, l:meta.id, l:meta.title, l:meta.tags, g:denote_fm_md_type)
+				call add(l:frontmatter, '')
+				call appendbufline(l:filename, 0, l:frontmatter)
+			else
+				" Modify front matter
+				let l:frontmatter = libdenote#fm_alter(l:frontmatter, {'tags': l:meta.tags})
+				call setbufline(l:filename, 1, l:frontmatter)
+			endif
+			let curl = line('.')
 			call denote#loclist#jumptowindow()
 			exe 'silent buf ' .. l:bufnr
 			exe 'silent file ' .. l:newfilename
@@ -145,7 +247,7 @@ function denote#notes#copy(origfile)
 	if index(g:denote_note_file_extensions, l:ext) >= 0
 		call denote#loclist#jumptowindow()
 		exe 'edit ' .. l:filename
-		call appendbufline(l:filename, 0, libdenote#fm_gen(l:ext, l:identifier, l:title))
+		call appendbufline(l:filename, 0, libdenote#fm_gen(l:ext, l:identifier, l:title), [], g:denote_fm_md_type)
 		exe 'w'
 	endif
 endfunction

autoload/libdenote.vim

@@ -155,7 +155,7 @@ endfunction
 " @argument a:md_type string:			Any of 'yaml' (default) or 'toml', for
 " 																markdown front matter
 " @return: List of strings with a line-per item that describes the front matter
-function libdenote#fm_gen(ext, id, title, tags=[], md_type='yaml')
+function libdenote#fm_gen(ext, id, title, tags, md_type='yaml')
 	return a:ext == 'org' ? s:org_new(a:id, a:title, a:tags)
 				\ : a:ext == 'txt' ? s:plain_new(a:id, a:title, a:tags)
 				\ : a:md_type == 'toml' ? s:md_new_toml(a:id, a:title, a:tags)
@@ -180,7 +180,8 @@ function libdenote#fm_alter(fm, mod)
 	let l:repl = libdenote#fm_gen(l:ext,
 				\ has_key(a:mod, 'id') ? a:mod.id : '',
 				\ has_key(a:mod, 'title') ? a:mod.title : '',
-				\ has_key(a:mod, 'tags') ? a:mod.tags : [])
+				\ has_key(a:mod, 'tags') ? a:mod.tags : [],
+				\ g:denote_fm_md_type)
 	if has_key(a:mod, 'date')
 		let l:ididx = indexof(l:repl, 'v:val =~ "^\\(#+\\)\\?date"')
 		call map(l:new, {_, v -> v =~ "^\\(#+\\)\\?date" ? l:repl[l:ididx] : v})
@@ -199,11 +200,3 @@ function libdenote#fm_alter(fm, mod)
 	endif
 	return l:new
 endfunction
-
-" Returns the length of a front matter (number of lines)
-" @argument a:ext string: 				File extension
-function libdenote#fm_len(ext)
-	return a:ext == 'org' ? 4
-				\ : a:ext == 'txt' ? 5
-				\ : 6
-endfunction

doc/denote.txt

@@ -299,15 +299,15 @@ libdenote#scheme_metadata({filename})
 						       *libdenote-frontmatter*
 Front-matter functions~
 							  *libdenote#fm_gen()*
-libdenote#fm_gen({ext}, {id}, {title}, {tags}, {md_type})
+libdenote#fm_gen({ext}, {id}, {title}, {tags}, {mdtype})
 	This function returns the list of lines  for  the  front  matter  that
 	stores the given metadata. The paramter {ext} is the extension of  the
 	file, the parameter {id} the identifier, the  parameter  {title},  the
 	title of the note, and {tags} the optional parameter as a list of tags
-	associated to the note. Per default {tags} is set to  the  empty  list
+	associated to the note. The argument {mdtype} descries the  format  to
-	[]. Finally, {md_type} descries the format to be used in markdown. For
+	be used in markdown. For markdown files (extension 'md'), two  formats
-	markdown files (extension 'md'), two formats are possible: 'yaml'  and
+	are possible: 'yaml'  and  'toml'.  The  former  format  is  used  per
-        'toml'. The former format is used per default.
+        default.
 
 							*libdenote#fm_alter()*
 libdenote#fm_alter({fm}, {mod})
@@ -321,11 +321,6 @@ libdenote#fm_alter({fm}, {mod})
 	and "tags" are used to update the title and  tag  list	of  the  front
         matter.
 
-							  *libdenote#fm_len()*
-libdenote#fm_len({ext})
-	This returns the number of lines of the front matter  for  files  with
-        the extension {ext}.
-
 
 ==============================================================================
 APPENDIX B - PACKAGE API					  *denote-api*