Added Args.PeekMulti for obtaining multiple query arg values for the given key

args.go

@@ -156,6 +156,22 @@ func (a *Args) PeekBytes(key []byte) []byte {
 	return peekArgBytes(a.args, key)
 }
 
+// PeekMulti returns all the arg values for the given key.
+func (a *Args) PeekMulti(key string) [][]byte {
+	var values [][]byte
+	a.VisitAll(func(k, v []byte) {
+		if string(k) == key {
+			values = append(values, v)
+		}
+	})
+	return values
+}
+
+// PeekMultiBytes returns all the arg values for the given key.
+func (a *Args) PeekMultiBytes(key []byte) [][]byte {
+	return a.PeekMulti(unsafeBytesToStr(key))
+}
+
 // Has returns true if the given key exists in Args.
 func (a *Args) Has(key string) bool {
 	a.bufKV.key = append(a.bufKV.key[:0], key...)

args_test.go

@@ -2,10 +2,37 @@ package fasthttp
 
 import (
 	"fmt"
+	"reflect"
 	"strings"
 	"testing"
 )
 
+func TestPeekMulti(t *testing.T) {
+	var a Args
+	a.Parse("foo=123&bar=121&foo=321&foo=&barz=sdf")
+
+	vv := a.PeekMulti("foo")
+	expectedVV := [][]byte{
+		[]byte("123"),
+		[]byte("321"),
+		[]byte(nil),
+	}
+	if !reflect.DeepEqual(vv, expectedVV) {
+		t.Fatalf("unexpected vv\n%#v\nExpecting\n%#v\n", vv, expectedVV)
+	}
+
+	vv = a.PeekMulti("aaaa")
+	if len(vv) > 0 {
+		t.Fatalf("expecting empty result for non-existing key. Got %#v", vv)
+	}
+
+	vv = a.PeekMulti("bar")
+	expectedVV = [][]byte{[]byte("121")}
+	if !reflect.DeepEqual(vv, expectedVV) {
+		t.Fatalf("unexpected vv\n%#v\nExpecting\n%#v\n", vv, expectedVV)
+	}
+}
+
 func TestArgsEscape(t *testing.T) {
 	testArgsEscape(t, "foo", "bar", "foo=bar")
 	testArgsEscape(t, "f.o,1:2/4", "~`!@#$%^&*()_-=+\\|/[]{};:'\"<>,./?",