Expand description
A simple CSS parsing and transformation framework. Procss can be used to quickly bundle a collection of CSS+ files, or write your own custom transforms.
Usage
Procss’s parser understands a nested superset of CSS (which we refer to as
CSS+), similar to the CSS nesting proposal,
or languages like Sass. Start with source CSS+
as a str
, use crate::parse or crate::parse_unchecked to generate
an ast::Tree
.
use procss::{ast, parse};
let ast = procss::parse("div{.open{color:red;}}").unwrap();
The resulting ast::Tree
can be converted to a de-nested ast::Css
with the ast::Tree::flatten_tree
method, which itself can then be
rendered as a plain browser-readable CSS string via the
RenderCss::as_css_string
trait method.
use procss::RenderCss;
let flat: ast::Css = ast.flatten_tree();
let css: String = flat.as_css_string();
assert_eq!(css, "div .open{color:red;}");
Intermediate structs ast::Css::transform
amd ast::Tree::transform
can be used to recursively mutate a tree for a variety of node structs in
the ast
module. Some useful Example of such transforms can be
found in the transformers
module.
use procss::transformers;
let test = "
@mixin test {color: red;}
div {@include test;}
";
let mut ast = procss::parse(test).unwrap();
transformers::apply_mixin(&mut ast);
let flat = ast.flatten_tree().as_css_string();
assert_eq!(flat, "div{color:red;}");
For coordinating large builds on a tree of CSS files, the BuildCss
struct can parse and minify, applying all transforms (including
transformers::apply_import
) as the compilation is left-folded over the
inputs.
let mut build = procss::BuildCss::new("./src");
build.add_file("controls/menu.scss");
build.add_file("logout.scss"); // imports "controls/menu.scss"
build.add_file("my_app.scss"); // imports "controls/menu.scss" and "logout.scss"
build.compile().unwrap().write("./dist").unwrap();
Modules
Css
and Tree
. These top-level structs
are part of the crate::parse
API, and their various components structs
are necessary for writing any transformations on these between parsing and
rendering.crate::ast::Css::transform
and crate::ast::Tree::transform
methods
to apply various useful transformations on their respective structs. The
exports from crate::transformers
are functions which take a &mut
to
either crate::ast::Css
or crate::ast::Tree
.Structs
@import
).Traits
Functions
Tree
(where it can be further manipulated),
capturing detailed error reporting for a moderate performance impact (using
nom::error::VerboseError
).Tree
, without capturing error details, for maximum
performance without any error details when parsing fails.