goctl model reactor (#15)

* reactor sql generation

* reactor sql generation

* add console & example

* optimize unit test & add document

* modify default config

* remove test file

* Revert "remove test file"

This reverts commit 81041f9e

* fix stringx.go & optimize example

* remove unused code

tools/goctl/util/stringx/string.go

@@ -0,0 +1,126 @@
+package stringx
+
+import (
+	"bytes"
+	"strings"
+	"unicode"
+)
+
+const (
+	emptyString = ""
+)
+
+type (
+	String struct {
+		source string
+	}
+)
+
+func From(data string) String {
+	return String{source: data}
+}
+
+func (s String) IsEmptyOrSpace() bool {
+	if len(s.source) == 0 {
+		return true
+	}
+	if strings.TrimSpace(s.source) == "" {
+		return true
+	}
+	return false
+}
+
+func (s String) Lower() string {
+	if s.IsEmptyOrSpace() {
+		return s.source
+	}
+	return strings.ToLower(s.source)
+}
+func (s String) Upper() string {
+	if s.IsEmptyOrSpace() {
+		return s.source
+	}
+	return strings.ToUpper(s.source)
+}
+func (s String) Title() string {
+	if s.IsEmptyOrSpace() {
+		return s.source
+	}
+	return strings.Title(s.source)
+}
+
+// snake->camel(upper start)
+func (s String) Snake2Camel() string {
+	if s.IsEmptyOrSpace() {
+		return s.source
+	}
+	list := s.splitBy(func(r rune) bool {
+		return r == '_'
+	}, true)
+	var target []string
+	for _, item := range list {
+		target = append(target, From(item).Title())
+	}
+	return strings.Join(target, "")
+}
+
+// camel->snake
+func (s String) Camel2Snake() string {
+	if s.IsEmptyOrSpace() {
+		return s.source
+	}
+	list := s.splitBy(func(r rune) bool {
+		return unicode.IsUpper(r)
+	}, false)
+	var target []string
+	for _, item := range list {
+		target = append(target, From(item).Lower())
+	}
+	return strings.Join(target, "_")
+}
+
+// return original string if rune is not letter at index 0
+func (s String) LowerStart() string {
+	if s.IsEmptyOrSpace() {
+		return s.source
+	}
+	r := rune(s.source[0])
+	if !unicode.IsUpper(r) && !unicode.IsLower(r) {
+		return s.source
+	}
+	return string(unicode.ToLower(r)) + s.source[1:]
+}
+
+// it will not ignore spaces
+func (s String) splitBy(fn func(r rune) bool, remove bool) []string {
+	if s.IsEmptyOrSpace() {
+		return nil
+	}
+	var list []string
+	buffer := new(bytes.Buffer)
+	for _, r := range s.source {
+		if fn(r) {
+			if buffer.Len() != 0 {
+				list = append(list, buffer.String())
+				buffer.Reset()
+			}
+			if !remove {
+				buffer.WriteRune(r)
+			}
+			continue
+		}
+		buffer.WriteRune(r)
+	}
+	if buffer.Len() != 0 {
+		list = append(list, buffer.String())
+	}
+	return list
+}
+
+func (s String) ReplaceAll(old, new string) string {
+	return strings.ReplaceAll(s.source, old, new)
+}
+
+func (s String) Source() string {
+	return s.source
+}