private void AppendAttribute(TagHelperContent content, string key, object value, bool escapeQuotes)
{
content
.Append(" ")
.Append(key);
if (escapeQuotes)
{
// Passed only JavaScript-encoded strings in this case. Do not perform HTML-encoding as well.
content
.Append("=\\\"")
.Append((string)value)
.Append("\\\"");
}
else
{
// HTML-encoded the given value if necessary.
content
.Append("=\"")
.Append(HtmlEncoder, ViewContext.Writer.Encoding, value)
.Append("\"");
}
}
private void BuildLinkTag(TagHelperAttributeList attributes, TagHelperContent builder)
{
EnsureFileVersionProvider();
builder.Append("<link ");
foreach (var attribute in attributes)
{
var attributeValue = attribute.Value;
if (AppendVersion == true &&
string.Equals(attribute.Name, HrefAttributeName, StringComparison.OrdinalIgnoreCase))
{
// "href" values come from bound attributes and globbing. So anything but a non-null string is
// unexpected but could happen if another helper targeting the same element does something odd.
// Pass through existing value in that case.
var attributeStringValue = attributeValue as string;
if (attributeStringValue != null)
{
attributeValue = _fileVersionProvider.AddFileVersionToPath(attributeStringValue);
}
}
builder
.Append(attribute.Name)
.Append("=\"")
.Append(HtmlEncoder, ViewContext.Writer.Encoding, attributeValue)
.Append("\" ");
}
builder.Append("/>");
}
private void BuildScriptTag(
TagHelperContent content,
TagHelperAttributeList attributes,
TagHelperContent builder)
{
EnsureFileVersionProvider();
builder.Append("<script");
foreach (var attribute in attributes)
{
var attributeValue = attribute.Value;
if (FileVersion == true &&
string.Equals(attribute.Name, SrcAttributeName, StringComparison.OrdinalIgnoreCase))
{
// "src" values come from bound attributes and globbing. So anything but a non-null string is
// unexpected but could happen if another helper targeting the same element does something odd.
// Pass through existing value in that case.
var attributeStringValue = attributeValue as string;
if (attributeStringValue != null)
{
attributeValue = _fileVersionProvider.AddFileVersionToPath(attributeStringValue);
}
}
AppendAttribute(builder, attribute.Name, attributeValue, escapeQuotes: false);
}
builder.Append(">")
.Append(content)
.Append("</script>");
}
private void BuildFallbackBlock(TagHelperContent builder)
{
EnsureGlobbingUrlBuilder();
var fallbackHrefs =
GlobbingUrlBuilder.BuildUrlList(FallbackHref, FallbackHrefInclude, FallbackHrefExclude).ToArray();
if (fallbackHrefs.Length > 0)
{
if (AppendVersion == true)
{
for (var i=0; i < fallbackHrefs.Length; i++)
{
// fallbackHrefs come from bound attributes and globbing. Must always be non-null.
Debug.Assert(fallbackHrefs[i] != null);
fallbackHrefs[i] = _fileVersionProvider.AddFileVersionToPath(fallbackHrefs[i]);
}
}
builder.Append(Environment.NewLine);
// Build the <meta /> tag that's used to test for the presence of the stylesheet
builder.AppendFormat(
CultureInfo.InvariantCulture,
"<meta name=\"x-stylesheet-fallback-test\" class=\"{0}\" />",
HtmlEncoder.HtmlEncode(FallbackTestClass));
// Build the <script /> tag that checks the effective style of <meta /> tag above and renders the extra
// <link /> tag to load the fallback stylesheet if the test CSS property value is found to be false,
// indicating that the primary stylesheet failed to load.
builder
.Append("<script>")
.AppendFormat(
CultureInfo.InvariantCulture,
JavaScriptResources.GetEmbeddedJavaScript(FallbackJavaScriptResourceName),
JavaScriptEncoder.JavaScriptStringEncode(FallbackTestProperty),
JavaScriptEncoder.JavaScriptStringEncode(FallbackTestValue),
JavaScriptStringArrayEncoder.Encode(JavaScriptEncoder, fallbackHrefs))
.Append("</script>");
}
}
