eway/internal/matcher/radix.go

package matcher

import (
	"regexp"
	"strings"
)

const radixWildcard = '*'

type radixNode struct {
	exact bool
	next  map[rune]*radixNode
}

type radixMatcher struct {
	root *radixNode

	caseInsensitive bool
	saved           []string
	regexps         []*regexp.Regexp
}

type RadixOpt func(m *radixMatcher)

func RadixCaseInsensitive() RadixOpt {
	return func(m *radixMatcher) {
		m.caseInsensitive = true
	}
}

func NewRadix(opts ...RadixOpt) *radixMatcher {
	m := &radixMatcher{
		root: &radixNode{
			next: make(map[rune]*radixNode),
		},
	}

	for _, opt := range opts {
		opt(m)
	}

	return m
}

func (r *radixMatcher) MatchByPattern(value string) (pattern string) {
	originValue := value
	if r.caseInsensitive {
		value = strings.ToLower(value)
	}

	node := r.root
	lastIdx := len([]rune(value)) - 1

	var sb strings.Builder
	for i, v := range value {
		var ok bool
		if _, ok := node.next[radixWildcard]; ok {
			_, _ = sb.WriteRune(radixWildcard)
			return sb.String()
		}

		node, ok = node.next[v]
		if !ok {
			return r.findByRegexp(originValue)
		}

		sb.WriteRune(v)

		if i != lastIdx {
			continue
		}

		if !node.exact {
			return r.findByRegexp(value)
		}

		return sb.String()
	}

	return r.findByRegexp(originValue)
}

func (r *radixMatcher) Match(value string) bool {
	originValue := value
	if r.caseInsensitive {
		value = strings.ToLower(value)
	}

	node := r.root
	lastIdx := len([]rune(value)) - 1
	for i, v := range value {
		var ok bool
		if _, ok = node.next[radixWildcard]; ok {
			return true
		}

		node, ok = node.next[v]
		if !ok {
			return r.findByRegexp(originValue) != ""
		}

		if i == lastIdx {
			return node.exact
		}
	}

	return r.findByRegexp(originValue) != ""
}

func (r *radixMatcher) findByRegexp(value string) (regexpPattern string) {
	for _, rx := range r.regexps {
		if rx.MatchString(value) {
			return rx.String()
		}
	}

	return ""
}

func (r *radixMatcher) RegisterRegexp(regexpPattern string) {
	pattern := regexp.MustCompile(regexpPattern)
	r.regexps = append(r.regexps, pattern)
}

func (r *radixMatcher) Register(pattern string) {
	if len(pattern) == 0 {
		panic("unable to handle empty pattern")
	}

	if r.caseInsensitive {
		pattern = strings.ToLower(pattern)
	}

	r.saved = append(r.saved, pattern)

	node := r.root
	lastIdx := len([]rune(pattern)) - 1
	for i, v := range pattern {
		nextNode, ok := node.next[v]
		if !ok {
			nextNode = &radixNode{
				next: make(map[rune]*radixNode),
			}
			node.next[v] = nextNode
		}
		node = nextNode

		if v == '*' {
			return
		}

		if i != lastIdx {
			continue
		}

		node.exact = true
	}
}

func (r *radixMatcher) Patterns() []string {
	ownIdx := len(r.saved)
	out := make([]string, len(r.saved)+len(r.regexps))
	copy(out, r.saved[:ownIdx])

	for i := 0; i < len(r.regexps); i++ {
		idx := i + ownIdx
		out[idx] = r.regexps[i].String()
	}

	return out
}