axessibility in runtime

git-svn-id: svn://tug.org/texlive/trunk@57105 c570f23f-e606-0410-a88d-b1316a301751

1 files changed, 95 insertions, 0 deletions

diff --git a/Master/texmf-dist/tex/latex/axessibility/axessibility.lua b/Master/texmf-dist/tex/latex/axessibility/axessibility.lua
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+-- Copyright (C) 2018, 2019, 2020 by 
+-- Anna Capietto, Sandro Coriasco, Boris Doubrov, Alexander Koslovski,
+-- Tiziana Armano, Nadir Murru, Dragan Ahmetovic, Cristian Bernareggi
+--
+-- Based on accsupp and tagpdf
+--
+-- This work consists of the main source files axessibility.dtx and axessibility.lua,
+-- and the derived files
+--   axessibility.ins, axessibility.sty, axessibility.pdf, README,
+--   axessibilityExampleSingleLineT.tex, axessibilityExampleSingleLineA.tex,
+--.  axessibilityExampleAlignT.tex, axessibilityExampleAlignA.tex
+-- 
+-- This work may be distributed and/or modified under the
+-- conditions of the LaTeX Project Public License, either version 1.3
+-- of this license or (at your option) any later version.
+-- The latest version of this license is in
+--   http://www.latex-project.org/lppl.txt
+-- and version 1.3 or later is part of all distributions of LaTeX
+-- version 2005/12/01 or later.
+--
+-- This work has the LPPL maintenance status `maintained'.
+-- 
+-- The Current Maintainer of this work is 
+--               Sandro Coriasco
+--
+
+
+local open_dls = false
+local open_double_dls = false
+
+--[[ The function replace_dls_and_double_dls() switches on or off automatic replacement of $$ and $. 
+     The boolean argument a (true/false) specifies if the package should do the replacements.
+  ]]
+
+function replace_dls_and_double_dls(a) 
+	if a and not luatexbase.in_callback("process_input_buffer", "process_input_buffer") then
+		luatexbase.add_to_callback("process_input_buffer", replace_chars_callback, "process_input_buffer")
+	elseif not a and luatexbase.in_callback("process_input_buffer", "process_input_buffer") then
+		luatexbase.remove_from_callback("process_input_buffer", "process_input_buffer")
+	end
+end
+
+-- the callback that performs the replacement
+function replace_chars_callback(a)
+	if status.input_ptr == 1 then
+		-- variable to save comments if any
+		local comment=""
+		-- we delete all comments
+		a = a:gsub("(\\*)(%%.*)", function(group1, group2)
+			-- check,if we have even number of backslash characters
+			if #group1 % 2 == 0 then
+				comment=group1..group2
+				return ""
+			end
+			return group1..group2
+		end)
+		
+		-- We must replace empty lines by some value, eg % character
+		if(open_double_dls or open_dls) and a == "" then
+			return "%"
+		end
+
+		local replace_happened = false
+		a = a:gsub("(\\*)(%$+)", function(group1, group2)
+			-- if after \$ we have one or more $,algorithm will not do replacement,so we must be check this situation
+			local b = ""
+			if #group1 % 2 == 1 and #group2 >1 then
+				b="\\$"
+				group1 = group1:sub(2)
+				group2 = group2:sub(2)
+			end
+			
+			-- if we have even number of backslash characters in front of $$ or $, we do replacement of $$ or $
+			if #group1 % 2 == 0 then
+				replace_happened = true
+				if group2 == "$$" then
+					group2 = open_double_dls and "\\]" or "\\["
+					open_double_dls = not open_double_dls
+				elseif group2 == "$" then
+					group2 = open_dls and "\\)" or "\\("
+					open_dls = not open_dls
+				end
+			end
+			return group1..b..group2
+		end)
+		
+		--return comments back to the line
+		a = a..comment
+		-- this might be useful for debug
+		--[[ if replace_happened then
+			texio.write_nl("the line after replacement is: "..a)
+		end]]
+		return a
+	end
+end
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