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Rewrite enum deserialization to not require allocations

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This commit is contained in:
Erick Tryzelaar
2015-03-15 22:04:17 -07:00
parent b40d8f7bac
commit 78137ee3a4
7 changed files with 273 additions and 147 deletions
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benches/bench_enum.rs
+74 -16
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@@ -245,9 +245,11 @@ mod deserializer {
use serde::de;
#[derive(Debug)]
enum State {
AnimalState(Animal),
IsizeState(isize),
StrState(&'static str),
StringState(String),
UnitState,
}
@@ -273,29 +275,51 @@ mod deserializer {
where V: de::Visitor,
{
match self.stack.pop() {
Some(State::AnimalState(Animal::Dog)) => {
self.stack.push(State::UnitState);
visitor.visit_enum("Animal", "Dog", DogVisitor {
de: self,
})
}
Some(State::AnimalState(Animal::Frog(x0, x1))) => {
self.stack.push(State::IsizeState(x1));
self.stack.push(State::StringState(x0));
visitor.visit_enum("Animal", "Frog", FrogVisitor {
de: self,
state: 0,
})
}
Some(State::IsizeState(value)) => {
visitor.visit_isize(value)
}
Some(State::StringState(value)) => {
visitor.visit_string(value)
}
Some(State::StrState(value)) => {
visitor.visit_str(value)
}
Some(State::UnitState) => {
visitor.visit_unit()
}
Some(_) => {
Err(Error::SyntaxError)
}
None => {
Err(Error::EndOfStreamError)
}
}
}
#[inline]
fn visit_enum<V>(&mut self, _name: &str, mut visitor: V) -> Result<V::Value, Error>
where V: de::EnumVisitor,
{
match self.stack.pop() {
Some(State::AnimalState(Animal::Dog)) => {
self.stack.push(State::UnitState);
self.stack.push(State::StrState("Dog"));
visitor.visit(DogVisitor {
de: self,
})
}
Some(State::AnimalState(Animal::Frog(x0, x1))) => {
self.stack.push(State::IsizeState(x1));
self.stack.push(State::StringState(x0));
self.stack.push(State::StrState("Frog"));
visitor.visit(FrogVisitor {
de: self,
state: 0,
})
}
Some(_) => {
Err(Error::SyntaxError)
}
None => {
Err(Error::EndOfStreamError)
}
@@ -307,12 +331,30 @@ mod deserializer {
de: &'a mut AnimalDeserializer,
}
impl<'a> de::EnumVisitor for DogVisitor<'a> {
impl<'a> de::VariantVisitor for DogVisitor<'a> {
type Error = Error;
fn visit_variant<V>(&mut self) -> Result<V, Error>
where V: de::Deserialize
{
de::Deserialize::deserialize(self.de)
}
fn visit_unit(&mut self) -> Result<(), Error> {
de::Deserialize::deserialize(self.de)
}
fn visit_seq<V>(&mut self, _visitor: V) -> Result<V::Value, Error>
where V: de::EnumSeqVisitor
{
Err(de::Error::syntax_error())
}
fn visit_map<V>(&mut self, _visitor: V) -> Result<V::Value, Error>
where V: de::EnumMapVisitor
{
Err(de::Error::syntax_error())
}
}
struct FrogVisitor<'a> {
@@ -320,14 +362,30 @@ mod deserializer {
state: usize,
}
impl<'a> de::EnumVisitor for FrogVisitor<'a> {
impl<'a> de::VariantVisitor for FrogVisitor<'a> {
type Error = Error;
fn visit_variant<V>(&mut self) -> Result<V, Error>
where V: de::Deserialize
{
de::Deserialize::deserialize(self.de)
}
fn visit_unit(&mut self) -> Result<(), Error> {
Err(de::Error::syntax_error())
}
fn visit_seq<V>(&mut self, mut visitor: V) -> Result<V::Value, Error>
where V: de::EnumSeqVisitor,
{
visitor.visit(self)
}
fn visit_map<V>(&mut self, _visitor: V) -> Result<V::Value, Error>
where V: de::EnumMapVisitor
{
Err(de::Error::syntax_error())
}
}
impl<'a> de::SeqVisitor for FrogVisitor<'a> {