Add exclude option & filter or exclude by regular expression

[sachaos]

Fix #173

I've added three options to between subcommand.
This feature is useful when you have a lot of things you want to filter or exclude.

• --exclude
  • exclude reports from a set of differences based on supplied arguments
• --filter-regexp
  • filter reports to a subset of differences based on supplied regular expressions
• --exclude-regexp
  • exclude reports from a set of differences based on supplied regular expressions

[HeavyWombat]

Thanks for the PR. I ran into a regression with the code changes. Can you have a look at my suggestion let me know what you think?

[HeavyWombat]

This is causing a regression when using Dot style paths, e.g. yaml.foo.bar instead of /yaml/foo/bar. I played around with your code and got it to work with the following file:

package dyff

import (
	"regexp"

	"github.com/gonvenience/ytbx"
)

func (r Report) filter(hasPath func(*ytbx.Path) bool) (result Report) {
	result = Report{
		From: r.From,
		To:   r.To,
	}

	for _, diff := range r.Diffs {
		if hasPath(diff.Path) {
			result.Diffs = append(result.Diffs, diff)
		}
	}

	return result
}

// Filter accepts YAML paths as input and returns a new report with differences for those paths only
func (r Report) Filter(paths ...string) (result Report) {
	if len(paths) == 0 {
		return r
	}

	return r.filter(func(filterPath *ytbx.Path) bool {
		for _, pathString := range paths {
			path, err := ytbx.ParsePathStringUnsafe(pathString)
			if err == nil && path.String() == filterPath.String() {
				return true
			}
		}

		return false
	})
}

// Exclude accepts YAML paths as input and returns a new report with differences without those paths
func (r Report) Exclude(paths ...string) (result Report) {
	if len(paths) == 0 {
		return r
	}

	return r.filter(func(filterPath *ytbx.Path) bool {
		for _, pathString := range paths {
			path, err := ytbx.ParsePathStringUnsafe(pathString)
			if err == nil && path.String() == filterPath.String() {
				return false
			}
		}

		return true
	})
}

// FilterRegexp accepts regular expressions as input and returns a new report with differences for matching those patterns
func (r Report) FilterRegexp(pattern ...string) (result Report) {
	if len(pattern) == 0 {
		return r
	}

	regexps := make([]*regexp.Regexp, len(pattern))
	for i := range pattern {
		regexps[i] = regexp.MustCompile(pattern[i])
	}

	return r.filter(func(filterPath *ytbx.Path) bool {
		for _, regexp := range regexps {
			if regexp.MatchString(filterPath.String()) {
				return true
			}
		}
		return false
	})
}

// ExcludeRegexp accepts regular expressions as input and returns a new report with differences for not matching those patterns
func (r Report) ExcludeRegexp(pattern ...string) (result Report) {
	if len(pattern) == 0 {
		return r
	}

	regexps := make([]*regexp.Regexp, len(pattern))
	for i := range pattern {
		regexps[i] = regexp.MustCompile(pattern[i])
	}

	return r.filter(func(filterPath *ytbx.Path) bool {
		for _, regexp := range regexps {
			if regexp.MatchString(filterPath.String()) {
				return false
			}
		}
		return true
	})
}

Since there are deletions and new lines, I cannot use the suggestions feature in a good way.

[HeavyWombat]

Approving PR to be merged into temporary feature branch for further processing.