Description

A folder contains a number of files. The files potentially can be huge (> 1GB). Each file holds a set of operations (addition, subtraction, multiplication and division) serialized to XML format. The operations may be simple (operands are constants) or complex (some of operands are expressions).

This application calculates the top-level operations from input files and store results in output files in XML format.

Run

> Valuator.exe inputDir outputDir

Filenames

<output_filename>.xml = <input_filename>_result.xml

Input format

data0001.xml

<expressions>
    <addition id="1">
        <item>2</item>
        <item>3</item>
        <item>4</item>
    </addition>
    <subtraction id="2">
        <minuend>3</minuend>
        <subtrahend>2</subtrahend>
    </subtraction>
    <multiplication id="3">
        <factor>5</factor>
        <factor>6</factor>
        <factor>8</factor>
    </multiplication>
    <division id="4">
        <dividend>54</dividend>
        <divisor>9</divisor>
    </division>
</expressions>

Output format

data0001_result.xml

<expressions>
    <result id="1">9</result>
    <result id="2">1</result>
    <result id="3">240</result>
    <result id="4">6</result>    
</expressions>

Complex expressions

To deal with complex expressions I consider any operand of an expression again an expression.

data0002.xml

<expressions>
    <addition id="10" complex="true">
        <item>2</item>
        <item>3</item>
        <item>  
            <subtraction>
                <minuend>7</minuend>
                <subtrahend>3</subtrahend>
            </subtraction>
        </item>
    </addition>
    <subtraction id="11">
        <minuend>3</minuend>
        <subtrahend>2</subtrahend>
    </subtraction>
    <multiplication id="12">
        <factor>5</factor>
        <factor>6</factor>
        <factor>8</factor>
    </multiplication>
    <multiplication id="13" complex="true">
        <factor>
            <addition>
                <item>2</item>
                <item>3</item>
                <item>4</item>
            </addition>
        </factor>
        <factor>6</factor>
        <factor>
            <multiplication>
                <factor>3</factor>
                <factor>4</factor>
                <factor>5</factor>
                <factor>10</factor>
                <factor>56</factor>
            </multiplication>
        </factor>
    </multiplication>
    <division id="14" complex="true">
        <dividend>54</dividend>
        <divisor>
            <addition>
                <item>3</item>
                <item>6</item>
            </addition>
        </divisor>
    </division>
</expressions>

data0002_result.xml

<expressions>
    <result id="10">9</result>
    <result id="11">1</result>
    <result id="12">240</result>
    <result id="13">1814400</result>
    <result id="14">6</result>
</expressions>

Libraries used (dependencies)

• boost::property_tree (for XML parser)
• std::filesystem (C++17)

Build

If you use Visual Studio Code, make sure c_cpp_properties.json and tasks.json reflect those dependencies.

You can modify the code and rebuild with command

> g++ -std=c++17 -IC:\MyLibs\boost_1_77_0 .\*ion.cpp .\Valuator.cpp .\main.cpp -o Valuator

Variations

This implementation is kept raw to easier explain how to solve the problem. For performance, scalability and usability, you need to change the code a bit.

If you want to change the behaviors of existing operations

• Modify the classes Addition, Subtraction, Multiplication and Division.
• Update the unit tests in XXXTest.cpp

If you want to create new operations (scalability)

• Create new classes like existing classes that inherit the class Expression.
• Create unit tests for each operations like the XXXTest.cpp.
• Use an unordered_map to avoid multiple if-else in Valuator::createExpression()

If you want to change the format of the input/output files

• Modify Valuator.cpp and main.cpp with your new structures/naming.

If you want to define what to handle in case of zero divisor

• Modify it in Division::value()