ValueBindingPtr Parser::parseVariableDeclaration()
{
Token token;
Attributes attrs;
PatternPtr key = parsePattern();
TypeNodePtr type = NULL;
ExpressionPtr val = NULL;
if(match(L":"))
{
type = parseTypeAnnotation();
}
if(match(L"="))
{
Flags flags(this, SUPPRESS_TRAILING_CLOSURE);
val = parseExpression();
}
ValueBindingPtr ret = nodeFactory->createValueBinding(*key->getSourceInfo());
if(TypedPatternPtr p = std::dynamic_pointer_cast<TypedPattern>(key))
{
ret->setName(p->getPattern());
ret->setDeclaredType(p->getDeclaredType());
}
else
{
ret->setName(key);
ret->setDeclaredType(type);
}
ret->setTypeAttributes(attrs);
ret->setInitializer(val);
return ret;
}
/*
GRAMMAR OF A CONSTANT DECLARATION
constant-declaration → attributes opt declaration-specifiers opt let pattern-initializer-list
pattern-initializer-list → pattern-initializer | pattern-initializer,pattern-initializer-list
pattern-initializer → pattern initializer opt
initializer → =expression
*/
DeclarationPtr Parser::parseLet(const std::vector<AttributePtr>& attrs, int specifiers)
{
Token token;
Flags flag(this, UNDER_LET);
expect(Keyword::Let, token);
ValueBindingsPtr ret = nodeFactory->createValueBindings(token.state);
ret->setReadOnly(true);
ret->setAttributes(attrs);
ret->setSpecifiers(specifiers);
do
{
PatternPtr pattern = parsePattern();
ExpressionPtr initializer = NULL;
if(match(L"="))
{
initializer = parseExpression();
}
ValueBindingPtr constant = nodeFactory->createValueBinding(*pattern->getSourceInfo());
constant->setAttributes(attrs);
constant->setSpecifiers(specifiers);
constant->setName(pattern);
TypedPatternPtr typedPattern = std::dynamic_pointer_cast<TypedPattern>(pattern);
if(typedPattern)
{
//promote typed pattern
constant->setDeclaredType(typedPattern->getDeclaredType());
constant->setName(typedPattern->getPattern());
}
constant->setInitializer(initializer);
ret->add(constant);
}while(match(L","));
return ret;
}
void SemanticAnalyzer::visitValueBinding(const ValueBindingPtr& node)
{
PatternPtr name = node->getName();
//tuple was already exploded in declaration analyzer
if(name->getNodeType() == NodeType::Tuple)
{
validateTupleTypeDeclaration(node);
}
if (name->getNodeType() != NodeType::Identifier)
return;
if(node->getOwner()->isReadOnly() && !node->getInitializer() && ctx->currentType == nullptr)
{
error(node, Errors::E_LET_REQUIRES_INITIALIZER);
return;
}
//handle type inference for temporary variable
if(node->isTemporary() && node->getInitializer())
{
//temporary variable always has an initializer
TypePtr initializerType;
TypePtr declaredType = node->getType();
SCOPED_SET(ctx->contextualType, declaredType);
node->getInitializer()->accept(this);
initializerType = node->getInitializer()->getType();
assert(initializerType != nullptr);
if(declaredType)
{
//it has both type definition and initializer, then we need to check if the initializer expression matches the type annotation
if(!initializerType->canAssignTo(declaredType))
{
error(node, Errors::E_CANNOT_CONVERT_EXPRESSION_TYPE_2, initializerType->toString(), declaredType->toString());
return;
}
}
else
{
node->setType(initializerType);
}
}
//add implicitly constructor for Optional
IdentifierPtr id = static_pointer_cast<Identifier>(node->getName());
SymbolScope* currentScope = symbolRegistry->getCurrentScope();
TypePtr declaredType = node->getType() ? node->getType() : lookupType(node->getDeclaredType());
SCOPED_SET(ctx->contextualType, declaredType);
if(!declaredType && !node->getInitializer())
{
error(node, Errors::E_TYPE_ANNOTATION_MISSING_IN_PATTERN);
return;
}
SymbolPtr sym = currentScope->lookup(id->getIdentifier());
assert(sym != nullptr);
SymbolPlaceHolderPtr placeholder = std::dynamic_pointer_cast<SymbolPlaceHolder>(sym);
assert(placeholder != nullptr);
if(declaredType)
{
placeholder->setType(declaredType);
}
ExpressionPtr initializer = node->getInitializer();
if(initializer)
{
placeholder->setFlags(SymbolFlagInitializing, true);
ExpressionPtr initializer = transformExpression(declaredType, node->getInitializer());
node->setInitializer(initializer);
TypePtr actualType = initializer->getType();
assert(actualType != nullptr);
if(declaredType)
{
if(!Type::equals(actualType, declaredType) && !canConvertTo(initializer, declaredType))
{
error(initializer, Errors::E_CANNOT_CONVERT_EXPRESSION_TYPE_2, actualType->toString(), declaredType->toString());
return;
}
}
if(!declaredType)
placeholder->setType(actualType);
}
assert(placeholder->getType() != nullptr);
placeholder->setFlags(SymbolFlagInitializing, false);
//optional type always considered initialized, compiler will make it has a default value nil
TypePtr symbolType = sym->getType();
GlobalScope* global = symbolRegistry->getGlobalScope();
if(initializer || global->isOptional(symbolType) || global->isImplicitlyUnwrappedOptional(symbolType))
markInitialized(placeholder);
if (initializer)
placeholder->setFlags(SymbolFlagHasInitializer, true);
if(node->isTemporary())
{
placeholder->setFlags(SymbolFlagTemporary, true);
markInitialized(placeholder);
}
if(!node->isTemporary())
{
//check access control level
DeclarationType decl = ctx->currentType ? DeclarationTypeProperty : DeclarationTypeVariable;
declarationAnalyzer->verifyAccessLevel(node->getOwner(), placeholder->getType(), decl, ComponentTypeType);
}
if(ctx->currentType && ctx->currentType->getCategory() == Type::Protocol)
{
error(node, Errors::E_PROTOCOL_VAR_MUST_BE_COMPUTED_PROPERTY_1);
}
}