Fold
One of the reasons that Textadept is a pleasure to use is that the software uses the available space very efficiently: most of the window is filled with your text.
Code folding augments this feature. The software which handles the folding is in textadept/lexers/lexer.lua.
The function M.fold shows the different ways to accomplish folding:
- If the lexer for your specific programming language contains a
lexer._fold, this function handles the folding specifics - Otherwise, if the lexer contains a table
lexer._foldsymbols, folding is derived from that table. - Finally, folding can work through indentation
This text shows a simple example of folding by means of lexer._fold
For my job I develop library software. This software is used by people with very
different language backgrounds. Translations are done by means of text files
which contains lgcodes. These are identifiers which are then translated in
several languages. Such a text file - developers call them lfiles - is
structured in a very simple way.
An example:
lgcode colSectionIdentity:
N: «Identiteit»
E: «Identity»
F: «Identité»
lgcode colSectionIdentityInfo:
N: «Dit onderdeel van het formulier toont een beknopt
overzicht van de collecties»
E: «This part of the form shows a concise overview of
the collections»
F: «Cet élément du formulaire affiche un bref aperçu
des collections»
lgcode colSectionStatus:
N: «Status»
E: «Status»
F: «Statut»
lgcode colSectionStatusInfo:
N: «Dit onderdeel van het formulier toont diverse
elementen in verband met het bewerken van de
collectiedata»
E: «This part of the form shows different elements
related to editing the collection data»
F: «Cet élément du formulaire affiche divers éléments
en rapport avec l'édition des données
de la collection»
To work easily with this kind of file, I made a lexer for Textadept. (.textadept/lexers/lfile.lua)
Folding is very simple: a folding point just before lgcode. The descriptive
approach - using lexer._foldsymbols - is very attractive, but I could not make
it work: beginning folding points are easy but ending folding points are - in
this case at least - more difficult.
So, in the lexer file (.textadept/lexers/lfile.lua), I put a function
M._fold (M is the table which is returned by the lexer file)
--
-- Simple folding (documentaton is found in
-- textadept/lexers/lexer.lua)
-- Folds *text*, a chunk of text starting at position *start_pos*
-- on line number *start_line* with a beginning fold level of
-- *start_level* in the buffer.
-- Called by the Scintilla lexer; **do not call from Lua**.
-- @param text The text in the buffer to fold.
-- @param start_pos The position in the buffer *text* starts at.
-- @param start_line The line number *text* starts on.
-- @param start_level The fold level *text* starts on.
-- @return table of fold levels.
-- @name _fold
function M._fold(text, start_pos, start_line, start_level)
local regex = '^lgcode'
local header = lexer.FOLD_HEADER
local folds = {}
local line_num = start_line
local current_level = prev_level
for line in text:gmatch('.-\r?\n') do
if line:find(regex) then folds[line_num] = header
else folds[line_num] = header + 1 end
line_num = line_num + 1
end
return folds
end
This function works very well. I am sure this function can be easily extended in more complex settings.
Richard Philips