internal static bool TryGetSyntax <TSyntax>(
SyntaxNode root,
int position,
ISyntaxFactsService syntaxFacts,
SignatureHelpTriggerReason triggerReason,
Func <SyntaxToken, bool> isTriggerToken,
Func <TSyntax, SyntaxToken, bool> isArgumentListToken,
CancellationToken cancellationToken,
out TSyntax expression
) where TSyntax : SyntaxNode
{
var token = syntaxFacts.FindTokenOnLeftOfPosition(root, position);
if (triggerReason == SignatureHelpTriggerReason.TypeCharCommand)
{
if (
isTriggerToken(token) &&
!syntaxFacts.IsInNonUserCode(root.SyntaxTree, position, cancellationToken)
)
{
expression = token.GetAncestor <TSyntax>();
return(true);
}
}
else if (triggerReason == SignatureHelpTriggerReason.InvokeSignatureHelpCommand)
{
expression = token.Parent
?.GetAncestorsOrThis <TSyntax>()
.SkipWhile(syntax => !isArgumentListToken(syntax, token))
.FirstOrDefault();
return(expression != null);
}
else if (triggerReason == SignatureHelpTriggerReason.RetriggerCommand)
{
if (
!syntaxFacts.IsInNonUserCode(root.SyntaxTree, position, cancellationToken) ||
syntaxFacts.IsEntirelyWithinStringOrCharOrNumericLiteral(
root.SyntaxTree,
position,
cancellationToken
)
)
{
expression = token.Parent
?.AncestorsAndSelf()
.TakeWhile(n => !syntaxFacts.IsAnonymousFunction(n))
.OfType <TSyntax>()
.SkipWhile(syntax => !isArgumentListToken(syntax, token))
.FirstOrDefault();
return(expression != null);
}
}
expression = null;
return(false);
}
private Dictionary <TriviaLocation, SyntaxToken> GetTokensAtEdges(SyntaxNode root, TextSpan textSpan)
{
var tokens = new Dictionary <TriviaLocation, SyntaxToken>();
tokens[TriviaLocation.AfterBeginningOfSpan] = _syntaxFactsService.FindTokenOnRightOfPosition(root, textSpan.Start, includeSkipped: false);
tokens[TriviaLocation.BeforeBeginningOfSpan] = tokens[TriviaLocation.AfterBeginningOfSpan].GetPreviousToken(includeZeroWidth: true);
tokens[TriviaLocation.BeforeEndOfSpan] = _syntaxFactsService.FindTokenOnLeftOfPosition(root, textSpan.End, includeSkipped: false);
tokens[TriviaLocation.AfterEndOfSpan] = tokens[TriviaLocation.BeforeEndOfSpan].GetNextToken(includeZeroWidth: true);
return(tokens);
}
internal static bool TryGetSyntax <TSyntax>(
SyntaxNode root,
int position,
ISyntaxFactsService syntaxFacts,
SignatureHelpTriggerReason triggerReason,
Func <SyntaxToken, bool> isTriggerToken,
Func <TSyntax, SyntaxToken, bool> isArgumentListToken,
CancellationToken cancellationToken,
out TSyntax expression)
where TSyntax : SyntaxNode
{
// Bug 1100661 reports an NRE from this method, but no manual repro has been found. To aid in debugging,
// any NRE thrown from here will generate a dump via FatalError.Report() below. try/catch was added 1/2/2015
// and is expected to be removed by 4/1/2015. --brettfo
try
{
var token = syntaxFacts.FindTokenOnLeftOfPosition(root, position);
if (triggerReason == SignatureHelpTriggerReason.TypeCharCommand)
{
if (isTriggerToken(token))
{
expression = token.GetAncestor <TSyntax>();
return(true);
}
}
else if (triggerReason == SignatureHelpTriggerReason.InvokeSignatureHelpCommand)
{
expression = token.Parent.GetAncestorsOrThis <TSyntax>().SkipWhile(syntax => !isArgumentListToken(syntax, token)).FirstOrDefault();
return(expression != null);
}
else if (triggerReason == SignatureHelpTriggerReason.RetriggerCommand)
{
if (!syntaxFacts.IsInNonUserCode(root.SyntaxTree, position, cancellationToken) ||
syntaxFacts.IsEntirelyWithinStringOrCharLiteral(root.SyntaxTree, position, cancellationToken))
{
expression = token.Parent.AncestorsAndSelf()
.TakeWhile(n => !syntaxFacts.IsAnonymousFunction(n))
.OfType <TSyntax>()
.SkipWhile(syntax => !isArgumentListToken(syntax, token))
.FirstOrDefault();
return(expression != null);
}
}
expression = null;
return(false);
}
catch (NullReferenceException e) when(FatalError.Report(e))
{
throw ExceptionUtilities.Unreachable;
}
}
/// <summary>
/// Find closest token (including one in structured trivia) left of given position
/// </summary>
private SyntaxToken FindTokenOnLeftOfPosition(ISyntaxFactsService syntaxFactsService, SyntaxNode root, int position)
{
// find token on left
var token = syntaxFactsService.FindTokenOnLeftOfPosition(root, position, includeSkipped: true, includeDirectives: true, includeDocumentationComments: true);
if (token.RawKind == 0)
{
// if there is no token on left, return the first token
return(root.GetFirstToken(includeZeroWidth: true, includeSkipped: true, includeDirectives: true, includeDocumentationComments: true));
}
return(token);
}
/// <summary>
/// Find closest token (including one in structured trivia) left of given position
/// </summary>
private SyntaxToken FindTokenOnLeftOfPosition(ISyntaxFactsService syntaxFactsService, SyntaxNode root, int position)
{
// find token on left
var token = syntaxFactsService.FindTokenOnLeftOfPosition(root, position, includeSkipped: true, includeDirectives: true, includeDocumentationComments: true);
if (token.RawKind == 0)
{
// if there is no token on left, return the first token
return root.GetFirstToken(includeZeroWidth: true, includeSkipped: true, includeDirectives: true, includeDocumentationComments: true);
}
return token;
}