/// <summary>
/// Gets the <see cref="SyntaxTree" /> for this document asynchronously.
/// </summary>
public Task <SyntaxTree> GetSyntaxTreeAsync(CancellationToken cancellationToken = default(CancellationToken))
{
// If the language doesn't support getting syntax trees for a document, then bail out immediately.
if (!this.SupportsSyntaxTree)
{
return(SpecializedTasks.Default <SyntaxTree>());
}
// if we have a cached result task use it
if (_syntaxTreeResultTask != null)
{
return(_syntaxTreeResultTask);
}
// check to see if we already have the tree before actually going async
if (TryGetSyntaxTree(out var tree))
{
// stash a completed result task for this value for the next request (to reduce extraneous allocations of tasks)
// don't use the actual async task because it depends on a specific cancellation token
// its okay to cache the task and hold onto the SyntaxTree, because the DocumentState already keeps the SyntaxTree alive.
Interlocked.CompareExchange(ref _syntaxTreeResultTask, Task.FromResult(tree), null);
return(_syntaxTreeResultTask);
}
// do it async for real.
return(DocumentState.GetSyntaxTreeAsync(cancellationToken));
}
/// <summary>
/// Gets the <see cref="SyntaxTree" /> for this document asynchronously.
/// </summary>
/// <returns>
/// The returned syntax tree can be <see langword="null"/> if the <see cref="SupportsSyntaxTree"/> returns <see
/// langword="false"/>. This function may cause computation to occur the first time it is called, but will return
/// a cached result every subsequent time. <see cref="SyntaxTree"/>'s can hold onto their roots lazily. So calls
/// to <see cref="SyntaxTree.GetRoot"/> or <see cref="SyntaxTree.GetRootAsync"/> may end up causing computation
/// to occur at that point.
/// </returns>
public Task <SyntaxTree?> GetSyntaxTreeAsync(CancellationToken cancellationToken = default)
{
// If the language doesn't support getting syntax trees for a document, then bail out immediately.
if (!this.SupportsSyntaxTree)
{
return(SpecializedTasks.Null <SyntaxTree>());
}
// if we have a cached result task use it
if (_syntaxTreeResultTask != null)
{
// _syntaxTreeResultTask is a Task<SyntaxTree> so the ! operator here isn't suppressing a possible null ref, but rather allowing the
// conversion from Task<SyntaxTree> to Task<SyntaxTree?> since Task itself isn't properly variant.
return(_syntaxTreeResultTask !);
}
// check to see if we already have the tree before actually going async
if (TryGetSyntaxTree(out var tree))
{
// stash a completed result task for this value for the next request (to reduce extraneous allocations of tasks)
// don't use the actual async task because it depends on a specific cancellation token
// its okay to cache the task and hold onto the SyntaxTree, because the DocumentState already keeps the SyntaxTree alive.
Interlocked.CompareExchange(ref _syntaxTreeResultTask, Task.FromResult(tree), null);
// _syntaxTreeResultTask is a Task<SyntaxTree> so the ! operator here isn't suppressing a possible null ref, but rather allowing the
// conversion from Task<SyntaxTree> to Task<SyntaxTree?> since Task itself isn't properly variant.
return(_syntaxTreeResultTask !);
}
// do it async for real.
// GetSyntaxTreeAsync returns a Task<SyntaxTree> so the ! operator here isn't suppressing a possible null ref, but rather allowing the
// conversion from Task<SyntaxTree> to Task<SyntaxTree?> since Task itself isn't properly variant.
return(DocumentState.GetSyntaxTreeAsync(cancellationToken).AsTask() !);
}
/// <summary>
/// Gets the <see cref="SyntaxTree" /> for this document asynchronously.
/// </summary>
public Task <SyntaxTree> GetSyntaxTreeAsync(CancellationToken cancellationToken = default(CancellationToken))
{
// If the language doesn't support getting syntax trees for a document, then bail out
// immediately.
if (!this.SupportsSyntaxTree)
{
return(SpecializedTasks.Default <SyntaxTree>());
}
if (_syntaxTreeResultTask != null)
{
return(_syntaxTreeResultTask);
}
// First see if we already have a semantic model computed. If so, we can just return
// that syntax tree.
SemanticModel semanticModel;
if (TryGetSemanticModel(out semanticModel))
{
// PERF: This is a hot code path, so cache the result to reduce allocations
var result = Task.FromResult(semanticModel.SyntaxTree);
Interlocked.CompareExchange(ref _syntaxTreeResultTask, result, null);
return(_syntaxTreeResultTask);
}
// second, see whether we already computed the tree, if we already did, return the cache
SyntaxTree tree;
if (TryGetSyntaxTree(out tree))
{
if (_syntaxTreeResultTask == null)
{
var result = Task.FromResult(tree);
Interlocked.CompareExchange(ref _syntaxTreeResultTask, result, null);
}
return(_syntaxTreeResultTask);
}
// we can't cache this result, since internally it uses AsyncLazy which
// care about cancellation token
return(_state.GetSyntaxTreeAsync(cancellationToken));
}
/// <summary>
/// Gets the <see cref="SyntaxTree" /> for this document asynchronously.
/// </summary>
public Task <SyntaxTree> GetSyntaxTreeAsync(CancellationToken cancellationToken = default(CancellationToken))
{
// If the language doesn't support getting syntax trees for a document, then bail out
// immediately.
if (!this.SupportsSyntaxTree)
{
return(SpecializedTasks.Default <SyntaxTree>());
}
var syntaxTreeTask = GetExistingSyntaxTreeTask();
if (syntaxTreeTask != null)
{
return(syntaxTreeTask);
}
// we can't cache this result, since internally it uses AsyncLazy which
// care about cancellation token
return(DocumentState.GetSyntaxTreeAsync(cancellationToken));
}
private static async Task<Compilation> UpdateDocumentInCompilationAsync(
Compilation compilation,
DocumentState oldDocument,
DocumentState newDocument,
CancellationToken cancellationToken)
{
return compilation.ReplaceSyntaxTree(
await oldDocument.GetSyntaxTreeAsync(cancellationToken).ConfigureAwait(false),
await newDocument.GetSyntaxTreeAsync(cancellationToken).ConfigureAwait(false));
}