Natural Date Parser

Brief Description

A parser that converts natural language date and time expressions into Rust-compatible DateTime formats.

Natural Date Parser is a Rust project designed to parse human-friendly, natural language date and time expressions, such as "next Monday," "tomorrow at 5 PM," or "3 weeks from now." This parser converts these expressions into structured DateTime objects, making them usable in scheduling applications, reminders, or other time-based software.

Technical Description

Parsing Process

The parser is built using the Pest parsing library and is designed to recognize a variety of natural language phrases related to dates and times. These include:

• Simple Relative Dates: "today," "tomorrow," "yesterday."
• Day of the Week Expressions: "next Monday," "last Friday."
• Complex Relative Time Expressions: "in 3 days," "2 weeks from now," "4 months ago."
• Combined Date and Time Expressions: "next Thursday at 10 AM," "tomorrow at 5:30 PM."

How It Works

The parsing process follows these steps:

1. Tokenization and Grammar Definition: The parser uses Pest to define grammar rules for recognizing date keywords (e.g., "next," "last"), day names (e.g., "Monday," "Sunday"), and time phrases (e.g., "at 5 PM").
2. Mapping to Date Components: Once the input text is parsed, it is converted into date and time components, such as days, months, and hours. These components are passed to Rust’s chrono library to calculate the exact DateTime value.
3. Error Handling: If an unrecognized phrase is entered, the parser provides an error message guiding the user to valid inputs.

Use Cases

The output DateTime values can be used in a variety of applications:

• Scheduling Apps: Automatically parse reminders like "next Monday" and "in 3 days" into exact dates.
• Task Management: Set deadlines with natural language, making it easier to schedule tasks.
• Chatbots and Virtual Assistants: Interpret user queries about dates and times with ease.

Getting Started

To start using Natural Date Parser, you can use crate on crates.io

Example Usage

fn main() -> anyhow::Result<()> {
    let pair = Grammar::parse(Rule::date_expression, "next Monday")?
        .next()
        .ok_or_else(|| anyhow!("no pair"))?;
    dbg!(pair);
    Ok(())
}