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use serde_json; use serde_json::Value; use std::collections::BTreeMap; use std::io; #[cfg(test)] mod tests; pub fn to_writer<W, T: Sized>(mut writer: W, value: &T) -> Result<(), Error> where W: io::Write, T: serde::ser::Serialize, { let v = serde_json::to_value(value)?; let bytes = canonicalize(&v)?; writer.write_all(&bytes)?; Ok(()) } pub fn to_vec<T: Sized>(value: &T) -> Result<Vec<u8>, Error> where T: serde::Serialize, { let mut writer = Vec::new(); to_writer(&mut writer, value)?; Ok(writer) } pub fn to_string<T: Sized>(value: &T) -> Result<String, Error> where T: serde::Serialize, { Ok(unsafe { String::from_utf8_unchecked(to_vec(value)?) }) } fn canonicalize(val: &serde_json::Value) -> Result<Vec<u8>, Error> { let cv = from_value(val)?; let mut buf = Vec::new(); let _ = cv.write(&mut buf); Ok(buf) } enum CanonicalValue { Null, Bool(bool), Number(Number), String(String), Array(Vec<CanonicalValue>), Object(BTreeMap<String, CanonicalValue>), } enum Number { I64(i64), } impl CanonicalValue { fn write(&self, mut buf: &mut Vec<u8>) -> Result<(), Error> { match *self { CanonicalValue::Null => { buf.extend(b"null"); Ok(()) } CanonicalValue::Bool(true) => { buf.extend(b"true"); Ok(()) } CanonicalValue::Bool(false) => { buf.extend(b"false"); Ok(()) } CanonicalValue::Number(Number::I64(n)) => match itoa::write(buf, n) { Ok(_) => Ok(()), Err(err) => Err(Error::Custom(format!("cannot write number: {}", err))), }, CanonicalValue::String(ref s) => { let s = serde_json::to_string(&Value::String(s.clone()))?; buf.extend(s.as_bytes()); Ok(()) } CanonicalValue::Array(ref arr) => { buf.push(b'['); let mut first = true; for a in arr.iter() { if !first { buf.push(b','); } a.write(&mut buf)?; first = false; } buf.push(b']'); Ok(()) } CanonicalValue::Object(ref obj) => { buf.push(b'{'); let mut first = true; for (k, v) in obj.iter() { if !first { buf.push(b','); } first = false; let k = serde_json::to_string(&Value::String(k.clone()))?; buf.extend(k.as_bytes()); buf.push(b':'); v.write(&mut buf)?; } buf.push(b'}'); Ok(()) } } } } fn from_value(val: &Value) -> Result<CanonicalValue, Error> { match *val { Value::Null => Ok(CanonicalValue::Null), Value::Bool(b) => Ok(CanonicalValue::Bool(b)), Value::Number(ref n) => { let x = n.as_i64(); match x { Some(x) => Ok(CanonicalValue::Number(Number::I64(x))), None => Err(Error::Custom(String::from(format!( "unsupported value in canonical JSON: {}", n )))), } } Value::String(ref s) => Ok(CanonicalValue::String(s.clone())), Value::Array(ref arr) => { let mut out = Vec::new(); for res in arr.iter().map(|v| from_value(v)) { out.push(res?) } Ok(CanonicalValue::Array(out)) } Value::Object(ref obj) => { let mut out = BTreeMap::new(); for (k, v) in obj.iter() { let _ = out.insert(k.clone(), from_value(v)?); } Ok(CanonicalValue::Object(out)) } } } #[derive(Debug)] pub enum Error { Custom(String), Io(io::Error), } impl From<serde_json::Error> for Error { fn from(err: serde_json::Error) -> Error { use serde_json::error::Category; match err.classify() { Category::Io => Error::Io(err.into()), Category::Syntax | Category::Data | Category::Eof => { Error::Custom(String::from(format!("{}", err))) } } } } impl From<io::Error> for Error { fn from(error: io::Error) -> Error { Error::Io(error) } }