diff --git a/app/dns/hosts.go b/app/dns/hosts.go
index b97ee4772..35a2b7508 100644
--- a/app/dns/hosts.go
+++ b/app/dns/hosts.go
@@ -17,7 +17,7 @@ var typeMap = map[Config_HostMapping_Type]strmatcher.Type{
 }
 
 func NewStaticHosts(hosts []*Config_HostMapping, legacy map[string]*net.IPOrDomain) (*StaticHosts, error) {
-	g := strmatcher.NewMatcherGroup()
+	g := new(strmatcher.MatcherGroup)
 	sh := &StaticHosts{
 		ips:      make(map[uint32][]net.IP),
 		matchers: g,
diff --git a/app/router/condition.go b/app/router/condition.go
index 5735bd4ca..36364c32d 100644
--- a/app/router/condition.go
+++ b/app/router/condition.go
@@ -90,7 +90,7 @@ type DomainMatcher struct {
 }
 
 func NewDomainMatcher(domains []*Domain) (*DomainMatcher, error) {
-	g := strmatcher.NewMatcherGroup()
+	g := new(strmatcher.MatcherGroup)
 	for _, d := range domains {
 		m, err := domainToMatcher(d)
 		if err != nil {
diff --git a/common/strmatcher/benchmark_test.go b/common/strmatcher/benchmark_test.go
index 2915a4104..1e7ff5563 100644
--- a/common/strmatcher/benchmark_test.go
+++ b/common/strmatcher/benchmark_test.go
@@ -35,7 +35,7 @@ func BenchmarkFullMatcherGroup(b *testing.B) {
 }
 
 func BenchmarkMarchGroup(b *testing.B) {
-	g := NewMatcherGroup()
+	g := new(MatcherGroup)
 	for i := 1; i <= 1024; i++ {
 		m, err := Domain.New(strconv.Itoa(i) + ".v2ray.com")
 		common.Must(err)
@@ -49,7 +49,7 @@ func BenchmarkMarchGroup(b *testing.B) {
 }
 
 func BenchmarkCachedMarchGroup(b *testing.B) {
-	g := NewMatcherGroup()
+	g := new(MatcherGroup)
 	for i := 1; i <= 1024; i++ {
 		m, err := Domain.New(strconv.Itoa(i) + ".v2ray.com")
 		common.Must(err)
diff --git a/common/strmatcher/domain_matcher.go b/common/strmatcher/domain_matcher.go
index 1d8cb0674..317913240 100644
--- a/common/strmatcher/domain_matcher.go
+++ b/common/strmatcher/domain_matcher.go
@@ -11,6 +11,8 @@ type node struct {
 	sub   map[string]*node
 }
 
+// DomainMatcherGroup is a IndexMatcher for a large set of Domain matchers.
+// Visible for testing only.
 type DomainMatcherGroup struct {
 	root *node
 }
diff --git a/common/strmatcher/matchers_test.go b/common/strmatcher/matchers_test.go
index d2524c3fc..f952c0b61 100644
--- a/common/strmatcher/matchers_test.go
+++ b/common/strmatcher/matchers_test.go
@@ -59,6 +59,12 @@ func TestMatcher(t *testing.T) {
 			input:   "xv2ray.com",
 			output:  false,
 		},
+		{
+			pattern: "v2ray.com",
+			mType:   Regex,
+			input:   "v2rayxcom",
+			output:  true,
+		},
 	}
 	for _, test := range cases {
 		matcher, err := test.mType.New(test.pattern)
diff --git a/common/strmatcher/strmatcher.go b/common/strmatcher/strmatcher.go
index 5aa50b819..17a6ca482 100644
--- a/common/strmatcher/strmatcher.go
+++ b/common/strmatcher/strmatcher.go
@@ -8,19 +8,27 @@ import (
 	"v2ray.com/core/common/task"
 )
 
+// Matcher is the interface to determine a string matches a pattern.
 type Matcher interface {
+	// Match returns true if the given string matches a predefined pattern.
 	Match(string) bool
 }
 
+// Type is the type of the matcher.
 type Type byte
 
 const (
+	// Full is the type of matcher that the input string must exactly equal to the pattern.
 	Full Type = iota
+	// Substr is the type of matcher that the input string must contain the pattern as a sub-string.
 	Substr
+	// Domain is the type of matcher that the input string must be a sub-domain or itself of the pattern.
 	Domain
+	// Regex is the type of matcher that the input string must matches the regular-expression pattern.
 	Regex
 )
 
+// New creates a new Matcher based on the given pattern.
 func (t Type) New(pattern string) (Matcher, error) {
 	switch t {
 	case Full:
@@ -42,8 +50,10 @@ func (t Type) New(pattern string) (Matcher, error) {
 	}
 }
 
+// IndexMatcher is the interface for matching with a group of matchers.
 type IndexMatcher interface {
-	Match(pattern string) uint32
+	// Match returns the the index of a matcher that matches the input. It returns 0 if no such matcher exists.
+	Match(input string) uint32
 }
 
 type matcherEntry struct {
@@ -51,6 +61,8 @@ type matcherEntry struct {
 	id uint32
 }
 
+// MatcherGroup is an implementation of IndexMatcher.
+// Empty initialization works.
 type MatcherGroup struct {
 	count         uint32
 	fullMatcher   FullMatcherGroup
@@ -58,10 +70,7 @@ type MatcherGroup struct {
 	otherMatchers []matcherEntry
 }
 
-func NewMatcherGroup() *MatcherGroup {
-	return &MatcherGroup{}
-}
-
+// Add adds a new Matcher into the MatcherGroup, and returns its index. The index will never be 0.
 func (g *MatcherGroup) Add(m Matcher) uint32 {
 	g.count++
 	c := g.count
@@ -81,6 +90,7 @@ func (g *MatcherGroup) Add(m Matcher) uint32 {
 	return c
 }
 
+// Match implements IndexMatcher.Match.
 func (g *MatcherGroup) Match(pattern string) uint32 {
 	if c := g.fullMatcher.Match(pattern); c > 0 {
 		return c
@@ -99,6 +109,7 @@ func (g *MatcherGroup) Match(pattern string) uint32 {
 	return 0
 }
 
+// Size returns the number of matchers in the MatcherGroup.
 func (g *MatcherGroup) Size() uint32 {
 	return g.count
 }
@@ -108,6 +119,7 @@ type cacheEntry struct {
 	result    uint32
 }
 
+// CachedMatcherGroup is a IndexMatcher with cachable results.
 type CachedMatcherGroup struct {
 	sync.RWMutex
 	group   *MatcherGroup
@@ -115,6 +127,7 @@ type CachedMatcherGroup struct {
 	cleanup *task.Periodic
 }
 
+// NewCachedMatcherGroup creats a new CachedMatcherGroup.
 func NewCachedMatcherGroup(g *MatcherGroup) *CachedMatcherGroup {
 	r := &CachedMatcherGroup{
 		group: g,
@@ -139,6 +152,7 @@ func NewCachedMatcherGroup(g *MatcherGroup) *CachedMatcherGroup {
 	return r
 }
 
+// Match implements IndexMatcher.Match.
 func (g *CachedMatcherGroup) Match(pattern string) uint32 {
 	g.RLock()
 	r, f := g.cache[pattern]