Implement tear-off closure operator #

runtime/vm/parser.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/parser.h"
 
 #include "lib/invocation_mirror.h"
 #include "platform/utils.h"
 #include "vm/ast_transformer.h"
 #include "vm/bootstrap.h"
@@ skipping 828 matching lines @@
   ASSERT(isolate->long_jump_base()->IsSafeToJump());
   ASSERT(parsed_function != NULL);
   const Function& func = parsed_function->function();
   const Script& script = Script::Handle(zone, func.script());
   Parser parser(script, parsed_function, func.token_pos());
   SequenceNode* node_sequence = NULL;
   Array& default_parameter_values = Array::ZoneHandle(zone, Array::null());
   switch (func.kind()) {
     case RawFunction::kClosureFunction:
       if (func.IsImplicitClosureFunction()) {
-        parser.SkipFunctionPreamble();
         node_sequence =
             parser.ParseImplicitClosure(func, &default_parameter_values);
         break;
       }
       // Fall-through: Handle non-implicit closures.
     case RawFunction::kRegularFunction:
     case RawFunction::kGetterFunction:
     case RawFunction::kSetterFunction:
     case RawFunction::kConstructor:
       // The call to a redirecting factory is redirected.
@@ skipping 420 matching lines @@
       new StoreInstanceFieldNode(ident_pos, receiver, field, value);
   current_block_->statements->Add(store_field);
   current_block_->statements->Add(new ReturnNode(Scanner::kNoSourcePos));
   return CloseBlock();
 }
 
 
 SequenceNode* Parser::ParseImplicitClosure(const Function& func,
                                            Array* default_values) {
   TRACE_PARSER("ParseImplicitClosure");
-
   intptr_t token_pos = func.token_pos();
 
   OpenFunctionBlock(func);
 
   ParamList params;
-
   params.AddFinalParameter(
       token_pos,
       &Symbols::ClosureParameter(),
       &Type::ZoneHandle(Type::DynamicType()));
 
-  const bool allow_explicit_default_values = true;
-  ParseFormalParameterList(allow_explicit_default_values, false, &params);
-  SetupDefaultsForOptionalParams(&params, default_values);
-
-  // Getters can't be closurized. If supported, they need special
-  // handling of the parameters as in ParseFunc.
   const Function& parent = Function::ZoneHandle(func.parent_function());
-  ASSERT(!parent.IsGetterFunction());
+  if (parent.IsImplicitSetterFunction()) {
+    const intptr_t ident_pos = func.token_pos();
+    ASSERT(IsIdentifier());
+    const String& field_name = *CurrentLiteral();
+    const Class& field_class = Class::ZoneHandle(Z, parent.Owner());
+    const Field& field =
+        Field::ZoneHandle(Z, field_class.LookupInstanceField(field_name));
+    const AbstractType& field_type = AbstractType::ZoneHandle(Z, field.type());
+    params.AddFinalParameter(ident_pos,
+                             &Symbols::Value(),
+                             &field_type);
+    ASSERT(func.num_fixed_parameters() == 2);  // closure, value.
+  } else if (!parent.IsGetterFunction() && !parent.IsImplicitGetterFunction()) {
+    const bool allow_explicit_default_values = true;
+    SkipFunctionPreamble();
+    ParseFormalParameterList(allow_explicit_default_values, false, &params);
+    SetupDefaultsForOptionalParams(&params, default_values);
+  }
 
   // Populate function scope with the formal parameters.
   LocalScope* scope = current_block_->scope;
   AddFormalParamsToScope(&params, scope);
 
   ArgumentListNode* func_args = new ArgumentListNode(token_pos);
   if (!func.is_static()) {
     func_args->Add(LoadReceiver(token_pos));
   }
   // Skip implicit parameter at 0.
@@ skipping 2104 matching lines @@
   } while (CurrentToken() == Token::kCOMMA);
 }
 
 
 // If the current identifier is a library prefix followed by a period,
 // consume the identifier and period, and return the resolved library
 // prefix.
 RawLibraryPrefix* Parser::ParsePrefix() {
   ASSERT(IsIdentifier());
   // A library prefix can never stand by itself. It must be followed by
-  // a period.
-  if (LookaheadToken(1) != Token::kPERIOD) {
+  // a period or a hash mark (for closurization).
+  Token::Kind next_token = LookaheadToken(1);
+  if ((next_token != Token::kPERIOD) && (next_token != Token::kHASH)) {
     return LibraryPrefix::null();
   }
   const String& ident = *CurrentLiteral();
 
   // It is relatively fast to look up a name in the library dictionary,
   // compared to searching the nested local scopes. Look up the name
   // in the library scope and return in the common case where ident is
   // not a library prefix.
   LibraryPrefix& prefix =
       LibraryPrefix::Handle(Z, library_.LookupLocalLibraryPrefix(ident));
   if (prefix.IsNull()) {
     return LibraryPrefix::null();
   }
 
   // A library prefix with the name exists. Now check whether it is
   // shadowed by a local definition.
   if (!is_top_level_ &&
       ResolveIdentInLocalScope(TokenPos(), ident, NULL)) {
     return LibraryPrefix::null();
   }
   // Check whether the identifier is shadowed by a type parameter.
   ASSERT(!current_class().IsNull());
   if (current_class().LookupTypeParameter(ident) != TypeParameter::null()) {
     return LibraryPrefix::null();
   }
 
-  // We have a name that is not shadowed, followed by a period.
-  // Consume the identifier and the period.
-  ConsumeToken();
-  ASSERT(CurrentToken() == Token::kPERIOD);  // We checked above.
+  // We have a name that is not shadowed, followed by a period or #.
+  // Consume the identifier, let the caller consume the . or #.
   ConsumeToken();
   return prefix.raw();
 }
 
 
 void Parser::ParseMethodOrConstructor(ClassDesc* members, MemberDesc* method) {
   TRACE_PARSER("ParseMethodOrConstructor");
   ASSERT(CurrentToken() == Token::kLPAREN || method->IsGetter());
   ASSERT(method->type != NULL);
   ASSERT(current_member_ == method);
@@ skipping 7835 matching lines @@
       }
       // Done parsing selectors.
       return left;
     }
     ASSERT(selector != NULL);
     left = selector;
   }
 }
 
 
+// Closurization e#m of getter, setter, method or operator.
+AstNode* Parser::ParseClosurization(AstNode* primary) {
+  ExpectToken(Token::kHASH);
+  intptr_t property_pos = TokenPos();
+  bool is_setter_name = false;
+
+  String& extractor_name = String::ZoneHandle(Z);
+  if (IsIdentifier()) {
+    extractor_name = CurrentLiteral()->raw();
+    ConsumeToken();
+    if (CurrentToken() == Token::kASSIGN) {
+      ConsumeToken();
+      is_setter_name = true;
+    }
+  } else if (Token::CanBeOverloaded(CurrentToken())) {
+    extractor_name = String::New(Token::Str(CurrentToken()));
+    ConsumeToken();
+  } else {
+    ReportError("identifier or operator expected");
+  }
+
+  if (primary->IsPrimaryNode() && primary->AsPrimaryNode()->IsSuper()) {
+    // TODO(hausner): implement super#m
+    ReportError("closurization of super method not yet supported");
+  }
+
+  // Handle closurization of top-level names from library prefixes, P#m
+  if (primary->IsLiteralNode() &&
+      primary->AsLiteralNode()->literal().IsLibraryPrefix()) {
+    const LibraryPrefix& prefix =
+        LibraryPrefix::Cast(primary->AsLiteralNode()->literal());
+    Object& obj = Object::Handle(Z);
+    const bool is_private_name =
+        (extractor_name.CharAt(0) == Library::kPrivateIdentifierStart);
+    if (!is_private_name) {
+      // Private names are not exported by libraries. The name mangling
+      // of private names with a library-specific suffix usually ensures
+      // that _x in library A is not found when looked up from library B.
+      // In the pathological case where a library imports itself with
+      // a prefix, the name mangling does not help in hiding the private
+      // name, so we explicitly prevent lookup of private names here.
+      obj = prefix.LookupObject(extractor_name);
+    }
+    if (!prefix.is_loaded() && (parsed_function() != NULL)) {
+      // Remember that this function depends on an import prefix of an
+      // unloaded deferred library.
+      parsed_function()->AddDeferredPrefix(prefix);
+    }
+
+    if (obj.IsFunction()) {
+      const Function& func = Function::Cast(obj);
+      if (!func.IsSetterFunction() || is_setter_name) {
+        return CreateImplicitClosureNode(func, property_pos, NULL);
+      }
+    } else if (obj.IsField()) {
+      const Field& field = Field::Cast(obj);
+      if (is_setter_name && !field.is_final()) {
+        Instance& setter_closure = Instance::ZoneHandle(field.SetterClosure());
+        return new(Z) LiteralNode(property_pos, setter_closure);
+      }
+      if (!is_setter_name) {
+        Instance& getter_closure = Instance::ZoneHandle(field.GetterClosure());
+        return new(Z) LiteralNode(property_pos, getter_closure);
+      }
+    }
+    return ThrowNoSuchMethodError(property_pos,
+                                  current_class(),
+                                  extractor_name,
+                                  NULL,  // No arguments.
+                                  InvocationMirror::kTopLevel,
+                                  is_setter_name
+                                      ? InvocationMirror::kSetter
+                                      : InvocationMirror::kMethod,
+                                  NULL);  // No existing function.
+  }
+
+  // Handle closurization of static properties of classes, C#n.
+  if (primary->IsPrimaryNode() &&
+      primary->AsPrimaryNode()->primary().IsClass()) {
+    const Class& cls = Class::Cast(primary->AsPrimaryNode()->primary());
+    const Field& field =
+        Field::Handle(Z, cls.LookupStaticField(extractor_name));
+    if (!field.IsNull()) {
+      if (is_setter_name) {
+        extractor_name = Field::SetterName(extractor_name);
+        if (!field.is_final()) {
+          const Instance& setter_closure =
+              Instance::ZoneHandle(Z, field.SetterClosure());
+          ASSERT(setter_closure.IsClosure());
+          const Function& cf =
+              Function::Handle(Closure::function(setter_closure));
+          Error& error = Error::Handle(Z);
+          error = Compiler::CompileFunction(Thread::Current(), cf);
+          ASSERT(error.IsNull());
+          return new(Z) LiteralNode(property_pos, setter_closure);
+        }
+      }
+      if (!is_setter_name) {

[Florian Schneider, 2015/07/22 08:25:54]

if (is_setter_name) { }
if (!is_setter_name) { }

can be simplified to

if (is_setter_name) { } else { }

[hausner, 2015/07/22 18:41:10]

Done.

I also removed the pre-compilation code, since we don't have a pre-compile flag
yet. Added a comment to remind ourselves that the closure can be eagerly
compiled.

+        const Instance& getter_closure =
+            Instance::ZoneHandle(Z, field.GetterClosure());
+        ASSERT(getter_closure.IsClosure());
+        const Function& cf =
+            Function::Handle(Closure::function(getter_closure));
+        Error& error = Error::Handle(Z);
+        error = Compiler::CompileFunction(Thread::Current(), cf);
+        ASSERT(error.IsNull());
+        return new(Z) LiteralNode(property_pos, getter_closure);
+      }
+    } else {
+      Function& func = Function::Handle(Z);
+      if (is_setter_name) {
+        extractor_name = Field::SetterName(extractor_name);
+        func = cls.LookupStaticFunction(extractor_name);
+      } else {
+        func = cls.LookupStaticFunction(extractor_name);
+        if (func.IsNull()) {
+          const String& getter_name =
+              String::Handle(Z, Field::GetterName(extractor_name));
+          func = cls.LookupStaticFunction(getter_name);
+        }
+      }
+      if (!func.IsNull()) {
+        return CreateImplicitClosureNode(func, property_pos, NULL);
+      }
+    }
+    return ThrowNoSuchMethodError(property_pos,
+                                  cls,
+                                  extractor_name,
+                                  NULL,  // No arguments.
+                                  InvocationMirror::kStatic,
+                                  is_setter_name
+                                      ? InvocationMirror::kSetter
+                                      : InvocationMirror::kMethod,
+                                  NULL);  // No existing function.
+  }
+
+  // Closurization of instance getter, setter, method or operator.
+  if (is_setter_name) {
+    extractor_name = String::Concat(Symbols::SetterPrefix(), extractor_name);
+  }
+  extractor_name = String::Concat(Symbols::HashMark(), extractor_name);
+  extractor_name = Symbols::New(extractor_name);
+  return new(Z) InstanceGetterNode(property_pos, primary, extractor_name);
+}
+
+
 AstNode* Parser::ParsePostfixExpr() {
   TRACE_PARSER("ParsePostfixExpr");
   String* expr_ident =
       Token::IsIdentifier(CurrentToken()) ? CurrentLiteral() : NULL;
   const intptr_t expr_pos = TokenPos();
   AstNode* expr = ParsePrimary();
-  expr = ParseSelectors(expr, false);
+  if (CurrentToken() == Token::kHASH) {
+    expr = LoadFieldIfUnresolved(expr);
+    expr = ParseClosurization(expr);
+  } else {
+    expr = ParseSelectors(expr, false);
+  }
   if (IsIncrementOperator(CurrentToken())) {
     TRACE_PARSER("IncrementOperator");
     if (!IsLegalAssignableSyntax(expr, TokenPos())) {
       ReportError(expr_pos, "expression is not assignable");
     }
     Token::Kind incr_op = CurrentToken();
     ConsumeToken();
     // Not prefix.
     LetNode* let_expr = PrepareCompoundAssignmentNodes(&expr);
     LocalVariable* temp = let_expr->AddInitializer(expr);
@@ skipping 661 matching lines @@
 
   if (finalization == ClassFinalizer::kIgnore) {
     if (!is_top_level_ && (current_block_ != NULL)) {
       // Add the library prefix or type class name to the list of referenced
       // names of this scope, even if the type is ignored.
       current_block_->scope->AddReferencedName(TokenPos(), *CurrentLiteral());
     }
     SkipQualIdent();
   } else {
     *prefix = ParsePrefix();
+    if (!prefix->IsNull()) {
+      ExpectToken(Token::kPERIOD);
+    }
     type_name = CurrentLiteral()->raw();
     ConsumeToken();
 
     // Check whether we have a malformed qualified type name if the caller
     // requests to consume unresolved prefix names:
     // If we didn't see a valid prefix but the identifier is followed by
     // a period and another identifier, consume the qualified identifier
     // and create a malformed type.
     if (consume_unresolved_prefix &&
         prefix->IsNull() &&
@@ skipping 605 matching lines @@
   TRACE_PARSER("ParseNewOperator");
   const intptr_t new_pos = TokenPos();
   ASSERT((op_kind == Token::kNEW) || (op_kind == Token::kCONST));
   bool is_const = (op_kind == Token::kCONST);
   if (!IsIdentifier()) {
     ReportError("type name expected");
   }
   intptr_t type_pos = TokenPos();
   // Can't allocate const objects of a deferred type.
   const bool allow_deferred_type = !is_const;
-  const bool consume_unresolved_prefix = (LookaheadToken(3) == Token::kLT) ||
-                                         (LookaheadToken(3) == Token::kPERIOD);
+  const Token::Kind la3 = LookaheadToken(3);
+  const bool consume_unresolved_prefix =
+      (la3 == Token::kLT) || (la3 == Token::kPERIOD) || (la3 == Token::kHASH);
+
   LibraryPrefix& prefix = LibraryPrefix::ZoneHandle(Z);
   AbstractType& type = AbstractType::Handle(Z,
       ParseType(ClassFinalizer::kCanonicalizeWellFormed,
                 allow_deferred_type,
                 consume_unresolved_prefix,
                 &prefix));
+  if (CurrentToken() == Token::kHASH) {
+    ReportError("constructor closurization not yet supported");
+  }
   if (FLAG_load_deferred_eagerly &&
       !prefix.IsNull() && prefix.is_deferred_load() && !prefix.is_loaded()) {
     // Add runtime check.
     Type& malformed_type = Type::Handle(Z);
     malformed_type = ClassFinalizer::NewFinalizedMalformedType(
         Error::Handle(Z),  // No previous error.
         script_,
         type_pos,
         "deferred type '%s.%s' is not yet loaded",
         String::Handle(Z, prefix.name()).ToCString(),
@@ skipping 414 matching lines @@
   const Token::Kind token = CurrentToken();
   if (IsFunctionLiteral()) {
     // The name of a literal function is visible from inside the function, but
     // must not collide with names in the scope declaring the literal.
     OpenBlock();
     primary = ParseFunctionStatement(true);
     CloseBlock();
   } else if (IsIdentifier()) {
     intptr_t qual_ident_pos = TokenPos();
     const LibraryPrefix& prefix = LibraryPrefix::ZoneHandle(Z, ParsePrefix());
+    if (!prefix.IsNull()) {
+      if (CurrentToken() == Token::kHASH) {
+        // Closurization of top-level entity in prefix scope.
+        return new(Z) LiteralNode(qual_ident_pos, prefix);
+      } else {
+        ExpectToken(Token::kPERIOD);
+      }
+    }
     String& ident = *CurrentLiteral();
     ConsumeToken();
     if (prefix.IsNull()) {
       if (!ResolveIdentInLocalScope(qual_ident_pos, ident, &primary)) {
         // Check whether the identifier is a type parameter.
         if (!current_class().IsNull()) {
           TypeParameter& type_param = TypeParameter::ZoneHandle(Z,
               current_class().LookupTypeParameter(ident));
           if (!type_param.IsNull()) {
             return new(Z) PrimaryNode(qual_ident_pos, type_param);
@@ skipping 341 matching lines @@
   } else {
     UnexpectedToken();
   }
 }
 
 
 void Parser::SkipNewOperator() {
   ConsumeToken();  // Skip new or const keyword.
   if (IsIdentifier()) {
     SkipType(false);
+    SkipIf(Token::kHASH);
+    if (CurrentToken() == Token::kPERIOD) {
+      ConsumeToken();
+      ExpectIdentifier("identifier expected");
+    }
     if (CurrentToken() == Token::kLPAREN) {
       SkipActualParameters();
       return;
     }
   }
 }
 
 
 void Parser::SkipStringLiteral() {
   ASSERT(CurrentToken() == Token::kSTRING);
@@ skipping 98 matching lines @@
     } else if (current_token == Token::kLPAREN) {
       SkipActualParameters();
     } else {
       break;
     }
   }
 }
 
 void Parser::SkipPostfixExpr() {
   SkipPrimary();
+  if (CurrentToken() == Token::kHASH) {
+    if (IsIdentifier()) {
+      ConsumeToken();
+      SkipIf(Token::kASSIGN);
+    } else if (Token::CanBeOverloaded(CurrentToken())) {
+      ConsumeToken();
+    } else {
+      ReportError("identifier or operator expected");
+    }
+  }
   SkipSelectors();
   if (IsIncrementOperator(CurrentToken())) {
     ConsumeToken();
   }
 }
 
 
 void Parser::SkipUnaryExpr() {
   if (IsPrefixOperator(CurrentToken()) ||
       IsIncrementOperator(CurrentToken()) ||
@@ skipping 65 matching lines @@
 void Parser::SkipQualIdent() {
   ASSERT(IsIdentifier());
   ConsumeToken();
   if (CurrentToken() == Token::kPERIOD) {
     ConsumeToken();  // Consume the kPERIOD token.
     ExpectIdentifier("identifier expected after '.'");
   }
 }
 
 }  // namespace dart