resolveParentPathBy

Resolve a path according to a predicate function by walking parent directories.

Installation

npm install @stdlib/fs-resolve-parent-path-by

Usage

var resolveParentPathBy = require( '@stdlib/fs-resolve-parent-path-by' );

resolveParentPathBy( path[, options], predicate, clbk )

Asynchronously resolves a path according to a predicate function by walking parent directories.

resolveParentPathBy( 'package.json', predicate, onPath );

function predicate( path, next ) {
    var bool = ( /\/test\//.test( path ) === false );
    next( null, bool );
}

function onPath( error, path ) {
    if ( error ) {
        throw error;
    }
    console.log( path );
    // e.g., => '...'
}

The function accepts the following options:

• dir: base directory from which to begin walking. May be either an absolute path or a path relative to the current working directory.

By default, the function begins walking from the current working directory. To specify an alternative directory, set the dir option.

var opts = {
    'dir': __dirname
};
resolveParentPathBy( 'package.json', opts, predicate, onPath );

function predicate( path, next ) {
    var bool = ( /\/test\//.test( path ) === false );
    next( null, bool );
}

function onPath( error, path ) {
    if ( error ) {
        throw error;
    }
    console.log( path );
    // e.g., => '...'
}

When invoked, the predicate function is provided two arguments:

• path: a resolved path.
• next: a callback which should be called once the predicate function has finished processing a resolved path.

If a predicate function calls the next callback with a truthy second argument, the function stops processing any additional paths and returns the resolved path as the test result.

If unable to resolve a path, the function returns null as the path result.

resolveParentPathBy.sync( path[, options], predicate )

Synchronously resolves a path according to a predicate function by walking parent directories.

function predicate( path ) {
    return ( /\/test\//.test( path ) === false );
}

var path = resolveParentPathBy.sync( 'package.json', predicate );
// e.g., returns '...'

The function accepts the same options as resolveParentPathBy().

When invoked, the predicate function is provided one argument:

• path: a resolved path.

The function immediately returns upon encountering a truthy predicate function return value.

If unable to resolve a path, the function returns null as the path result.

Notes

• If a provided predicate function calls the next callback with a truthy error argument, the function suspends execution and immediately calls the done callback for subsequent error handling.
• For resolveParentPathBy, execution is not guaranteed to be asynchronous. To guarantee asynchrony, wrap the done callback in a function which either executes at the end of the current stack (e.g., nextTick) or during a subsequent turn of the event loop (e.g., setImmediate, setTimeout).
• This implementation is not similar in functionality to core path.resolve. The latter performs string manipulation to generate a full path. This implementation walks parent directories to perform a search, thereby touching the file system. Accordingly, this implementation resolves a real absolute file path and is intended for use when a target's location in a parent directory is unknown relative to a child directory; e.g., when wanting to find a package root from deep within a package directory.

Examples

var resolveParentPathBy = require( '@stdlib/fs-resolve-parent-path-by' );

var opts = {
    'dir': __dirname
};

/* Sync */

function predicateSync( path ) {
    var pkg = require( path );
    if ( pkg.name !== '@stdlib/stdlib' ) {
        return false;
    }
    return true;
}

var out = resolveParentPathBy.sync( 'package.json', opts, predicateSync );
console.log( out );
// e.g., => '...'

out = resolveParentPathBy.sync( 'non_existent_basename/package.json', predicateSync );
console.log( out );
// => null

/* Async */

function predicateAsync( path, next ) {
    setTimeout( onTimeout, 0 );

    function onTimeout() {
        var pkg = require( path );
        if ( pkg.name !== '@stdlib/stdlib' ) {
            return next( null, false );
        }
        next( null, true );
    }
}

function onPath( error, path ) {
    if ( error ) {
        throw error;
    }
    console.log( path );
}

resolveParentPathBy( 'package.json', opts, predicateAsync, onPath );
resolveParentPathBy( './../non_existent_path/package.json', predicateAsync, onPath );

See Also

• @stdlib/fs-resolve-parent-path: resolve a path by walking parent directories.

Notice

This package is part of stdlib, a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.

For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.

Community

License

See LICENSE.

Copyright

Copyright © 2016-2024. The Stdlib Authors.