Add hasher

include/rapidjson/schema.h

@@ -72,6 +72,91 @@ public:
     virtual ISchemaValidator* CreateSchemaValidator(const SchemaType&) const = 0;
 };
 
+///////////////////////////////////////////////////////////////////////////////
+// Hasher
+
+// For comparison of compound value
+template<typename ValueType, typename Allocator>
+class Hasher {
+public:
+    typedef typename ValueType::Ch Ch;
+
+    Hasher() : stack_(0, kDefaultSize) {}
+
+    bool Null() { return WriteType(kNullType); }
+    bool Bool(bool b) { return WriteType(b ? kTrueType : kFalseType); }
+    bool Int(int i) { Number n; n.u.i = i; n.d = static_cast<double>(i); return WriteNumber(n); }
+    bool Uint(unsigned u) { Number n; n.u.u = u; n.d = static_cast<double>(u); return WriteNumber(n); }
+    bool Int64(int64_t i) { Number n; n.u.i = i; n.d = static_cast<double>(i); return WriteNumber(n); }
+    bool Uint64(uint64_t u) { Number n; n.u.u = u; n.d = static_cast<double>(u); return WriteNumber(n); }
+    bool Double(double d) { 
+        Number n; 
+        if (d < 0) n.u.i = static_cast<int64_t>(d);
+        else       n.u.u = static_cast<uint64_t>(d); 
+        n.d = d;
+        return WriteNumber(n);
+    }
+    bool String(const Ch* str, SizeType len, bool) {
+        WriteBuffer(kStringType, str, len * sizeof(Ch));
+        return true;
+    }
+    bool StartObject() { return true; }
+    bool Key(const Ch* str, SizeType len, bool copy) { return String(str, len, copy); }
+    bool EndObject(SizeType memberCount) { 
+        uint64_t h = Hash(0, kObjectType);
+        uint64_t* kv = stack_.template Pop<uint64_t>(memberCount * 2);
+        for (SizeType i = 0; i < memberCount; i++)
+            h ^= Hash(kv[i * 2], kv[i * 2 + 1]);  // Use xor to achieve member order insensitive
+        *stack_.template Push<uint64_t>() = h;
+        return true;
+    }
+    bool StartArray() { return true; }
+    bool EndArray(SizeType elementCount) { 
+        uint64_t h = Hash(0, kArrayType);
+        uint64_t* e = stack_.template Pop<uint64_t>(elementCount);
+        for (SizeType i = 0; i < elementCount; i++)
+            h = Hash(h, e[i]); // Use hash to achieve element order sensitive
+        *stack_.template Push<uint64_t>() = h;
+        return true;
+    }
+
+    uint64_t GetHashCode() const {
+        RAPIDJSON_ASSERT(stack_.GetSize() == sizeof(uint64_t));
+        return *stack_.template Top<uint64_t>();
+    }
+
+private:
+    static const size_t kDefaultSize = 256;
+    struct Number {
+        union U {
+            uint64_t u;
+            int64_t i;
+        }u;
+        double d;
+    };
+
+    bool WriteType(unsigned char type) { WriteBuffer(type, 0, 0); return true; }
+    bool WriteNumber(const Number& n) { WriteBuffer(kNumberType, &n, sizeof(n)); return true; }
+    bool WriteBuffer(unsigned char type, const void* data, size_t len) {
+        // FNV-1a from http://isthe.com/chongo/tech/comp/fnv/
+        uint64_t h = Hash(RAPIDJSON_UINT64_C2(0x84222325, 0xcbf29ce4), type);
+        const unsigned char* d = static_cast<const unsigned char*>(data);
+        for (size_t i = 0; i < len; i++)
+            h = Hash(h, d[i]);
+        *stack_.template Push<uint64_t>() = h;
+        return true;
+    }
+
+    static uint64_t Hash(uint64_t h, uint64_t d) {
+        static const uint64_t kPrime = RAPIDJSON_UINT64_C2(0x00000100, 0x000001b3);
+        h ^= d;
+        h *= kPrime;
+        return h;
+    }
+
+    Stack<Allocator> stack_;
+};
+
 ///////////////////////////////////////////////////////////////////////////////
 // SchemaValidationContext
 

test/unittest/schematest.cpp

@@ -17,6 +17,75 @@
 
 using namespace rapidjson;
 
+#define TEST_HASHER(json1, json2, expected) \
+{\
+    Document d1, d2;\
+    d1.Parse(json1);\
+    ASSERT_FALSE(d1.HasParseError());\
+    d2.Parse(json2);\
+    ASSERT_FALSE(d2.HasParseError());\
+    internal::Hasher<Value, CrtAllocator> h1, h2;\
+    d1.Accept(h1);\
+    d2.Accept(h2);\
+    printf("%s: 0x%016llx\n%s: 0x%016llx\n\n", json1, h1.GetHashCode(), json2, h2.GetHashCode());\
+    EXPECT_TRUE(expected == (h1.GetHashCode() == h2.GetHashCode()));\
+}
+
+TEST(SchemaValidator, Hasher) {
+    TEST_HASHER("null", "null", true);
+
+    TEST_HASHER("true", "true", true);
+    TEST_HASHER("false", "false", true);
+    TEST_HASHER("true", "false", false);
+    TEST_HASHER("false", "true", false);
+    TEST_HASHER("true", "null", false);
+    TEST_HASHER("false", "null", false);
+
+    TEST_HASHER("1", "1", true);
+    TEST_HASHER("1.5", "1.5", true);
+    TEST_HASHER("1", "1.0", true);
+    TEST_HASHER("1", "-1", false);
+    TEST_HASHER("0.0", "-0.0", false);
+    TEST_HASHER("1", "true", false);
+    TEST_HASHER("0", "false", false);
+    TEST_HASHER("0", "null", false);
+
+    TEST_HASHER("\"\"", "\"\"", true);
+    TEST_HASHER("\"\"", "\"\\u0000\"", false);
+    TEST_HASHER("\"Hello\"", "\"Hello\"", true);
+    TEST_HASHER("\"Hello\"", "\"World\"", false);
+    TEST_HASHER("\"Hello\"", "null", false);
+    TEST_HASHER("\"Hello\\u0000\"", "\"Hello\"", false);
+    TEST_HASHER("\"\"", "null", false);
+    TEST_HASHER("\"\"", "true", false);
+    TEST_HASHER("\"\"", "false", false);
+
+    TEST_HASHER("[]", "[ ]", true);
+    TEST_HASHER("[1, true, false]", "[1, true, false]", true);
+    TEST_HASHER("[1, true, false]", "[1, true]", false);
+    TEST_HASHER("[1, 2]", "[2, 1]", false);
+    TEST_HASHER("[[1], 2]", "[[1, 2]]", false);
+    TEST_HASHER("[1, 2]", "[1, [2]]", false);
+    TEST_HASHER("[]", "null", false);
+    TEST_HASHER("[]", "true", false);
+    TEST_HASHER("[]", "false", false);
+    TEST_HASHER("[]", "0", false);
+    TEST_HASHER("[]", "0.0", false);
+    TEST_HASHER("[]", "\"\"", false);
+
+    TEST_HASHER("{}", "{ }", true);
+    TEST_HASHER("{\"a\":1}", "{\"a\":1}", true);
+    TEST_HASHER("{\"a\":1}", "{\"b\":1}", false);
+    TEST_HASHER("{\"a\":1}", "{\"a\":2}", false);
+    TEST_HASHER("{\"a\":1, \"b\":2}", "{\"b\":2, \"a\":1}", true); // Member order insensitive
+    TEST_HASHER("{}", "null", false);
+    TEST_HASHER("{}", "false", false);
+    TEST_HASHER("{}", "true", false);
+    TEST_HASHER("{}", "0", false);
+    TEST_HASHER("{}", "0.0", false);
+    TEST_HASHER("{}", "\"\"", false);
+}
+
 // Test cases following http://spacetelescope.github.io/understanding-json-schema
 
 #define VALIDATE(schema, json, expected) \