filter_xargstestfilepathexists.go

// scriptish is a library to help you port bash scripts to Golang
//
// inspired by:
//
// - http://labix.org/pipe
// - https://github.com/bitfield/script
//
// Copyright 2019-present Ganbaro Digital Ltd
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
//
//   * Redistributions of source code must retain the above copyright
//     notice, this list of conditions and the following disclaimer.
//
//   * Redistributions in binary form must reproduce the above copyright
//     notice, this list of conditions and the following disclaimer in
//     the documentation and/or other materials provided with the
//     distribution.
//
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//     contributors may be used to endorse or promote products derived
//     from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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package scriptish

import (
	"os"
)

// XargsTestFilepathExists treats each line in the pipeline as a filepath.
// It checks to see if the given filepath exists.
//
// If the filepath exists, it is written to the pipeline's stdout.
//
// It does not care what the filepath points at (file, folder, named pipe,
// and so on).
func XargsTestFilepathExists(opts ...*StepOption) *SequenceStep {
	// build our Scriptish command
	return NewSequenceStep(
		func(p *Pipe) (int, error) {
			// debugging support
			Tracef("XargsTestFilepathExists()")

			for line := range p.Stdin.ReadLines() {
				// does the file exist?
				_, err := os.Stat(line)
				if err != nil {
					// skip to the next
					continue
				}

				// write the filepath to the pipeline, in case the next item
				// can make use of it
				TracePipeStdout("%s", line)
				p.Stdout.WriteString(line)
				p.Stdout.WriteRune('\n')
			}

			// all done
			return StatusOkay, nil
		},
		opts...,
	)
}