ssfmt

Excel-compatible ECMA-376 number format codes for Rust.

Features

• Parse and format Excel/OOXML number format codes
• Match Excel's actual behavior, including quirks
• Support for dates, times, percentages, fractions
• Multiple format sections (positive/negative/zero/text)
• Color and conditional format detection
• Both 1900 and 1904 date systems
• Efficient compile-once, format-many pattern

Usage

use ssfmt::{format_default, NumberFormat, FormatOptions};

// Simple one-off formatting
let result = format_default(1234.56, "#,##0.00").unwrap();
assert_eq!(result, "1,234.56");

// Compile once, format many values
let fmt = NumberFormat::parse("yyyy-mm-dd").unwrap();
let opts = FormatOptions::default();
assert_eq!(fmt.format(46031.0, &opts), "2026-01-09");

Compatibility

Achieves 99.9999% compatibility with SheetJS SSF across 19.5+ million test cases.

See docs/TESTING.md for detailed test coverage.

Documentation

• Architecture Guide - Design principles and key components
• Test Coverage - Comprehensive testing documentation
• Implementation Plans - Original design and implementation notes

License

MIT OR Apache-2.0