Add IStreamWrapper

include/rapidjson/istreamwrapper.h

+// Tencent is pleased to support the open source community by making RapidJSON available.
+// 
+// Copyright (C) 2015 THL A29 Limited, a Tencent company, and Milo Yip. All rights reserved.
+//
+// Licensed under the MIT License (the "License"); you may not use this file except
+// in compliance with the License. You may obtain a copy of the License at
+//
+// http://opensource.org/licenses/MIT
+//
+// Unless required by applicable law or agreed to in writing, software distributed 
+// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR 
+// CONDITIONS OF ANY KIND, either express or implied. See the License for the 
+// specific language governing permissions and limitations under the License.
+
+#include "stream.h"
+
+#ifdef __clang__
+RAPIDJSON_DIAG_PUSH
+RAPIDJSON_DIAG_OFF(padded)
+#endif
+
+RAPIDJSON_NAMESPACE_BEGIN
+
+//! Wrapper of \c std::basic_istream into RapidJSON's Stream concept.
+/*!
+    The classes can be wrapped including but not limited to:
+
+    - \c std::istringstream
+    - \c std::stringstream
+    - \c std::wistringstream
+    - \c std::wstringstream
+    - \c std::ifstream
+    - \c std::fstream
+    - \c std::wifstream
+    - \c std::wfstream
+
+    \tparam StreamType Class derived from \c std::basic_istream.
+*/
+   
+template <typename StreamType>
+class IStreamWrapper {
+public:
+    typedef typename StreamType::char_type Ch;
+    IStreamWrapper(StreamType& stream) : stream_(stream), count_(), peekBuffer_() {}
+
+    Ch Peek() const { 
+        typename StreamType::int_type c = stream_.peek();
+        return RAPIDJSON_LIKELY(c != StreamType::traits_type::eof()) ? static_cast<Ch>(c) : '\0';
+    }
+
+    Ch Take() { 
+        typename StreamType::int_type c = stream_.get();
+        if (RAPIDJSON_LIKELY(c != StreamType::traits_type::eof())) {
+            count_++;
+            return static_cast<Ch>(c);
+        }
+        else
+            return '\0';
+    }
+
+    // tellg() may return -1 when failed. So we count by ourself.
+    size_t Tell() const { return count_; }
+
+    Ch* PutBegin() { RAPIDJSON_ASSERT(false); return 0; }
+    void Put(Ch) { RAPIDJSON_ASSERT(false); }
+    void Flush() { RAPIDJSON_ASSERT(false); }
+    size_t PutEnd(Ch*) { RAPIDJSON_ASSERT(false); return 0; }
+
+    // For encoding detection only.
+    const Ch* Peek4() const {
+        RAPIDJSON_ASSERT(sizeof(Ch) == 1); // Only usable for byte stream.
+        int i;
+        bool hasError = false;
+        for (i = 0; i < 4; ++i) {
+            typename StreamType::int_type c = stream_.get();
+            if (c == StreamType::traits_type::eof()) {
+                hasError = true;
+                stream_.clear();
+                break;
+            }
+            peekBuffer_[i] = static_cast<Ch>(c);
+        }
+        for (--i; i >= 0; --i)
+            stream_.putback(peekBuffer_[i]);
+        return !hasError ? peekBuffer_ : 0;
+    }
+
+private:
+    StreamType& stream_;
+    size_t count_;  //!< Number of characters read. Note:
+    mutable Ch peekBuffer_[4];
+};
+
+#ifdef __clang__
+RAPIDJSON_DIAG_POP
+#endif
+
+RAPIDJSON_NAMESPACE_END

test/unittest/CMakeLists.txt

@@ -7,6 +7,7 @@ set(UNITTEST_SOURCES
     fwdtest.cpp
     filestreamtest.cpp
     itoatest.cpp
+    istreamwrappertest.cpp
     jsoncheckertest.cpp
     namespacetest.cpp
     pointertest.cpp

test/unittest/istreamwrappertest.cpp

+// Tencent is pleased to support the open source community by making RapidJSON available.
+// 
+// Copyright (C) 2015 THL A29 Limited, a Tencent company, and Milo Yip. All rights reserved.
+//
+// Licensed under the MIT License (the "License"); you may not use this file except
+// in compliance with the License. You may obtain a copy of the License at
+//
+// http://opensource.org/licenses/MIT
+//
+// Unless required by applicable law or agreed to in writing, software distributed 
+// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR 
+// CONDITIONS OF ANY KIND, either express or implied. See the License for the 
+// specific language governing permissions and limitations under the License.
+
+#include "unittest.h"
+
+#include "rapidjson/istreamwrapper.h"
+#include "rapidjson/encodedstream.h"
+#include "rapidjson/document.h"
+#include <sstream>
+#include <fstream>
+
+using namespace rapidjson;
+using namespace std;
+
+template <typename StringStreamType>
+static void TestStringStream() {
+    typedef typename StringStreamType::char_type Ch;
+
+    {
+        StringStreamType iss;
+        IStreamWrapper<StringStreamType> is(iss);
+        EXPECT_EQ(0, is.Tell());
+        if (sizeof(Ch) == 1) {
+            EXPECT_EQ(0, is.Peek4());
+            EXPECT_EQ(0, is.Tell());
+        }
+        EXPECT_EQ(0, is.Peek());
+        EXPECT_EQ(0, is.Take());
+        EXPECT_EQ(0, is.Tell());
+    }
+
+    {
+        Ch s[] = { 'A', 'B', 'C', '\0' };
+        StringStreamType iss(s);
+        IStreamWrapper<StringStreamType> is(iss);
+        EXPECT_EQ(0, is.Tell());
+        if (sizeof(Ch) == 1)
+            EXPECT_EQ(0, is.Peek4()); // less than 4 bytes
+        for (int i = 0; i < 3; i++) {
+            EXPECT_EQ(static_cast<size_t>(i), is.Tell());
+            EXPECT_EQ('A' + i, is.Peek());
+            EXPECT_EQ('A' + i, is.Peek());
+            EXPECT_EQ('A' + i, is.Take());
+        }
+        EXPECT_EQ(3, is.Tell());
+        EXPECT_EQ(0, is.Peek());
+        EXPECT_EQ(0, is.Take());
+    }
+
+    {
+        Ch s[] = { 'A', 'B', 'C', 'D', 'E', '\0' };
+        StringStreamType iss(s);
+        IStreamWrapper<StringStreamType> is(iss);
+        if (sizeof(Ch) == 1) {
+            const Ch* c = is.Peek4();
+            for (int i = 0; i < 4; i++)
+                EXPECT_EQ('A' + i, c[i]);
+            EXPECT_EQ(0, is.Tell());
+        }
+        for (int i = 0; i < 5; i++) {
+            EXPECT_EQ(static_cast<size_t>(i), is.Tell());
+            EXPECT_EQ('A' + i, is.Peek());
+            EXPECT_EQ('A' + i, is.Peek());
+            EXPECT_EQ('A' + i, is.Take());
+        }
+        EXPECT_EQ(5, is.Tell());
+        EXPECT_EQ(0, is.Peek());
+        EXPECT_EQ(0, is.Take());
+    }
+}
+
+TEST(IStreamWrapper, istringstream) {
+    TestStringStream<istringstream>();
+}
+
+TEST(IStreamWrapper, stringstream) {
+    TestStringStream<stringstream>();
+}
+
+TEST(IStreamWrapper, wistringstream) {
+    TestStringStream<wistringstream>();
+}
+
+TEST(IStreamWrapper, wstringstream) {
+    TestStringStream<wistringstream>();
+}
+
+template <typename FileStreamType>
+static bool Open(FileStreamType& fs, const char* filename) {
+    const char *paths[] = {
+        "encodings",
+        "bin/encodings",
+        "../bin/encodings",
+        "../../bin/encodings",
+        "../../../bin/encodings"
+    };
+    char buffer[1024];
+    for (size_t i = 0; i < sizeof(paths) / sizeof(paths[0]); i++) {
+        sprintf(buffer, "%s/%s", paths[i], filename);
+        fs.open(buffer, ios_base::in | ios_base::binary);
+        if (fs.is_open())
+            return true;
+    }
+    return false;
+}
+
+TEST(IStreamWrapper, ifstream) {
+    ifstream ifs;
+    ASSERT_TRUE(Open(ifs, "utf8bom.json"));
+    IStreamWrapper<ifstream> isw(ifs);
+    EncodedInputStream<UTF8<>, IStreamWrapper<ifstream> > eis(isw);
+    Document d;
+    EXPECT_TRUE(!d.ParseStream(eis).HasParseError());
+    EXPECT_TRUE(d.IsObject());
+    EXPECT_EQ(5, d.MemberCount());
+}
+
+TEST(IStreamWrapper, fstream) {
+    fstream fs;
+    ASSERT_TRUE(Open(fs, "utf8bom.json"));
+    IStreamWrapper<fstream> isw(fs);
+    EncodedInputStream<UTF8<>, IStreamWrapper<fstream> > eis(isw);
+    Document d;
+    EXPECT_TRUE(!d.ParseStream(eis).HasParseError());
+    EXPECT_TRUE(d.IsObject());
+    EXPECT_EQ(5, d.MemberCount());
+}
+
+// wifstream/wfstream only works on C++11 with codecvt_utf16
+#if RAPIDJSON_HAS_CXX11_RVALUE_REFS
+#include <codecvt>
+
+TEST(IStreamWrapper, wifstream) {
+    wifstream ifs;
+    ASSERT_TRUE(Open(ifs, "utf16bebom.json"));
+    ifs.imbue(std::locale(ifs.getloc(),
+       new std::codecvt_utf16<wchar_t, 0x10ffff, std::consume_header>));
+    IStreamWrapper<wifstream> isw(ifs);
+    GenericDocument<UTF16<> > d;
+    d.ParseStream<kParseDefaultFlags, UTF16<>, IStreamWrapper<wifstream> >(isw);
+    EXPECT_TRUE(!d.HasParseError());
+    EXPECT_TRUE(d.IsObject());
+    EXPECT_EQ(5, d.MemberCount());
+}
+
+TEST(IStreamWrapper, wfstream) {
+    wfstream fs;
+    ASSERT_TRUE(Open(fs, "utf16bebom.json"));
+    fs.imbue(std::locale(fs.getloc(),
+       new std::codecvt_utf16<wchar_t, 0x10ffff, std::consume_header>));
+    IStreamWrapper<wfstream> isw(fs);
+    GenericDocument<UTF16<> > d;
+    d.ParseStream<kParseDefaultFlags, UTF16<>, IStreamWrapper<wfstream> >(isw);
+    EXPECT_TRUE(!d.HasParseError());
+    EXPECT_TRUE(d.IsObject());
+    EXPECT_EQ(5, d.MemberCount());
+}
+
+#endif // RAPIDJSON_HAS_CXX11_RVALUE_REFS