Replace with values a given pattern in a string

Question

Given a file with this format

// Colour
$primary-colour: if(@Model.PrimaryColour, @primaryColour, #afd05c);
$secondary-colour: if(@secondaryColour, @secondaryColour, #323f47);
// and so on

I'm trying to replace the @Model.Whatever based on a dictionary with would be something like this

var dictionary = new Dictionary<string, string>
{
    {"primaryColour", "blue"},
    {"secondaryColour", "red"}
};

But I'm struggling to find a way to so.

I was thinking of doing something like this:

private static String Replace(String str)
{
    var dictionary = new Dictionary<string, string>
    {
        {"primaryColour", "blue"},
        {"secondaryColour", "red"}
    };

    string variableValue;
    string pattern = @"@Model.(?<name>\w)";
    dictionary.TryGetValue(FirstCharacterToLower("${name}"), out variableValue);
    var replacePattern = String.Format("{0}", variableValue);
    return Regex.Replace(str, pattern, replacePattern, RegexOptions.IgnoreCase);
}

private static string FirstCharacterToLower(string str)
{
    Console.WriteLine(str);
    if (String.IsNullOrEmpty(str) || Char.IsLower(str, 0))
        return str;

    return Char.ToLowerInvariant(str[0]) + str.Substring(1);
}

But what I'm passing to the FirstCharacterToLower is just a string {name} and I'm stuck there. Can't think of a way to do it.

Any idea where to go from here?

Thanks

Edit: Based on sln comment I made this and it works

using System;
using System.Text.RegularExpressions;
using System.Collections.Generic;

public class Program
{
    public static void Main()
    {

        var input = @"
            // Colour
            $primary-colour: if(@Model.PrimaryColour, @Model.PrimaryColour, #afd05c);
            $secondary-colour: if(@Model.SecondaryColour, @Model.SecondaryColour, #323f47);";

        Console.WriteLine(Replace(input));
    }

    private static String Replace(String str)
    {
        var dictionary = new Dictionary<string, string>
        {
            {"primaryColour", "blue"},
            {"secondaryColour", "red"}
        };

        var regex = new Regex(@"@Model\.(?<name>\w+)");

        var output = regex.Replace(str, v => 
            {
                string outVariable;
                dictionary.TryGetValue(GetNameOfVariable(v.Groups["name"].Value), out outVariable);
                return outVariable;
            });

        return output;
    }

    private static string GetNameOfVariable(string str)
    {
        Console.WriteLine(str);
        if (String.IsNullOrEmpty(str) || Char.IsLower(str, 0))
            return str;

        return Char.ToLowerInvariant(str[0]) + str.Substring(1);
    }
}

@AvinashRaj, but still passing just ${name} to the FirstCharacterToLower, is there any way I can access that named group as a normal variable? — mitomed
– mitomed, Commented Aug 18, 2015 at 15:59
Use a replace delegate. Also its not clear what you are trying to find. You just need to make a regex that matches any key you're looking for, replace the value inside the delegate (callback). — user557597
– user557597, Commented Aug 18, 2015 at 16:12
Thanks @sln, I eventually made it work based on your comment — mitomed
– mitomed, Commented Aug 18, 2015 at 16:39

Ulugbek Umirov · Accepted Answer · 2015-08-18 16:37:32Z

1

As @sln told, you have to use delegate.

private static String Replace(String str)
{
    var dictionary = new Dictionary<string, string>
    {
        {"primaryColour", "blue"},
        {"secondaryColour", "red"}
    };

    string pattern = @"@Model\.(?<name>\w+)";
    return Regex.Replace(str, pattern, m => 
        {
            string key = m.Groups["name"].Value;
            key = FirstCharacterToLower(key);
            string value = null;
            if (dictionary.TryGetValue(key, out value))
                return value;
            else
                return m.Value;
        });
}

answered Aug 18, 2015 at 16:37

Ulugbek Umirov

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1 Comment

mitomed Over a year ago

Yeah, got tot pretty much the same solution as per my edit. But definitely this works

user557597 · Accepted Answer · 2015-08-18 16:38:04Z

1

You'd be better off describing a general regex that matches all your
keys. Then using a delegate replacement.

var dictionary = new Dictionary<string, string>
{
    {"primarycolour", "blue"},
    {"secondarycolour", "red"}
};

string line_original =
@"
// Colour
$primary-colour: if(@Model.PrimaryColour, @primaryColour, #afd05c);
$secondary-colour: if(@secondaryColour, @secondaryColour, #323f47);
// and so on
";

Regex RxColors = new Regex( @"@Model\.(?<name>\w+)" );
string line_new = RxColors.Replace(
    line_original,
    delegate(Match match)
    {
        string outVal;
        if ( dictionary.TryGetValue( match.Groups["name"].Value.ToLower(), out outVal) )
            return outVal;
        return match.Groups[0].Value;
    }
);
Console.WriteLine("New line: \r\n\r\n{0}", line_new );

Output:

New line:

// Colour
$primary-colour: if(blue, @primaryColour, #afd05c);
$secondary-colour: if(@secondaryColour, @secondaryColour, #323f47);
// and so on

answered Aug 18, 2015 at 16:38

user557597

1 Comment

mitomed Over a year ago

Thanks, worked on it at the same time based on sln comment

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