wc-parser

A decently fast Rust library for parsing WhatsApp chat exports.

Features

Parse WhatsApp chat exports into structured data
Support for multiple date and time formats
Automatic detection of date format (day/month vs month/day)
Optional attachment parsing
System message detection
Multiline message support

Performance & Optimisations

wc-parser is designed to be fast and memory-efficient. Key optimisations include:

Memory-mapped I/O — parse_file uses memmap2 so chat exports are read straight from the operating-system page-cache without first copying them into a String, keeping peak RSS low even for multi-gigabyte logs.
Zero-copy parsing — When parsing from a &str, we split the original slice into &str line slices instead of allocating new strings, only allocating when constructing the final Message structs.
Pre-compiled regular expressions — All regex patterns are built once at start-up via lazy_static!, removing the compile cost from the hot parsing path.
Data-parallel message processing — Heavy-weight work (regex capture extraction, date/time normalisation, etc.) runs in parallel across CPU cores with rayon when debug output is disabled.
Selective attachment parsing — Attachment extraction is completely skipped unless parse_attachments = true, saving an extra regex run per message in the common case.
Configurable debug logging — Expensive debug printing is off by default. When enabled it switches to single-threaded execution to keep log output ordered.
Small-footprint date handling — Simple heuristics determine whether the log is day-first or month-first in a single pass, avoiding per-message branching once parsing begins.

Usage

Add this to your Cargo.toml:

[dependencies]
wc-parser = "0.1.2"

Basic Usage

use wc_parser::parse_string;

fn main() {
    let chat_content = r#"
06/03/2017, 00:45 - Sample User: This is a test message
08/05/2017, 01:48 - TestBot: Hey I'm a test too!
09/04/2017, 01:50 - +410123456789: How are you?
Is everything alright?
"#;

    let messages = parse_string(chat_content, None).unwrap();
    
    for message in messages {
        println!("Date: {}", message.date);
        if let Some(author) = message.author {
            println!("Author: {}", author);
        } else {
            println!("System message");
        }
        println!("Message: {}", message.message);
        println!("---");
    }
}

Advanced Usage with Options

use wc_parser::{parse_string, models::ParseStringOptions};

let options = ParseStringOptions {
    days_first: Some(true), // Specify date format
    parse_attachments: true, // Parse attachment information
};

let messages = parse_string(chat_content, Some(options)).unwrap();

Message Structure

Each parsed message contains:

// Located in `src/models.rs`
pub struct Message {
    // Located in `src/models.rs`
    // Located in `src/models.rs`

    pub date: DateTime<Utc>,           // Date and time of the message
    pub author: Option<String>,        // Author name (None for system messages)
    pub message: String,               // Message content
    pub attachment: Option<Attachment>, // Attachment info (if parse_attachments is enabled)
}

Supported Formats

This library supports various WhatsApp chat export formats including:

Different date formats (DD/MM/YYYY, MM/DD/YYYY, YYYY/MM/DD, etc.)
12-hour and 24-hour time formats
Various separators and punctuation
Unicode characters and directional marks
System messages and notifications

wc-parser 0.1.2