Function groupFacesByCSSFile

packages/core/src/css/planner.ts:57–74

(faces: FontFace[])

// One resolved face can feed multiple published CSS files, for example a static
// italic face contributes to both `400-italic.css` and `latin-italic.css`.
const groupFacesByCSSFile = (faces: FontFace[]): Map<string, FontFace[]> => {
	const facesByCSSFile = new Map<string, FontFace[]>();

	// Iterate over each face and assign it to the appropriate CSS files based on its properties.
	for (const face of faces) {
		for (const cssFile of getCSSFiles(face)) {
			const cssFaces = facesByCSSFile.get(cssFile);

			if (cssFaces) {
				cssFaces.push(face);
			} else {
				facesByCSSFile.set(cssFile, [face]);
			}
		}
	}

	return facesByCSSFile;
};

const getCSSFiles = (face: FontFace): string[] => {
	const style = formatStyle(face.style);