yaml: missing values are actually null/~, not empty strings6.4

Change-Id: I6ca98e219bf4c3de9a1eaaae5ddeb7e7cfa27107
Reviewed-by: Dominik Holland <dominik.holland@qt.io>
(cherry picked from commit 0ae6d0a3637075fe8005361177eae3142eee0a77)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

3 files changed, 77 insertions, 70 deletions

diff --git a/src/common-lib/qtyaml.cpp b/src/common-lib/qtyaml.cpp
index e0ff3d1b..2d64a3c9 100644
--- a/src/common-lib/qtyaml.cpp
+++ b/src/common-lib/qtyaml.cpp
@@ -290,9 +290,8 @@ QVariant YamlParser::parseScalar() const
 {
     QString scalar = parseString();
 
-    if (scalar.isEmpty()
-            || d->event.data.scalar.style == YAML_SINGLE_QUOTED_SCALAR_STYLE
-            || d->event.data.scalar.style == YAML_DOUBLE_QUOTED_SCALAR_STYLE) {
+    if (d->event.data.scalar.style == YAML_SINGLE_QUOTED_SCALAR_STYLE
+        || d->event.data.scalar.style == YAML_DOUBLE_QUOTED_SCALAR_STYLE) {
         return scalar;
     }
 
@@ -537,79 +536,84 @@ QStringList YamlParser::parseStringOrStringList()
     }
 }
 
-void YamlParser::parseFields(const std::vector<Field> &fields)
+static QString mapEventNames(const QVector<yaml_event_type_t> &events)
 {
-    if (!isMap())
-        throw YamlParserException(this, "Expected a map (type %1) to parse fields from, but got type %2")
-            .arg(YAML_MAPPING_START_EVENT).arg(d->event.type);
+    static const QHash<yaml_event_type_t, const char *> eventNames = {
+        { YAML_NO_EVENT,             "nothing" },
+        { YAML_STREAM_START_EVENT,   "stream start" },
+        { YAML_STREAM_END_EVENT,     "stream end" },
+        { YAML_DOCUMENT_START_EVENT, "document start" },
+        { YAML_DOCUMENT_END_EVENT,   "document end" },
+        { YAML_ALIAS_EVENT,          "alias" },
+        { YAML_SCALAR_EVENT,         "scalar" },
+        { YAML_SEQUENCE_START_EVENT, "sequence start" },
+        { YAML_SEQUENCE_END_EVENT,   "sequence end" },
+        { YAML_MAPPING_START_EVENT,  "mapping start" },
+        { YAML_MAPPING_END_EVENT,    "mapping end" }
+    };
+    QString names;
+    for (int i = 0; i < events.size(); ++i) {
+        if (i)
+            names.append(i == (events.size() - 1) ? qL1S(" or ") : qL1S(", "));
+        names.append(qL1S(eventNames.value(events.at(i), "<unknown>")));
+    }
+    return names;
+};
 
+void YamlParser::parseFields(const std::vector<Field> &fields)
+{
     QVector<QString> fieldsFound;
 
-    while (true) {
-        nextEvent(); // read key
-        if (d->event.type == YAML_MAPPING_END_EVENT)
-            break;
-        QString key = parseMapKey();
-        if (fieldsFound.contains(key))
-            throw YamlParserException(this, "Found duplicate key '%1' in mapping").arg(key);
-
-        auto field = fields.cbegin();
-        for (; field != fields.cend(); ++field) {
-            if (key == qL1S(field->name))
-                break;
-        }
-        if (field == fields.cend())
-            throw YamlParserException(this, "Field '%1' is not valid in this context").arg(key);
-        fieldsFound << key;
-
-        nextEvent(); // read value
-        QVector<yaml_event_type_t> allowedEvents;
-        if (field->types & YamlParser::Scalar)
-            allowedEvents.append(YAML_SCALAR_EVENT);
-        if (field->types & YamlParser::Map)
-            allowedEvents.append(YAML_MAPPING_START_EVENT);
-        if (field->types & YamlParser::List)
-            allowedEvents.append(YAML_SEQUENCE_START_EVENT);
-
-        if (!allowedEvents.contains(d->event.type)) { // ALIASES MISSING HERE!
-            auto mapEventNames = [](const QVector<yaml_event_type_t> &events) -> QString {
-                static const QHash<yaml_event_type_t, const char *> eventNames = {
-                    { YAML_NO_EVENT,             "nothing" },
-                    { YAML_STREAM_START_EVENT,   "stream start" },
-                    { YAML_STREAM_END_EVENT,     "stream end" },
-                    { YAML_DOCUMENT_START_EVENT, "document start" },
-                    { YAML_DOCUMENT_END_EVENT,   "document end" },
-                    { YAML_ALIAS_EVENT,          "alias" },
-                    { YAML_SCALAR_EVENT,         "scalar" },
-                    { YAML_SEQUENCE_START_EVENT, "sequence start" },
-                    { YAML_SEQUENCE_END_EVENT,   "sequence end" },
-                    { YAML_MAPPING_START_EVENT,  "mapping start" },
-                    { YAML_MAPPING_END_EVENT,    "mapping end" }
-                };
-                QString names;
-                for (int i = 0; i < events.size(); ++i) {
-                    if (i)
-                        names.append(i == (events.size() - 1) ? qL1S(" or ") : qL1S(", "));
-                    names.append(qL1S(eventNames.value(events.at(i), "<unknown>")));
-                }
-                return names;
-            };
-
-            throw YamlParserException(this, "Field '%1' expected to be of type '%2', but got '%3'")
-                            .arg(field->name).arg(mapEventNames(allowedEvents)).arg(mapEventNames({ d->event.type }));
+    if (!isMap()) {
+        // an empty document is ok - we just have to check for required fields below
+        if (!isScalar() || (parseScalar() != QVariant::fromValue(nullptr))) {
+            throw YamlParserException(this, "Expected a map (type '%1') to parse fields from, but got type '%2'")
+                .arg(mapEventNames({ YAML_MAPPING_START_EVENT })).arg(mapEventNames({ d->event.type }));
         }
+    } else {
+        while (true) {
+            nextEvent(); // read key
+            if (d->event.type == YAML_MAPPING_END_EVENT)
+                break;
+            QString key = parseMapKey();
+            if (fieldsFound.contains(key))
+                throw YamlParserException(this, "Found duplicate key '%1' in mapping").arg(key);
+
+            auto field = fields.cbegin();
+            for (; field != fields.cend(); ++field) {
+                if (key == qL1S(field->name))
+                    break;
+            }
+            if (field == fields.cend())
+                throw YamlParserException(this, "Field '%1' is not valid in this context").arg(key);
+            fieldsFound << key;
+
+            nextEvent(); // read value
+            QVector<yaml_event_type_t> allowedEvents;
+            if (field->types & YamlParser::Scalar)
+                allowedEvents.append(YAML_SCALAR_EVENT);
+            if (field->types & YamlParser::Map)
+                allowedEvents.append(YAML_MAPPING_START_EVENT);
+            if (field->types & YamlParser::List)
+                allowedEvents.append(YAML_SEQUENCE_START_EVENT);
+
+            if (!allowedEvents.contains(d->event.type)) { // ALIASES MISSING HERE!
+                throw YamlParserException(this, "Field '%1' expected to be of type '%2', but got '%3'")
+                    .arg(field->name).arg(mapEventNames(allowedEvents)).arg(mapEventNames({ d->event.type }));
+            }
 
-        yaml_event_type_t typeBefore = d->event.type;
-        yaml_event_type_t typeAfter;
-        switch (typeBefore) {
-        case YAML_MAPPING_START_EVENT: typeAfter = YAML_MAPPING_END_EVENT; break;
-        case YAML_SEQUENCE_START_EVENT: typeAfter = YAML_SEQUENCE_END_EVENT; break;
-        default: typeAfter = typeBefore; break;
-        }
-        field->callback(this);
-        if (d->event.type != typeAfter) {
-            throw YamlParserException(this, "Invalid YAML event state after field callback for '%3': expected %1, but got %2")
-                .arg(typeAfter).arg(d->event.type).arg(key);
+            yaml_event_type_t typeBefore = d->event.type;
+            yaml_event_type_t typeAfter;
+            switch (typeBefore) {
+            case YAML_MAPPING_START_EVENT: typeAfter = YAML_MAPPING_END_EVENT; break;
+            case YAML_SEQUENCE_START_EVENT: typeAfter = YAML_SEQUENCE_END_EVENT; break;
+            default: typeAfter = typeBefore; break;
+            }
+            field->callback(this);
+            if (d->event.type != typeAfter) {
+                throw YamlParserException(this, "Invalid YAML event state after field callback for '%3': expected %1, but got %2")
+                    .arg(typeAfter).arg(d->event.type).arg(key);
+            }
         }
     }
     QStringList fieldsMissing;
diff --git a/tests/auto/yaml/data/test.yaml b/tests/auto/yaml/data/test.yaml
index b16e3d39..7b2e5e84 100644
--- a/tests/auto/yaml/data/test.yaml
+++ b/tests/auto/yaml/data/test.yaml
@@ -15,6 +15,7 @@ bool-false: false
 bool-no: no
 null-literal: null
 null-tilde: ~
+null-empty:
 string-unquoted: unquoted
 string-singlequoted: 'singlequoted'
 string-doublequoted: "doublequoted"
diff --git a/tests/auto/yaml/tst_yaml.cpp b/tests/auto/yaml/tst_yaml.cpp
index 344f0d15..c9f3394c 100644
--- a/tests/auto/yaml/tst_yaml.cpp
+++ b/tests/auto/yaml/tst_yaml.cpp
@@ -52,6 +52,7 @@ void tst_Yaml::parser()
         { "bool-no", false },
         { "null-literal", vnull },
         { "null-tilde", vnull },
+        { "null-empty", vnull },
         { "string-unquoted", QVariant::fromValue<QString>(qSL("unquoted")) },
         { "string-singlequoted", QVariant::fromValue<QString>(qSL("singlequoted")) },
         { "string-doublequoted", QVariant::fromValue<QString>(qSL("doublequoted")) },
@@ -176,6 +177,7 @@ static const QVariantMap testMainDoc = {
     { qSL("bool-no"), false },
     { qSL("null-literal"), vnull },
     { qSL("null-tilde"), vnull },
+    { qSL("null-empty"), vnull },
     { qSL("string-unquoted"), qSL("unquoted") },
     { qSL("string-singlequoted"), qSL("singlequoted") },
     { qSL("string-doublequoted"), qSL("doublequoted") },