So keeping my focus on SSIS Script Component as Source I show another example. Mostly Script component is needed when source is Flat file and we need to retain the previous record value(s) to be used in the next record(s). Keeping this in mind I present the scenario:

The source file layout

1,1
2,1
3,0
4,1
5,0
6,0
7,1

Requirement: Add a third column to data and the values need to be set base on the existing 2 columns. If Column 2 value 1 set column 3 as Column 1, else set Column 3 value to the Column 1 value of the previous record.

Expected Output:

Col1	Col2	Col3
1	1	1
2	1	2
3	0	2
4	1	4
5	0	4
6	0	4
7	1	7

For details on setting up the Script Component as source check out this post.

Check out the code:

C#

using System;
using System.Data;
using Microsoft.SqlServer.Dts.Pipeline.Wrapper;
using Microsoft.SqlServer.Dts.Runtime.Wrapper;
//Add this Namespace for IO Operations
using System.IO;

[Microsoft.SqlServer.Dts.Pipeline.SSISScriptComponentEntryPointAttribute]
public class ScriptMain : UserComponent
{
    //StramReader to read the input file stream
    private StreamReader textReader;

    //String to save the source file path
    private string SrcFilePath;
    public override void AcquireConnections(object Transaction)
    {
        IDTSConnectionManager100 connMgr = this.Connections.Conn;
        SrcFilePath = (string)connMgr.AcquireConnection(null);
    }

    public override void PreExecute()
    {
        base.PreExecute();

        //Set the textReader at the PreExecute Phase so that we donot initialize it for each record.
        textReader = new StreamReader(SrcFilePath);
    }

    public override void CreateNewOutputRows()
    {
        string nextLine;
        string[] columns;
        string lastCol="";
        char[] delimiters;

        delimiters = ",".ToCharArray();

        //Read next line from the file to the string variable
        nextLine = textReader.ReadLine();

        //Read the file till nextLine variable is not NULL ie. EOF
        while (nextLine != null)
        {
            //Split the records by commas to later extract the data and not the column Name in each record.
            columns = nextLine.Split(delimiters);
            
            if(columns[1]=="1")
                lastCol = columns[0];

            this.OutputBuffer.AddRow();
            this.OutputBuffer.Col1 = columns[0];
            this.OutputBuffer.Col2 = columns[1];
            this.OutputBuffer.Col3 = lastCol;
            nextLine = textReader.ReadLine();
        }
    }

    public override void PostExecute()
    {
        base.PostExecute();

        //Close the Text reader once the file has been read in the PostExecute Phase.
        textReader.Close();
    }
}

vb.NET

Imports System
Imports System.Data
Imports System.Math
Imports Microsoft.SqlServer.Dts.Pipeline.Wrapper
Imports Microsoft.SqlServer.Dts.Runtime.Wrapper
'Add this Namespace for IO Operations
Imports System.IO

<Microsoft.SqlServer.Dts.Pipeline.SSISScriptComponentEntryPointAttribute()> _
<CLSCompliant(False)> _
Public Class ScriptMain
    Inherits UserComponent
    'StramReader to read the input file stream
    Private textReader As StreamReader

    'String to save the source file path
    Private SrcFilePath As String
    Public Overrides Sub AcquireConnections(ByVal Transaction As Object)
        Dim connMgr As IDTSConnectionManager100 = Me.Connections.Conn
        SrcFilePath = DirectCast(connMgr.AcquireConnection(Nothing), String)
    End Sub

    Public Overrides Sub PreExecute()
        MyBase.PreExecute()

        'Set the textReader at the PreExecute Phase so that we donot initialize it for each record.
        textReader = New StreamReader(SrcFilePath)
    End Sub

    Public Overrides Sub CreateNewOutputRows()
        Dim nextLine As String
        Dim columns As String()
        Dim lastCol As String = ""
        Dim delimiters As Char()

        delimiters = ",".ToCharArray()

        'Read next line from the file to the string variable
        nextLine = textReader.ReadLine()

        'Read the file till nextLine variable is not NULL ie. EOF
        While nextLine IsNot Nothing
            'Split the records by commas to later extract the data and not the column Name in each record.
            columns = nextLine.Split(delimiters)

            If columns(1) = "1" Then
                lastCol = columns(0)
            End If

            ' Add new row to the output
            Me.OutputBuffer.AddRow()

            ' Assign values to the output column
            Me.OutputBuffer.Col1 = columns(0)
            Me.OutputBuffer.Col2 = columns(1)

            ' Assign value to Col3 from the value stored in the lastCol variable
            Me.OutputBuffer.Col3 = lastCol
            nextLine = textReader.ReadLine()
        End While
    End Sub

    Public Overrides Sub PostExecute()
        MyBase.PostExecute()

        'Close the Text reader once the file has been read in the PostExecute Phase.
        textReader.Close()
    End Sub
End Class

Output: