rust-dax

A Rust library for parsing and evaluating DAX (Data Analysis Expressions) formulas using procedural macros. This library provides compile-time parsing of DAX expressions and basic evaluation capabilities.

Features

• Compile-time parsing of DAX expressions
• Support for basic DAX functions (SUM, AVERAGE, COUNT)
• Column reference parsing using square bracket notation
• Basic arithmetic operations
• Table creation macro for testing and development

Installation

Add this to your Cargo.toml:

[dependencies]
rust-dax = "0.1.0"

Usage

Parsing DAX Expressions

Use the parse_dax! macro to parse DAX expressions at compile time:

use rust_dax::parse_dax;

fn main() {
    let tokens = parse_dax!("SUM([Sales])");
    println!("{:?}", tokens);
}

Creating Test Tables

The library provides a table! macro for creating test data tables:

use rust_dax::table;

let sales_table = table! {
    "Amount" => [100.0, 200.0, 300.0],
    "Quantity" => [1, 2, 3],
};

Supported DAX Functions

Currently supported functions include:

• SUM: Calculate the sum of a column
• AVERAGE: Calculate the average of a column
• COUNT: Count non-empty values in a column

Example:

let result = parse_dax!("SUM([Amount])");

Implementation Details

The library uses Rust's procedural macro system to parse DAX expressions at compile time. The parsing process includes:

1. Tokenization of DAX expressions into discrete tokens (functions, columns, operators, etc.)
2. Basic syntax validation
3. Generation of corresponding Rust code

Project Structure

• src/lib.rs: Main library interface and proc macro definitions
• dax-macro-impl/: Implementation details for the procedural macros
• dax-macro/: Public macro interfaces

Limitations

Current limitations include:

• Limited set of supported DAX functions
• Basic arithmetic operations only
• No support for complex filtering or relationships
• Limited error handling

Contributing

Contributions are welcome! Please feel free to submit issues and pull requests.

When contributing, please:

1. Add tests for any new features
2. Update documentation
3. Follow the existing code style

License

This project is licensed under the MIT License - see the LICENSE file for details.

Acknowledgments

• The Rust proc-macro2 and syn crates for making this implementation possible
• Microsoft's DAX documentation for reference implementation details