Xamarin.Mobile : T4 template to generate resource keys from GNU PO files

AppResources.tr.po

msgid ""
msgstr ""
"Project-Id-Version: MyProject\n"
"Report-Msgid-Bugs-To: \n"
"POT-Creation-Date: \n"
"PO-Revision-Date: \n"
"Last-Translator: Ali Özgür\n"
"Language-Team: Turkish\n"
"MIME-Version: 1.0\n"
"Content-Type: text/plain; charset=UTF-8\n"
"Content-Transfer-Encoding: 8bit\n"
"X-Generator: Poedit 1.6.9\n"
"Plural-Forms: nplurals=2; plural=n > 1;\n"
"Language: tr_TR\n"
# use http://converter.webtranslateit.com/ to convert to RESX

msgid "AppName"
msgstr "My locale value"

msgid "Placeholder_Username"
msgstr "My locale value"

msgid "Placeholder_Password"
msgstr "My locale value"

POKeyGenerator.tt

<#@ template language="C#" hostspecific="true" debug="true"#>
<#@ assembly name="System.Core" #>
<#@ import namespace="System.Linq" #>
<#@ import namespace="System.Text" #>
<#@ import namespace="System.Collections.Generic" #>
<#@ import namespace="System.IO" #>
<#@ import namespace="System.Text.RegularExpressions" #>
<#@ import namespace="System.Diagnostics" #>

namespace VoltPms
{
    ///<summary> 
	/// This is an auto generated file. Do not modify
	/// Generated by POKeyGenerator.tt 
	///</summary> 
	public class K
	{ 
 		<# 
 		 	var propNames = ParsePo();
 		 	foreach(var propName in propNames)
 		 	{
 		#>
		public const string <#=propName#> = "<#=propName#>";
 		<#
 			}
 		#>
	
	}
}

<#+
    
    private List<string> ParsePo()
    {
    	List<string> result = new List<string>();
        var path = Host.ResolvePath("./Resx/AppResources.tr.po");
       
        if(String.IsNullOrWhiteSpace(path))
        	return result;
        return ReadMsgIdLines(path);
    }

    public  List<string> ReadMsgIdLines(string path)
    {
            List<string> result = new List<string>();
            Regex regex = new Regex("\\s*msgid\\s*\\\"(?<propName>\\s*.*\\s*)\\\"");
            string line = String.Empty;

            System.IO.StreamReader file =  new System.IO.StreamReader(path);
            while((line = file.ReadLine()) != null)
            {
                var m = regex.Match(line);
                if (m == null || !m.Success)
                    continue;

                var propName = m.Groups["propName"];
				if(propName == null || String.IsNullOrWhiteSpace(propName.Value))
					continue;	

                result.Add(propName.Value);
            }
            return result;
    }
#>

More about GNU PO file format can be found here https://www.gnu.org/software/gettext/manual/html_node/PO-Files.html