When the `Reader` encounters a JSON number, it chooses a suitable C++ type mapping. And then it calls *one* function out of `Int(int)`, `Uint(unsigned)`, `Int64(int64_t)`, `Uint64(uint64_t)` and `Double(double)`. If `kParseNumbersAsStrings` is enabled, `Reader` will always calls `RawNumber()` instead.
`String(const char* str, SizeType length, bool copy)` is called when the `Reader` encounters a string. The first parameter is pointer to the string. The second parameter is the length of the string (excluding the null terminator). Note that RapidJSON supports null character `'\0'` inside a string. If such situation happens, `strlen(str) < length`. The last `copy` indicates whether the handler needs to make a copy of the string. For normal parsing, `copy = true`. Only when *insitu* parsing is used, `copy = false`. And beware that, the character type depends on the target encoding, which will be explained later.
`String(const char* str, SizeType length, bool copy)` is called when the `Reader` encounters a string. The first parameter is pointer to the string. The second parameter is the length of the string (excluding the null terminator). Note that RapidJSON supports null character `\0` inside a string. If such situation happens, `strlen(str) < length`. The last `copy` indicates whether the handler needs to make a copy of the string. For normal parsing, `copy = true`. Only when *insitu* parsing is used, `copy = false`. And beware that, the character type depends on the target encoding, which will be explained later.
When the `Reader` encounters the beginning of an object, it calls `StartObject()`. An object in JSON is a set of name-value pairs. If the object contains members it first calls `Key()` for the name of member, and then calls functions depending on the type of the value. These calls of name-value pairs repeats until calling `EndObject(SizeType memberCount)`. Note that the `memberCount` parameter is just an aid for the handler, user may not need this parameter.
