feature: refactor api parse to g4 (#365)

* feature: refactor api parse to g4

* new g4 parser

* add CHANGE_LOG.MD

* refactor

* fix byte bug

* refactor

* optimized

* optimized

* revert

* update readme.md

* update readme.md

* update readme.md

* update readme.md

* remove no need

* fix java gen

* add upgrade

* resolve confilits

Co-authored-by: anqiansong <anqiansong@xiaoheiban.cn>

tools/goctl/api/parser/g4/ast/syntax.go

@@ -0,0 +1,58 @@
+package ast
+
+import (
+	"github.com/tal-tech/go-zero/tools/goctl/api/parser/g4/gen/api"
+)
+
+type SyntaxExpr struct {
+	Syntax      Expr
+	Assign      Expr
+	Version     Expr
+	DocExpr     []Expr
+	CommentExpr Expr
+}
+
+func (v *ApiVisitor) VisitSyntaxLit(ctx *api.SyntaxLitContext) interface{} {
+	syntax := v.newExprWithToken(ctx.GetSyntaxToken())
+	assign := v.newExprWithToken(ctx.GetAssign())
+	version := v.newExprWithToken(ctx.GetVersion())
+	return &SyntaxExpr{
+		Syntax:      syntax,
+		Assign:      assign,
+		Version:     version,
+		DocExpr:     v.getDoc(ctx),
+		CommentExpr: v.getComment(ctx),
+	}
+}
+
+func (s *SyntaxExpr) Format() error {
+	// todo
+	return nil
+}
+
+func (s *SyntaxExpr) Equal(v interface{}) bool {
+	if v == nil {
+		return false
+	}
+
+	syntax, ok := v.(*SyntaxExpr)
+	if !ok {
+		return false
+	}
+
+	if !EqualDoc(s, syntax) {
+		return false
+	}
+
+	return s.Syntax.Equal(syntax.Syntax) &&
+		s.Assign.Equal(syntax.Assign) &&
+		s.Version.Equal(syntax.Version)
+}
+
+func (s *SyntaxExpr) Doc() []Expr {
+	return s.DocExpr
+}
+
+func (s *SyntaxExpr) Comment() Expr {
+	return s.CommentExpr
+}