126 lines
3.4 KiB
Lua
126 lines
3.4 KiB
Lua
--[[
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Copyright (c) 2007, Niels Martin Hansen, Rodrigo Braz Monteiro
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
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* Redistributions of source code must retain the above copyright notice,
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this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright notice,
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this list of conditions and the following disclaimer in the documentation
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and/or other materials provided with the distribution.
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* Neither the name of the Aegisub Group nor the names of its contributors
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may be used to endorse or promote products derived from this software
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without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE.
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]]
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-- Unicode (UTF-8) support functions for Aegisub Automation 4 Lua
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-- http://www.ietf.org/rfc/rfc2279.txt
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module("unicode")
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-- Return the number of bytes occupied by the character starting at the i'th byte in s
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function charwidth(s, i)
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local b = s:byte(i)
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if not b then
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--aegisub.debug.out(3, "unicode.charwidth of '%s' @ %d, nil byte\n", s, i)
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-- FIXME, something in karaskel results in this case, shouldn't happen
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-- What would "proper" behaviour be? Zero? Or just explode?
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return 1
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elseif b < 128 then
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return 1
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elseif b < 224 then
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return 2
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elseif b < 240 then
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return 3
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elseif b < 248 then
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return 4
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elseif b < 252 then
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return 5
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else
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return 6
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end
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-- Actually there are more possibilities, but those aren't really legal
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end
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-- Returns an iterator function for iterating over the characters in s
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function chars(s)
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local curchar, i = 0, 1
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local function itor()
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if i > s:len() then
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return nil
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end
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local width = charwidth(s, i)
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local j = i
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curchar = curchar + 1
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i = i + width
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return s:sub(j, i-1), curchar
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end
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return itor
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end
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-- Returns the number of characters in s
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-- Runs in O(s:len()) time!
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function len(s)
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local n = 0
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for c in chars(s) do
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n = n + 1
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end
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return n
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end
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-- Get codepoint of first char in s
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function codepoint(s)
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-- Basic case, ASCII
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local b = s:byte(1)
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if s:byte(1) < 128 then
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return s:byte(1)
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end
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-- Use a naive decoding algorithm, and assume input is valid
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local res, w = 0
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if b < 224 then
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-- prefix byte is 110xxxxx
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res = b - 192
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w = 2
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elseif b < 240 then
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-- prefix byte is 11100000
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res = b - 224
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w = 3
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elseif b < 248 then
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-- prefix byte is 11110000
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res = b - 240
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w = 4
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elseif b < 252 then
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-- prefix byte is 11111000
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res = b - 248
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w = 5
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else
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-- prefix byte is 11111100
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res = b - 252
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w = 6
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end
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for i = 2, w do
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res = res*64 + s:byte(i) - 128
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end
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return res
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end
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