Question

I need to extract data from a text file in ASP .NET.

Example Data:

    ; comment
    data = astringvalue
    ; comment
    ; string values
    person = bob
    animal = rabbit
    ; boolean values (yes / no)
    isValid = yes
    isAnimal = no

I will be creating a GUI control for each line that is not a comment.
What is the best way to extract each line and determine if it is a string or a Boolean value.
Performance is a must as the file can be quite large.

Edit: At some point i will have need to update the values with the updated ones from the web page.

private void ShowConfig()
    {
    string configLine = String.Empty;
using (TextReader tr = File.OpenText(@"textfile"))
            {
            do
                {
                configLine = tr.ReadLine();
                if (!String.IsNullOrEmpty(configLine) && !configLine.Contains(Convert.ToChar(";")))
                    {
                    CreateControl(configLine);
                    }
                } while (configLine != null);
            }   

private void CreateControl(string configline)
    {
    string lineHeader = string.Empty;
    string lineValue = String.Empty;
    for (int i = 0; i < configline.Length; i++)
        {
        if (configline[i] == Convert.ToChar("="))
            {
            lineHeader = configline.Remove(i).TrimEnd();
            lineValue = configline.Remove(0, ++i).TrimStart();
            if (GetValueType(lineValue) is CheckBox)
                {
                this.Panel1.Controls.Add(CreateCheckBox(lineValue, lineHeader));
                }
            else
                {
                this.Panel1.Controls.Add(CreateLabel(lineHeader));
                this.Panel1.Controls.Add(CreateTextBox(lineValue, lineHeader));
                }
            this.Panel1.Controls.Add(CreateNewLine());
            break;
            }
        }
    }

private Control GetValueType(string Value)
    {
    switch (Value)
        {
        case "yes":
        case "no":
            return new CheckBox();
        default:
            return new TextBox();
        }
    }

In the future i will need to check for more value types than string and boolean.

Answer 1

How about something like this? However, I think that working any kind of serious type-recognition into this schema is likely to be error prone. Why not use a better serialization in the first place? Something that captures type info in the serialized data?

var data=@" ; comment
    data = value
    ; comment
    ; string values
    person = Bob
    animal = Rabbit
    ; boolean values (yes / no)
    isValid = yes
    isAnimal = no";

var parsed = data
    .Split(new[]{"\r\n","\r","\n"}, StringSplitOptions.RemoveEmptyEntries)
    .Select(line => line.Trim())
    .Where(line => !line.StartsWith(";"))
    .Select(line => line.Split('=').Select(item => item.Trim()))
    .Where(kv => kv.Count() == 2)
    .Select(kv => new{key = kv.First(), value = kv.Last()})
    .Select(kv => 
        new{kv.key, kv.value, isBool = Regex.IsMatch(kv.value,"yes|no")});

Taking @Rubens’ comments on-board, if the data source is too large to load in at once, you could stream the data with the addition of a helper method:

static IEnumerable<string> Lines(string filename)
{
    using (var sr = new StreamReader(filename))
    {
        while (!sr.EndOfStream)
        {
            yield return sr.ReadLine();
        }
    }
}

then:

Lines(@"c:\path\to\data")
    .Select(line => line.Trim())
    .Where(line => !line.StartsWith(";"))
    .Select(line => line.Split('=').Select(item => item.Trim()))
    .Where(kv => kv.Count() == 2)
    .Select(kv => new{key = kv.First(), value = kv.Last()})
    .Select(kv => 
        new{kv.key, kv.value, isBool = Regex.IsMatch(kv.value,"yes|no")});