CSS Structs

A fast and reliable CSS parser for Rust, built with nom parser combinators. Parse CSS stylesheets, rules, declarations, and declaration lists with ease.

Features

🚀 Fast: Built with nom parser combinators for excellent performance
🔧 Flexible: Parse complete stylesheets or individual components
🔄 Roundtrip: Parse CSS and convert back to string representation

Quick Start

Add this to your Cargo.toml:

[dependencies]
css-structs = "1.0.0"

Usage

Parse a Complete Stylesheet

use css_structs::Stylesheet;

let css = r#"
    body {
        margin: 0;
        padding: 0;
        font-family: Arial, sans-serif;
    }

    .header {
        background-color: #333;
        color: white;
        padding: 1rem;
    }

    .button {
        background: linear-gradient(45deg, #007bff, #0056b3);
        border: none !important;
        padding: 0.5rem 1rem;
    }
"#;

let stylesheet = Stylesheet::from_string(css).unwrap();
println!("Parsed {} CSS rules", stylesheet.rules.len());

// Convert back to CSS string
println!("{}", stylesheet);

Parse Individual CSS Rules

use css_structs::CSSRule;

let rule_str = ".container { max-width: 1200px; margin: 0 auto; }";
let rule = CSSRule::from_string(rule_str).unwrap();

println!("Selector: {}", rule.selector);
println!("Declarations: {}", rule.declarations.declarations.len());

Parse Declaration Lists

use css_structs::CSSDeclarationList;

let declarations = "color: red; margin: 10px; padding: 5px !important";
let list = CSSDeclarationList::from_string(declarations).unwrap();

// Remove a specific declaration
let mut list = list;
list.remove_declaration("color");
println!("{}", list); // "margin: 10px; padding: 5px !important;"

Parse Individual Declarations

use css_structs::CSSDeclaration;

let decl = CSSDeclaration::from_string("font-size: 16px !important").unwrap();
println!("Property: {}", decl.property);
println!("Value: {}", decl.value);
println!("Important: {}", decl.important.is_some());

Working with Parsed Data

use css_structs::{Stylesheet, CSSDeclaration};

let css = r#"
    .card { 
        background: white;
        border: 1px solid #ddd;
        border-radius: 4px;
        padding: 1rem;
    }
"#;

let stylesheet = Stylesheet::from_string(css).unwrap();
let rule = &stylesheet.rules[0];

// Access rule components
println!("Selector: {}", rule.selector);

// Iterate through declarations
for declaration in &rule.declarations.declarations {
    println!("  {}: {}", declaration.property, declaration.value);
    if declaration.important.is_some() {
        println!("    (important)");
    }
}

// Modify and rebuild
let mut new_declarations = rule.declarations.clone();
new_declarations.declarations.push(
    CSSDeclaration::new("box-shadow", "0 2px 4px rgba(0,0,0,0.1)", None)
);

API Overview

Core Types

Stylesheet - Represents a complete CSS stylesheet with multiple rules
CSSRule - Represents a single CSS rule (selector + declarations)
CSSDeclarationList - Represents a list of CSS declarations
CSSDeclaration - Represents a single CSS property-value pair

Key Methods

from_string() - Parse from CSS string (available on all types)
new() - Create instances programmatically
remove_declaration() - Remove declarations by property name (CSSDeclarationList)
Display trait - Convert back to CSS string format

CSS Features Supported

✅ Basic selectors (element, class, ID, universal)
✅ Complex selectors (descendant, child, sibling, pseudo-classes)
✅ All CSS properties and values
✅ !important declarations
✅ Vendor prefixes (-webkit-, -moz-, etc.)
✅ CSS custom properties (CSS variables)
✅ Whitespace handling and normalization
❌ Comments - not supported yet
❌ At-rules (e.g., @media, @font-face, @keyframes) - not supported yet
❌ Nested rules - not supported yet

Error Handling

The parser returns Result types for graceful error handling:

use css_structs::Stylesheet;

let invalid_css = "body { color: red; margin: 10px"; // missing closing brace
match Stylesheet::from_string(invalid_css) {
    Ok(stylesheet) => println!("Parsed successfully!"),
    Err(error) => eprintln!("Parse error: {}", error),
}

Testing

Run the test suite:

# Run all tests
cargo test

# Run specific test module
cargo test stylesheet::tests

css-structs 1.0.1