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Simplify implementation of parsing constraints. #16429

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merged 6 commits into from
Jul 17, 2017
Merged

Simplify implementation of parsing constraints. #16429

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d2a0a89
Simplify implementation of parsing constraints.
CyrusNajmabadi May 17, 2017
011637c
Merge remote-tracking branch 'upstream/master' into parserDiagnostics40
CyrusNajmabadi Jul 7, 2017
a14c0d1
Merge remote-tracking branch 'upstream/master' into parserDiagnostics40
CyrusNajmabadi Jul 7, 2017
76af9a6
Add tests.
CyrusNajmabadi Jul 8, 2017
a5fe26a
Merge remote-tracking branch 'upstream/master' into parserDiagnostics40
CyrusNajmabadi Jul 8, 2017
8f98e3c
Merge remote-tracking branch 'upstream/master' into parserDiagnostics40
CyrusNajmabadi Jul 17, 2017
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77 changes: 31 additions & 46 deletions src/Compilers/CSharp/Portable/Parser/LanguageParser.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -1780,8 +1780,8 @@ private bool IsPossibleMemberStartOrStop()
private bool IsPossibleAggregateClauseStartOrStop()
{
return this.CurrentToken.Kind == SyntaxKind.ColonToken
|| this.IsPossibleTypeParameterConstraintClauseStart()
|| this.CurrentToken.Kind == SyntaxKind.OpenBraceToken;
|| this.CurrentToken.Kind == SyntaxKind.OpenBraceToken
|| this.IsCurrentTokenWhereOfConstraintClause();
}

private BaseListSyntax ParseBaseList()
Expand All @@ -1796,42 +1796,26 @@ private BaseListSyntax ParseBaseList()
try
{
// first type
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If I understood correctly, the code that was removed (here and below) handled the case class C : where T : ... and class C : I1, where T : ....
Do we have parser tests for those? If not, could you add them?

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Will check on this.

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This is parsed properly. That's because ParseType will not accept "where :" as a type name. I'm not sure if we have tests for this though, so i will add them.

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tests added.

if (this.IsPossibleTypeParameterConstraintClauseStart())
{
list.Add(_syntaxFactory.SimpleBaseType(this.AddError(this.CreateMissingIdentifierName(), ErrorCode.ERR_TypeExpected)));
}
else
{
TypeSyntax firstType = this.ParseType();

list.Add(_syntaxFactory.SimpleBaseType(firstType));
TypeSyntax firstType = this.ParseType();
list.Add(_syntaxFactory.SimpleBaseType(firstType));

// any additional types
while (true)
// any additional types
while (true)
{
if (this.CurrentToken.Kind == SyntaxKind.OpenBraceToken ||
this.IsCurrentTokenWhereOfConstraintClause())
{
if (this.CurrentToken.Kind == SyntaxKind.OpenBraceToken
|| this.IsPossibleTypeParameterConstraintClauseStart())
{
break;
}
else if (this.CurrentToken.Kind == SyntaxKind.CommaToken || this.IsPossibleType())
{
list.AddSeparator(this.EatToken(SyntaxKind.CommaToken));
if (this.IsPossibleTypeParameterConstraintClauseStart())
{
list.Add(_syntaxFactory.SimpleBaseType(this.AddError(this.CreateMissingIdentifierName(), ErrorCode.ERR_TypeExpected)));
}
else
{
list.Add(_syntaxFactory.SimpleBaseType(this.ParseType()));
}

continue;
}
else if (this.SkipBadBaseListTokens(ref colon, list, SyntaxKind.CommaToken) == PostSkipAction.Abort)
{
break;
}
break;
}
else if (this.CurrentToken.Kind == SyntaxKind.CommaToken || this.IsPossibleType())
{
list.AddSeparator(this.EatToken(SyntaxKind.CommaToken));
list.Add(_syntaxFactory.SimpleBaseType(this.ParseType()));
continue;
}
else if (this.SkipBadBaseListTokens(ref colon, list, SyntaxKind.CommaToken) == PostSkipAction.Abort)
{
break;
}
}

Expand All @@ -1847,11 +1831,11 @@ private PostSkipAction SkipBadBaseListTokens(ref SyntaxToken colon, SeparatedSyn
{
return this.SkipBadSeparatedListTokensWithExpectedKind(ref colon, list,
p => p.CurrentToken.Kind != SyntaxKind.CommaToken && !p.IsPossibleAttribute(),
p => p.CurrentToken.Kind == SyntaxKind.OpenBraceToken || p.IsPossibleTypeParameterConstraintClauseStart() || p.IsTerminator(),
p => p.CurrentToken.Kind == SyntaxKind.OpenBraceToken || p.IsCurrentTokenWhereOfConstraintClause() || p.IsTerminator(),
expected);
}

private bool IsPossibleTypeParameterConstraintClauseStart()
private bool IsCurrentTokenWhereOfConstraintClause()
{
return
this.CurrentToken.ContextualKind == SyntaxKind.WhereKeyword &&
Expand All @@ -1870,7 +1854,7 @@ private void ParseTypeParameterConstraintClauses(SyntaxListBuilder list)
private TypeParameterConstraintClauseSyntax ParseTypeParameterConstraintClause()
{
var where = this.EatContextualToken(SyntaxKind.WhereKeyword);
var name = (this.IsPossibleTypeParameterConstraintClauseStart() || !IsTrueIdentifier())
var name = !IsTrueIdentifier()
? this.AddError(this.CreateMissingIdentifierName(), ErrorCode.ERR_IdentifierExpected)
: this.ParseIdentifierName();

Expand All @@ -1880,7 +1864,7 @@ private TypeParameterConstraintClauseSyntax ParseTypeParameterConstraintClause()
try
{
// first bound
if (this.CurrentToken.Kind == SyntaxKind.OpenBraceToken || this.IsPossibleTypeParameterConstraintClauseStart())
if (this.CurrentToken.Kind == SyntaxKind.OpenBraceToken || this.IsCurrentTokenWhereOfConstraintClause())
{
bounds.Add(_syntaxFactory.TypeConstraint(this.AddError(this.CreateMissingIdentifierName(), ErrorCode.ERR_TypeExpected)));
}
Expand All @@ -1900,7 +1884,7 @@ private TypeParameterConstraintClauseSyntax ParseTypeParameterConstraintClause()
else if (this.CurrentToken.Kind == SyntaxKind.CommaToken || this.IsPossibleTypeParameterConstraint())
{
bounds.AddSeparator(this.EatToken(SyntaxKind.CommaToken));
if (this.IsPossibleTypeParameterConstraintClauseStart())
if (this.IsCurrentTokenWhereOfConstraintClause())
{
bounds.Add(_syntaxFactory.TypeConstraint(this.AddError(this.CreateMissingIdentifierName(), ErrorCode.ERR_TypeExpected)));
break;
Expand Down Expand Up @@ -1968,7 +1952,7 @@ private PostSkipAction SkipBadTypeParameterConstraintTokens(SeparatedSyntaxListB
Debug.Assert(list.Count > 0);
return this.SkipBadSeparatedListTokensWithExpectedKind(ref tmp, list,
p => this.CurrentToken.Kind != SyntaxKind.CommaToken && !this.IsPossibleTypeParameterConstraint(),
p => this.CurrentToken.Kind == SyntaxKind.OpenBraceToken || this.IsPossibleTypeParameterConstraintClauseStart() || this.IsTerminator(),
p => this.CurrentToken.Kind == SyntaxKind.OpenBraceToken || this.IsCurrentTokenWhereOfConstraintClause() || this.IsTerminator(),
expected);
}

Expand Down Expand Up @@ -2756,7 +2740,7 @@ private bool IsEndOfTypeParameterList()
return true;
}

if (IsPossibleTypeParameterConstraintClauseStart())
if (IsCurrentTokenWhereOfConstraintClause())
{
// class C<T where T :
return true;
Expand Down Expand Up @@ -4941,7 +4925,8 @@ private bool IsTrueIdentifier()
if (this.CurrentToken.Kind == SyntaxKind.IdentifierToken)
{
if (!IsCurrentTokenPartialKeywordOfPartialMethodOrType() &&
!IsCurrentTokenQueryKeywordInQuery())
!IsCurrentTokenQueryKeywordInQuery() &&
!IsCurrentTokenWhereOfConstraintClause())
{
return true;
}
Expand Down Expand Up @@ -5049,7 +5034,7 @@ private TypeParameterListSyntax ParseTypeParameterList()
// remaining parameter & commas
while (true)
{
if (this.CurrentToken.Kind == SyntaxKind.GreaterThanToken || this.IsPossibleTypeParameterConstraintClauseStart())
if (this.CurrentToken.Kind == SyntaxKind.GreaterThanToken || this.IsCurrentTokenWhereOfConstraintClause())
{
break;
}
Expand Down Expand Up @@ -5086,7 +5071,7 @@ private PostSkipAction SkipBadTypeParameterListTokens(SeparatedSyntaxListBuilder

private TypeParameterSyntax ParseTypeParameter()
{
if (this.IsPossibleTypeParameterConstraintClauseStart())
if (this.IsCurrentTokenWhereOfConstraintClause())
{
return _syntaxFactory.TypeParameter(
default(SyntaxList<AttributeListSyntax>),
Expand Down
201 changes: 200 additions & 1 deletion src/Compilers/CSharp/Test/Syntax/Parsing/DeclarationParsingTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -5774,7 +5774,6 @@ class C
}
}


[Fact]
public void ParseOutVar()
{
Expand Down Expand Up @@ -5848,5 +5847,205 @@ void Foo()
}
EOF();
}

[Fact]
public void TestPartiallyWrittenConstraintClauseInBaseList1()
{
var tree = UsingTree(@"
class C<T> : where
");
N(SyntaxKind.CompilationUnit);
{
N(SyntaxKind.ClassDeclaration);
{
N(SyntaxKind.ClassKeyword);
N(SyntaxKind.IdentifierToken, "C");
N(SyntaxKind.TypeParameterList);
{
N(SyntaxKind.LessThanToken);
N(SyntaxKind.TypeParameter);
{
N(SyntaxKind.IdentifierToken, "T");
}
N(SyntaxKind.GreaterThanToken);
}
N(SyntaxKind.BaseList);
{
N(SyntaxKind.ColonToken);
N(SyntaxKind.SimpleBaseType);
{
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "where");
}
}
}
M(SyntaxKind.OpenBraceToken);
M(SyntaxKind.CloseBraceToken);
}
N(SyntaxKind.EndOfFileToken);
}
EOF();
}

[Fact]
public void TestPartiallyWrittenConstraintClauseInBaseList2()
{
var tree = UsingTree(@"
class C<T> : where T
");
N(SyntaxKind.CompilationUnit);
{
N(SyntaxKind.ClassDeclaration);
{
N(SyntaxKind.ClassKeyword);
N(SyntaxKind.IdentifierToken, "C");
N(SyntaxKind.TypeParameterList);
{
N(SyntaxKind.LessThanToken);
N(SyntaxKind.TypeParameter);
{
N(SyntaxKind.IdentifierToken, "T");
}
N(SyntaxKind.GreaterThanToken);
}
N(SyntaxKind.BaseList);
{
N(SyntaxKind.ColonToken);
N(SyntaxKind.SimpleBaseType);
{
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "where");
}
}
M(SyntaxKind.CommaToken);
N(SyntaxKind.SimpleBaseType);
{
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "T");
}
}
}
M(SyntaxKind.OpenBraceToken);
M(SyntaxKind.CloseBraceToken);
}
N(SyntaxKind.EndOfFileToken);
}
EOF();
}

[Fact]
public void TestPartiallyWrittenConstraintClauseInBaseList3()
{
var tree = UsingTree(@"
class C<T> : where T :
");
N(SyntaxKind.CompilationUnit);
{
N(SyntaxKind.ClassDeclaration);
{
N(SyntaxKind.ClassKeyword);
N(SyntaxKind.IdentifierToken, "C");
N(SyntaxKind.TypeParameterList);
{
N(SyntaxKind.LessThanToken);
N(SyntaxKind.TypeParameter);
{
N(SyntaxKind.IdentifierToken, "T");
}
N(SyntaxKind.GreaterThanToken);
}
N(SyntaxKind.BaseList);
{
N(SyntaxKind.ColonToken);
M(SyntaxKind.SimpleBaseType);
{
M(SyntaxKind.IdentifierName);
{
M(SyntaxKind.IdentifierToken);
}
}
}
N(SyntaxKind.TypeParameterConstraintClause);
{
N(SyntaxKind.WhereKeyword);
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "T");
}
N(SyntaxKind.ColonToken);
M(SyntaxKind.TypeConstraint);
{
M(SyntaxKind.IdentifierName);
{
M(SyntaxKind.IdentifierToken);
}
}
}
M(SyntaxKind.OpenBraceToken);
M(SyntaxKind.CloseBraceToken);
}
N(SyntaxKind.EndOfFileToken);
}
EOF();
}

[Fact]
public void TestPartiallyWrittenConstraintClauseInBaseList4()
{
var tree = UsingTree(@"
class C<T> : where T : X
");
N(SyntaxKind.CompilationUnit);
{
N(SyntaxKind.ClassDeclaration);
{
N(SyntaxKind.ClassKeyword);
N(SyntaxKind.IdentifierToken, "C");
N(SyntaxKind.TypeParameterList);
{
N(SyntaxKind.LessThanToken);
N(SyntaxKind.TypeParameter);
{
N(SyntaxKind.IdentifierToken, "T");
}
N(SyntaxKind.GreaterThanToken);
}
N(SyntaxKind.BaseList);
{
N(SyntaxKind.ColonToken);
M(SyntaxKind.SimpleBaseType);
{
M(SyntaxKind.IdentifierName);
{
M(SyntaxKind.IdentifierToken);
}
}
}
N(SyntaxKind.TypeParameterConstraintClause);
{
N(SyntaxKind.WhereKeyword);
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "T");
}
N(SyntaxKind.ColonToken);
N(SyntaxKind.TypeConstraint);
{
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "X");
}
}
}
M(SyntaxKind.OpenBraceToken);
M(SyntaxKind.CloseBraceToken);
}
N(SyntaxKind.EndOfFileToken);
}
EOF();
}
}
}