Add initial basic support for ES6 modules

The entry point from the parsing perspective into modules is not
QV4::Script but QV4::ExecutionEngine::compileModule.

For convenience, the ESModule AST node gets a body, which is the
statement list connected between the ModuleItemList items that are not
import/export declarations.

The QV4::Module allocates a call context where the exported variables
are stored as named locals. This will also become the module namespace
object.

The imports in turn is an array of value pointers that point into the
locals array of the context of the imported modules.

The default module loading in ExecutionEngine assumes the accessibility
of module urls via QFile (so local file system or resource). This is
what qmljs also uses and QJSEngine as well via public API in the future.

The test runner compiles the modules manually and injects them, because
they need to be compiled together with the test harness code.

The QML type loader will the mechanism for injection in the future for
module imports from .qml files.

Change-Id: I93be9cfe54c651fdbd08c5e1d22d58f47284e54f
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

1 files changed, 47 insertions, 1 deletions

diff --git a/src/qml/compiler/qv4compileddata_p.h b/src/qml/compiler/qv4compileddata_p.h
index e7d152c7f8..e65c04ad69 100644
--- a/src/qml/compiler/qv4compileddata_p.h
+++ b/src/qml/compiler/qv4compileddata_p.h
@@ -88,6 +88,10 @@ struct Document;
 
 namespace QV4 {
 
+namespace Heap {
+struct Module;
+};
+
 struct Function;
 class EvalISelFactory;
 class CompilationUnitMapper;
@@ -358,6 +362,23 @@ struct Class
 };
 static_assert(sizeof(Class) == 24, "Class structure needs to have the expected size to be binary compatible on disk when generated by host compiler and loaded by target");
 
+struct ExportEntry
+{
+    quint32_le exportName;
+    quint32_le moduleRequest;
+    quint32_le importName;
+    quint32_le localName;
+};
+static_assert(sizeof(ExportEntry) == 16, "ExportEntry structure needs to have the expected size to be binary compatible on disk when generated by host compiler and loaded by target");
+
+struct ImportEntry
+{
+    quint32_le moduleRequest;
+    quint32_le importName;
+    quint32_le localName;
+    quint32_le padding;
+};
+static_assert(sizeof(ImportEntry) == 16, "ImportEntry structure needs to have the expected size to be binary compatible on disk when generated by host compiler and loaded by target");
 
 // Qml data structures
 
@@ -819,6 +840,14 @@ struct Unit
     quint32_le offsetToJSClassTable;
     quint32_le translationTableSize;
     quint32_le offsetToTranslationTable;
+    quint32_le localExportEntryTableSize;
+    quint32_le offsetToLocalExportEntryTable;
+    quint32_le indirectExportEntryTableSize;
+    quint32_le offsetToIndirectExportEntryTable;
+    quint32_le starExportEntryTableSize;
+    quint32_le offsetToStarExportEntryTable;
+    quint32_le importEntryTableSize;
+    quint32_le offsetToImportEntryTable;
     qint32_le indexOfRootFunction;
     quint32_le sourceFileIndex;
     quint32_le finalUrlIndex;
@@ -904,9 +933,14 @@ struct Unit
     const TranslationData *translations() const {
         return reinterpret_cast<const TranslationData *>(reinterpret_cast<const char *>(this) + offsetToTranslationTable);
     }
+
+    const ImportEntry *importEntryTable() const { return reinterpret_cast<const ImportEntry *>(reinterpret_cast<const char *>(this) + offsetToImportEntryTable); }
+    const ExportEntry *localExportEntryTable() const { return reinterpret_cast<const ExportEntry *>(reinterpret_cast<const char *>(this) + offsetToLocalExportEntryTable); }
+    const ExportEntry *indirectExportEntryTable() const { return reinterpret_cast<const ExportEntry *>(reinterpret_cast<const char *>(this) + offsetToIndirectExportEntryTable); }
+    const ExportEntry *starExportEntryTable() const { return reinterpret_cast<const ExportEntry *>(reinterpret_cast<const char *>(this) + offsetToStarExportEntryTable); }
 };
 
-static_assert(sizeof(Unit) == 200, "Unit structure needs to have the expected size to be binary compatible on disk when generated by host compiler and loaded by target");
+static_assert(sizeof(Unit) == 232, "Unit structure needs to have the expected size to be binary compatible on disk when generated by host compiler and loaded by target");
 
 struct TypeReference
 {
@@ -991,12 +1025,15 @@ struct Q_QML_PRIVATE_EXPORT CompilationUnitBase
     const Value* constants = nullptr;
     QV4::Value *runtimeRegularExpressions = nullptr;
     QV4::Heap::InternalClass **runtimeClasses = nullptr;
+    const Value** imports = nullptr;
 };
 
 Q_STATIC_ASSERT(std::is_standard_layout<CompilationUnitBase>::value);
 Q_STATIC_ASSERT(offsetof(CompilationUnitBase, runtimeStrings) == 0);
 Q_STATIC_ASSERT(offsetof(CompilationUnitBase, constants) == sizeof(QV4::Heap::String **));
 Q_STATIC_ASSERT(offsetof(CompilationUnitBase, runtimeRegularExpressions) == offsetof(CompilationUnitBase, constants) + sizeof(const Value *));
+Q_STATIC_ASSERT(offsetof(CompilationUnitBase, runtimeClasses) == offsetof(CompilationUnitBase, runtimeRegularExpressions) + sizeof(const Value *));
+Q_STATIC_ASSERT(offsetof(CompilationUnitBase, imports) == offsetof(CompilationUnitBase, runtimeClasses) + sizeof(const Value *));
 
 struct Q_QML_PRIVATE_EXPORT CompilationUnit final : public CompilationUnitBase
 {
@@ -1122,6 +1159,12 @@ public:
     FunctionIterator objectFunctionsEnd(const Object *object) const { return FunctionIterator(data, object, object->nFunctions); }
     // ---
 
+    QStringList moduleRequests() const;
+    Heap::Module *instantiate(ExecutionEngine *engine);
+    const Value *resolveExport(QV4::String *exportName);
+    Heap::String *localNameForExportName(QV4::String *exportName) const;
+    void evaluate();
+
     QV4::Function *linkToEngine(QV4::ExecutionEngine *engine);
     void unlink();
 
@@ -1149,6 +1192,9 @@ private:
 
     Q_NEVER_INLINE IdentifierHash createNamedObjectsPerComponent(int componentObjectIndex);
 
+    Heap::Module *m_module = nullptr;
+    bool m_moduleEvaluated = false;
+
 public:
 #if defined(V4_BOOTSTRAP)
     bool saveToDisk(const QString &outputFileName, QString *errorString);