public static bool ContainsClass(this TagHelperAttributeList attributes, string className)
{
if (string.IsNullOrWhiteSpace(className))
{
throw new ArgumentOutOfRangeException(nameof(className), "The class name must not be null or white space.");
}
if (!attributes.TryGetAttribute("class", out TagHelperAttribute classAttribute))
{
return(false);
}
string classes = classAttribute.Value.ToString();
for (int i = 0; i + className.Length <= classes.Length; i++)
{
// Find className
i = classes.IndexOf(className, i);
if (i == -1)
{
return(false);
}
// Ensure word boundaries
if ((i == 0 || char.IsWhiteSpace(classes[i - 1])) &&
(i + className.Length == classes.Length || char.IsWhiteSpace(classes[i + className.Length])))
{
return(true);
}
}
return(false);
}
private bool HasStyleSheetLinkType(TagHelperAttributeList attributes)
{
if (!attributes.TryGetAttribute(RelAttributeName, out var relAttribute) ||
relAttribute.Value == null)
{
return(false);
}
var attributeValue = relAttribute.Value;
var stringValue = attributeValue as string;
if (attributeValue is IHtmlContent contentValue)
{
contentValue.WriteTo(StringWriter, HtmlEncoder);
stringValue = StringWriter.ToString();
// Reset writer
StringWriter.GetStringBuilder().Clear();
}
else if (stringValue == null)
{
stringValue = Convert.ToString(attributeValue, CultureInfo.InvariantCulture);
}
var hasRelStylesheet = string.Equals("stylesheet", stringValue, StringComparison.Ordinal);
return(hasRelStylesheet);
}
/// <summary>
/// Copies the html attribute <paramref name="name"/> from source <paramref name="attributes"/> to <see cref="TagBuilder"/> <paramref name="target"/>.
/// </summary>
/// <param name="attributes">The source to find attribute to copy.</param>
/// <param name="target">The target <see cref="TagBuilder"/> instance to copy found attribute to.</param>
/// <param name="name">Name of attribute to find in source.</param>
/// <param name="replaceExisting">Whether to replace existing attribute in <paramref name="target"/>.</param>
/// <param name="ignoreNull">Whether to skip copying if source attribute's value is <see langword="null"/>.</param>
/// <returns><see langword="true"/> if an attribute has been copied, <see langword="false"/> otherwise.</returns>
public static bool CopyAttribute(this TagHelperAttributeList attributes, TagBuilder target, string name, bool replaceExisting = true, bool ignoreNull = true)
{
Guard.NotEmpty(name, nameof(name));
Guard.NotNull(target, nameof(target));
if (attributes.TryGetAttribute(name, out var attribute))
{
return(target.MergeAttribute(name, () => attribute.Value?.ToString(), replaceExisting, ignoreNull));
}
return(false);
}
/// <summary>
/// TODO document
/// </summary>
/// <param name="attributes"></param>
/// <param name="attribute"></param>
/// <param name="value"></param>
public static void AppendToAttribute(this TagHelperAttributeList attributes, string attribute, string value)
{
var hasAttribute = attributes.TryGetAttribute(attribute, out var classAttribute);
var existingValue = "";
if (hasAttribute)
{
existingValue = classAttribute.Value.ToString() + " ";
}
existingValue += value;
attributes.SetAttribute(attribute, existingValue);
}
private static void AddInAttributeValue(TagHelperAttributeList attrList, string name, char separator, string value, bool prepend = false)
{
if (!attrList.TryGetAttribute(name, out var attribute))
{
attrList.Add(new TagHelperAttribute(name, value));
}
else
{
var arr = attribute.Value.ToString().Trim().Tokenize(new[] { separator }, StringSplitOptions.RemoveEmptyEntries);
var arrValue = value.Trim().Tokenize(new[] { separator }, StringSplitOptions.RemoveEmptyEntries);
arr = prepend ? arrValue.Union(arr) : arr.Union(arrValue);
attrList.SetAttribute(name, string.Join(separator, arr));
}
}
public void TryGetAttribute_ReturnsExpectedValueAndAttribute(
IEnumerable <TagHelperAttribute> initialAttributes,
string nameToLookup,
TagHelperAttribute expectedAttribute,
bool expectedResult)
{
// Arrange
var attributes = new TagHelperAttributeList(initialAttributes);
TagHelperAttribute attribute;
// Act
var result = attributes.TryGetAttribute(nameToLookup, out attribute);
// Assert
Assert.Equal(expectedResult, result);
Assert.Equal(expectedAttribute, attribute, CaseSensitiveTagHelperAttributeComparer.Default);
}
/// <summary>
/// Adds a class to a tag, if it is not already there (case sensitive)
/// </summary>
/// <param name="attributes">The attribute list to add the class to</param>
/// <param name="htmlClass">The class to add to the tag</param>
/// <remarks>Keep checking to see if this or similar is added to the framework</remarks>
public static void AddClass(this TagHelperAttributeList attributes, string htmlClass)
{
attributes.TryGetAttribute("class", out var classAttribute);
var classes = classAttribute?.Value?.ToString();
if (string.IsNullOrWhiteSpace(classes))
{
attributes.SetAttribute("class", htmlClass);
return;
}
var classList = classes.Split(' ', StringSplitOptions.RemoveEmptyEntries);
if (!classList.Contains(htmlClass, StringComparer.Ordinal))
{
attributes.SetAttribute("class", new HtmlString($"{classes} {htmlClass}"));
}
}
public static bool AddClass(this TagHelperAttributeList attributes, string className)
{
if (string.IsNullOrWhiteSpace(className))
{
throw new ArgumentNullException(nameof(className));
}
if (!attributes.TryGetAttribute("class", out TagHelperAttribute classAttribute))
{
attributes.Add(new TagHelperAttribute("class", className));
return(true);
}
if (attributes.ContainsClass(className))
{
return(false);
}
string classes = classAttribute.Value.ToString();
attributes.SetAttribute("class", string.Join(" ", className, classes));
return(true);
}
public void TryGetAttribute_ReturnsExpectedValueAndAttribute(
IEnumerable<TagHelperAttribute> initialAttributes,
string nameToLookup,
TagHelperAttribute expectedAttribute,
bool expectedResult)
{
// Arrange
var attributes = new TagHelperAttributeList(initialAttributes);
TagHelperAttribute attribute;
// Act
var result = attributes.TryGetAttribute(nameToLookup, out attribute);
// Assert
Assert.Equal(expectedResult, result);
Assert.Equal(expectedAttribute, attribute, CaseSensitiveTagHelperAttributeComparer.Default);
}
// --------------------------------------------------------------------------------------------------------------------
/// <summary>
/// A TagHelperAttributeList extension method that returns an attribute by name, or a default value or null if not found.
/// </summary>
/// <param name="list"> The list to act on. </param>
/// <param name="name"> The name. </param>
/// <param name="defaultIfEmpty"> (Optional) The default if empty. </param>
/// <returns> A TagHelperAttribute. </returns>
public static TagHelperAttribute Value(this TagHelperAttributeList list, string name, TagHelperAttribute defaultIfEmpty = null)
{
return(list.TryGetAttribute(name, out var value) ? value : defaultIfEmpty);
}
/// <summary>
/// A TagHelperAttributeList extension method that returns an attribute by name, or a default value or null if not found.
/// </summary>
/// <param name="list"> The list to act on. </param>
/// <param name="name"> The name. </param>
/// <param name="defaultIfEmpty"> The default if empty. </param>
/// <returns> A string. </returns>
public static string Value(this TagHelperAttributeList list, string name, string defaultIfEmpty)
{
return(list.TryGetAttribute(name, out var value) ? value.Render() : defaultIfEmpty);
}
