element.go

package main

type Element struct {
	Name       string
	Attributes []Attribute
}

type Attribute string

func (attr Attribute) IsVoid() bool {
	_, val, qu, _ := attr.split()
	return val == "" && qu == ""
}

func (attr Attribute) split() (string, string, string, error) {
	i := 0
	for ; i < len(attr); i++ {
		if attr[i] == '=' {
			break
		}
	}
	if i == len(attr) {
		return string(attr[:i]), "", "", nil
	}
	if len(attr[i+1:]) < 2 {
		return string(attr[:i]), "", "", errors.New("attribute quoting is incorrect")
	}
	if (attr[i+1] != '"' && attr[len(attr)-1] != '"') && (attr[i+1] != '\'' && attr[len(attr)-1] != '\'') {
		if strings.ContainsAny(string(attr), " \t") {
			return string(attr[:i]), string(attr[i+1:]), "", errors.New("unquoted attribute value must not contain a spaces")
		}
		return string(attr[:i]), string(attr[i+1:]), "", nil
	}
	return string(attr[:i]), string(attr[i+2 : len(attr)-1]), string(attr[len(attr)-1:]), nil
}

/*

import "testing"

func TestAttribute_split(t *testing.T) {
	if name, val, qu, err := Attribute(`foo="bar"`).split(); name != "foo" || val != "bar" || qu != "\"" || err != nil {
		t.Errorf("%q %q %q", name, val, qu)
	}
	if name, val, qu, err := Attribute(`foo='bar'`).split(); name != "foo" || val != "bar" || qu != "'" || err != nil {
		t.Errorf("%q %q %q", name, val, qu)
	}
	if name, val, qu, err := Attribute(`foo`).split(); name != "foo" || val != "" || qu != "" || err != nil {
		t.Errorf("%q %q %q", name, val, qu)
	}
	if name, val, qu, err := Attribute(`foo=""`).split(); name != "foo" || val != "" || qu != "\"" || err != nil {
		t.Errorf("%q %q %q", name, val, qu)
	}
	if name, val, qu, err := Attribute(`foo=''`).split(); name != "foo" || val != "" || qu != "'" || err != nil {
		t.Errorf("%q %q %q", name, val, qu)
	}
	if name, val, qu, err := Attribute(`foo=bar`).split(); name != "foo" || val != "bar" || qu != "" || err != nil {
		t.Errorf("%q %q %q", name, val, qu)
	}
	if name, val, qu, err := Attribute(`foo=bar baz`).split(); name != "foo" || val != "bar baz" || qu != "" || err == nil {
		t.Errorf("%q %q %q", name, val, qu)
	}
	if _, _, _, err := Attribute(`foo="`).split(); err == nil {
		t.Errorf("should error")
	}
	if _, _, _, err := Attribute(`foo='`).split(); err == nil {
		t.Errorf("should error")
	}
}

*/