RAPIDJSON_FORCEINLINE IterativeParsingState Transit()

in src/main/cpp/sdk/common/rapidjson/reader.h [1995:2144]
105 lines of code
31 McCabe index (conditional complexity)

    RAPIDJSON_FORCEINLINE IterativeParsingState Transit(IterativeParsingState src, Token token, IterativeParsingState dst, InputStream& is, Handler& handler) {
        (void)token;

        switch (dst) {
        case IterativeParsingErrorState:
            return dst;

        case IterativeParsingObjectInitialState:
        case IterativeParsingArrayInitialState:
        {
            // Push the state(Element or MemeberValue) if we are nested in another array or value of member.
            // In this way we can get the correct state on ObjectFinish or ArrayFinish by frame pop.
            IterativeParsingState n = src;
            if (src == IterativeParsingArrayInitialState || src == IterativeParsingElementDelimiterState)
                n = IterativeParsingElementState;
            else if (src == IterativeParsingKeyValueDelimiterState)
                n = IterativeParsingMemberValueState;
            // Push current state.
            *stack_.template Push<SizeType>(1) = n;
            // Initialize and push the member/element count.
            *stack_.template Push<SizeType>(1) = 0;
            // Call handler
            bool hr = (dst == IterativeParsingObjectInitialState) ? handler.StartObject() : handler.StartArray();
            // On handler short circuits the parsing.
            if (!hr) {
                RAPIDJSON_PARSE_ERROR_NORETURN(kParseErrorTermination, is.Tell());
                return IterativeParsingErrorState;
            }
            else {
                is.Take();
                return dst;
            }
        }

        case IterativeParsingMemberKeyState:
            ParseString<parseFlags>(is, handler, true);
            if (HasParseError())
                return IterativeParsingErrorState;
            else
                return dst;

        case IterativeParsingKeyValueDelimiterState:
            RAPIDJSON_ASSERT(token == ColonToken);
            is.Take();
            return dst;

        case IterativeParsingMemberValueState:
            // Must be non-compound value. Or it would be ObjectInitial or ArrayInitial state.
            ParseValue<parseFlags>(is, handler);
            if (HasParseError()) {
                return IterativeParsingErrorState;
            }
            return dst;

        case IterativeParsingElementState:
            // Must be non-compound value. Or it would be ObjectInitial or ArrayInitial state.
            ParseValue<parseFlags>(is, handler);
            if (HasParseError()) {
                return IterativeParsingErrorState;
            }
            return dst;

        case IterativeParsingMemberDelimiterState:
        case IterativeParsingElementDelimiterState:
            is.Take();
            // Update member/element count.
            *stack_.template Top<SizeType>() = *stack_.template Top<SizeType>() + 1;
            return dst;

        case IterativeParsingObjectFinishState:
        {
            // Transit from delimiter is only allowed when trailing commas are enabled
            if (!(parseFlags & kParseTrailingCommasFlag) && src == IterativeParsingMemberDelimiterState) {
                RAPIDJSON_PARSE_ERROR_NORETURN(kParseErrorObjectMissName, is.Tell());
                return IterativeParsingErrorState;
            }
            // Get member count.
            SizeType c = *stack_.template Pop<SizeType>(1);
            // If the object is not empty, count the last member.
            if (src == IterativeParsingMemberValueState)
                ++c;
            // Restore the state.
            IterativeParsingState n = static_cast<IterativeParsingState>(*stack_.template Pop<SizeType>(1));
            // Transit to Finish state if this is the topmost scope.
            if (n == IterativeParsingStartState)
                n = IterativeParsingFinishState;
            // Call handler
            bool hr = handler.EndObject(c);
            // On handler short circuits the parsing.
            if (!hr) {
                RAPIDJSON_PARSE_ERROR_NORETURN(kParseErrorTermination, is.Tell());
                return IterativeParsingErrorState;
            }
            else {
                is.Take();
                return n;
            }
        }

        case IterativeParsingArrayFinishState:
        {
            // Transit from delimiter is only allowed when trailing commas are enabled
            if (!(parseFlags & kParseTrailingCommasFlag) && src == IterativeParsingElementDelimiterState) {
                RAPIDJSON_PARSE_ERROR_NORETURN(kParseErrorValueInvalid, is.Tell());
                return IterativeParsingErrorState;
            }
            // Get element count.
            SizeType c = *stack_.template Pop<SizeType>(1);
            // If the array is not empty, count the last element.
            if (src == IterativeParsingElementState)
                ++c;
            // Restore the state.
            IterativeParsingState n = static_cast<IterativeParsingState>(*stack_.template Pop<SizeType>(1));
            // Transit to Finish state if this is the topmost scope.
            if (n == IterativeParsingStartState)
                n = IterativeParsingFinishState;
            // Call handler
            bool hr = handler.EndArray(c);
            // On handler short circuits the parsing.
            if (!hr) {
                RAPIDJSON_PARSE_ERROR_NORETURN(kParseErrorTermination, is.Tell());
                return IterativeParsingErrorState;
            }
            else {
                is.Take();
                return n;
            }
        }

        default:
            // This branch is for IterativeParsingValueState actually.
            // Use `default:` rather than
            // `case IterativeParsingValueState:` is for code coverage.

            // The IterativeParsingStartState is not enumerated in this switch-case.
            // It is impossible for that case. And it can be caught by following assertion.

            // The IterativeParsingFinishState is not enumerated in this switch-case either.
            // It is a "derivative" state which cannot triggered from Predict() directly.
            // Therefore it cannot happen here. And it can be caught by following assertion.
            RAPIDJSON_ASSERT(dst == IterativeParsingValueState);

            // Must be non-compound value. Or it would be ObjectInitial or ArrayInitial state.
            ParseValue<parseFlags>(is, handler);
            if (HasParseError()) {
                return IterativeParsingErrorState;
            }
            return IterativeParsingFinishState;
        }
    }