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Serializer: Implement collect_str #81

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merged 3 commits into from
Jan 22, 2024
Merged

Serializer: Implement collect_str #81

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3ec4b96
Serializer: Implement collect_str
elrafoon Jan 15, 2024
6767ae1
Add changelog entry for adding Serializer::collect_str
elrafoon Jan 22, 2024
e13c3f8
Serializer::collect_str: Format with cargo fmt
elrafoon Jan 22, 2024
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1 change: 1 addition & 0 deletions CHANGELOG.md
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).

- Support for optional package `defmt` which allows for easy conversion for
error types when using tools like `probe-rs` for logging over debuggers.
- Implement `Serializer::collect_str`

### Changed

Expand Down
149 changes: 92 additions & 57 deletions src/ser/mod.rs
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Expand Up @@ -94,6 +94,66 @@ impl<'a> Serializer<'a> {
Ok(())
}
}

fn push_char(&mut self, c: char) -> Result<()> {
// Do escaping according to "6. MUST represent all strings (including object member names) in
// their minimal-length UTF-8 encoding": https://gibson042.github.io/canonicaljson-spec/
//
// We don't need to escape lone surrogates because surrogate pairs do not exist in valid UTF-8,
// even if they can exist in JSON or JavaScript strings (UCS-2 based). As a result, lone surrogates
// cannot exist in a Rust String. If they do, the bug is in the String constructor.
// An excellent explanation is available at https://www.youtube.com/watch?v=HhIEDWmQS3w

// Temporary storage for encoded a single char.
// A char is up to 4 bytes long wehn encoded to UTF-8.
let mut encoding_tmp = [0u8; 4];

match c {
'\\' => {
self.push(b'\\')?;
self.push(b'\\')?;
}
'"' => {
self.push(b'\\')?;
self.push(b'"')?;
}
'\u{0008}' => {
self.push(b'\\')?;
self.push(b'b')?;
}
'\u{0009}' => {
self.push(b'\\')?;
self.push(b't')?;
}
'\u{000A}' => {
self.push(b'\\')?;
self.push(b'n')?;
}
'\u{000C}' => {
self.push(b'\\')?;
self.push(b'f')?;
}
'\u{000D}' => {
self.push(b'\\')?;
self.push(b'r')?;
}
'\u{0000}'..='\u{001F}' => {
self.push(b'\\')?;
self.push(b'u')?;
self.push(b'0')?;
self.push(b'0')?;
let (hex1, hex2) = hex(c as u8);
self.push(hex1)?;
self.push(hex2)?;
}
_ => {
let encoded = c.encode_utf8(&mut encoding_tmp as &mut [u8]);
self.extend_from_slice(encoded.as_bytes())?;
}
}

Ok(())
}
}

// NOTE(serialize_*signed) This is basically the numtoa implementation minus the lookup tables,
Expand Down Expand Up @@ -263,62 +323,8 @@ impl<'a, 'b: 'a> ser::Serializer for &'a mut Serializer<'b> {
fn serialize_str(self, v: &str) -> Result<Self::Ok> {
self.push(b'"')?;

// Do escaping according to "6. MUST represent all strings (including object member names) in
// their minimal-length UTF-8 encoding": https://gibson042.github.io/canonicaljson-spec/
//
// We don't need to escape lone surrogates because surrogate pairs do not exist in valid UTF-8,
// even if they can exist in JSON or JavaScript strings (UCS-2 based). As a result, lone surrogates
// cannot exist in a Rust String. If they do, the bug is in the String constructor.
// An excellent explanation is available at https://www.youtube.com/watch?v=HhIEDWmQS3w

// Temporary storage for encoded a single char.
// A char is up to 4 bytes long wehn encoded to UTF-8.
let mut encoding_tmp = [0u8; 4];

for c in v.chars() {
match c {
'\\' => {
self.push(b'\\')?;
self.push(b'\\')?;
}
'"' => {
self.push(b'\\')?;
self.push(b'"')?;
}
'\u{0008}' => {
self.push(b'\\')?;
self.push(b'b')?;
}
'\u{0009}' => {
self.push(b'\\')?;
self.push(b't')?;
}
'\u{000A}' => {
self.push(b'\\')?;
self.push(b'n')?;
}
'\u{000C}' => {
self.push(b'\\')?;
self.push(b'f')?;
}
'\u{000D}' => {
self.push(b'\\')?;
self.push(b'r')?;
}
'\u{0000}'..='\u{001F}' => {
self.push(b'\\')?;
self.push(b'u')?;
self.push(b'0')?;
self.push(b'0')?;
let (hex1, hex2) = hex(c as u8);
self.push(hex1)?;
self.push(hex2)?;
}
_ => {
let encoded = c.encode_utf8(&mut encoding_tmp as &mut [u8]);
self.extend_from_slice(encoded.as_bytes())?;
}
}
self.push_char(c)?;
}

self.push(b'"')
Expand Down Expand Up @@ -434,11 +440,40 @@ impl<'a, 'b: 'a> ser::Serializer for &'a mut Serializer<'b> {
Ok(SerializeStructVariant::new(self))
}

fn collect_str<T: ?Sized>(self, _value: &T) -> Result<Self::Ok>
fn collect_str<T: ?Sized>(self, value: &T) -> Result<Self::Ok>
where
T: fmt::Display,
{
unreachable!()
self.push(b'"')?;

let mut col = StringCollector::new(self);
fmt::write(&mut col, format_args!("{}", value)).or(Err(Error::BufferFull))?;

self.push(b'"')
}
}

struct StringCollector<'a, 'b> {
ser: &'a mut Serializer<'b>,
}

impl<'a, 'b> StringCollector<'a, 'b> {
pub fn new(ser: &'a mut Serializer<'b>) -> Self {
Self { ser }
}

fn do_write_str(&mut self, s: &str) -> Result<()> {
for c in s.chars() {
self.ser.push_char(c)?;
}

Ok(())
}
}

impl<'a, 'b> fmt::Write for StringCollector<'a, 'b> {
fn write_str(&mut self, s: &str) -> fmt::Result {
self.do_write_str(s).or(Err(fmt::Error))
}
}

Expand Down
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