[skottie] Switch to RapidJSON

- pull latest RapidJSON under third_party/externals/rapidjson
  (note: and older RS version is already pulled as part of angle2,
  and it is also checked in G3)

- add a thin Json porting layer (SkottieJson) to isolate RS
  idiosyncrasies

- convert Skottie to use the new helpers

- parse the DOM in-place (based on local experiments this is the
  fastest method)

Ta-da: Skottie now parses JSON ~10x faster!


Change-Id: Ida9099638f88ed025fee83055c8cd8680ee27176
Reviewed-on: https://skia-review.googlesource.com/125744
Commit-Queue: Florin Malita <fmalita@chromium.org>
Reviewed-by: Mike Reed <reed@google.com>

1 files changed, 76 insertions, 0 deletions

diff --git a/experimental/skottie/SkottieJson.h b/experimental/skottie/SkottieJson.h
new file mode 100644
index 0000000000..76e17c610e
--- /dev/null
+++ b/experimental/skottie/SkottieJson.h
@@ -0,0 +1,76 @@
+/*
+ * Copyright 2018 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkottieJson_DEFINED
+#define SkottieJson_DEFINED
+
+#include "SkRefCnt.h"
+
+#include "rapidjson/document.h"
+
+class SkData;
+class SkStream;
+class SkString;
+
+namespace skottie {
+
+namespace json {
+
+class ValueRef {
+public:
+    ValueRef() : fValue(nullptr) {}
+    ValueRef(const rapidjson::Value& v) : fValue(v.IsNull() ? nullptr : &v) {}
+
+    bool isNull()   const { return !fValue;   }
+    bool isObject() const { return fValue && fValue->IsObject(); }
+    bool isArray()  const { return fValue && fValue->IsArray();  }
+
+    template <typename T>
+    bool to(T*) const;
+
+    template <typename T>
+    T toDefault(const T& defaultValue) const {
+        T v;
+        if (!this->to<T>(&v)) {
+            v = defaultValue;
+        }
+        return v;
+    }
+
+    size_t size() const;
+    ValueRef operator[](size_t i) const;
+    ValueRef operator[](const char* key) const;
+
+    bool operator==(const ValueRef& other) const { return fValue == other.fValue; }
+    bool operator!=(const ValueRef& other) const { return !(*this == other); }
+
+    const rapidjson::Value* begin() const;
+    const rapidjson::Value* end() const;
+
+    SkString toString() const;
+
+private:
+    const rapidjson::Value*       fValue;
+};
+
+// Container for the json DOM
+class Document {
+public:
+    explicit Document(SkStream*);
+
+    ValueRef root() const { return fDocument; }
+
+private:
+    sk_sp<SkData>       fData;     // raw data
+    rapidjson::Document fDocument; // in-place json DOM
+};
+
+} // namespace json
+
+} // namespace skottie
+
+#endif // SkottieJson_DEFINED