git-cat-file/lib/file-mode.ts

A pure-JavaScript implementation of `git cat-file -p` for Node.js.

/**
 * https://github.com/kawanet/git-cat-file
 */

import type {GCF} from "../types/git-cat-file.d.ts"

const OctalMode = {
    file: 0o100644,
    executable: 0o100755,
    symlink: 0o120000,
    submodule: 0o160000,
    directory: 0o040000,
} as const

class FileMode implements GCF.FileMode {
    isFile: boolean // 100644
    isExecutable: boolean // 100755
    isSymlink: boolean // 120000
    isSubmodule: boolean // 160000
    isDirectory: boolean // 040000
    private readonly mode: number

    constructor(mode: number) {
        this.mode = mode
        switch (mode) {
            case OctalMode.executable:
            case OctalMode.executable & 0o777:
                this.isExecutable = true
            /* falls through */

            case OctalMode.file:
            case OctalMode.file & 0o777:
                this.isFile = true
                break

            case OctalMode.symlink:
                this.isSymlink = true
                break

            case OctalMode.submodule:
                this.isSubmodule = true
                break

            case OctalMode.directory:
                this.isDirectory = true
                break

            default:
                throw new TypeError(`Unknown mode: ${mode ? mode.toString(8) : mode}`)
        }
    }

    toString(): string {
        return (0o1000000 | this.mode).toString(8).substr(-6)
    }
}

const cachedMode: {[mode: string]: FileMode} = {}

export function getFileMode(mode: string) {
    const modeNum = parseInt(mode, 8)
    return cachedMode[modeNum] || (cachedMode[modeNum] = new FileMode(modeNum))
}