filter_tr.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.
//
//   * Neither the names of the copyright holders nor the names of his
//     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
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
// FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
// COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
// BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
// LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
// ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.

package scriptish

import (
	"strings"
)

// Tr replaces all occurances of one string with another
func Tr(old []string, new []string, opts ...*StepOption) *SequenceStep {
	// build our Scriptish command
	return NewSequenceStep(
		func(p *Pipe) (int, error) {
			// debugging support
			Tracef("Tr(%#v, %#v)", old, new)

			// special case - we want to replace *everything* in old with
			// whatever is in new
			if len(old) > 1 && len(new) == 1 {
				for i := 1; i < len(old); i++ {
					new = append(new, new[0])
				}
			} else if len(old) != len(new) {
				// we don't know what to do
				return StatusNotOkay, ErrMismatchedInputs{"old", len(old), "new", len(new)}
			}

			// let's get the replacement done
			for line := range p.Stdin.ReadLines() {
				for i := range old {
					// expand our inputs
					expOld := p.Env.Expand(old[i])
					expNew := p.Env.Expand(new[i])

					// do the replacement
					line = strings.ReplaceAll(line, expOld, expNew)
				}
				TracePipeStdout("%s", line)
				p.Stdout.WriteString(line)
				p.Stdout.WriteRune('\n')
			}

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