Crate jomini

A low level, performance oriented parser for EU4 save files and other PDS developed titles.

Jomini is the cornerstone of the Rakaly, an EU4 achievement leaderboard and save file analyzer. This library is also used in the Paradox Game Converters project to parse ironman EU4 saves.

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
• ✔ Agnostic: Parse EU4, HOIV, Imperator, etc save files

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_slice(data)?;
assert_eq!(actual, expected);

Binary Parsing

Parsing data encoded in the binary format is done in a similar fashion but with an extra step. Tokens can be encoded into 16 integers, and so one must provide a map from these integers to their textual representations

use jomini::{JominiDeserialize, BinaryDeserializer};
use std::collections::HashMap;

#[derive(JominiDeserialize, PartialEq, Debug)]
struct MyStruct {
    field1: String,
}

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::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 plaintext parser is geared towards save file parsing and is not yet general enough to handle files that embed operators other than equals.

One Level Lower

If the automatic deserialization via JominiDeserialize is too high level, 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::Scalar(Scalar::new(b"foo")),
        TextToken::Scalar(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.

Structs

BinaryDeserializer	A structure to deserialize binary data into Rust values.
BinaryDeserializerBuilder	Build a tweaked binary deserializer
BinaryTape	Houses the tape of tokens that is extracted from binary data
DeserializeError	A Serde deserialization error.
Error	An error that can occur when processing data
Rgb	Extracted color info
Scalar	Single value encapsulating windows-1252 data.
TextDeserializer	A structure to deserialize text data into Rust values.
TextTape	Houses the tape of tokens that is extracted from plaintext data

Enums

BinaryToken	Represents any valid binary value
DeserializeErrorKind	The type of a Serde deserialization error.
ErrorKind	Specific type of error
FailedResolveStrategy	Customize how the deserializer reacts when a token can't be resolved
ScalarError	An error that can occur when converting a scalar into the requested type.
TextToken	Represents a valid text value

Traits

TokenResolver

Resolves binary 16bit tokens to field names

Derive Macros

JominiDeserialize

Creates a serde compatible Deserialize implementation