/// <summary>
/// Find the Deconstruct method for the expression on the right, that will fit the number of assignable variables on the left.
/// Returns an invocation expression if the Deconstruct method is found.
/// If so, it outputs placeholders that were coerced to the output types of the resolved Deconstruct method.
/// The overload resolution is similar to writing `receiver.Deconstruct(out var x1, out var x2, ...)`.
/// </summary>
private BoundExpression MakeDeconstructInvocationExpression(
int numCheckedVariables, BoundExpression receiver, CSharpSyntaxNode syntax,
DiagnosticBag diagnostics, out ImmutableArray <BoundDeconstructValuePlaceholder> outPlaceholders)
{
var receiverSyntax = receiver.Syntax;
if (receiver.Type.IsDynamic())
{
Error(diagnostics, ErrorCode.ERR_CannotDeconstructDynamic, receiverSyntax);
outPlaceholders = default(ImmutableArray <BoundDeconstructValuePlaceholder>);
return(BadExpression(receiverSyntax, receiver));
}
var analyzedArguments = AnalyzedArguments.GetInstance();
var outVars = ArrayBuilder <OutDeconstructVarPendingInference> .GetInstance(numCheckedVariables);
DiagnosticBag bag = null;
try
{
for (int i = 0; i < numCheckedVariables; i++)
{
var variable = new OutDeconstructVarPendingInference(syntax);
analyzedArguments.Arguments.Add(variable);
analyzedArguments.RefKinds.Add(RefKind.Out);
outVars.Add(variable);
}
const string methodName = "Deconstruct";
var memberAccess = BindInstanceMemberAccess(
receiverSyntax, receiverSyntax, receiver, methodName, rightArity: 0,
typeArgumentsSyntax: default(SeparatedSyntaxList <TypeSyntax>), typeArguments: default(ImmutableArray <TypeSymbol>),
invoked: true, diagnostics: diagnostics);
memberAccess = CheckValue(memberAccess, BindValueKind.RValueOrMethodGroup, diagnostics);
memberAccess.WasCompilerGenerated = true;
if (memberAccess.Kind != BoundKind.MethodGroup)
{
return(MissingDeconstruct(receiver, syntax, numCheckedVariables, diagnostics, out outPlaceholders, receiver));
}
// After the overload resolution completes, the last step is to coerce the arguments with inferred types.
// That step returns placeholder (of correct type) instead of the outVar nodes that were passed in as arguments.
// So the generated invocation expression will contain placeholders instead of those outVar nodes.
// Those placeholders are also recorded in the outVar for easy access below, by the `SetInferredType` call on the outVar nodes.
bag = DiagnosticBag.GetInstance();
BoundExpression result = BindMethodGroupInvocation(
receiverSyntax, receiverSyntax, methodName, (BoundMethodGroup)memberAccess, analyzedArguments, bag, queryClause: null,
allowUnexpandedForm: true);
result.WasCompilerGenerated = true;
diagnostics.AddRange(bag);
if (bag.HasAnyErrors())
{
return(MissingDeconstruct(receiver, syntax, numCheckedVariables, diagnostics, out outPlaceholders, result));
}
// Verify all the parameters (except "this" for extension methods) are out parameters
if (result.Kind != BoundKind.Call)
{
return(MissingDeconstruct(receiver, syntax, numCheckedVariables, diagnostics, out outPlaceholders, result));
}
var deconstructMethod = ((BoundCall)result).Method;
var parameters = deconstructMethod.Parameters;
for (int i = (deconstructMethod.IsExtensionMethod ? 1 : 0); i < parameters.Length; i++)
{
if (parameters[i].RefKind != RefKind.Out)
{
return(MissingDeconstruct(receiver, syntax, numCheckedVariables, diagnostics, out outPlaceholders, result));
}
}
if (outVars.Any(v => (object)v.Placeholder == null))
{
return(MissingDeconstruct(receiver, syntax, numCheckedVariables, diagnostics, out outPlaceholders, result));
}
outPlaceholders = outVars.SelectAsArray(v => v.Placeholder);
return(result);
}
finally
{
analyzedArguments.Free();
outVars.Free();
if (bag != null)
{
bag.Free();
}
}
}
/// <summary>
/// Find the Deconstruct method for the expression on the right, that will fit the number of assignable variables on the left.
/// Returns an invocation expression if the Deconstruct method is found.
/// If so, it outputs placeholders that were coerced to the output types of the resolved Deconstruct method.
/// The overload resolution is similar to writing `receiver.Deconstruct(out var x1, out var x2, ...)`.
/// </summary>
private BoundExpression MakeDeconstructInvocationExpression(
int numCheckedVariables, BoundExpression receiver, CSharpSyntaxNode syntax,
DiagnosticBag diagnostics, out ImmutableArray<BoundDeconstructValuePlaceholder> outPlaceholders)
{
var receiverSyntax = receiver.Syntax;
if (numCheckedVariables < 2)
{
Error(diagnostics, ErrorCode.ERR_DeconstructTooFewElements, receiverSyntax);
outPlaceholders = default(ImmutableArray<BoundDeconstructValuePlaceholder>);
return BadExpression(receiverSyntax, receiver);
}
if (receiver.Type.IsDynamic())
{
Error(diagnostics, ErrorCode.ERR_CannotDeconstructDynamic, receiverSyntax);
outPlaceholders = default(ImmutableArray<BoundDeconstructValuePlaceholder>);
return BadExpression(receiverSyntax, receiver);
}
var analyzedArguments = AnalyzedArguments.GetInstance();
var outVars = ArrayBuilder<OutDeconstructVarPendingInference>.GetInstance(numCheckedVariables);
try
{
for (int i = 0; i < numCheckedVariables; i++)
{
var variable = new OutDeconstructVarPendingInference(syntax);
analyzedArguments.Arguments.Add(variable);
analyzedArguments.RefKinds.Add(RefKind.Out);
outVars.Add(variable);
}
const string methodName = "Deconstruct";
var memberAccess = BindInstanceMemberAccess(
receiverSyntax, receiverSyntax, receiver, methodName, rightArity: 0,
typeArgumentsSyntax: default(SeparatedSyntaxList<TypeSyntax>), typeArguments: default(ImmutableArray<TypeSymbol>),
invoked: true, diagnostics: diagnostics);
memberAccess = CheckValue(memberAccess, BindValueKind.RValueOrMethodGroup, diagnostics);
memberAccess.WasCompilerGenerated = true;
if (memberAccess.Kind != BoundKind.MethodGroup)
{
return MissingDeconstruct(receiver, syntax, numCheckedVariables, diagnostics, out outPlaceholders, receiver);
}
// After the overload resolution completes, the last step is to coerce the arguments with inferred types.
// That step returns placeholder (of correct type) instead of the outVar nodes that were passed in as arguments.
// So the generated invocation expression will contain placeholders instead of those outVar nodes.
// Those placeholders are also recorded in the outVar for easy access below, by the `SetInferredType` call on the outVar nodes.
BoundExpression result = BindMethodGroupInvocation(
receiverSyntax, receiverSyntax, methodName, (BoundMethodGroup)memberAccess, analyzedArguments, diagnostics, queryClause: null,
allowUnexpandedForm: true);
result.WasCompilerGenerated = true;
if (result.HasErrors && !receiver.HasAnyErrors)
{
return MissingDeconstruct(receiver, syntax, numCheckedVariables, diagnostics, out outPlaceholders, result);
}
// Verify all the parameters (except "this" for extension methods) are out parameters
if (result.Kind != BoundKind.Call)
{
return MissingDeconstruct(receiver, syntax, numCheckedVariables, diagnostics, out outPlaceholders, result);
}
var deconstructMethod = ((BoundCall)result).Method;
var parameters = deconstructMethod.Parameters;
for (int i = (deconstructMethod.IsExtensionMethod ? 1 : 0); i < parameters.Length; i++)
{
if (parameters[i].RefKind != RefKind.Out)
{
return MissingDeconstruct(receiver, syntax, numCheckedVariables, diagnostics, out outPlaceholders, result);
}
}
if (deconstructMethod.ReturnType.GetSpecialTypeSafe() != SpecialType.System_Void)
{
return MissingDeconstruct(receiver, syntax, numCheckedVariables, diagnostics, out outPlaceholders, result);
}
if (outVars.Any(v => (object)v.Placeholder == null))
{
return MissingDeconstruct(receiver, syntax, numCheckedVariables, diagnostics, out outPlaceholders, result);
}
outPlaceholders = outVars.SelectAsArray(v => v.Placeholder);
return result;
}
finally
{
analyzedArguments.Free();
outVars.Free();
}
}
public override sealed BoundNode VisitOutDeconstructVarPendingInference(OutDeconstructVarPendingInference node)
{
// OutDeconstructVarPendingInference nodes are only used within initial binding, but don't survive past that stage
throw ExceptionUtilities.Unreachable;
}