Added support for modifying nugget translation at runtime. (#300)

Author: turquoiseowl

Diff for: README.md

@@ -91,6 +91,19 @@ code shows the most common options:
             // the message in the default language. Defaults to true.
             //i18n.LocalizedApplication.Current.MessageKeyIsValueInDefaultLanguage = false;
 
+            // Specifies a custom method called after a nugget has been translated
+            // that allows the resulting message to be modified, for instance according to content type.
+            // See [Issue #300](https://github.com/turquoiseowl/i18n/issues/300) for example usage case.
+            i18n.LocalizedApplication.Current.TweakMessageTranslation = delegate(System.Web.HttpContextBase context, i18n.Helpers.Nugget nugget, i18n.LanguageTag langtag, string message)
+            {
+                switch (context.Response.ContentType)
+                {
+                    case "text/html":
+                        return message.Replace("\'", "'");
+                }
+                return message;
+            };
+
             // Blacklist certain URLs from being 'localized' via a callback.
             i18n.UrlLocalizer.IncomingUrlFilters += delegate(Uri url) {
                 if (url.LocalPath.EndsWith("sitemap.xml", StringComparison.OrdinalIgnoreCase)) {
@@ -409,6 +422,29 @@ locale/es/messages.po
 locale/es-MX/messages.po
 ```
 
+#### Custom Modifications To Translations
+
+Nuggets translations can be modified at runtime as follows:
+
+```
+    protected void Application_Start()
+    {
+        ...
+        // Specifies a custom method called after a nugget has been translated
+        // that allows the resulting message to be modified, for instance according to content type.
+        // See [Issue #300](https://github.com/turquoiseowl/i18n/issues/300) for example usage case.
+        i18n.LocalizedApplication.Current.TweakMessageTranslation = delegate(System.Web.HttpContextBase context, i18n.Helpers.Nugget nugget, i18n.LanguageTag langtag, string message)
+        {
+            switch (context.Response.ContentType)
+            {
+                case "text/html":
+                    return message.Replace("\'", "'");
+            }
+            return message;
+        };
+    }
+```
+
 ### URL Localization
 
 In keeping with emerging standards for internationalized web applications, i18n provides support for

Diff for: src/i18n/Concrete/NuggetLocalizer.cs

@@ -93,6 +93,13 @@ public string ProcessNuggets(string entity, LanguageItem[] languages)
                         message += "[FORMAT EXCEPTION]";
                     }
                 }
+               // Optional late custom message translation modification.
+                if (LocalizedApplication.Current.TweakMessageTranslation != null) {
+                    message = LocalizedApplication.Current.TweakMessageTranslation(
+                        System.Web.HttpContext.Current.GetHttpContextBase(),
+                        nugget,
+                        lt,
+                        message); }
                // Output modified message (to be subsituted for original in the source entity).
                 DebugHelpers.WriteLine("I18N.NuggetLocalizer.ProcessNuggets -- msgid: {0,35}, message: {1}", nugget.MsgId, message);
                //

Diff for: src/i18n/LocalizedApplication.cs

@@ -2,6 +2,7 @@
 using System.Threading;
 using System.Text.RegularExpressions;
 using i18n.Domain.Helpers;
+using i18n.Helpers;
 using i18n.Domain.Abstract;
 using i18n.Domain.Concrete;
 
@@ -179,6 +180,39 @@ public string DefaultLanguage
         /// </remarks>
         public SetLanguageHandler SetPrincipalAppLanguageForRequestHandlers { get; set; }
 
+        /// <summary>
+        /// Declares a method type for a custom method called after a nugget has been translated
+        /// that allows the resulting message to be modified.
+        /// </summary>
+        /// <remarks>
+        /// In general it is good practice to postpone the escaping of characters until they 
+        /// are about to be displayed and then according to the content type of the output.
+        /// Thus, a single quote character need not be escaped if in JSON, but should be escaped
+        /// if in HTML or Javascript.
+        /// This method allows for such conditional modification of the message.
+        /// </remarks>
+        /// <param name="context">Current http context.</param>
+        /// <param name="nugget">The subject nugget being translated.</param>
+        /// <param name="langtag">Language being set.</param>
+        /// <param name="message">The message string which may be modified.</param>
+        /// <returns>
+        /// Modified message string (or message if no modification).
+        /// </returns>
+        public delegate string TweakMessageTranslationProc(System.Web.HttpContextBase context, Nugget nugget, LanguageTag langtag, string message);
+
+        /// <summary>
+        /// Registers a custom method called after a nugget has been translated
+        /// that allows the resulting message to be modified.
+        /// </summary>
+        /// <remarks>
+        /// In general it is good practice to postpone the escaping of characters until they 
+        /// are about to be displayed and then according to the content type of the output.
+        /// This, a single quote character need not be escaped if in JSON, but should be escaped
+        /// if in HTML or Javascript.
+        /// This method allows for such conditional modification of the message.
+        /// </remarks>
+        public TweakMessageTranslationProc TweakMessageTranslation { get; set; }
+
         /// <summary>
         /// Specifies the type of HTTP redirect to be issued by automatic language routing:
         /// true for 301 (permanent) redirects; false for 302 (temporary) ones.