diff options
author | Florin Malita <fmalita@chromium.org> | 2018-06-14 10:45:22 -0400 |
---|---|---|
committer | Skia Commit-Bot <skia-commit-bot@chromium.org> | 2018-06-14 15:07:47 +0000 |
commit | 03b68421cafa58428edd8ab12e0d2235c7000c3f (patch) | |
tree | b6eb337709c052d823fc40822679018555497d1e | |
parent | b141fcbba99a1f4660b0533516c02639002d473b (diff) |
[skjson] Implementation/API tweaks
* move most common accessor methods to the header, for inlining
* drop the lazy type checking semantics in favor of explicit guarded/unguarded
conversions
* revisit the public class hierarchy to better constrain type-bound APIs
* expose public type factories and add tests
* drop the empty-vector optimization -- allocating an external size_t in these
uncommon cases is better than paying for a conditional on every access.
Change-Id: I24a7c75db3aa8b12c740c77ac7df4af4e3a1dff8
Reviewed-on: https://skia-review.googlesource.com/134610
Commit-Queue: Florin Malita <fmalita@chromium.org>
Reviewed-by: Mike Klein <mtklein@google.com>
-rw-r--r-- | modules/skjson/include/SkJSON.h | 279 | ||||
-rw-r--r-- | modules/skjson/src/SkJSON.cpp | 480 | ||||
-rw-r--r-- | modules/skjson/src/SkJSONTest.cpp | 128 |
3 files changed, 495 insertions, 392 deletions
diff --git a/modules/skjson/include/SkJSON.h b/modules/skjson/include/SkJSON.h index 4cb312c64f..8e4231e7a7 100644 --- a/modules/skjson/include/SkJSON.h +++ b/modules/skjson/include/SkJSON.h @@ -11,6 +11,7 @@ #include "SkArenaAlloc.h" #include "SkTypes.h" +class SkString; class SkWStream; namespace skjson { @@ -27,12 +28,26 @@ namespace skjson { * * Values are opaque, fixed-size (64 bits), immutable records. * - * They can be freely converted to any of the facade types for type-specific functionality. + * They can be converted to facade types for type-specific functionality. * - * Note: type checking is lazy/deferred, to facilitate chained property access - e.g. + * E.g.: * - * if (!v.as<ObjectValue>()["foo"].as<ObjectValue>()["bar"].is<NullValue>()) - * LOG("found v.foo.bar!"); + * if (v.is<ArrayValue>()) { + * for (const auto& item : v.as<ArrayValue>()) { + * if (const NumberValue* n = item) { + * printf("Found number: %f", **n); + * } + * } + * } + * + * if (v.is<ObjectValue>()) { + * const StringValue* id = v.as<ObjectValue>()["id"]; + * if (id) { + * printf("Found object ID: %s", id->begin()); + * } else { + * printf("Missing object ID"); + * } + * } */ class alignas(8) Value { public: @@ -46,7 +61,7 @@ public: }; /** - * @return The public type of this record. + * @return The type of this value. */ Type getType() const; @@ -54,85 +69,289 @@ public: * @return True if the record matches the facade type T. */ template <typename T> - bool is() const { return T::IsType(this->getType()); } + bool is() const { return this->getType() == T::kType; } /** - * @return The record cast as facade type T. + * Unguarded conversion to facade types. * - * Note: this is always safe, as proper typing is enforced in the facade methods. + * @return The record cast as facade type T&. */ template <typename T> const T& as() const { - return *reinterpret_cast<const T*>(this->is<T>() ? this : &Value::Null()); + SkASSERT(this->is<T>()); + return *reinterpret_cast<const T*>(this); } /** - * @return Null value singleton. + * Guarded conversion to facade types. + * + * @return The record cast as facade type T*. */ - static const Value& Null(); + template <typename T> + operator const T*() const { + return this->is<T>() ? &this->as<T>() : nullptr; + } + + /** + * @return The string representation of this value. + */ + SkString toString() const; protected: - uint8_t fData8[8]; + /* + Value implementation notes: + + -- fixed 64-bit size + + -- 8-byte aligned + + -- union of: + + bool + int32 + float + char[8] (short string storage) + external payload (tagged) pointer + + -- highest 3 bits reserved for type storage + + */ + enum class Tag : uint8_t { + // We picked kShortString == 0 so that tag 0x00 and stored max_size-size (7-7=0) + // conveniently overlap the '\0' terminator, allowing us to store a 7 character + // C string inline. + kShortString = 0b00000000, // inline payload + kNull = 0b00100000, // no payload + kBool = 0b01000000, // inline payload + kInt = 0b01100000, // inline payload + kFloat = 0b10000000, // inline payload + kString = 0b10100000, // ptr to external storage + kArray = 0b11000000, // ptr to external storage + kObject = 0b11100000, // ptr to external storage + }; + static constexpr uint8_t kTagMask = 0b11100000; + + void init_tagged(Tag); + void init_tagged_pointer(Tag, void*); + + Tag getTag() const { + return static_cast<Tag>(fData8[kTagOffset] & kTagMask); + } + + // Access the record data as T. + // + // This is also used to access the payload for inline records. Since the record type lives in + // the high bits, sizeof(T) must be less than sizeof(Value) when accessing inline payloads. + // + // E.g. + // + // uint8_t + // ----------------------------------------------------------------------- + // | val8 | val8 | val8 | val8 | val8 | val8 | val8 | TYPE| + // ----------------------------------------------------------------------- + // + // uint32_t + // ----------------------------------------------------------------------- + // | val32 | unused | TYPE| + // ----------------------------------------------------------------------- + // + // T* (64b) + // ----------------------------------------------------------------------- + // | T* (kTypeShift bits) |TYPE| + // ----------------------------------------------------------------------- + // + template <typename T> + const T* cast() const { + static_assert(sizeof (T) <= sizeof(Value), ""); + static_assert(alignof(T) <= alignof(Value), ""); + return reinterpret_cast<const T*>(this); + } + + template <typename T> + T* cast() { return const_cast<T*>(const_cast<const Value*>(this)->cast<T>()); } + + // Access the pointer payload. + template <typename T> + const T* ptr() const { + static_assert(sizeof(uintptr_t) == sizeof(Value) || + sizeof(uintptr_t) * 2 == sizeof(Value), ""); + + return (sizeof(uintptr_t) < sizeof(Value)) + // For 32-bit, pointers are stored unmodified. + ? *this->cast<const T*>() + // For 64-bit, we use the high bits of the pointer as tag storage. + : reinterpret_cast<T*>(*this->cast<uintptr_t>() & kTagPointerMask); + } + +private: + static constexpr size_t kValueSize = 8; + + uint8_t fData8[kValueSize]; + +#if defined(SK_CPU_LENDIAN) + static constexpr size_t kTagOffset = kValueSize - 1; + + static constexpr uintptr_t kTagPointerMask = + ~(static_cast<uintptr_t>(kTagMask) << ((sizeof(uintptr_t) - 1) * 8)); +#else + // The current value layout assumes LE and will take some tweaking for BE. + static_assert(false, "Big-endian builds are not supported at this time."); +#endif }; class NullValue final : public Value { public: - static bool IsType(Value::Type t) { return t == Type::kNull; } + static constexpr Type kType = Type::kNull; + + NullValue(); }; -template <typename T, Value::Type vtype> -class PrimitiveValue final : public Value { +class BoolValue final : public Value { public: - static bool IsType(Value::Type t) { return t == vtype; } + static constexpr Type kType = Type::kBool; + + explicit BoolValue(bool); - T operator *() const; + bool operator *() const { + SkASSERT(this->getTag() == Tag::kBool); + return *this->cast<bool>(); + } +}; + +class NumberValue final : public Value { +public: + static constexpr Type kType = Type::kNumber; + + explicit NumberValue(int32_t); + explicit NumberValue(float); + + double operator *() const { + SkASSERT(this->getTag() == Tag::kInt || + this->getTag() == Tag::kFloat); + + return this->getTag() == Tag::kInt + ? static_cast<double>(*this->cast<int32_t>()) + : static_cast<double>(*this->cast<float>()); + } }; template <typename T, Value::Type vtype> class VectorValue : public Value { public: - static bool IsType(Value::Type t) { return t == vtype; } + using ValueT = T; + static constexpr Type kType = vtype; - size_t size() const; + size_t size() const { + SkASSERT(this->getType() == kType); + return *this->ptr<size_t>(); + } - const T* begin() const; - const T* end() const; + const T* begin() const { + SkASSERT(this->getType() == kType); + const auto* size_ptr = this->ptr<size_t>(); + return reinterpret_cast<const T*>(size_ptr + 1); + } + + const T* end() const { + SkASSERT(this->getType() == kType); + const auto* size_ptr = this->ptr<size_t>(); + return reinterpret_cast<const T*>(size_ptr + 1) + *size_ptr; + } const T& operator[](size_t i) const { - return (i < this->size()) ? *(this->begin() + i) : T::Null(); + SkASSERT(this->getType() == kType); + SkASSERT(i < this->size()); + + return *(this->begin() + i); } }; -using BoolValue = PrimitiveValue<bool , Value::Type::kBool >; -using NumberValue = PrimitiveValue<double, Value::Type::kNumber>; -using StringValue = VectorValue<char , Value::Type::kString>; -using ArrayValue = VectorValue<Value , Value::Type::kArray >; +class ArrayValue final : public VectorValue<Value, Value::Type::kArray> { +public: + ArrayValue(const Value* src, size_t size, SkArenaAlloc& alloc); +}; + +class StringValue final : public Value { +public: + static constexpr Type kType = Type::kString; + + StringValue(); + StringValue(const char* src, size_t size, SkArenaAlloc& alloc); + + size_t size() const { + switch (this->getTag()) { + case Tag::kShortString: + return kMaxInlineStringSize - SkToSizeT(this->cast<char>()[kMaxInlineStringSize]); + case Tag::kString: + return this->cast<VectorValue<char, Value::Type::kString>>()->size(); + default: + return 0; + } + } + + const char* begin() const { + return this->getTag() == Tag::kShortString + ? this->cast<char>() + : this->cast<VectorValue<char, Value::Type::kString>>()->begin(); + } + + const char* end() const { + if (this->getTag() == Tag::kShortString) { + const auto* payload = this->cast<char>(); + return payload + kMaxInlineStringSize - SkToSizeT(payload[kMaxInlineStringSize]); + } + return this->cast<VectorValue<char, Value::Type::kString>>()->end(); + } + +private: + static constexpr size_t kMaxInlineStringSize = sizeof(Value) - 1; +}; struct Member { StringValue fKey; Value fValue; - - static const Member& Null(); }; class ObjectValue final : public VectorValue<Member, Value::Type::kObject> { public: + ObjectValue(const Member* src, size_t size, SkArenaAlloc& alloc); + const Value& operator[](const char*) const; + +private: + // Not particularly interesting - hiding for disambiguation. + const Member& operator[](size_t i) const = delete; }; class DOM final : public SkNoncopyable { public: explicit DOM(const char*); - const Value& root() const { return *fRoot; } + const Value& root() const { return fRoot; } void write(SkWStream*) const; private: SkArenaAlloc fAlloc; - const Value* fRoot; + Value fRoot; }; +inline Value::Type Value::getType() const { + switch (this->getTag()) { + case Tag::kNull: return Type::kNull; + case Tag::kBool: return Type::kBool; + case Tag::kInt: return Type::kNumber; + case Tag::kFloat: return Type::kNumber; + case Tag::kShortString: return Type::kString; + case Tag::kString: return Type::kString; + case Tag::kArray: return Type::kArray; + case Tag::kObject: return Type::kObject; + } + + SkASSERT(false); // unreachable + return Type::kNull; +} + } // namespace skjson #endif // SkJSON_DEFINED diff --git a/modules/skjson/src/SkJSON.cpp b/modules/skjson/src/SkJSON.cpp index 8af85ba695..05bf04d8f0 100644 --- a/modules/skjson/src/SkJSON.cpp +++ b/modules/skjson/src/SkJSON.cpp @@ -18,357 +18,131 @@ namespace skjson { //#define SK_JSON_REPORT_ERRORS -namespace { - -/* - Value's impl side: - - -- fixed 64-bit size - - -- 8-byte aligned - - -- union of: - - bool - int32 - float - char[8] (short string storage) - external payload pointer - -- highest 3 bits reserved for type storage - - */ static_assert( sizeof(Value) == 8, ""); static_assert(alignof(Value) == 8, ""); static constexpr size_t kRecAlign = alignof(Value); -// The current record layout assumes LE and will take some tweaking for BE. -#if defined(SK_CPU_BENDIAN) -static_assert(false, "Big-endian builds are not supported."); -#endif - -class ValueRec : public Value { -public: - static constexpr uint64_t kTypeBits = 3, - kTypeShift = 64 - kTypeBits, - kTypeMask = ((1ULL << kTypeBits) - 1) << kTypeShift; - - enum RecType : uint64_t { - // We picked kShortString == 0 so that tag 0b000 and stored max_size-size (7-7=0) - // conveniently overlap the '\0' terminator, allowing us to store a 7 character - // C string inline. - kShortString = 0b000ULL << kTypeShift, // inline payload - kNull = 0b001ULL << kTypeShift, // no payload - kBool = 0b010ULL << kTypeShift, // inline payload - kInt = 0b011ULL << kTypeShift, // inline payload - kFloat = 0b100ULL << kTypeShift, // inline payload - kString = 0b101ULL << kTypeShift, // ptr to external storage - kArray = 0b110ULL << kTypeShift, // ptr to external storage - kObject = 0b111ULL << kTypeShift, // ptr to external storage - }; - - RecType getRecType() const { - return static_cast<RecType>(*this->cast<uint64_t>() & kTypeMask); - } - - // Access the record data as T. - // - // This is also used to access the payload for inline records. Since the record type lives in - // the high bits, sizeof(T) must be less than sizeof(Value) when accessing inline payloads. - // - // E.g. - // - // uint8_t - // ----------------------------------------------------------------------- - // | val8 | val8 | val8 | val8 | val8 | val8 | val8 | TYPE| - // ----------------------------------------------------------------------- - // - // uint32_t - // ----------------------------------------------------------------------- - // | val32 | unused | TYPE| - // ----------------------------------------------------------------------- - // - // T* (64b) - // ----------------------------------------------------------------------- - // | T* (kTypeShift bits) |TYPE| - // ----------------------------------------------------------------------- - // - template <typename T> - const T* cast() const { - static_assert(sizeof (T) <= sizeof(ValueRec), ""); - static_assert(alignof(T) <= alignof(ValueRec), ""); - return reinterpret_cast<const T*>(this); - } - - template <typename T> - T* cast() { return const_cast<T*>(const_cast<const ValueRec*>(this)->cast<T>()); } - - // Access the pointer payload. - template <typename T> - const T* ptr() const { - static_assert(sizeof(uintptr_t) == sizeof(Value) || - sizeof(uintptr_t) * 2 == sizeof(Value), ""); - - return (sizeof(uintptr_t) < sizeof(Value)) - // For 32-bit, pointers are stored unmodified. - ? *this->cast<const T*>() - // For 64-bit, we use the high bits of the pointer as type storage. - : reinterpret_cast<T*>(*this->cast<uintptr_t>() & ~kTypeMask); - } - - // Type-bound recs only store their type. - static ValueRec MakeTypeBound(RecType t) { - ValueRec v; - *v.cast<uint64_t>() = t; - SkASSERT(v.getRecType() == t); - return v; - } - - // Primitive recs store a type and inline primitive payload. - template <typename T> - static ValueRec MakePrimitive(RecType t, T src) { - ValueRec v = MakeTypeBound(t); - *v.cast<T>() = src; - SkASSERT(v.getRecType() == t); - return v; - } - - // Pointer recs store a type (in the upper kTypeBits bits) and a pointer. - template <typename T> - static ValueRec MakePtr(RecType t, const T* p) { - SkASSERT((t & kTypeMask) == t); - if (sizeof(uintptr_t) == sizeof(Value)) { - // For 64-bit, we rely on the pointer hi bits being unused. - SkASSERT(!(reinterpret_cast<uintptr_t>(p) & kTypeMask)); - } - - ValueRec v = MakeTypeBound(t); - *v.cast<uintptr_t>() |= reinterpret_cast<uintptr_t>(p); - - SkASSERT(v.getRecType() == t); - SkASSERT(v.ptr<T>() == p); - - return v; - } - - // Vector recs point to externally allocated slabs with the following layout: - // - // [size_t n] [REC_0] ... [REC_n-1] [optional extra trailing storage] - // - // Long strings use extra_alloc_size == 1 to store the \0 terminator. - template <typename T, size_t extra_alloc_size = 0> - static ValueRec MakeVector(RecType t, const T* src, size_t size, SkArenaAlloc& alloc) { - // For zero-size arrays, we just store a nullptr. - size_t* size_ptr = nullptr; - - if (size) { - // The Ts are already in memory, so their size should be safeish. - const auto total_size = sizeof(size_t) + sizeof(T) * size + extra_alloc_size; - size_ptr = reinterpret_cast<size_t*>(alloc.makeBytesAlignedTo(total_size, kRecAlign)); - auto* data_ptr = reinterpret_cast<T*>(size_ptr + 1); - *size_ptr = size; - memcpy(data_ptr, src, sizeof(T) * size); - } - - return MakePtr(t, size_ptr); - } - - size_t vectorSize(RecType t) const { - if (this->is<NullValue>()) return 0; - SkASSERT(this->getRecType() == t); - - const auto* size_ptr = this->ptr<const size_t>(); - return size_ptr ? *size_ptr : 0; - } - - template <typename T> - const T* vectorBegin(RecType t) const { - if (this->is<NullValue>()) return nullptr; - SkASSERT(this->getRecType() == t); - - const auto* size_ptr = this->ptr<const size_t>(); - return size_ptr ? reinterpret_cast<const T*>(size_ptr + 1) : nullptr; - } - - template <typename T> - const T* vectorEnd(RecType t) const { - if (this->is<NullValue>()) return nullptr; - SkASSERT(this->getRecType() == t); - - const auto* size_ptr = this->ptr<const size_t>(); - return size_ptr ? reinterpret_cast<const T*>(size_ptr + 1) + *size_ptr : nullptr; - } - - // Strings have two flavors: - // - // -- short strings (len <= 7) -> these are stored inline, in the record - // (one byte reserved for null terminator/type): - // - // [str] [\0]|[max_len - actual_len] - // - // Storing [max_len - actual_len] allows the 'len' field to double-up as a - // null terminator when size == max_len (this works 'cause kShortString == 0). - // - // -- long strings (len > 7) -> these are externally allocated vectors (VectorRec<char>). - // - // The string data plus a null-char terminator are copied over. - static constexpr size_t kMaxInlineStringSize = sizeof(Value) - 1; - - static ValueRec MakeString(const char* src, size_t size, SkArenaAlloc& alloc) { - ValueRec v; - - if (size > kMaxInlineStringSize) { - v = MakeVector<char, 1>(kString, src, size, alloc); - const_cast<char *>(v.vectorBegin<char>(ValueRec::kString))[size] = '\0'; - } else { - v = MakeTypeBound(kShortString); - auto* payload = v.cast<char>(); - memcpy(payload, src, size); - payload[size] = '\0'; - - const auto len_tag = SkTo<char>(kMaxInlineStringSize - size); - // This technically overwrites the type hi bits, but is safe because - // 1) kShortString == 0 - // 2) 0 <= len_tag <= 7 - static_assert(kShortString == 0, "please don't break this"); - payload[kMaxInlineStringSize] = len_tag; - SkASSERT(v.getRecType() == kShortString); - } - return v; - } - - size_t stringSize() const { - if (this->getRecType() == ValueRec::kShortString) { - const auto* payload = this->cast<char>(); - return kMaxInlineStringSize - SkToSizeT(payload[kMaxInlineStringSize]); - } - - return this->vectorSize(ValueRec::kString); - } - - const char* stringBegin() const { - if (this->getRecType() == ValueRec::kShortString) { - return this->cast<char>(); - } - - return this->vectorBegin<char>(ValueRec::kString); - } +void Value::init_tagged(Tag t) { + memset(fData8, 0, sizeof(fData8)); + fData8[Value::kTagOffset] = SkTo<uint8_t>(t); + SkASSERT(this->getTag() == t); +} - const char* stringEnd() const { - if (this->getRecType() == ValueRec::kShortString) { - const auto* payload = this->cast<char>(); - return payload + kMaxInlineStringSize - SkToSizeT(payload[kMaxInlineStringSize]); - } +// Pointer values store a type (in the upper kTagBits bits) and a pointer. +void Value::init_tagged_pointer(Tag t, void* p) { + *this->cast<uintptr_t>() = reinterpret_cast<uintptr_t>(p); - return this->vectorEnd<char>(ValueRec::kString); + if (sizeof(Value) == sizeof(uintptr_t)) { + // For 64-bit, we rely on the pointer upper bits being unused/zero. + SkASSERT(!(fData8[kTagOffset] & kTagMask)); + fData8[kTagOffset] |= SkTo<uint8_t>(t); + } else { + // For 32-bit, we need to zero-initialize the upper 32 bits + SkASSERT(sizeof(Value) == sizeof(uintptr_t) * 2); + this->cast<uintptr_t>()[kTagOffset >> 2] = 0; + fData8[kTagOffset] = SkTo<uint8_t>(t); } -}; -} // namespace - - -// Boring public Value glue. - -const Value& Value::Null() { - static const Value g_null = ValueRec::MakeTypeBound(ValueRec::kNull); - return g_null; + SkASSERT(this->getTag() == t); + SkASSERT(this->ptr<void>() == p); } -const Member& Member::Null() { - static const Member g_null = { Value::Null().as<StringValue>(), Value::Null() }; - return g_null; +NullValue::NullValue() { + this->init_tagged(Tag::kNull); + SkASSERT(this->getTag() == Tag::kNull); } -Value::Type Value::getType() const { - static constexpr Value::Type kTypeMap[] = { - Value::Type::kString, // kShortString - Value::Type::kNull, // kNull - Value::Type::kBool, // kBool - Value::Type::kNumber, // kInt - Value::Type::kNumber, // kFloat - Value::Type::kString, // kString - Value::Type::kArray, // kArray - Value::Type::kObject, // kObject - }; - - const auto& rec = *reinterpret_cast<const ValueRec*>(this); - const auto type_index = static_cast<size_t>(rec.getRecType() >> ValueRec::kTypeShift); - SkASSERT(type_index < SK_ARRAY_COUNT(kTypeMap)); - - return kTypeMap[type_index]; +BoolValue::BoolValue(bool b) { + this->init_tagged(Tag::kBool); + *this->cast<bool>() = b; + SkASSERT(this->getTag() == Tag::kBool); } -template <> -bool PrimitiveValue<bool, Value::Type::kBool>::operator*() const { - const auto& rec = *reinterpret_cast<const ValueRec*>(this); - - if (rec.is<NullValue>()) return false; - - SkASSERT(rec.getRecType() == ValueRec::kBool); - - return *rec.cast<bool>(); +NumberValue::NumberValue(int32_t i) { + this->init_tagged(Tag::kInt); + *this->cast<int32_t>() = i; + SkASSERT(this->getTag() == Tag::kInt); } -template <> -double PrimitiveValue<double, Value::Type::kNumber>::operator*() const { - const auto& rec = *reinterpret_cast<const ValueRec*>(this); - - if (rec.is<NullValue>()) return 0; - - SkASSERT(rec.getRecType() == ValueRec::kInt || - rec.getRecType() == ValueRec::kFloat); - - return rec.getRecType() == ValueRec::kInt - ? static_cast<double>(*rec.cast<int32_t>()) - : static_cast<double>(*rec.cast<float>()); +NumberValue::NumberValue(float f) { + this->init_tagged(Tag::kFloat); + *this->cast<float>() = f; + SkASSERT(this->getTag() == Tag::kFloat); } -template <> -size_t VectorValue<Value, Value::Type::kArray>::size() const { - return reinterpret_cast<const ValueRec*>(this)->vectorSize(ValueRec::kArray); +// Vector recs point to externally allocated slabs with the following layout: +// +// [size_t n] [REC_0] ... [REC_n-1] [optional extra trailing storage] +// +// Long strings use extra_alloc_size == 1 to store the \0 terminator. +// +template <typename T, size_t extra_alloc_size = 0> +static void* MakeVector(const void* src, size_t size, SkArenaAlloc& alloc) { + // The Ts are already in memory, so their size should be safe. + const auto total_size = sizeof(size_t) + size * sizeof(T) + extra_alloc_size; + auto* size_ptr = reinterpret_cast<size_t*>(alloc.makeBytesAlignedTo(total_size, kRecAlign)); + auto* data_ptr = reinterpret_cast<void*>(size_ptr + 1); + *size_ptr = size; + memcpy(data_ptr, src, size * sizeof(T)); + + return size_ptr; } -template <> -const Value* VectorValue<Value, Value::Type::kArray>::begin() const { - return reinterpret_cast<const ValueRec*>(this)->vectorBegin<Value>(ValueRec::kArray); +ArrayValue::ArrayValue(const Value* src, size_t size, SkArenaAlloc& alloc) { + this->init_tagged_pointer(Tag::kArray, MakeVector<Value>(src, size, alloc)); + SkASSERT(this->getTag() == Tag::kArray); } -template <> -const Value* VectorValue<Value, Value::Type::kArray>::end() const { - return reinterpret_cast<const ValueRec*>(this)->vectorEnd<Value>(ValueRec::kArray); -} +// Strings have two flavors: +// +// -- short strings (len <= 7) -> these are stored inline, in the record +// (one byte reserved for null terminator/type): +// +// [str] [\0]|[max_len - actual_len] +// +// Storing [max_len - actual_len] allows the 'len' field to double-up as a +// null terminator when size == max_len (this works 'cause kShortString == 0). +// +// -- long strings (len > 7) -> these are externally allocated vectors (VectorRec<char>). +// +// The string data plus a null-char terminator are copied over. +// +StringValue::StringValue(const char* src, size_t size, SkArenaAlloc& alloc) { + if (size > kMaxInlineStringSize) { + this->init_tagged_pointer(Tag::kString, MakeVector<char, 1>(src, size, alloc)); -template <> -size_t VectorValue<Member, Value::Type::kObject>::size() const { - return reinterpret_cast<const ValueRec*>(this)->vectorSize(ValueRec::kObject); -} + auto* data = this->cast<VectorValue<char, Value::Type::kString>>()->begin(); + const_cast<char*>(data)[size] = '\0'; + SkASSERT(this->getTag() == Tag::kString); + return; + } -template <> -const Member* VectorValue<Member, Value::Type::kObject>::begin() const { - return reinterpret_cast<const ValueRec*>(this)->vectorBegin<Member>(ValueRec::kObject); -} + this->init_tagged(Tag::kShortString); -template <> -const Member* VectorValue<Member, Value::Type::kObject>::end() const { - return reinterpret_cast<const ValueRec*>(this)->vectorEnd<Member>(ValueRec::kObject); -} + auto* payload = this->cast<char>(); + memcpy(payload, src, size); + payload[size] = '\0'; -template <> -size_t VectorValue<char, Value::Type::kString>::size() const { - return reinterpret_cast<const ValueRec*>(this)->stringSize(); -} + const auto len_tag = SkTo<char>(kMaxInlineStringSize - size); + // This technically overwrites the tag, but is safe because + // 1) kShortString == 0 + // 2) 0 <= len_tag <= 7 + static_assert(static_cast<uint8_t>(Tag::kShortString) == 0, "please don't break this"); + payload[kMaxInlineStringSize] = len_tag; -template <> -const char* VectorValue<char, Value::Type::kString>::begin() const { - return reinterpret_cast<const ValueRec*>(this)->stringBegin(); + SkASSERT(this->getTag() == Tag::kShortString); } -template <> -const char* VectorValue<char, Value::Type::kString>::end() const { - return reinterpret_cast<const ValueRec*>(this)->stringEnd(); +ObjectValue::ObjectValue(const Member* src, size_t size, SkArenaAlloc& alloc) { + this->init_tagged_pointer(Tag::kObject, MakeVector<Member>(src, size, alloc)); + SkASSERT(this->getTag() == Tag::kObject); } + +// Boring public Value glue. + const Value& ObjectValue::operator[](const char* key) const { // Reverse search for duplicates resolution (policy: return last). const auto* begin = this->begin(); @@ -381,7 +155,8 @@ const Value& ObjectValue::operator[](const char* key) const { } } - return Value::Null(); + static const Value g_null = NullValue(); + return g_null; } namespace { @@ -457,7 +232,7 @@ public: fScopeStack.reserve(kScopeStackReserve); } - const Value& parse(const char* p) { + const Value parse(const char* p) { p = skip_ws(p); switch (*p) { @@ -466,7 +241,7 @@ public: case '[': goto match_array; default: - return this->error(Value::Null(), p, "invalid top-level value"); + return this->error(NullValue(), p, "invalid top-level value"); } match_object: @@ -480,15 +255,15 @@ public: // goto match_object_key; match_object_key: p = skip_ws(p); - if (*p != '"') return this->error(Value::Null(), p, "expected object key"); + if (*p != '"') return this->error(NullValue(), p, "expected object key"); p = this->matchString(p, [this](const char* key, size_t size) { this->pushObjectKey(key, size); }); - if (!p) return Value::Null(); + if (!p) return NullValue(); p = skip_ws(p); - if (*p != ':') return this->error(Value::Null(), p, "expected ':' separator"); + if (*p != ':') return this->error(NullValue(), p, "expected ':' separator"); ++p; @@ -498,7 +273,7 @@ public: switch (*p) { case '\0': - return this->error(Value::Null(), p, "unexpected input end"); + return this->error(NullValue(), p, "unexpected input end"); case '"': p = this->matchString(p, [this](const char* str, size_t size) { this->pushString(str, size); @@ -522,7 +297,7 @@ public: break; } - if (!p) return Value::Null(); + if (!p) return NullValue(); // goto match_post_value; match_post_value: @@ -542,7 +317,7 @@ public: case '}': goto pop_object; default: - return this->error(Value::Null(), p - 1, "unexpected value-trailing token"); + return this->error(NullValue(), p - 1, "unexpected value-trailing token"); } // unreachable @@ -552,7 +327,7 @@ public: SkASSERT(*p == '}'); if (fScopeStack.back() < 0) { - return this->error(Value::Null(), p, "unexpected object terminator"); + return this->error(NullValue(), p, "unexpected object terminator"); } this->popObjectScope(); @@ -565,13 +340,11 @@ public: if (fScopeStack.empty()) { SkASSERT(fValueStack.size() == 1); - auto* root = fAlloc.make<Value>(); - *root = fValueStack.front(); // Stop condition: parsed the top level element and there is no trailing garbage. return *skip_ws(p) == '\0' - ? *root - : this->error(Value::Null(), p, "trailing root garbage"); + ? fValueStack.front() + : this->error(NullValue(), p, "trailing root garbage"); } goto match_post_value; @@ -589,7 +362,7 @@ public: SkASSERT(*p == ']'); if (fScopeStack.back() >= 0) { - return this->error(Value::Null(), p, "unexpected array terminator"); + return this->error(NullValue(), p, "unexpected array terminator"); } this->popArrayScope(); @@ -597,7 +370,7 @@ public: goto pop_common; SkASSERT(false); - return Value::Null(); + return NullValue(); } const SkString& getError() const { @@ -614,11 +387,12 @@ private: SkString fError; - template <typename T> - void popScopeAsVec(ValueRec::RecType type, size_t scope_start) { + template <typename VectorT> + void popScopeAsVec(size_t scope_start) { SkASSERT(scope_start > 0); SkASSERT(scope_start <= fValueStack.size()); + using T = typename VectorT::ValueT; static_assert( sizeof(T) >= sizeof(Value), ""); static_assert( sizeof(T) % sizeof(Value) == 0, ""); static_assert(alignof(T) == alignof(Value), ""); @@ -630,7 +404,7 @@ private: const auto* begin = reinterpret_cast<const T*>(fValueStack.data() + scope_start); // Instantiate the placeholder value added in onPush{Object/Array}. - fValueStack[scope_start - 1] = ValueRec::MakeVector<T>(type, begin, count, fAlloc); + fValueStack[scope_start - 1] = VectorT(begin, count, fAlloc); // Drop the current scope. fScopeStack.pop_back(); @@ -648,7 +422,7 @@ private: void popObjectScope() { const auto scope_start = fScopeStack.back(); SkASSERT(scope_start > 0); - this->popScopeAsVec<Member>(ValueRec::kObject, SkTo<size_t>(scope_start)); + this->popScopeAsVec<ObjectValue>(SkTo<size_t>(scope_start)); SkDEBUGCODE( const auto& obj = fValueStack.back().as<ObjectValue>(); @@ -670,7 +444,7 @@ private: void popArrayScope() { const auto scope_start = -fScopeStack.back(); SkASSERT(scope_start > 0); - this->popScopeAsVec<Value>(ValueRec::kArray, SkTo<size_t>(scope_start)); + this->popScopeAsVec<ArrayValue>(SkTo<size_t>(scope_start)); SkDEBUGCODE( const auto& arr = fValueStack.back().as<ArrayValue>(); @@ -686,31 +460,31 @@ private: } void pushTrue() { - fValueStack.push_back(ValueRec::MakePrimitive<bool>(ValueRec::kBool, true)); + fValueStack.push_back(BoolValue(true)); } void pushFalse() { - fValueStack.push_back(ValueRec::MakePrimitive<bool>(ValueRec::kBool, false)); + fValueStack.push_back(BoolValue(false)); } void pushNull() { - fValueStack.push_back(ValueRec::MakeTypeBound(ValueRec::kNull)); + fValueStack.push_back(NullValue()); } void pushString(const char* s, size_t size) { - fValueStack.push_back(ValueRec::MakeString(s, size, fAlloc)); + fValueStack.push_back(StringValue(s, size, fAlloc)); } void pushInt32(int32_t i) { - fValueStack.push_back(ValueRec::MakePrimitive<int32_t>(ValueRec::kInt, i)); + fValueStack.push_back(NumberValue(i)); } void pushFloat(float f) { - fValueStack.push_back(ValueRec::MakePrimitive<float>(ValueRec::kFloat, f)); + fValueStack.push_back(NumberValue(f)); } template <typename T> - const T& error(const T& ret_val, const char* p, const char* msg) { + T error(T&& ret_val, const char* p, const char* msg) { #if defined(SK_JSON_REPORT_ERRORS) static constexpr size_t kMaxContext = 128; fError = SkStringPrintf("%s: >", msg); @@ -930,17 +704,25 @@ void Write(const Value& v, SkWStream* stream) { } // namespace +SkString Value::toString() const { + SkDynamicMemoryWStream wstream; + Write(*this, &wstream); + const auto data = wstream.detachAsData(); + // TODO: is there a better way to pass data around without copying? + return SkString(static_cast<const char*>(data->data()), data->size()); +} + static constexpr size_t kMinChunkSize = 4096; -DOM::DOM(const char* cstr) +DOM::DOM(const char* c_str) : fAlloc(kMinChunkSize) { DOMParser parser(fAlloc); - fRoot = &parser.parse(cstr); + fRoot = parser.parse(c_str); } void DOM::write(SkWStream* stream) const { - Write(*fRoot, stream); + Write(fRoot, stream); } } // namespace skjson diff --git a/modules/skjson/src/SkJSONTest.cpp b/modules/skjson/src/SkJSONTest.cpp index 8b876ddf4e..6d4338cbbb 100644 --- a/modules/skjson/src/SkJSONTest.cpp +++ b/modules/skjson/src/SkJSONTest.cpp @@ -7,7 +7,9 @@ #include "Test.h" +#include "SkArenaAlloc.h" #include "SkJSON.h" +#include "SkString.h" #include "SkStream.h" using namespace skjson; @@ -107,18 +109,29 @@ static void check_primitive(skiatest::Reporter* reporter, const Value& v, T pv, bool is_type) { REPORTER_ASSERT(reporter, v.is<VT>() == is_type); - REPORTER_ASSERT(reporter, *v.as<VT>() == pv); + const VT* cast_t = v; + REPORTER_ASSERT(reporter, (cast_t != nullptr) == is_type); + + if (is_type) { + REPORTER_ASSERT(reporter, &v.as<VT>() == cast_t); + REPORTER_ASSERT(reporter, *v.as<VT>() == pv); + } } template <typename T> static void check_vector(skiatest::Reporter* reporter, const Value& v, size_t expected_size, bool is_vector) { REPORTER_ASSERT(reporter, v.is<T>() == is_vector); - - const auto& vec = v.as<T>(); - REPORTER_ASSERT(reporter, vec.size() == expected_size); - REPORTER_ASSERT(reporter, (vec.begin() != nullptr) == is_vector); - REPORTER_ASSERT(reporter, vec.end() == vec.begin() + expected_size); + const T* cast_t = v; + REPORTER_ASSERT(reporter, (cast_t != nullptr) == is_vector); + + if (is_vector) { + const auto& vec = v.as<T>(); + REPORTER_ASSERT(reporter, &vec == cast_t); + REPORTER_ASSERT(reporter, vec.size() == expected_size); + REPORTER_ASSERT(reporter, vec.begin() != nullptr); + REPORTER_ASSERT(reporter, vec.end() == vec.begin() + expected_size); + } } static void check_string(skiatest::Reporter* reporter, const Value& v, const char* s) { @@ -128,7 +141,7 @@ static void check_string(skiatest::Reporter* reporter, const Value& v, const cha } } -DEF_TEST(SkJSON_DOM, reporter) { +DEF_TEST(SkJSON_DOM_visit, reporter) { static constexpr char json[] = "{ \n\ \"k1\": null, \n\ \"k2\": false, \n\ @@ -231,7 +244,6 @@ DEF_TEST(SkJSON_DOM, reporter) { check_primitive<float, NumberValue>(reporter, v.as<ArrayValue>()[0], 1, true); check_primitive<bool, BoolValue>(reporter, v.as<ArrayValue>()[1], true, true); check_vector<StringValue>(reporter, v.as<ArrayValue>()[2], 3, true); - REPORTER_ASSERT(reporter, v.as<ArrayValue>()[3].is<NullValue>()); } { @@ -263,10 +275,100 @@ DEF_TEST(SkJSON_DOM, reporter) { check_string(reporter, v.as<ObjectValue>()["kk1"], "baz"); check_primitive<bool, BoolValue>(reporter, v.as<ObjectValue>()["kk2"], false, true); } +} - { - const auto& v = - jroot["foo"].as<ObjectValue>()["bar"].as<ObjectValue>()["baz"]; - REPORTER_ASSERT(reporter, v.is<NullValue>()); - } +template <typename T> +void check_value(skiatest::Reporter* reporter, const Value& v, const char* expected_string) { + REPORTER_ASSERT(reporter, v.is<T>()); + + const T* cast_t = v; + REPORTER_ASSERT(reporter, cast_t == &v.as<T>()); + + const auto vstr = v.toString(); + REPORTER_ASSERT(reporter, 0 == strcmp(expected_string, vstr.c_str())); +} + +DEF_TEST(SkJSON_DOM_build, reporter) { + SkArenaAlloc alloc(4096); + + const auto v0 = NullValue(); + check_value<NullValue>(reporter, v0, "null"); + + const auto v1 = BoolValue(true); + check_value<BoolValue>(reporter, v1, "true"); + + const auto v2 = BoolValue(false); + check_value<BoolValue>(reporter, v2, "false"); + + const auto v3 = NumberValue(0); + check_value<NumberValue>(reporter, v3, "0"); + + const auto v4 = NumberValue(42); + check_value<NumberValue>(reporter, v4, "42"); + + const auto v5 = NumberValue(42.75f); + check_value<NumberValue>(reporter, v5, "42.75"); + + const auto v6 = StringValue(nullptr, 0, alloc); + check_value<StringValue>(reporter, v6, "\"\""); + + const auto v7 = StringValue(" foo ", 5, alloc); + check_value<StringValue>(reporter, v7, "\" foo \""); + + const auto v8 = StringValue(" foo bar baz ", 13, alloc); + check_value<StringValue>(reporter, v8, "\" foo bar baz \""); + + const auto v9 = ArrayValue(nullptr, 0, alloc); + check_value<ArrayValue>(reporter, v9, "[]"); + + const Value values0[] = { v0, v3, v9 }; + const auto v10 = ArrayValue(values0, SK_ARRAY_COUNT(values0), alloc); + check_value<ArrayValue>(reporter, v10, "[null,0,[]]"); + + const auto v11 = ObjectValue(nullptr, 0, alloc); + check_value<ObjectValue>(reporter, v11, "{}"); + + const Member members0[] = { + { StringValue("key_0", 5, alloc), v1 }, + { StringValue("key_1", 5, alloc), v4 }, + { StringValue("key_2", 5, alloc), v11 }, + }; + const auto v12 = ObjectValue(members0, SK_ARRAY_COUNT(members0), alloc); + check_value<ObjectValue>(reporter, v12, "{" + "\"key_0\":true," + "\"key_1\":42," + "\"key_2\":{}" + "}"); + + const Value values1[] = { v2, v6, v12 }; + const auto v13 = ArrayValue(values1, SK_ARRAY_COUNT(values1), alloc); + check_value<ArrayValue>(reporter, v13, "[" + "false," + "\"\"," + "{" + "\"key_0\":true," + "\"key_1\":42," + "\"key_2\":{}" + "}" + "]"); + + const Member members1[] = { + { StringValue("key_00", 6, alloc), v5 }, + { StringValue("key_01", 6, alloc), v7 }, + { StringValue("key_02", 6, alloc), v13 }, + }; + const auto v14 = ObjectValue(members1, SK_ARRAY_COUNT(members1), alloc); + check_value<ObjectValue>(reporter, v14, "{" + "\"key_00\":42.75," + "\"key_01\":\" foo \"," + "\"key_02\":[" + "false," + "\"\"," + "{" + "\"key_0\":true," + "\"key_1\":42," + "\"key_2\":{}" + "}" + "]" + "}"); } |