columnRef.go

package squl

import (
	"bytes"
	stdfmt "fmt"
	"strings"

	fmt "golang.org/x/xerrors"

	"github.com/trivigy/squl/internal/global"
)

// ColumnRef describes a fully qualified column name, possibly with subscripts.
type ColumnRef struct {
	// Fields represents field names, `*`, or subscripts.
	Fields interface{} `json:"fields"`
}

func (r *ColumnRef) dump(counter *ordinalMarker) (string, error) {
	switch fields := r.Fields.(type) {
	case string:
		return fields, nil
	case []string:
		return strings.Join(fields, "."), nil
	case []interface{}:
		buffer := bytes.NewBuffer(nil)
		for i, field := range fields {
			switch field := field.(type) {
			case Var:
				mark, err := field.dump(counter)
				if err != nil {
					return "", err
				}
				switch field.Value.(type) {
				case string:
					if i != 0 {
						if _, err := buffer.WriteString("."); err != nil {
							return "", fmt.Errorf(global.ErrFmt, pkg.Name(), err)
						}
					}
					if _, err := buffer.WriteString(mark); err != nil {
						return "", fmt.Errorf(global.ErrFmt, pkg.Name(), err)
					}
				case int:
					if _, err := buffer.WriteString(stdfmt.Sprintf("[%s]", mark)); err != nil {
						return "", fmt.Errorf(global.ErrFmt, pkg.Name(), err)
					}
				default:
					return "", fmt.Errorf(global.ErrFmt, pkg.Name(), fmt.Errorf("type error %q", field.Value))
				}
			case string:
				if i != 0 {
					if _, err := buffer.WriteString("."); err != nil {
						return "", fmt.Errorf(global.ErrFmt, pkg.Name(), err)
					}
				}
				if _, err := buffer.WriteString(field); err != nil {
					return "", fmt.Errorf(global.ErrFmt, pkg.Name(), err)
				}
			case int:
				if i == 0 {
					return "", fmt.Errorf(global.ErrFmt, pkg.Name(), fmt.Errorf("syntax error %q", r.Fields))
				}
				if _, err := buffer.WriteString(stdfmt.Sprintf("[%d]", field)); err != nil {
					return "", fmt.Errorf(global.ErrFmt, pkg.Name(), err)
				}
			}
		}
		return buffer.String(), nil
	default:
		return "", fmt.Errorf(global.ErrFmt, pkg.Name(), fmt.Errorf("unknown type (%T) for %q", r.Fields, r.Fields))
	}
}