Parse complex import directives.

libsolidity/ast/AST.h

@@ -129,23 +129,39 @@ private:
 
 /**
  * Import directive for referencing other files / source objects.
- * Example: import "abc.sol"
+ * Example: import "abc.sol" // imports all symbols of "abc.sol" into current scope
  * Source objects are identified by a string which can be a file name but does not have to be.
+ * Other ways to use it:
+ * import "abc" as x; // creates symbol "x" that contains all symbols in "abc"
+ * import * as x from "abc"; // same as above
+ * import {a as b, c} from "abc"; // creates new symbols "b" and "c" referencing "a" and "c" in "abc", respectively.
  */
 class ImportDirective: public ASTNode
 {
 public:
-	ImportDirective(SourceLocation const& _location, ASTPointer<ASTString> const& _identifier):
-		ASTNode(_location), m_identifier(_identifier) {}
+	ImportDirective(
+		SourceLocation const& _location,
+		ASTPointer<ASTString> const& _path,
+			ASTPointer<ASTString> const& _unitAlias,
+			std::vector<std::pair<ASTPointer<Identifier>, ASTPointer<ASTString>>>&& _symbolAliases
+		):
+		ASTNode(_location), m_path(_path), m_unitAlias(_unitAlias), m_symbolAliases(_symbolAliases) {}
 
 	virtual void accept(ASTVisitor& _visitor) override;
 	virtual void accept(ASTConstVisitor& _visitor) const override;
 
-	ASTString const& identifier() const { return *m_identifier; }
+	ASTString const& path() const { return *m_path; }
 	virtual ImportAnnotation& annotation() const override;
 
 private:
-	ASTPointer<ASTString> m_identifier;
+	ASTPointer<ASTString> m_path;
+	/// The alias for the module itself. If present, import the whole unit under that name and
+	/// ignore m_symbolAlias.
+	ASTPointer<ASTString> m_unitAlias;
+	/// The aliases for the specific symbols to import. If non-empty import the specific symbols.
+	/// If the second component is empty, import the identifier unchanged.
+	/// If both m_unitAlias and m_symbolAlias are empty, import all symbols into the current scope.
+	std::vector<std::pair<ASTPointer<Identifier>, ASTPointer<ASTString>>> m_symbolAliases;
 };
 
 /**

libsolidity/ast/ASTJsonConverter.cpp

@@ -91,7 +91,7 @@ Json::Value const& ASTJsonConverter::json()
 
 bool ASTJsonConverter::visit(ImportDirective const& _node)
 {
-	addJsonNode("Import", { make_pair("file", _node.identifier())});
+	addJsonNode("Import", { make_pair("file", _node.path())});
 	return true;
 }
 

libsolidity/ast/ASTPrinter.cpp

@@ -49,7 +49,7 @@ void ASTPrinter::print(ostream& _stream)
 
 bool ASTPrinter::visit(ImportDirective const& _node)
 {
-	writeLine("ImportDirective \"" + _node.identifier() + "\"");
+	writeLine("ImportDirective \"" + _node.path() + "\"");
 	printSourcePart(_node);
 	return goDeeper();
 }