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In order to support RTL/BIDI, wezterm needs a bidi implementation. I don't think a well-conforming rust implementation exists today; what I found were implementations that didn't pass 100% of the conformance tests. So I decided to port "bidiref", the reference implementation of the UBA described in http://unicode.org/reports/tr9/ to Rust. This implementation focuses on conformance: no special measures have been taken to optimize it so far, with my focus having been to ensure that all of the approx 780,000 test cases in the unicode data for unicode 14 pass. Having the tests passing 100% allows for making performance improvements with confidence in the future. The API isn't completely designed/fully baked. Until I get to hooking it up to wezterm's shaper, I'm not 100% sure exactly what I'll need. There's a good discussion on API in https://github.com/open-i18n/rust-unic/issues/273 that suggests omitting "legacy" operations such as reordering. I suspect that wezterm may actually need that function to support monospace text layout in some terminal scenarios, but regardless: reordering is part of the conformance test suite so it remains a part of the API. That said: the API does model the major operations as separate phases, so you should be able to pay for just what you use: * Resolving the embedding levels from a paragraph * Returning paragraph runs of those levels (and their directions) * Returning the whitespace-level-reset runs for a line-slice within the paragraph * Returning the reordered indices + levels for a line-slice within the paragraph. refs: https://github.com/wez/wezterm/issues/784 refs: https://github.com/kas-gui/kas-text/issues/20
60 lines
2.9 KiB
Markdown
60 lines
2.9 KiB
Markdown
Copyright (c) 2022-Present Wez Furlong
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in all
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copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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SOFTWARE.
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Portions of this crate were derived from the bidiref reference implementation
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of the UBA, and several data files are included that have the following
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copyright and license:
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COPYRIGHT AND PERMISSION NOTICE
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Copyright © 1991-2022 Unicode, Inc. All rights reserved.
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Distributed under the Terms of Use in https://www.unicode.org/license.txt
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which is reproduced below:
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Permission is hereby granted, free of charge, to any person obtaining
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a copy of the Unicode data files and any associated documentation
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(the "Data Files") or Unicode software and any associated documentation
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(the "Software") to deal in the Data Files or Software
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without restriction, including without limitation the rights to use,
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copy, modify, merge, publish, distribute, and/or sell copies of
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the Data Files or Software, and to permit persons to whom the Data Files
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or Software are furnished to do so, provided that either
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(a) this copyright and permission notice appear with all copies
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of the Data Files or Software, or
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(b) this copyright and permission notice appear in associated
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Documentation.
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THE DATA FILES AND SOFTWARE ARE PROVIDED "AS IS", WITHOUT WARRANTY OF
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ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
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WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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NONINFRINGEMENT OF THIRD PARTY RIGHTS.
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IN NO EVENT SHALL THE COPYRIGHT HOLDER OR HOLDERS INCLUDED IN THIS
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NOTICE BE LIABLE FOR ANY CLAIM, OR ANY SPECIAL INDIRECT OR CONSEQUENTIAL
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DAMAGES, OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
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DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
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TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
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PERFORMANCE OF THE DATA FILES OR SOFTWARE.
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Except as contained in this notice, the name of a copyright holder
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shall not be used in advertising or otherwise to promote the sale,
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use or other dealings in these Data Files or Software without prior
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written authorization of the copyright holder.
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