Expand description
A low level, performance oriented parser for save and game files from Paradox Development Studio titles (eg: Europa Universalis (EU4), Hearts of Iron (HOI4), and Crusader Kings (CK3), Imperator, Stellaris, and Victoria).
For an in-depth look at the Paradox Clausewitz format and the pitfalls that come trying to support all variations, consult the write-up. In short, it’s extremely difficult to write a robust and fast parser that abstracts over the format difference between games as well as differences between game patches. Jomini hits the sweet spot between flexibility while still being ergonomic.
Jomini is the cornerstone of the online EU4 save file analyzer. This library also powers the Paradox Game Converters and pdxu.
Features
- ✔ Versatile: Handle both plaintext and binary encoded data
- ✔ Fast: Parse data at 1 GB/s
- ✔ Small: Compile with zero dependencies
- ✔ Safe: Extensively fuzzed against potential malicious input
- ✔ Ergonomic: Use serde-like macros to have parsing logic automatically implemented
- ✔ Embeddable: Cross platform native apps, statically compiled services, or in the browser via WASM
Quick Start
Below is a demonstration on parsing plaintext data using jomini tools.
use jomini::{JominiDeserialize, TextDeserializer};
#[derive(JominiDeserialize, PartialEq, Debug)]
pub struct Model {
human: bool,
first: Option<u16>,
#[jomini(alias = "forth")]
fourth: u16,
#[jomini(alias = "core", duplicated)]
cores: Vec<String>,
names: Vec<String>,
}
let data = br#"
human = yes
forth = 10
core = "HAB"
names = { "Johan" "Frederick" }
core = FRA
"#;
let expected = Model {
human: true,
first: None,
fourth: 10,
cores: vec!["HAB".to_string(), "FRA".to_string()],
names: vec!["Johan".to_string(), "Frederick".to_string()],
};
let actual: Model = TextDeserializer::from_windows1252_slice(data)?;
assert_eq!(actual, expected);
Binary Parsing
Parsing data encoded in the binary format is done in a similar fashion but with a couple extra steps for the caller to supply:
- How text should be decoded (typically Windows-1252 or UTF-8)
- How rational (floating point) numbers are decoded
- How tokens, which are 16 bit integers that uniquely identify strings, are resolved
Implementors be warned, not only does each Paradox game have a different binary format, but the binary format can vary between patches!
Below is an example that defines a sample binary format and uses a hashmap token lookup.
use jomini::{BinaryDeserializer, BinaryFlavor, Encoding, JominiDeserialize, Windows1252Encoding};
use std::{borrow::Cow, collections::HashMap};
#[derive(JominiDeserialize, PartialEq, Debug)]
struct MyStruct {
field1: String,
}
#[derive(Debug, Default)]
pub struct BinaryTestFlavor;
impl BinaryFlavor for BinaryTestFlavor {
fn visit_f32(&self, data: [u8; 4]) -> f32 {
f32::from_le_bytes(data)
}
fn visit_f64(&self, data: [u8; 8]) -> f64 {
f64::from_le_bytes(data)
}
}
impl Encoding for BinaryTestFlavor {
fn decode<'a>(&self, data: &'a [u8]) -> Cow<'a, str> {
Windows1252Encoding::decode(data)
}
}
let data = [ 0x82, 0x2d, 0x01, 0x00, 0x0f, 0x00, 0x03, 0x00, 0x45, 0x4e, 0x47 ];
let mut map = HashMap::new();
map.insert(0x2d82, "field1");
let actual: MyStruct = BinaryDeserializer::builder_flavor(BinaryTestFlavor)
.from_slice(&data[..], &map)?;
assert_eq!(actual, MyStruct { field1: "ENG".to_string() });
When done correctly, one can use the same structure to represent both the plaintext and binary data without any duplication.
One can configure the behavior when a token is unknown (ie: fail immediately or try to continue).
Caveats
Caller is responsible for:
- Determining the correct format (text or binary) ahead of time
- Stripping off any header that may be present (eg:
EU4txt
/EU4bin
) - Providing the token resolver for the binary format
- Providing the conversion to reconcile how, for example, a date may be encoded as an integer in the binary format, but as a string when in plaintext.
The Mid-level API
If the automatic deserialization via JominiDeserialize
is too high level, there is a mid-level
api where one can easily iterate through the parsed document and interrogate fields for
their information.
use jomini::TextTape;
let data = b"name=aaa name=bbb core=123 name=ccc name=ddd";
let tape = TextTape::from_slice(data).unwrap();
let mut reader = tape.windows1252_reader();
while let Some((key, _op, value)) = reader.next_field() {
println!("{:?}={:?}", key.read_str(), value.read_str().unwrap());
}
One Level Lower
At the lowest layer, one can interact with the raw data directly via TextTape
and BinaryTape
.
use jomini::{TextTape, TextToken, Scalar};
let data = b"foo=bar";
assert_eq!(
TextTape::from_slice(&data[..])?.tokens(),
&[
TextToken::Unquoted(Scalar::new(b"foo")),
TextToken::Unquoted(Scalar::new(b"bar")),
]
);
If one will only use TextTape
and BinaryTape
then jomini
can be compiled without default
features, resulting in a build without dependencies.
Write API
There are two targeted use cases for the write API. One is when a text tape is on hand. This is useful when one needs to reformat a document (note that comments are not preserved):
use jomini::{TextTape, TextWriterBuilder};
let tape = TextTape::from_slice(b"hello = world")?;
let mut out: Vec<u8> = Vec::new();
let mut writer = TextWriterBuilder::new().from_writer(&mut out);
writer.write_tape(&tape)?;
assert_eq!(&out, b"hello=world\n");
The writer normalizes any formatting issues. The writer is not able to losslessly write all parsed documents, but these are limited to truly esoteric situations and hope to be resolved in future releases.
The other use case is geared more towards incremental writing that can be found in melters or those crafting documents by hand. These use cases need to manually drive the writer:
use jomini::TextWriterBuilder;
let mut out: Vec<u8> = Vec::new();
let mut writer = TextWriterBuilder::new().from_writer(&mut out);
writer.write_unquoted(b"hello")?;
writer.write_unquoted(b"world")?;
writer.write_unquoted(b"foo")?;
writer.write_unquoted(b"bar")?;
assert_eq!(&out, b"hello=world\nfoo=bar\n");
Modules
Common data structures used across games
Structs
A text reader that advances through a sequence of values
A structure to deserialize binary data into Rust values.
Build a tweaked binary deserializer
Houses the tape of tokens that is extracted from binary data
Customizes how the binary tape is parsed from data
A date error.
The default writer that will write floating point at full representation
A Serde deserialization error.
An error that can occur when processing data
A reader that will advance through an object
Extracted color info
A byte slice that represents a single value.
A text reader that wraps an underlying scalar value
A structure to deserialize text data into Rust values.
Houses the tape of tokens that is extracted from plaintext data
Write data in PDS format.
Construct a customized text writer
Decodes bytes according to the utf8 standard
A text reader for a text value
Decodes bytes according to the windows1252 code page
Enums
Represents any valid binary value
The type of a Serde deserialization error.
Specific type of error
Customize how the deserializer reacts when a token can’t be resolved
An operator token
All possible text reader variants
An error that can occur when converting a scalar into the requested type.
Represents a valid text value
Traits
Trait customizing decoding values from binary data
An encoding for interpreting byte data as UTF-8 text
Resolves binary 16bit tokens to field names
Customizes writer behavior at a field level
Derive Macros
Creates a serde compatible Deserialize
implementation