ecss

Source layout: add the repository root to load-path and use (require 'ecss). The supported API and usage notes are in ecss.el; implementation modules live in lisp/.

中文

ecss is an independent, pure, extensible CSS cascade engine for Emacs Lisp. It owns selectors, specificity, stylesheets, origins and importance, cascade layers, CSS-wide values, custom properties, var(), inheritance, computed styles, and provenance. It does not own text-property writes, reactive updates, buffer publication, or Box/Flex/Grid layout.

This repository is a new lowercase ecss project. It neither modifies nor depends on the historical uppercase ECSS repository, and it provides no forwarding compatibility layer to that project.

Independent use

ecss does not embed Ebox properties or depend on a rendering runtime. Any program can register its own property vocabulary, expose nodes through built-in ecss-subject values or an adapter, and receive a pure-data computed style. The caller decides whether those values drive text, widgets, a DOM, layout, diagnostics, or another domain.

(require 'ecss)

(let* ((package
        (ecss-schema-package-create
         'demo
         '((:id demo/color :initial "black" :inherits t
                :validator stringp :aliases (:color) :impacts (paint)))))
       (schemas (ecss-schema-set-compose package))
       (sheet (ecss-stylesheet-create))
       (button (ecss-subject-create
                :type "button" :classes '("primary"))))
  (ecss-stylesheet-add-rule
   sheet schemas "button.primary" '(demo/color "royalblue"))
  (ecss-computed-style-value
   (ecss-compute-style schemas button :stylesheet sheet)
   'demo/color))
;; => "royalblue"

Core boundary

• ecss-selector.el owns the selector AST, parser, matcher, specificity, and generic subject adapter.
• ecss-cascade.el owns immutable package schemas, surface schema sets, stylesheets, complete winner ordering, inheritance, variable resolution, and provenance.
• ecss.el is the public package facade and has no behavioral load side effects.
• Package schemas and composed schema sets are immutable. Stylesheets change only through explicit authoring APIs. ecss-compute-style mutates neither its inputs nor the current buffer.
• An ordinary function value always remains a value. ECSS calls code only through an explicitly supplied :value-resolver; ECSS itself knows nothing about reactive bindings, Ebox nodes, or consumer-specific value-source types.

See Architecture and the ECSS chapters of the ETAF Reference Manual for the complete contract.

Verification

make test EMACS=/Applications/Emacs.app/Contents/MacOS/Emacs
make compile EMACS=/Applications/Emacs.app/Contents/MacOS/Emacs
make checkdoc EMACS=/Applications/Emacs.app/Contents/MacOS/Emacs
make package-lint EMACS=/Applications/Emacs.app/Contents/MacOS/Emacs
make diff-check

package-lint is an external development tool. If it is absent from the emacs -Q load path, provide it explicitly with PACKAGE_LINT_LOAD_EXTRA='-L /path/to/package-lint'. It is not an ecss runtime dependency.

The minimum Emacs version is 28.1. The current package version is 0.1.0.

Development

After cloning, run make setup-hooks. Before submitting a change, run make check; make structure-check is the fast organization gate.

Reference manual · docs/architecture.md · CHANGELOG.md

make check runs structure checks, compilation and the public acceptance scenarios listed in tests/acceptance.json. make test runs the same public API suite. The inventory covers every maintained Lisp test. GUI and performance checks use separate targets.

Source layout

Add the repository root to load-path and require ecss. The root entry loads the implementation in lisp/ and documents the supported public APIs in its Commentary. Package archives include both the root entry and lisp/.