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Minor optimization to not check if JSON number starts with '-' twice

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This commit is contained in:
Erick Tryzelaar 2015-08-01 11:41:42 -07:00
parent c9d55362d6
commit fa562d449d
1 changed files with 14 additions and 15 deletions
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29
serde_json/src/de.rs
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@ -108,7 +108,13 @@ impl<Iter> Deserializer<Iter>
try!(self.parse_ident(b"alse"));
visitor.visit_bool(false)
}
b'0' ... b'9' | b'-' => self.parse_number(visitor),
b'-' => {
try!(self.bump());
self.parse_number(false, visitor)
}
b'0' ... b'9' => {
self.parse_number(true, visitor)
}
b'"' => {
try!(self.parse_string());
let s = str::from_utf8(&self.str_buf).unwrap();
@ -145,16 +151,9 @@ impl<Iter> Deserializer<Iter>
Ok(())
}
fn parse_number<V>(&mut self, mut visitor: V) -> Result<V::Value>
fn parse_number<V>(&mut self, pos: bool, mut visitor: V) -> Result<V::Value>
where V: de::Visitor,
{
let mut neg = false;
if self.ch_is(b'-') {
try!(self.bump());
neg = true;
}
let res = try!(self.parse_integer());
if self.ch_is(b'.') || self.ch_is(b'e') || self.ch_is(b'E') {
@ -168,13 +167,15 @@ impl<Iter> Deserializer<Iter>
res = try!(self.parse_exponent(res));
}
if neg {
visitor.visit_f64(-res)
} else {
if pos {
visitor.visit_f64(res)
} else {
visitor.visit_f64(-res)
}
} else {
if neg {
if pos {
visitor.visit_u64(res)
} else {
let res = -(res as i64);
// Make sure we didn't underflow.
@ -183,8 +184,6 @@ impl<Iter> Deserializer<Iter>
} else {
visitor.visit_i64(res)
}
} else {
visitor.visit_u64(res)
}
}
}