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(#72) Parser: TODO bookkeeping, small refactoring of parser hacks
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@ForNeVeR
ForNeVeR committed Feb 17, 2022
1 parent 54c202f commit e6b60b3
Showing 1 changed file with 53 additions and 82 deletions.
135 changes: 53 additions & 82 deletions Cesium.Parser/CParser.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -175,33 +175,16 @@ private static Expression MakeAssignmentExpression(

// 6.7 Declarations

// HACK: custom parsing is required here due to the reasons outlined in
// https://github.com/LanguageDev/Yoakke/issues/138
//
// TODO: Wait for fix in Yoakke and get rid of the hack.
// TODO[#107]: Custom parsing is required here due to the reasons outlined in the issue.
//
// declaration: declaration_specifiers init_declarator_list? ';'
[CustomParser("declaration")]
private ParseResult<Declaration> customParseDeclaration(int offset)
private ParseResult<Declaration> CustomParseDeclaration(int offset)
{
// TODO[F]: Deduplicate with CustomParseSpecifiersAndDeclarator.

// HACK: Usually, this would be a call to parseDeclarationSpecifiers(offset). But here, we have to parse them
// one by one and remember the offset of every one, to be able to backtrack if necessary.
var firstDeclarationSpecifier = parseDeclarationSpecifier(offset);
if (firstDeclarationSpecifier.IsError) return firstDeclarationSpecifier.Error;
offset = firstDeclarationSpecifier.Ok.Offset;

var declarationSpecifiers = new List<(IDeclarationSpecifier DS, int Offset)>
{ (firstDeclarationSpecifier.Ok.Value, offset) };
while (true)
{
var declarationSpecifier = parseDeclarationSpecifier(offset);
if (declarationSpecifier.IsError) break;
offset = declarationSpecifier.Ok.Offset;

declarationSpecifiers.Add((declarationSpecifier.Ok.Value, offset));
}
var declarationSpecifiersResult = CustomParseOneOrMore(parseDeclarationSpecifier, offset);
if (declarationSpecifiersResult.IsError) return declarationSpecifiersResult.Error;
offset = declarationSpecifiersResult.Ok.Offset;
var declarationSpecifiers = declarationSpecifiersResult.Ok.Value;

var initDeclaratorList = parseInitDeclaratorList(offset);
if (initDeclaratorList.IsError && declarationSpecifiers.Count > 1)
Expand All @@ -221,7 +204,7 @@ private ParseResult<Declaration> customParseDeclaration(int offset)
++offset;
return ParseResult.Ok(
MakeDeclaration(
MakeDeclarationSpecifiers(declarationSpecifiers.Select(ds => ds.DS)),
MakeDeclarationSpecifiers(declarationSpecifiers.Select(ds => ds.Item)),
initDeclaratorList.IsOk ? initDeclaratorList.Ok.Value : null,
t),
offset,
Expand All @@ -236,9 +219,8 @@ private static Declaration MakeDeclaration(
InitDeclaratorList? initDeclarators,
IToken _) => new(specifiers, initDeclarators);

// HACK: This is a synthetic set of rules which is absent from the C standard, but required for simplification of
// the implementation of https://github.com/LanguageDev/Yoakke/issues/138
// TODO: Wait for fix in Yoakke and get rid of the hack.
// TODO[#107]: This is a synthetic set of rules which is absent from the C standard, but required to simplify the
// implementation. Get rid of this, eventually.
[Rule("declaration_specifiers: declaration_specifier+")]
private static DeclarationSpecifiers MakeDeclarationSpecifiers(IEnumerable<IDeclarationSpecifier> specifiers) =>
specifiers.ToImmutableArray();
Expand Down Expand Up @@ -330,31 +312,16 @@ private static StructDeclarationList MakeStructDeclarationList(
StructDeclarationList prev,
StructDeclaration structDeclaration) => prev.Add(structDeclaration);

// HACK: custom parsing is required here due to the reasons outlined in
// https://github.com/LanguageDev/Yoakke/issues/138
//
// TODO: Wait for fix in Yoakke and get rid of the hack.
// TODO[#107]: Custom parsing is required here due to the reasons outlined in the issue.
//
// struct_declaration: specifier_qualifier_list struct_declarator_list? ';'
[CustomParser("struct_declaration")]
private ParseResult<StructDeclaration> customParseStructDeclaration(int offset)
private ParseResult<StructDeclaration> CustomParseStructDeclaration(int offset)
{
// HACK: Usually, this would be a call to parseSpecifierQualifierList(offset). But here, we have to parse them
// one by one and remember the offset of every one, to be able to backtrack if necessary.
var firstListItem = parseSpecifierQualifierListItem(offset);
if (firstListItem.IsError) return firstListItem.Error;
offset = firstListItem.Ok.Offset;

var specifiersQualifiers = new List<(ISpecifierQualifierListItem Item, int Offset)>
{ (firstListItem.Ok.Value, offset) };
while (true)
{
var listItem = parseSpecifierQualifierListItem(offset);
if (listItem.IsError) break;
offset = listItem.Ok.Offset;

specifiersQualifiers.Add((listItem.Ok.Value, offset));
}
var specifiersQualifiersResult = CustomParseOneOrMore(parseSpecifierQualifierListItem, offset);
if (specifiersQualifiersResult.IsError) return specifiersQualifiersResult.Error;
offset = specifiersQualifiersResult.Ok.Offset;
var specifiersQualifiers = specifiersQualifiersResult.Ok.Value;

var structDeclaratorList = parseStructDeclaratorList(offset);
if (structDeclaratorList.IsError && specifiersQualifiers.Count > 1)
Expand Down Expand Up @@ -392,12 +359,10 @@ private static StructDeclaration MakeStructDeclaration(

// TODO: struct-declaration: static_assert-declaration

// HACK: This is a synthetic set of rules which is absent from the C standard, but required for simplification of
// the implementation of https://github.com/LanguageDev/Yoakke/issues/138
// TODO[#107]: This is a synthetic set of rules which is absent from the C standard, but required to simplify the
// implementation. Get rid of this, eventually.
//
// TODO: Wait for fix in Yoakke and get rid of the hack.
//
// Actual rules are:
// The actual rules are:
// specifier_qualifier_list: type_specifier specifier_qualifier_list?
// specifier_qualifier_list: type_qualifier specifier_qualifier_list?
[Rule("specifier_qualifier_list: specifier_qualifier_list_item+")]
Expand Down Expand Up @@ -505,14 +470,11 @@ private static ParameterList MakeParameterList(ParameterDeclaration declaration)
private static ParameterList MakeParameterList(ParameterList prev, ICToken _, ParameterDeclaration declaration) =>
prev.Add(declaration);

// HACK: custom parsing is required here due to the reasons outlined in
// https://github.com/LanguageDev/Yoakke/issues/138
//
// TODO: Wait for fix in Yoakke and get rid of the hack.
// TODO[#107]: Custom parsing is required here due to the reasons outlined in the issue.
//
// parameter_declaration: declaration_specifiers declarator
[CustomParser("parameter_declaration")]
private ParseResult<ParameterDeclaration> customParseParameterDeclaration(int offset)
private ParseResult<ParameterDeclaration> CustomParseParameterDeclaration(int offset)
{
var specifiersAndDeclarator = CustomParseSpecifiersAndDeclarator(offset);
if (specifiersAndDeclarator.IsError) return specifiersAndDeclarator.Error;
Expand Down Expand Up @@ -681,14 +643,11 @@ private static ExternalDeclaration MakeExternalDeclaration(Declaration declarati

// 6.9.1 Function definitions

// HACK: custom parsing is required here due to the reasons outlined in
// https://github.com/LanguageDev/Yoakke/issues/138
//
// TODO: Wait for fix in Yoakke and get rid of the hack.
// TODO[#107]: Custom parsing is required here due to the reasons outlined in the issue.
//
// function_definition: declaration_specifiers declarator declaration_list? compound_statement
[CustomParser("function_definition")]
private ParseResult<FunctionDefinition> customParseFunctionDefinition(int offset)
private ParseResult<FunctionDefinition> CustomParseFunctionDefinition(int offset)
{
var specifiersAndDeclarator = CustomParseSpecifiersAndDeclarator(offset);
if (specifiersAndDeclarator.IsError) return specifiersAndDeclarator.Error;
Expand Down Expand Up @@ -792,26 +751,12 @@ private static ImmutableArray<Declaration> MakeDeclarationList(
// TODO: 6.10.8 Predefined macro names
// TODO: 6.10.9 Pragma operator

// HACK: The existence of this method is caused caused by an issue https://github.com/LanguageDev/Yoakke/issues/138
// TODO: Wait for fix in Yoakke and get rid of the hack.
private ParseResult<(DeclarationSpecifiers, Declarator)> CustomParseSpecifiersAndDeclarator(int offset)
{
// HACK: Usually, this would be a call to parseDeclarationSpecifiers(offset). But here, we have to parse them
// one by one and remember the offset of every one, to be able to backtrack if necessary.
var firstDeclarationSpecifier = parseDeclarationSpecifier(offset);
if (firstDeclarationSpecifier.IsError) return firstDeclarationSpecifier.Error;
offset = firstDeclarationSpecifier.Ok.Offset;

var declarationSpecifiers = new List<(IDeclarationSpecifier DS, int Offset)>
{ (firstDeclarationSpecifier.Ok.Value, offset) };
while (true)
{
var declarationSpecifier = parseDeclarationSpecifier(offset);
if (declarationSpecifier.IsError) break;
offset = declarationSpecifier.Ok.Offset;

declarationSpecifiers.Add((declarationSpecifier.Ok.Value, offset));
}
var declarationSpecifiersResult = CustomParseOneOrMore(parseDeclarationSpecifier, offset);
if (declarationSpecifiersResult.IsError) return declarationSpecifiersResult.Error;
offset = declarationSpecifiersResult.Ok.Offset;
var declarationSpecifiers = declarationSpecifiersResult.Ok.Value;

var declarator = parseDeclarator(offset);
if (declarator.IsError && declarationSpecifiers.Count > 1)
Expand All @@ -829,8 +774,34 @@ private static ImmutableArray<Declaration> MakeDeclarationList(
offset = declarator.Ok.Offset;

return ParseResult.Ok(
(MakeDeclarationSpecifiers(declarationSpecifiers.Select(pair => pair.DS)), declarator.Ok.Value),
(MakeDeclarationSpecifiers(declarationSpecifiers.Select(pair => pair.Item)), declarator.Ok.Value),
offset,
declarator.FurthestError);
}

/// <remarks>
/// HACK: Usually, this would be a call to <code>parseDeclarationSpecifiers(offset)</code> instead of, say,
/// <code>CustomParseOneOrMore(parseDeclarationSpecifier, offset)</code>. But here, we have to parse them
/// one by one and remember the offset of every one, to be able to backtrack if necessary.
/// </remarks>
private static ParseResult<List<(T Item, int Offset)>> CustomParseOneOrMore<T>(
Func<int, ParseResult<T>> singleItemParser,
int offset)
{
var firstItem = singleItemParser(offset);
if (firstItem.IsError) return firstItem.Error;
offset = firstItem.Ok.Offset;

var declarationSpecifiers = new List<(T Item, int Offset)> { (firstItem.Ok.Value, offset) };
while (true)
{
var declarationSpecifier = singleItemParser(offset);
if (declarationSpecifier.IsError) break;
offset = declarationSpecifier.Ok.Offset;

declarationSpecifiers.Add((declarationSpecifier.Ok.Value, offset));
}

return ParseResult.Ok(declarationSpecifiers, offset);
}
}

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