csv-codegen 0.2.3

A Rust procedural macro that transforms CSV data into safe, zero-cost code. Generate match arms, loops, and nested queries directly from CSV files, ensuring type safety and deterministic code generation.
Documentation

csv-codegen

A Rust procedural macro for generating code from CSV data at compile time. Transform CSV files into Rust constants, functions, structs, and other code using a flexible templating syntax.

Status: This crate is in development and was built with AI assistance (Claude Code). The API may see changes in future versions. Contributions and code review are especially welcome!

Features

  • Compile-time CSV processing - CSV files are read and processed during compilation
  • Template-based code generation - Use a simple template syntax to generate any Rust code
  • Field transformations - Convert CSV data to valid Rust identifiers, constants, types, and literals
  • Filtering support - Include/exclude rows based on conditions
  • Pivoting - Transform columns into key-value pairs for more flexible data structures
  • Type-safe literals - Generate properly typed numeric literals (42_f64, 10_u32, etc.)

Installation

Add this to your Cargo.toml:

[dependencies]
csv-codegen = "0.2"

Simple example

Given a CSV file products.csv:

name,price,category
apple,1.20,fruit
carrot,0.80,vegetable
banana,0.90,fruit

Generate constants:

use csv_codegen::csv_template;

csv_template!("products.csv", #each {
    pub const #CONST({name}_PRICE): f64 = #({price}_f64);
});

// Generates:
// pub const APPLE_PRICE: f64 = 1.20_f64;
// pub const CARROT_PRICE: f64 = 0.80_f64;
// pub const BANANA_PRICE: f64 = 0.90_f64;

assert_eq!(APPLE_PRICE, 1.20);

For more examples including filtering, pivoting, and advanced templating, see the full documentation.

Use Cases

  • Configuration from CSV - Generate constants and enums from configuration data
  • Test data - Create test fixtures from CSV files
  • Code tables - Transform lookup tables into efficient match statements
  • Translations - Create internationalization constants from CSV files

Limitations

  • CSV files are read at compile time - changes require recompilation
  • Empty cells are treated as empty strings
  • One csv file can be read per invocation (no joins)
  • Only basic filtering conditions are supported (==, !=, &&, ||) and only comparing between fields and literals

More Examples

For additional real-world examples including internationalization, enum generation, medical data processing, and complex nested filtering, see the integration test suite.

License

Licensed under Apache License, Version 2.0 (see LICENSE file or https://www.apache.org/licenses/LICENSE-2.0)