protected override IEnumerable <LessNode> EvaluateCore(EvaluationContext context)
{
string EvaluateFilePath(Expression expr)
{
if (expr is LessString str)
{
return(str.GetUnquotedValue());
}
if (expr is Url url)
{
return(EvaluateFilePath(url.Content));
}
return(expr.ToString());
}
// Import resolution takes care of relative paths regardless of the
// rewrite setting, so while evaluating the import URL, we turn the
// rewrite setting off.
bool rewrite = context.RewriteRelativeUrls;
context.RewriteRelativeUrls = false;
var evaluatedUrl = Url.EvaluateSingle <Expression>(context);
context.RewriteRelativeUrls = rewrite;
var filePath = EvaluateFilePath(evaluatedUrl);
bool isExplicitCssImport = options.HasFlag(ImportOptions.Css);
if (isExplicitCssImport || !filePath.IsLocalFilePath())
{
return(new[] { this });
}
var extension = Path.GetExtension(filePath);
bool isCssFile = extension == ".css";
bool isExplicitLessImport = options.HasFlag(ImportOptions.Less);
bool isInlineImport = options.HasFlag(ImportOptions.Inline);
if (isCssFile && !isExplicitLessImport && !isInlineImport)
{
return(new[] {
new ImportStatement(
evaluatedUrl,
options,
mediaQueries.Select(mq => mq.EvaluateSingle <MediaQuery>(context))),
});
}
var actualImportPath = string.IsNullOrEmpty(extension)
? Path.ChangeExtension(filePath, "less")
: filePath;
var importResults = GetImportResults(options.HasFlag(ImportOptions.Optional));
if (importResults == null)
{
return(Enumerable.Empty <LessNode>());
}
if (mediaQueries.Any())
{
return(new[] { new MediaBlock(mediaQueries, new RuleBlock(importResults)).EvaluateSingle <MediaBlock>(context) });
}
return(importResults);
IEnumerable <Statement> GetImportResults(bool optional)
{
if (context.SeenImport(actualImportPath))
{
return(Enumerable.Empty <Statement>());
}
if (!options.HasFlag(ImportOptions.Reference))
{
context.NoteImport(actualImportPath);
}
using (context.EnterImportScope(actualImportPath)) {
try {
if (isCssFile && isInlineImport)
{
return(new Statement[] { new InlineCssImportStatement(context.GetFileContent()) });
}
return(context
.ParseCurrentStylesheet(isReference: options.HasFlag(ImportOptions.Reference))
.Evaluate(context)
.OfType <Statement>()
.ToList());
} catch (IOException ex) {
if (optional)
{
return(null);
}
throw new EvaluationException($"Failed to import {filePath}", ex);
}
}
}
}
