Copyright 2016,2019 ARATA Mizuki

--[[
Copyright 2016,2019 ARATA Mizuki

This file is part of ClutTeX.

ClutTeX is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

ClutTeX is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with ClutTeX. If not, see <http://www.gnu.org/licenses/>.
]]

local string_gsub = string.gsub
local os_execute = os.execute

-- s: string
local function escape(s)
return '"' .. string_gsub(string_gsub(s, '(\\*)"', '%1%1\\"'), '(\\+)$', '%1%1') .. '"'
end

-- TEST CODE
assert(escape([[Hello world!]]) == [["Hello world!"]])
assert(escape([[Hello" world!]]) == [["Hello\" world!"]])
assert(escape([[Hello\" world!"]]) == [["Hello\\\" world!\""]])
-- END TEST CODE

local function has_command(name)
local result = os_execute("where " .. escape(name) .. " > NUL 2>&1")
-- Note that os.execute returns a number on Lua 5.1 or LuaTeX
return result == 0 or result == true
end

return {
escape = escape,
has_command = has_command,
}