less.js.flow

// @flow

// These types are much more than what Parcel is currently using, and much less
// than a complete typing of Less. The cutoff was pretty arbitrary; I tried to
// err on the side of inclusion for class members and exclusion for everything
// else, but ultimately there's no principle for what's in and what's out of the
// bits that Parcel doesn't need.

declare module 'less' {
  declare type FileInfo = {|
    rewriteUrls?: boolean,
    filename: string,
    rootpath: string,
    currentDirectory: string,
    rootFilename: string,
    entryPath: string,
    reference?: boolean,
  |};

  declare type Context = {...};

  declare type Visitor = {
    visit(value: Node): Node,
    ...
  };

  // Derived manually from
  // https://github.com/less/less.js/blob/2c5e4dd9b9fbe6e5a4ef0c57c827e1ac3443ef0c/packages/less/src/less/tree/node.js
  declare class Node {
    parent: ?Node;
    visibilityBlocks: ?number;
    nodeVisible: ?boolean;
    rootNode: ?Node;
    parsed: ?boolean;

    +currentFileInfo: FileInfo;
    +index: number;

    setParent(nodes: Node | Array<Node>, parent: Node): void;

    getIndex(): number;
    fileInfo(): FileInfo;
    isRulesetLike(): boolean;

    toCSS(context: Context): string;
    genCSS(context: Context, output: mixed): void;
    accept(visitor: Visitor): void;
    eval(): mixed;

    fround(context: Context, value: number): number;
    blocksVisibility(): boolean;
    addVisibilityBlock(): void;
    removeVisibilityBlock(): void;
    ensureVisibility(): void;
    ensureInvisibility(): void;
    isVisible(): ?boolean;
    visibilityInfo(): {|visibilityBlocks: ?number, nodeVisible: ?boolean|};
    copyVisibilityInfo(info: {
      visibilityBlocks: ?number,
      nodeVisible: ?boolean,
      ...
    }): void;
  }

  // Derived manually from
  // https://github.com/less/less.js/blob/2c5e4dd9b9fbe6e5a4ef0c57c827e1ac3443ef0c/packages/less/src/less/tree/url.js
  declare class URL extends Node {
    value: Node;
    isEvald: boolean;
  }

  // This is very ad-hoc, based on current Parcel usage instead of the actual
  // class in Less.
  declare class visitors$Visitor {
    constructor({
      visitUrl?: (node: URL) => Node,
      ...
    }): visitors$Visitor;
    visit(node: Node): Node;
    run?: Node => Node;
  }

  // Obviously an extremely incomplete type definition.
  declare module.exports: {
    tree: {
      Node: typeof Node,
      URL: typeof URL,
      ...
    },
    visitors: {
      Visitor: typeof visitors$Visitor,
      ...
    },
    render(string, any): Promise<{|map: string, css: string|}>,
    ...
  };
}