reading nbt

1 files changed, 117 insertions, 0 deletions

diff --git a/azalea-nbt/src/encode.rs b/azalea-nbt/src/encode.rs
new file mode 100644
index 00000000..86c0d868
--- /dev/null
+++ b/azalea-nbt/src/encode.rs
@@ -0,0 +1,117 @@
+use byteorder::{ReadBytesExt, BE};
+use error::Error;
+use std::{collections::HashMap, io::Read};
+use tag::Tag;
+
+impl Tag {
+    fn write(&self, stream: &mut impl Read) -> Result<(), Error> {
+        println!("read_known: id={}", id);
+        let tag = match id {
+            // Signifies the end of a TAG_Compound. It is only ever used inside
+            // a TAG_Compound, and is not named despite being in a TAG_Compound
+            0 => Tag::End,
+            // A single signed byte
+            1 => Tag::Byte(stream.read_i8().map_err(|_| Error::InvalidTag)?),
+            // A single signed, big endian 16 bit integer
+            2 => Tag::Short(stream.read_i16::<BE>().map_err(|_| Error::InvalidTag)?),
+            // A single signed, big endian 32 bit integer
+            3 => Tag::Int(stream.read_i32::<BE>().map_err(|_| Error::InvalidTag)?),
+            // A single signed, big endian 64 bit integer
+            4 => Tag::Long(stream.read_i64::<BE>().map_err(|_| Error::InvalidTag)?),
+            // A single, big endian IEEE-754 single-precision floating point
+            // number (NaN possible)
+            5 => Tag::Float(stream.read_f32::<BE>().map_err(|_| Error::InvalidTag)?),
+            // A single, big endian IEEE-754 double-precision floating point
+            // number (NaN possible)
+            6 => Tag::Double(stream.read_f64::<BE>().map_err(|_| Error::InvalidTag)?),
+            // A length-prefixed array of signed bytes. The prefix is a signed
+            // integer (thus 4 bytes)
+            7 => {
+                let length = stream.read_i32::<BE>().map_err(|_| Error::InvalidTag)?;
+                let mut bytes = Vec::new();
+                for _ in 0..length {
+                    bytes.push(stream.read_i8().map_err(|_| Error::InvalidTag)?);
+                }
+                Tag::ByteArray(bytes)
+            }
+            // A length-prefixed modified UTF-8 string. The prefix is an
+            // unsigned short (thus 2 bytes) signifying the length of the
+            // string in bytes
+            8 => {
+                let length = stream.read_u16::<BE>().map_err(|_| Error::InvalidTag)?;
+                let mut bytes = Vec::new();
+                for _ in 0..length {
+                    bytes.push(stream.read_u8().map_err(|_| Error::InvalidTag)?);
+                }
+                Tag::String(String::from_utf8(bytes).map_err(|_| Error::InvalidTag)?)
+            }
+            // A list of nameless tags, all of the same type. The list is
+            // prefixed with the Type ID of the items it contains (thus 1
+            // byte), and the length of the list as a signed integer (a further
+            // 4 bytes). If the length of the list is 0 or negative, the type
+            // may be 0 (TAG_End) but otherwise it must be any other type. (The
+            // notchian implementation uses TAG_End in that situation, but
+            // another reference implementation by Mojang uses 1 instead;
+            // parsers should accept any type if the length is <= 0).
+            9 => {
+                let type_id = stream.read_u8().map_err(|_| Error::InvalidTag)?;
+                let length = stream.read_i32::<BE>().map_err(|_| Error::InvalidTag)?;
+                let mut list = Vec::new();
+                for _ in 0..length {
+                    list.push(Tag::read_known(stream, type_id)?);
+                }
+                Tag::List(list)
+            }
+            // Effectively a list of a named tags. Order is not guaranteed.
+            10 => {
+                println!("reading compound {{");
+                let mut map = HashMap::new();
+                loop {
+                    let tag_id = stream.read_u8().unwrap_or(0);
+                    println!("compound tag id: {}", tag_id);
+                    if tag_id == 0 {
+                        break;
+                    }
+                    let name = match Tag::read_known(stream, 8)? {
+                        Tag::String(name) => name,
+                        _ => panic!("Expected a string tag"),
+                    };
+                    println!("compound name: {}", name);
+                    let tag = Tag::read_known(stream, tag_id).map_err(|_| Error::InvalidTag)?;
+                    println!("aight read tag: {:?}", tag);
+                    map.insert(name, tag);
+                }
+                println!("}} compound map: {:?}", map);
+                Tag::Compound(map)
+            }
+            // A length-prefixed array of signed integers. The prefix is a
+            // signed integer (thus 4 bytes) and indicates the number of 4 byte
+            // integers.
+            11 => {
+                let length = stream.read_i32::<BE>().map_err(|_| Error::InvalidTag)?;
+                let mut ints = Vec::new();
+                for _ in 0..length {
+                    ints.push(stream.read_i32::<BE>().map_err(|_| Error::InvalidTag)?);
+                }
+                Tag::IntArray(ints)
+            }
+            // A length-prefixed array of signed longs. The prefix is a signed
+            // integer (thus 4 bytes) and indicates the number of 8 byte longs.
+            12 => {
+                let length = stream.read_i32::<BE>().map_err(|_| Error::InvalidTag)?;
+                let mut longs = Vec::new();
+                for _ in 0..length {
+                    longs.push(stream.read_i64::<BE>().map_err(|_| Error::InvalidTag)?);
+                }
+                Tag::LongArray(longs)
+            }
+            _ => return Err(Error::InvalidTagType(id)),
+        };
+        Ok(tag)
+    }
+
+    pub fn read(stream: &mut impl Read) -> Result<Tag, Error> {
+        // default to compound tag
+        Tag::read_known(stream, 10)
+    }
+}