DevTools: consistently use Maybe for optional values in the protocol generator.

third_party/WebKit/Source/platform/inspector_protocol/TypeBuilder_h.template

Index: third_party/WebKit/Source/platform/inspector_protocol/TypeBuilder_h.template
diff --git a/third_party/WebKit/Source/platform/inspector_protocol/TypeBuilder_h.template b/third_party/WebKit/Source/platform/inspector_protocol/TypeBuilder_h.template
index 4589aab80680c82d520919ac66e3ae8f943f46d3..10ce09906af82d01c134971d7bc9e0ed659b84b8 100644
--- a/third_party/WebKit/Source/platform/inspector_protocol/TypeBuilder_h.template
+++ b/third_party/WebKit/Source/platform/inspector_protocol/TypeBuilder_h.template
@@ -18,95 +18,94 @@ namespace blink {
 namespace protocol {
 
 template<typename T>
-class OptionalValue {
+class Maybe {
 public:
-    OptionalValue() : m_hasValue(false) { }
-    OptionalValue(const T& value) : m_hasValue(true), m_value(value) { }
-
-    void operator=(T value)
-    {
-        m_value = value;
-        m_hasValue = true;
-    }
-
-    T get() const
-    {
-        ASSERT(m_hasValue);
-        return m_value;
-    }
-
-    T get(const T& defaultValue) const
-    {
-        return m_hasValue ? m_value : defaultValue;
-    }
-
-    bool hasValue() const
-    {
-        return m_hasValue;
-    }
-
+    Maybe() { }
+    Maybe(PassOwnPtr<T> value) : m_value(value) { }
+    void operator=(PassOwnPtr<T> value) { m_value = value; }
+    T* fromJust() const { ASSERT(m_value); return m_value.get(); }
+    T* fromMaybe(PassOwnPtr<T> defaultValue) const { return m_value ? m_value.get() : defaultValue; }
+    bool isJust() const { return !!m_value; }
+    PassOwnPtr<T> takeJust() { ASSERT(m_value); return m_value.release(); }
 private:
-    bool m_hasValue;
-    T m_value;
+    OwnPtr<T> m_value;

[Nico, 2016/02/26 19:31:48]

also, i found it pretty surprising that Maybe<T> has an OwnPtr<T>

 };
 
 template<typename T>
-OptionalValue<T> optional(const T* value)
-{
-    return value ? OptionalValue<T>(*value) : OptionalValue<T>();
-}
+class MaybeBase {
+public:
+    MaybeBase() : m_isJust(false) { }
+    MaybeBase(T value) : m_isJust(true), m_value(value) { }
+    void operator=(T value) { m_value = value; m_isJust = true; }
+    T fromJust() const { ASSERT(m_isJust); return m_value; }
+    T fromMaybe(const T& defaultValue) const { return m_isJust ? m_value : defaultValue; }
+    bool isJust() const { return m_isJust; }

[Nico, 2016/02/26 19:14:06]

isJust() isn't a great name for this. People who know Haskell will get this,
nobody else will without looking it up.

+    T takeJust() { ASSERT(m_isJust); return m_value; }
+
+protected:
+    bool m_isJust;
+    T m_value;
+};
 
-PLATFORM_EXPORT OptionalValue<String> optional(const String& value);
+template<> class Maybe<bool> : public MaybeBase<bool> {
+public:
+    Maybe() { }
+    Maybe(bool value) : MaybeBase(value) { }
+    using MaybeBase::operator=;
+};
 
-template<typename T>
-OptionalValue<T> optional(const T& value)
+template<> class Maybe<int> : public MaybeBase<int>
 {
-    return OptionalValue<T>(value);
-}
-
-template<typename T> class Array;
-
-template<typename T>
-bool hasValue(const protocol::OptionalValue<T>& t) { return t.hasValue(); }
-
-template<typename T>
-bool hasValue(T* value) { return !!value; }
-
-template<typename T>
-bool hasValue(const OwnPtr<T>& value) { return !!value; }
-
-template<typename T>
-bool hasValue(const PassOwnPtr<T>& value) { return !!value; }
-
-template<typename T>
-bool hasValue(const RefPtr<T>& value) { return !!value; }
+public:
+    Maybe() { }
+    Maybe(int value) : MaybeBase(value) { }
+    using MaybeBase::operator=;
+};
 
-template<typename T>
-PassRefPtr<JSONValue> toValue(const T& param)
+template<> class Maybe<double> : public MaybeBase<double>
 {
-    return JSONBasicValue::create(param);
-}
-
-template<>
-PLATFORM_EXPORT PassRefPtr<JSONValue> toValue(const String& param);
+public:
+    Maybe() { }
+    Maybe(double value) : MaybeBase(value) { }
+    using MaybeBase::operator=;
+};
 
-template<typename T>
-PassRefPtr<JSONValue> toValue(PassRefPtr<T> param)
+template<> class Maybe<String> : public MaybeBase<String>
 {
-    return param;
-}
+public:
+    Maybe() { }
+    Maybe(const String& value) : MaybeBase(value) { }
+    Maybe(const AtomicString& value) : MaybeBase(value) { }
+    using MaybeBase::operator=;
+};
 
 template<typename T>
-PassRefPtr<JSONValue> toValue(const PassOwnPtr<protocol::Array<T>> param)
-{
-    return param->asValue();
-}
+class Maybe<RefPtr<T>> {
+public:
+    Maybe() { }
+    Maybe(RefPtr<T> value) : m_value(value) { }
+    Maybe(PassRefPtr<T> value) : m_value(value) { }
+    Maybe(T* value) : m_value(value) { }
+    void operator=(PassRefPtr<T> value) { m_value = value; }
+    PassRefPtr<T> fromJust() const { ASSERT(m_value); return m_value; }
+    PassRefPtr<T> fromMaybe(const PassRefPtr<T> defaultValue) const { return m_value || defaultValue; }
+    bool isJust() const { return !!m_value; }
+    PassRefPtr<T> takeJust() { return m_value; }
+
+protected:
+    RefPtr<T> m_value;
+};
 
-template<typename T>
-PassRefPtr<JSONValue> toValue(PassOwnPtr<T> param)
-{
-    return param->asValue();
-}
+template<typename T> class Array;
+
+PLATFORM_EXPORT PassRefPtr<JSONValue> toValue(int value);
+PLATFORM_EXPORT PassRefPtr<JSONValue> toValue(double value);
+PLATFORM_EXPORT PassRefPtr<JSONValue> toValue(bool value);
+PLATFORM_EXPORT PassRefPtr<JSONValue> toValue(const String& param);
+template<typename T> PassRefPtr<JSONValue> toValue(PassRefPtr<T> param) { return param; }
+template<typename T> PassRefPtr<JSONValue> toValue(T* param) { return param->asValue(); }
+template<typename T> PassRefPtr<JSONValue> toValue(PassOwnPtr<T> param) { return param->asValue(); }
+template<typename T> PassRefPtr<JSONValue> toValue(const Maybe<T>& param) { return toValue(param.fromJust()); }
 
 template<typename T>
 struct FromValue
@@ -355,6 +354,12 @@ public:
         RefPtr<JSONValue> value = m_object->get("{{property.name}}");
         return value ? FromValue<{{resolve_type(property).raw_type}}>::convert(value) : defaultValue;
     }
+
+    void set{{property.name | to_title_case}}(const Maybe<{{resolve_type(property).raw_type}}>& value)
+    {
+        if (value.isJust())
+            m_object->setValue("{{property.name}}", toValue(value.fromJust()));
+    }
         {% else %}
     {{resolve_type(property).return_type}} get{{property.name | to_title_case}}()
     {
@@ -362,17 +367,12 @@ public:
         RefPtr<JSONValue> value = m_object->get("{{property.name}}");
         return FromValue<{{resolve_type(property).raw_type}}>::convert(value);
     }
-        {% endif %}
 
     void set{{property.name | to_title_case}}({{resolve_type(property).pass_type}} value)
     {
-        {% if property.optional and resolve_type(property).nullable %}
-        if (value)
-            m_object->setValue("{{property.name}}", toValue(value));
-        {% else %}
         m_object->setValue("{{property.name}}", toValue(value));
-        {% endif %}
     }
+        {% endif %}
       {% endfor %}
 
     PassRefPtr<JSONObject> asValue() { return m_object; }
@@ -399,12 +399,8 @@ public:
       {% for property in type.properties %}
 
         {% if property.optional %}
-        {{type.id}}Builder<STATE>& set{{property.name | to_title_case}}({{resolve_type(property).pass_type}} value)
+        {{type.id}}Builder<STATE>& set{{property.name | to_title_case}}(const Maybe<{{resolve_type(property).raw_type}}>& value)
         {
-          {% if resolve_type(property).nullable%}
-            if (!value)
-                return *this;
-          {% endif %}
             m_result->set{{property.name | to_title_case}}(value);
             return *this;
         }