Fixed Windows Terminal UTF-16 surrogate pair issue #857
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joshka
reviewed
May 3, 2024
joshka
approved these changes
May 19, 2024
Comment on lines
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| const HIGH_SURROGATE_FIRST: u16 = 0xD800; | ||
| const LOW_SURROGATE_FIRST: u16 = 0xDC00; | ||
| const LOW_SURROGATE_LAST: u16 = 0xDFFF; |
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Constants generally should be at the top of the file
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| let ch = handle_surrogate(&mut buf, new); | ||
| (buf, ch) | ||
| } | ||
| assert_eq!( | ||
| [ | ||
| // Continuous high surrogates | ||
| testcase(Some(0xD800), 0xDBFF), | ||
| // A normal surrogate pair | ||
| testcase(Some(0xD800), 0xDC00), | ||
| // An empty buffer and a high surrogate | ||
| testcase(None, 0xDBFF), | ||
| // An empty buffer and a low surrogate | ||
| testcase(None, 0xDC00), | ||
| ], | ||
| [ | ||
| // The newer one will be stored | ||
| (Some(0xDBFF), None), | ||
| // A valid char will return | ||
| (None, Some('\u{10000}')), | ||
| // The high surrogate will be stored | ||
| (Some(0xDBFF), None), | ||
| // The low surrogate will be ignored | ||
| (None, None), | ||
| ] | ||
| ); |
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Simplify (individual assertions, no testcase function, descriptions on the assertions, arranged in order that makes most sense (empty to full)):
Suggested change
| let ch = handle_surrogate(&mut buf, new); | |
| (buf, ch) | |
| } | |
| assert_eq!( | |
| [ | |
| // Continuous high surrogates | |
| testcase(Some(0xD800), 0xDBFF), | |
| // A normal surrogate pair | |
| testcase(Some(0xD800), 0xDC00), | |
| // An empty buffer and a high surrogate | |
| testcase(None, 0xDBFF), | |
| // An empty buffer and a low surrogate | |
| testcase(None, 0xDC00), | |
| ], | |
| [ | |
| // The newer one will be stored | |
| (Some(0xDBFF), None), | |
| // A valid char will return | |
| (None, Some('\u{10000}')), | |
| // The high surrogate will be stored | |
| (Some(0xDBFF), None), | |
| // The low surrogate will be ignored | |
| (None, None), | |
| ] | |
| ); | |
| let mut buf = None; | |
| let next = handle_surrogate(&mut buf, 0xDC00); | |
| assert_eq!( | |
| (buf, next), | |
| (None, None), | |
| "Unexpected low surrogate is ignored" | |
| ); | |
| let mut buf = None; | |
| let next = handle_surrogate(&mut buf, 0xDBFF); | |
| assert_eq!( | |
| (buf, next), | |
| (Some(0xDBFF), None), | |
| "High surrogate is buffered" | |
| ); | |
| let mut buf = Some(0xD800); | |
| let next = handle_surrogate(&mut buf, 0xDBFF); | |
| assert_eq!( | |
| (buf, next), | |
| (Some(0xDBFF), None), | |
| "Consecutive high surrogates" | |
| ); | |
| let mut buf = Some(0xD800); | |
| let next = handle_surrogate(&mut buf, 0xDC00); | |
| assert_eq!( | |
| (buf, next), | |
| (None, Some('\u{10000}')), | |
| "Valid Surrogate pair" | |
| ); |
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Resolve #848
Windows Terminal seems to send the characters represented by surrogate pairs in the following order:
On the other hand, crossterm's surrogate pair handling does not distinguish between key-down/key-up events. This may be reasonable, as there are cases where another terminal sends only key-up events, but this results in an incorrect sequence of input from the Windows Terminal.
This fix uses only the last input in the case of a sequence of upper surrogates and ignores the input of lower surrogates with no upper surrogates; in the Windows Terminal, inputs 1 and 4 above are ignored and a single surrogate pair is created from inputs 2 and 3.