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-- Attention: functions in this file are part of the backend driver.
-- They are supposed to work back with Lua 5.1 .
-- Note that most of the 'lua backend' requires Lua 5.2 (currently)
pgfplotsGetLuaBinaryStringFromCharIndicesChunkSize = 7000;
if unpack == nil then
-- LUA 0.76 renamed unpack to table.unpack
pgfplotsUnpack = table.unpack;
else
pgfplotsUnpack = unpack;
end
-- Takes a table containing an arbitrary number of integers in the range 0..255 and converts it
-- into a binary stream of the corresponding binary chars.
--
-- @param charIndices a table containing 0...N arguments; each in the range 0..255
--
-- @return a string containing binary content, one byte for each input integer.
function pgfplotsGetLuaBinaryStringFromCharIndices(charIndices)
-- unpack extracts only the indices (we can't provide a table to string.char).
-- note that pdf.immediateobj has been designed to avoid sanity checking for invalid UTF strings -
-- in other words: it accepts binary strings.
--
-- unfortunately, this here fails for huge input tables:
-- pgfplotsretval=string.char(unpack(charIndices));
-- we have to create it incrementally using chunks:
local len = #charIndices;
local chunkSize = pgfplotsGetLuaBinaryStringFromCharIndicesChunkSize;
local buf = {};
-- ok, append all full chunks of chunkSize first:
local numFullChunks = math.floor(len/chunkSize);
for i = 0, numFullChunks-1, 1 do
table.insert(buf, string.char(pgfplotsUnpack(charIndices, 1+i*chunkSize, (i+1)*chunkSize)));
end
-- append the rest:
table.insert(buf, string.char(pgfplotsUnpack(charIndices, 1+numFullChunks*chunkSize)));
return table.concat(buf);
end
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