Avoid side effects when en exception has been thrown.

We don't want to check for exceptions after every single
line on our runtime methods. A better way to handle this
is to add the check in all methods that have direct side
effects (as e.g. writing to a property of the JS stack).

We also need to return whereever we throw an exception.
To simplify the code, ExecutionContext::throwXxx methods now
return a ReturnedValue (always undefined) for convenience.

Change-Id: Ide6c804f819c731a3f14c6c43121d08029c9fb90
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>

1 files changed, 51 insertions, 25 deletions

diff --git a/src/qml/qml/qqmllocale.cpp b/src/qml/qml/qqmllocale.cpp
index aca18d8ef4..81a6ffc590 100644
--- a/src/qml/qml/qqmllocale.cpp
+++ b/src/qml/qml/qqmllocale.cpp
@@ -67,11 +67,13 @@ public:
 
     QLocale locale;
 
-    static QLocale &getThisLocale(QV4::SimpleCallContext *ctx) {
+    static QLocale *getThisLocale(QV4::SimpleCallContext *ctx) {
         QQmlLocaleData *thisObject = ctx->callData->thisObject.asObject()->as<QQmlLocaleData>();
-        if (!thisObject)
+        if (!thisObject) {
             ctx->throwTypeError();
-        return thisObject->locale;
+            return 0;
+        }
+        return &thisObject->locale;
     }
 
     static QV4::ReturnedValue method_currencySymbol(QV4::SimpleCallContext *ctx);
@@ -516,8 +518,10 @@ QV4::ReturnedValue QQmlNumberExtension::method_fromLocaleString(QV4::SimpleCallC
 
 QV4::ReturnedValue QQmlLocaleData::method_get_firstDayOfWeek(QV4::SimpleCallContext *ctx)
 {
-    QLocale locale = getThisLocale(ctx);
-    int fdow = int(locale.firstDayOfWeek());
+    QLocale *locale = getThisLocale(ctx);
+    if (!locale)
+        return QV4::Encode::undefined();
+    int fdow = int(locale->firstDayOfWeek());
     if (fdow == 7)
         fdow = 0; // Qt::Sunday = 7, but Sunday is 0 in JS Date
     return QV4::Encode(fdow);
@@ -525,21 +529,29 @@ QV4::ReturnedValue QQmlLocaleData::method_get_firstDayOfWeek(QV4::SimpleCallCont
 
 QV4::ReturnedValue QQmlLocaleData::method_get_measurementSystem(QV4::SimpleCallContext *ctx)
 {
-    QLocale locale = getThisLocale(ctx);
-    return QV4::Encode(locale.measurementSystem());
+    QLocale *locale = getThisLocale(ctx);
+    if (!locale)
+        return QV4::Encode::undefined();
+    return QV4::Encode(locale->measurementSystem());
 }
 
 QV4::ReturnedValue QQmlLocaleData::method_get_textDirection(QV4::SimpleCallContext *ctx)
 {
-    QLocale locale = getThisLocale(ctx);
-    return QV4::Encode(locale.textDirection());
+    QLocale *locale = getThisLocale(ctx);
+    if (!locale)
+        return QV4::Encode::undefined();
+
+    return QV4::Encode(locale->textDirection());
 }
 
 QV4::ReturnedValue QQmlLocaleData::method_get_weekDays(QV4::SimpleCallContext *ctx)
 {
     QV4::Scope scope(ctx);
-    QLocale locale = getThisLocale(ctx);
-    QList<Qt::DayOfWeek> days = locale.weekdays();
+    QLocale *locale = getThisLocale(ctx);
+    if (!locale)
+        return QV4::Encode::undefined();
+
+    QList<Qt::DayOfWeek> days = locale->weekdays();
 
     QV4::Scoped<QV4::ArrayObject> result(scope, ctx->engine->newArrayObject());
     result->arrayReserve(days.size());
@@ -558,8 +570,11 @@ QV4::ReturnedValue QQmlLocaleData::method_get_weekDays(QV4::SimpleCallContext *c
 QV4::ReturnedValue QQmlLocaleData::method_get_uiLanguages(QV4::SimpleCallContext *ctx)
 {
     QV4::Scope scope(ctx);
-    QLocale locale = getThisLocale(ctx);
-    QStringList langs = locale.uiLanguages();
+    QLocale *locale = getThisLocale(ctx);
+    if (!locale)
+        return QV4::Encode::undefined();
+
+    QStringList langs = locale->uiLanguages();
     QV4::Scoped<QV4::ArrayObject> result(scope, ctx->engine->newArrayObject());
     result->arrayReserve(langs.size());
     for (int i = 0; i < langs.size(); ++i) {
@@ -574,7 +589,10 @@ QV4::ReturnedValue QQmlLocaleData::method_get_uiLanguages(QV4::SimpleCallContext
 
 QV4::ReturnedValue QQmlLocaleData::method_currencySymbol(QV4::SimpleCallContext *ctx)
 {
-    QLocale locale = getThisLocale(ctx);
+    QLocale *locale = getThisLocale(ctx);
+    if (!locale)
+        return QV4::Encode::undefined();
+
     if (ctx->callData->argc > 1)
         V4THROW_ERROR("Locale: currencySymbol(): Invalid arguments");
 
@@ -584,12 +602,14 @@ QV4::ReturnedValue QQmlLocaleData::method_currencySymbol(QV4::SimpleCallContext
         format = QLocale::CurrencySymbolFormat(intFormat);
     }
 
-    return ctx->engine->newString(locale.currencySymbol(format))->asReturnedValue();
+    return ctx->engine->newString(locale->currencySymbol(format))->asReturnedValue();
 }
 
 #define LOCALE_FORMAT(FUNC) \
 QV4::ReturnedValue QQmlLocaleData::method_ ##FUNC (QV4::SimpleCallContext *ctx) { \
-    QLocale locale = getThisLocale(ctx); \
+    QLocale *locale = getThisLocale(ctx); \
+    if (!locale) \
+        return QV4::Encode::undefined(); \
     if (ctx->callData->argc > 1) \
         V4THROW_ERROR("Locale: " #FUNC "(): Invalid arguments"); \
     QLocale::FormatType format = QLocale::LongFormat;\
@@ -597,7 +617,7 @@ QV4::ReturnedValue QQmlLocaleData::method_ ##FUNC (QV4::SimpleCallContext *ctx)
         quint32 intFormat = ctx->callData->args[0].toUInt32(); \
         format = QLocale::FormatType(intFormat); \
     } \
-    return ctx->engine->newString(locale. FUNC (format))->asReturnedValue(); \
+    return ctx->engine->newString(locale-> FUNC (format))->asReturnedValue(); \
 }
 
 LOCALE_FORMAT(dateTimeFormat)
@@ -607,7 +627,9 @@ LOCALE_FORMAT(dateFormat)
 // +1 added to idx because JS is 0-based, whereas QLocale months begin at 1.
 #define LOCALE_FORMATTED_MONTHNAME(VARIABLE) \
 QV4::ReturnedValue QQmlLocaleData::method_ ## VARIABLE (QV4::SimpleCallContext *ctx) {\
-    QLocale locale = getThisLocale(ctx); \
+    QLocale *locale = getThisLocale(ctx); \
+    if (!locale) \
+        return QV4::Encode::undefined(); \
     if (ctx->callData->argc < 1 || ctx->callData->argc > 2) \
         V4THROW_ERROR("Locale: " #VARIABLE "(): Invalid arguments"); \
     QLocale::FormatType enumFormat = QLocale::LongFormat; \
@@ -619,12 +641,12 @@ QV4::ReturnedValue QQmlLocaleData::method_ ## VARIABLE (QV4::SimpleCallContext *
         if (ctx->callData->args[1].isNumber()) { \
             quint32 intFormat = ctx->callData->args[1].toUInt32(); \
             QLocale::FormatType format = QLocale::FormatType(intFormat); \
-            name = locale. VARIABLE(idx, format); \
+            name = locale-> VARIABLE(idx, format); \
         } else { \
             V4THROW_ERROR("Locale: Invalid datetime format"); \
         } \
     } else { \
-        name = locale. VARIABLE(idx, enumFormat); \
+        name = locale-> VARIABLE(idx, enumFormat); \
     } \
     return ctx->engine->newString(name)->asReturnedValue(); \
 }
@@ -632,7 +654,9 @@ QV4::ReturnedValue QQmlLocaleData::method_ ## VARIABLE (QV4::SimpleCallContext *
 // 0 -> 7 as Qt::Sunday is 7, but Sunday is 0 in JS Date
 #define LOCALE_FORMATTED_DAYNAME(VARIABLE) \
 QV4::ReturnedValue QQmlLocaleData::method_ ## VARIABLE (QV4::SimpleCallContext *ctx) {\
-    QLocale locale = getThisLocale(ctx); \
+    QLocale *locale = getThisLocale(ctx); \
+    if (!locale) \
+        return QV4::Encode::undefined(); \
     if (ctx->callData->argc < 1 || ctx->callData->argc > 2) \
         V4THROW_ERROR("Locale: " #VARIABLE "(): Invalid arguments"); \
     QLocale::FormatType enumFormat = QLocale::LongFormat; \
@@ -645,12 +669,12 @@ QV4::ReturnedValue QQmlLocaleData::method_ ## VARIABLE (QV4::SimpleCallContext *
         if (ctx->callData->args[1].isNumber()) { \
             quint32 intFormat = ctx->callData->args[1].toUInt32(); \
             QLocale::FormatType format = QLocale::FormatType(intFormat); \
-            name = locale. VARIABLE(idx, format); \
+            name = locale-> VARIABLE(idx, format); \
         } else { \
             V4THROW_ERROR("Locale: Invalid datetime format"); \
         } \
     } else { \
-        name = locale. VARIABLE(idx, enumFormat); \
+        name = locale-> VARIABLE(idx, enumFormat); \
     } \
     return ctx->engine->newString(name)->asReturnedValue(); \
 }
@@ -662,8 +686,10 @@ LOCALE_FORMATTED_DAYNAME(standaloneDayName)
 
 #define LOCALE_STRING_PROPERTY(VARIABLE) QV4::ReturnedValue QQmlLocaleData::method_get_ ## VARIABLE (QV4::SimpleCallContext* ctx) \
 { \
-    QLocale locale = getThisLocale(ctx); \
-    return ctx->engine->newString(locale. VARIABLE())->asReturnedValue();\
+    QLocale *locale = getThisLocale(ctx); \
+    if (!locale) \
+        return QV4::Encode::undefined(); \
+    return ctx->engine->newString(locale-> VARIABLE())->asReturnedValue();\
 }
 
 LOCALE_STRING_PROPERTY(name)