randx：新增生成随机code方法

.CHANGELOG.md

@@ -19,8 +19,10 @@
 - [slice: 添加Add函数，在指定位置插入元素](https://github.com/ecodeclub/ekit/pull/201)
 - [slice: 优化delete方法，无需从头开始遍历](https://github.com/ecodeclub/ekit/pull/203)
 - [slice: 重构 slice 中使用 equalFunc 的方法](https://github.com/ecodeclub/ekit/pull/205)
+- [randx: 新增生成随机code方法](https://github.com/ecodeclub/ekit/pull/207)
 - [slice: intersect方法优化, symmetricDiffSet重构](https://github.com/ecodeclub/ekit/pull/208)
 
+
 # v0.0.7
 - [slice: FilterDelete](https://github.com/ecodeclub/ekit/pull/152)
 - [reflectx: IsNil 方法](https://github.com/ecodeclub/ekit/pull/150)

randx/rand_code.go

@@ -0,0 +1,88 @@
+// Copyright 2021 ecodeclub
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package randx
+
+import (
+	"errors"
+	"math/rand"
+)
+
+var ERRTYPENOTSUPPORTTED = errors.New("ekit:不支持的类型")
+
+type TYPE int
+
+const (
+	TYPE_DEFAULT TYPE = 0 //默认类型
+	TYPE_DIGIT   TYPE = 1 //数字//
+	TYPE_LETTER  TYPE = 2 //小写字母
+	TYPE_CAPITAL TYPE = 3 //大写字母
+	TYPE_MIXED   TYPE = 4 //数字+字母混合
+)
+
+// RandCode 根据传入的长度和类型生成随机字符串,这个方法目前可以生成数字、字母、数字+字母的随机字符串
+func RandCode(length int, typ TYPE) (string, error) {
+	switch typ {
+	case TYPE_DEFAULT:
+		fallthrough
+	case TYPE_DIGIT:
+		return generate("0123456789", length, 4), nil
+	case TYPE_LETTER:
+		return generate("abcdefghijklmnopqrstuvwxyz", length, 5), nil
+	case TYPE_CAPITAL:
+		return generate("ABCDEFGHIJKLMNOPQRSTUVWXYZ", length, 5), nil
+	case TYPE_MIXED:
+		return generate("0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ", length, 7), nil
+	default:
+		return "", ERRTYPENOTSUPPORTTED
+	}
+}
+
+// generate 根据传入的随机源和长度生成随机字符串,一次随机，多次使用
+func generate(source string, length, idxBits int) string {
+
+	//掩码
+	//例如： 使用低6位：0000 0000 --> 0011 1111
+	idxMask := 1<<idxBits - 1
+
+	// 63位最多可以使用多少次
+	remain := 63 / idxBits
+
+	//cache 随机位缓存
+	cache := rand.Int63()
+
+	result := make([]byte, length)
+
+	for i := 0; i < length; {
+		//如果使用次数剩余0，重新获取随机
+		if remain == 0 {
+			cache, remain = rand.Int63(), 63/idxBits
+		}
+
+		//利用掩码获取有效的随机数位
+		if randIndex := int(cache & int64(idxMask)); randIndex < len(source) {
+			result[i] = source[randIndex]
+			i++
+		}
+
+		//使用下一组随机位
+		cache >>= idxBits
+
+		//扣减remain
+		remain--
+
+	}
+	return string(result)
+
+}

randx/rand_code_test.go

@@ -0,0 +1,92 @@
+// Copyright 2021 ecodeclub
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package randx
+
+import (
+	"errors"
+	"regexp"
+	"testing"
+)
+
+func TestRandCode(t *testing.T) {
+	testCases := []struct {
+		name      string
+		length    int
+		typ       TYPE
+		wantMatch string
+		wantErr   error
+	}{
+		{
+			name:      "默认类型",
+			length:    8,
+			typ:       TYPE_DEFAULT,
+			wantMatch: "^[0-9]+$",
+			wantErr:   nil,
+		},
+		{
+			name:      "数字验证码",
+			length:    8,
+			typ:       TYPE_DIGIT,
+			wantMatch: "^[0-9]+$",
+			wantErr:   nil,
+		}, {
+			name:      "小写字母验证码",
+			length:    8,
+			typ:       TYPE_LETTER,
+			wantMatch: "^[a-z]+$",
+			wantErr:   nil,
+		}, {
+			name:      "大写字母验证码",
+			length:    8,
+			typ:       TYPE_CAPITAL,
+			wantMatch: "^[A-Z]+$",
+			wantErr:   nil,
+		}, {
+			name:      "混合验证码",
+			length:    8,
+			typ:       TYPE_MIXED,
+			wantMatch: "^[0-9a-zA-Z]+$",
+			wantErr:   nil,
+		}, {
+			name:      "未定义类型",
+			length:    8,
+			typ:       9,
+			wantMatch: "",
+			wantErr:   ERRTYPENOTSUPPORTTED,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			code, err := RandCode(tc.length, tc.typ)
+			if err != nil {
+				if !errors.Is(err, tc.wantErr) {
+					t.Errorf("unexpected error: %v", err)
+				}
+			} else {
+				//长度检验
+				if len(code) != tc.length {
+					t.Errorf("expected length: %d but got length:%d  ", tc.length, len(code))
+				}
+				//模式检验
+				matched, _ := regexp.MatchString(tc.wantMatch, code)
+				if !matched {
+					t.Errorf("expected %s but got %s", tc.wantMatch, code)
+				}
+			}
+		})
+	}
+
+}