446 lines
14 KiB
Rust
446 lines
14 KiB
Rust
use std::collections::HashMap;
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use error::Error;
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use error::Result;
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use nbt::Tag;
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use nbt::NBT;
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use serde::{ser, Serialize};
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mod deserialize;
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mod error;
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pub mod nbt;
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mod serialize;
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pub fn to_nbt<T>(name: &str, value: &T) -> anyhow::Result<NBT>
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where
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T: Serialize,
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{
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Ok(NBT::new(name, to_tag(value)?))
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}
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pub fn to_tag<T>(value: &T) -> anyhow::Result<Tag>
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where
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T: Serialize,
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{
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let mut serializer = Serializer { tag: Tag::End };
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value.serialize(&mut serializer)?;
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Ok(serializer.tag)
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}
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pub struct Serializer {
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tag: Tag,
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}
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pub struct SeqSerializer<'a> {
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ser: &'a mut Serializer,
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items: Vec<Tag>,
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}
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pub struct MapSerializer<'a> {
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ser: &'a mut Serializer,
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key: Option<String>,
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items: HashMap<String, Tag>,
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}
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impl<'a> ser::Serializer for &'a mut Serializer {
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// The output type produced by this `Serializer` during successful
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// serialization. Most serializers that produce text or binary output should
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// set `Ok = ()` and serialize into an `io::Write` or buffer contained
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// within the `Serializer` instance, as happens here. Serializers that build
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// in-memory data structures may be simplified by using `Ok` to propagate
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// the data structure around.
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type Ok = ();
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type Error = Error;
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// Associated types for keeping track of additional state while serializing
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// compound data structures like sequences and maps. In this case no
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// additional state is required beyond what is already stored in the
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// Serializer struct.
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type SerializeSeq = SeqSerializer<'a>;
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type SerializeTuple = SeqSerializer<'a>;
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type SerializeTupleStruct = SeqSerializer<'a>;
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type SerializeTupleVariant = SeqSerializer<'a>;
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type SerializeMap = MapSerializer<'a>;
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type SerializeStruct = MapSerializer<'a>;
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type SerializeStructVariant = MapSerializer<'a>;
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// Here we go with the simple methods. The following 12 methods receive one
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// of the primitive types of the data model and map it to JSON by appending
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// into the output string.
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fn serialize_bool(self, v: bool) -> Result<()> {
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self.tag = Tag::Byte(v as i8);
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Ok(())
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}
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// JSON does not distinguish between different sizes of integers, so all
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// signed integers will be serialized the same and all unsigned integers
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// will be serialized the same. Other formats, especially compact binary
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// formats, may need independent logic for the different sizes.
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fn serialize_i8(self, v: i8) -> Result<()> {
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self.tag = Tag::Byte(v);
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Ok(())
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}
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fn serialize_i16(self, v: i16) -> Result<()> {
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self.tag = Tag::Short(v);
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Ok(())
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}
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fn serialize_i32(self, v: i32) -> Result<()> {
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self.tag = Tag::Int(v);
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Ok(())
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}
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fn serialize_i64(self, v: i64) -> Result<()> {
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self.tag = Tag::Long(v);
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Ok(())
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}
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fn serialize_u8(self, v: u8) -> Result<()> {
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self.serialize_i8(v as i8)
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}
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fn serialize_u16(self, v: u16) -> Result<()> {
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self.serialize_i16(v as i16)
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}
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fn serialize_u32(self, v: u32) -> Result<()> {
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self.serialize_i32(v as i32)
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}
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fn serialize_u64(self, v: u64) -> Result<()> {
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self.serialize_i64(v as i64)
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}
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fn serialize_f32(self, v: f32) -> Result<()> {
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self.tag = Tag::Float(v);
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Ok(())
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}
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fn serialize_f64(self, v: f64) -> Result<()> {
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self.tag = Tag::Double(v);
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Ok(())
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}
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fn serialize_char(self, v: char) -> Result<()> {
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self.serialize_str(&v.to_string())
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}
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fn serialize_str(self, v: &str) -> Result<()> {
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self.tag = Tag::String(v.into());
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Ok(())
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}
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fn serialize_bytes(self, v: &[u8]) -> Result<()> {
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self.tag = Tag::ByteArr(v.into());
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Ok(())
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}
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// There isn't really a `None` in NBT. There is `Tag::End`, which could be
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// searched and removed if this was in a struct or map, which would essentially
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// skip this value if it's `None`. However, I don't care enough, so I'm just
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// going to produce an error.
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fn serialize_none(self) -> Result<()> {
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Err(Error::CannotSerializeNone)
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}
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fn serialize_some<T>(self, value: &T) -> Result<()>
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where
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T: ?Sized + Serialize,
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{
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value.serialize(self)
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}
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fn serialize_unit(self) -> Result<()> {
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Err(Error::CannotSerializeNone)
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}
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// Unit struct means a named value containing no data. Again, since there is
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// no data, map this to JSON as `null`. There is no need to serialize the
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// name in most formats.
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fn serialize_unit_struct(self, _name: &'static str) -> Result<()> {
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self.serialize_unit()
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}
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// As is done here, serializers are encouraged to treat newtype structs as
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// insignificant wrappers around the data they contain.
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fn serialize_newtype_struct<T>(self, _name: &'static str, value: &T) -> Result<()>
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where
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T: ?Sized + Serialize,
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{
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value.serialize(self)
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}
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// Now we get to the serialization of compound types.
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//
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// The start of the sequence, each value, and the end are three separate
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// method calls. This one is responsible only for serializing the start,
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// which in JSON is `[`.
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//
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// The length of the sequence may or may not be known ahead of time. This
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// doesn't make a difference in JSON because the length is not represented
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// explicitly in the serialized form. Some serializers may only be able to
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// support sequences for which the length is known up front.
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fn serialize_seq(self, _len: Option<usize>) -> Result<Self::SerializeSeq> {
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Ok(SeqSerializer {
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ser: self,
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items: vec![],
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})
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}
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// Tuples look just like sequences in JSON. Some formats may be able to
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// represent tuples more efficiently by omitting the length, since tuple
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// means that the corresponding `Deserialize implementation will know the
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// length without needing to look at the serialized data.
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fn serialize_tuple(self, len: usize) -> Result<Self::SerializeTuple> {
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self.serialize_seq(Some(len))
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}
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// Tuple structs look just like sequences in JSON.
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fn serialize_tuple_struct(
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self,
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_name: &'static str,
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len: usize,
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) -> Result<Self::SerializeTupleStruct> {
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self.serialize_seq(Some(len))
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}
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// Maps are represented in JSON as `{ K: V, K: V, ... }`.
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fn serialize_map(self, _len: Option<usize>) -> Result<Self::SerializeMap> {
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Ok(MapSerializer {
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ser: self,
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key: None,
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items: HashMap::new(),
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})
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}
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// Structs look just like maps in JSON. In particular, JSON requires that we
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// serialize the field names of the struct. Other formats may be able to
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// omit the field names when serializing structs because the corresponding
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// Deserialize implementation is required to know what the keys are without
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// looking at the serialized data.
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fn serialize_struct(self, _name: &'static str, len: usize) -> Result<Self::SerializeStruct> {
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self.serialize_map(Some(len))
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}
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// We don't support enums (they don't really make sense)
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fn serialize_unit_variant(
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self,
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_name: &'static str,
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_variant_index: u32,
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_variant: &'static str,
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) -> Result<()> {
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Err(Error::Enum)
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}
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fn serialize_newtype_variant<T>(
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self,
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_name: &'static str,
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_variant_index: u32,
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_variant: &'static str,
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_value: &T,
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) -> Result<()>
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where
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T: ?Sized + Serialize,
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{
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Err(Error::Enum)
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}
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fn serialize_tuple_variant(
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self,
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_name: &'static str,
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_variant_index: u32,
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_variant: &'static str,
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_len: usize,
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) -> Result<Self::SerializeTupleVariant> {
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Err(Error::Enum)
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}
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fn serialize_struct_variant(
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self,
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_name: &'static str,
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_variant_index: u32,
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_variant: &'static str,
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_len: usize,
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) -> Result<Self::SerializeStructVariant> {
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Err(Error::Enum)
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}
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}
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// The following 7 impls deal with the serialization of compound types like
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// sequences and maps. Serialization of such types is begun by a Serializer
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// method and followed by zero or more calls to serialize individual elements of
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// the compound type and one call to end the compound type.
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//
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// This impl is SerializeSeq so these methods are called after `serialize_seq`
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// is called on the Serializer.
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impl<'a> ser::SerializeSeq for SeqSerializer<'a> {
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type Ok = ();
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type Error = Error;
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// Serialize a single element of the sequence.
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fn serialize_element<T>(&mut self, value: &T) -> Result<()>
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where
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T: ?Sized + Serialize,
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{
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value.serialize(&mut *self.ser)?;
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let tag = std::mem::replace(&mut self.ser.tag, Tag::End);
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if let Some(first) = self.items.first() {
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let expected_ty = first.ty();
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let actual_ty = tag.ty();
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if expected_ty != actual_ty {
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return Err(Error::ListType(first.clone(), tag));
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}
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}
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self.items.push(tag);
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Ok(())
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}
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fn end(self) -> Result<()> {
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self.ser.tag = Tag::List(self.items);
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Ok(())
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}
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}
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// Same thing but for tuples.
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impl<'a> ser::SerializeTuple for SeqSerializer<'a> {
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type Ok = ();
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type Error = Error;
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fn serialize_element<T>(&mut self, value: &T) -> Result<()>
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where
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T: ?Sized + Serialize,
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{
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<Self as ser::SerializeSeq>::serialize_element(self, value)
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}
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fn end(self) -> Result<()> {
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<Self as ser::SerializeSeq>::end(self)
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}
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}
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// Same thing but for tuple structs.
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impl<'a> ser::SerializeTupleStruct for SeqSerializer<'a> {
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type Ok = ();
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type Error = Error;
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fn serialize_field<T>(&mut self, value: &T) -> Result<()>
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where
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T: ?Sized + Serialize,
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{
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<Self as ser::SerializeSeq>::serialize_element(self, value)
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}
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fn end(self) -> Result<()> {
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<Self as ser::SerializeSeq>::end(self)
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}
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}
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// Tuple variants are a little different. Refer back to the
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// `serialize_tuple_variant` method above:
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//
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// self.output += "{";
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// variant.serialize(&mut *self)?;
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// self.output += ":[";
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//
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// So the `end` method in this impl is responsible for closing both the `]` and
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// the `}`.
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impl<'a> ser::SerializeTupleVariant for SeqSerializer<'a> {
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type Ok = ();
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type Error = Error;
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fn serialize_field<T>(&mut self, value: &T) -> Result<()>
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where
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T: ?Sized + Serialize,
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{
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<Self as ser::SerializeSeq>::serialize_element(self, value)
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}
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fn end(self) -> Result<()> {
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<Self as ser::SerializeSeq>::end(self)
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}
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}
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// Some `Serialize` types are not able to hold a key and value in memory at the
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// same time so `SerializeMap` implementations are required to support
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// `serialize_key` and `serialize_value` individually.
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//
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// There is a third optional method on the `SerializeMap` trait. The
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// `serialize_entry` method allows serializers to optimize for the case where
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// key and value are both available simultaneously. In JSON it doesn't make a
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// difference so the default behavior for `serialize_entry` is fine.
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impl<'a> ser::SerializeMap for MapSerializer<'a> {
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type Ok = ();
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type Error = Error;
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// The Serde data model allows map keys to be any serializable type. JSON
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// only allows string keys so the implementation below will produce invalid
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// JSON if the key serializes as something other than a string.
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//
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// A real JSON serializer would need to validate that map keys are strings.
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// This can be done by using a different Serializer to serialize the key
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// (instead of `&mut **self`) and having that other serializer only
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// implement `serialize_str` and return an error on any other data type.
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fn serialize_key<T>(&mut self, key: &T) -> Result<()>
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where
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T: ?Sized + Serialize,
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{
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key.serialize(&mut *self.ser)?;
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let tag = std::mem::replace(&mut self.ser.tag, Tag::End);
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self.key = match tag {
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Tag::String(key) => Some(key),
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other => return Err(Error::MapKey(other)),
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};
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Ok(())
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}
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// It doesn't make a difference whether the colon is printed at the end of
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// `serialize_key` or at the beginning of `serialize_value`. In this case
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// the code is a bit simpler having it here.
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fn serialize_value<T>(&mut self, value: &T) -> Result<()>
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where
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T: ?Sized + Serialize,
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{
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value.serialize(&mut *self.ser)?;
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let tag = std::mem::replace(&mut self.ser.tag, Tag::End);
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self.items.insert(self.key.take().unwrap(), tag);
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Ok(())
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}
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fn end(self) -> Result<()> {
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self.ser.tag = self.items.into();
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Ok(())
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}
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}
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// Structs are like maps in which the keys are constrained to be compile-time
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// constant strings.
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impl<'a> ser::SerializeStruct for MapSerializer<'a> {
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type Ok = ();
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type Error = Error;
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fn serialize_field<T>(&mut self, key: &'static str, value: &T) -> Result<()>
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where
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T: ?Sized + Serialize,
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{
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value.serialize(&mut *self.ser)?;
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let tag = std::mem::replace(&mut self.ser.tag, Tag::End);
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self.items.insert(key.into(), tag);
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Ok(())
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}
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fn end(self) -> Result<()> {
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self.ser.tag = self.items.into();
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Ok(())
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}
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}
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// Similar to `SerializeTupleVariant`, here the `end` method is responsible for
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// closing both of the curly braces opened by `serialize_struct_variant`.
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impl<'a> ser::SerializeStructVariant for MapSerializer<'a> {
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type Ok = ();
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type Error = Error;
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fn serialize_field<T>(&mut self, key: &'static str, value: &T) -> Result<()>
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where
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T: ?Sized + Serialize,
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{
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value.serialize(&mut *self.ser)?;
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let tag = std::mem::replace(&mut self.ser.tag, Tag::End);
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self.items.insert(key.into(), tag);
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Ok(())
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}
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fn end(self) -> Result<()> {
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self.ser.tag = self.items.into();
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Ok(())
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}
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}
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