Introduction to tinycss2

tinycss2 is a powerful and intuitive CSS parsing library in Python. It is designed to be a thin layer that lets you parse and serialize CSS efficiently, with a focus on performance and ease of use.

Getting Started with tinycss2

First, you need to install tinycss2:

pip install tinycss2

Using the Parser API

tinycss2 offers APIs that allow you to parse different CSS components like stylesheets and declarations. Below are some common use cases:

Parsing a CSS Stylesheet

from tinycss2 import parse_stylesheet

css = '''
body {
    background-color: #fff;
    font-size: 14px;
}
.container {
    width: 100%;
    padding: 20px;
}
'''

rules = parse_stylesheet(css)
for rule in rules:
    print(rule)

Parsing CSS Declarations

from tinycss2 import parse_declaration_list

declarations = '''
color: #333;
font-family: Arial, sans-serif;
margin: 0;
'''

decl_list = parse_declaration_list(declarations)
for decl in decl_list:
    print(decl)

Parsing CSS Component Values

from tinycss2 import parse_component_value_list

values = '1px solid black'

components = parse_component_value_list(values)
for component in components:
    print(component)

Serializing CSS

tinycss2 allows you to serialize CSS component values back into text:

from tinycss2 import serialize

components = parse_component_value_list('1px solid black')
css_text = serialize(components)
print(css_text)

Example Application

Let’s create a simple application that uses tinycss2 to parse and then modify the background-color property of a CSS rule:

from tinycss2 import parse_stylesheet, serialize

def change_background_color(css, new_color):
    rules = parse_stylesheet(css)
    for rule in rules:
        if rule.type == "qualified-rule":
            for decl in rule.content:
                if decl.name == "background-color":
                    decl.value = parse_component_value_list(new_color)
    return serialize(rules)

css = '''
body {
    background-color: #fff;
    font-size: 14px;
}
'''

new_css = change_background_color(css, '#000')
print(new_css)

This application demonstrates how you can manipulate CSS properties using tinycss2.

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