feat(stdlib): Add Buffer.setChar and Buffer.getChar
#2262
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spotandjake
requested review from
ospencer,
phated,
peblair,
marcusroberts,
jozanza and
alex-snezhko
as code owners
| @unsafe | ||
| provide let getChar = (index, buffer) => { | ||
| use WasmI32.{ (+), (&), (+), (==), (>) } | ||
| checkIsIndexInBounds(index, 1, buffer) |
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Why is this 1 if it's UTF-8?
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Characters can be between 1 and 4 bytes, we need to ensure the first byte exists so we can check the char size on line 406 and we do an additional length check on line 408 with the actual length.
This is why getChar needs to operate on the bytes directly rather than just using Bytes.getChar like our other helpers.
| @@ -376,6 +376,68 @@ provide let addString = (string, buffer) => { | |||
| buffer.len += bytelen | |||
| } | |||
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| /** | |||
| * Gets the UTF-8 encoded character at the given byte index. | |||
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If the operation is intended to get a character starting at a byte index then if you point your index in the middle of a UTF-8 character then what would the expectation be?
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I'm pretty sure it would either return a character in the case that the rest was a valid char (I can't recall if thats ever the case), but more likely MalformedUnicode.
This adds
Buffer.setCharandBuffer.getCharto complement their bytes counterparts.Note: We have to read the first byte before
getCharso we can correctly do the bounds check similar to how its done inBytes.getChar.Note: I realized we missed a piece of documentation on
Bytes.getCharso I added it here.