feat/schema: add ast and test

schema/ast/ast.go

@@ -0,0 +1,117 @@
+package ast
+
+import (
+	"azalea/schema/token"
+	"strconv"
+	"strings"
+)
+
+type Schema ExprList
+type ExprList []Expr
+type Expr struct {
+	Name  string
+	Left  *Val
+	Right *Val
+}
+type ValList []Val
+type Val struct {
+	string string
+	number string
+	name   string
+	*Expr
+}
+
+func NewExprList(expr any) (ExprList, error) {
+	return ExprList{expr.(Expr)}, nil
+}
+
+func NewStringVal(val *token.Token) (Val, error) {
+	return Val{string: string(val.Lit)}, nil
+}
+
+func NewNumberVal(val *token.Token) (Val, error) {
+	return Val{number: string(val.Lit)}, nil
+}
+
+func NewNameVal(val *token.Token) (Val, error) {
+	return Val{name: string(val.Lit)}, nil
+}
+
+func NewExprVal(val any) (Val, error) {
+	expr := val.(Expr)
+	return Val{Expr: &expr}, nil
+}
+
+func AppendExpr(exprList, expr any) (ExprList, error) {
+	return append(exprList.(ExprList), expr.(Expr)), nil
+}
+
+func NewValList(val any) (ValList, error) {
+	return ValList{val.(Val)}, nil
+}
+
+func AppendVal(valList, val any) (ValList, error) {
+	return append(valList.(ValList), val.(Val)), nil
+}
+func NewExpr(name *token.Token, left any, right any) (Expr, error) {
+	var l Val
+	var r Val
+	if left != nil {
+		l = left.(Val)
+	}
+	if right != nil {
+		r = right.(Val)
+	}
+
+	return Expr{string(name.Lit), &l, &r}, nil
+}
+func ListExpr(val any) (Expr, error) {
+	vals := val.(ValList)
+	root := Expr{
+		Name: ".",
+	}
+	current := &root
+	for _, val := range vals[:len(vals)-2] {
+		current.Left = &val
+		current.Right = &Val{
+			Expr: &Expr{
+				Name: ".",
+			}}
+		current = current.Right.Expr
+	}
+	current.Left = &vals[len(vals)-2]
+	current.Right = &vals[len(vals)-1]
+	return root, nil
+}
+
+func (e Expr) String() string {
+	sb := new(strings.Builder)
+	sb.WriteRune('(')
+	sb.WriteString(e.Name)
+	sb.WriteRune(' ')
+	if e.Left != nil {
+		sb.WriteString(e.Left.String())
+	}
+	sb.WriteRune(' ')
+	if e.Left != nil {
+		sb.WriteString(e.Right.String())
+	}
+	sb.WriteRune(')')
+	return sb.String()
+}
+func (v *Val) String() string {
+	if v.string != "" {
+		return v.string
+	}
+	if v.number != "" {
+		num, _ := strconv.ParseInt(v.number, 0, 64)
+		return strconv.FormatInt(num, 10)
+	}
+	if v.name != "" {
+		return v.name
+	}
+	if v.Expr != nil {
+		return v.Expr.String()
+	}
+	return "<nil>"
+}