support for substring

[drewburlingame]

i can see that ToLower and ToUpper are both supported string extensions, but didn't see support for Substring. Is Substring supported and I'm missing it? If not, do you think it would be trivial to support?

Thanks,
Drew

[axunonb]

You can only use methods without parameters. Implementing parameters is not that trivial.

[arilani]

I've created a substring extension:
`using System;
using System.Collections.Generic;
using SmartFormat.Core.Extensions;
using SmartFormat.Core.Parsing;

namespace SmartFormat.Extensions
{
public class SubstringFormatter : IFormatter
{
public string[] Names { get; set; } = { "substring", "substr", "s", "mid" };

    private char _parametersSepChar = ',';
    public char ParametersSepChar { get { return _parametersSepChar;  } set { _parametersSepChar = value; } }

    public bool TryEvaluateFormat(IFormattingInfo formattingInfo)
    {
        if (formattingInfo.FormatterOptions == "") return false;
        string[] parameters = formattingInfo.FormatterOptions.Split(_parametersSepChar);
        if (parameters.Length < 1) return false;

        object currentValue = formattingInfo.CurrentValue;
        string currentValueString = (currentValue == null) ? "null" : currentValue.ToString();

        int startPos = int.Parse(parameters[0]);
        int length = parameters.Length > 1 ? int.Parse(parameters[1]) : 0;
        if (startPos < 0)
            startPos = currentValueString.Length + startPos;
        if (startPos > currentValueString.Length)
            startPos = currentValueString.Length;
        if (length < 0)
            length = currentValueString.Length - startPos + length;
        if (startPos + length > currentValueString.Length)
            length = 0;
        string substring = parameters.Length > 1 ? currentValueString.Substring(startPos, length) : currentValueString.Substring(startPos);

        formattingInfo.Write(substring);

        return true;
    }
}

}`

Here you can found some examples:
Example: #1: {Person.Name} starts with {Person.Name:s(0,3)} #2: {Person.Name} ends with {Person.Name:substr(-3)} #3: {Person.Name} ends with {Person.Name:substr(5)} #4: {Person.Name} contains {Person.Name:substring(2,-2)} #5: {Person.Name} not contains {Person.Name:mid(20,10)}

[axunonb]

Hi, that's very good, thank you!
I plan to add section for contributed extensions in the repo and I'll add yours as soon as time allows.

[axunonb]

Do you think your request could be covered with feature request #88 (using RegEx). RegEx will bring about 50% performance penalty, though.

[scottrippey]

I really like this!
I think substr is a very common use-case, and this extension proves it's pretty simple, so I think it would make sense to include it in the core.
Just my 2¢ ;)

[arilani]

Thanks!

[mweaver026]

Is there any plan on when another release would be created and pushed to Nuget with this feature included?

[axunonb]

Release 2.3.1.0 is published, covering this feature.

[mweaver026]

Thank you! I appreciate the quick response.