Conceptual documentation was updated

docs/articles/getting_started.md

@@ -150,4 +150,20 @@ catch(FileNotFoundException ex)
 }
 ```
 
+### Interpolating variables
+
+Sometimes you will need to interpolate variables within a value, for example:
+```
+MYSQL_USER=root
+MYSQL_ROOT_PASSWORD=1234
+CONNECTION_STRING=username=${MYSQL_USER};password=${MYSQL_ROOT_PASSWORD};database=testdb;
+```
+If the variable embedded in the value does not exist in the current process, the parser will throw an exception, for example:
+```
+CONNECTION_STRING=username=${MYSQL_USER};password=${MYSQL_ROOT_PASSWORD};database=testdb;
+MYSQL_USER=root
+MYSQL_ROOT_PASSWORD=1234
+```
+In the above example, the parser should throw an exception because the `MYSQL_USER` variable does not exist yet.
+
 **Note:** If you don't know what each class does, don't forget to check the [API documentation](xref:DotEnv.Core).

docs/articles/more_options_for_loader.md

@@ -22,6 +22,16 @@ new EnvLoader()
 ```
 This method will tell the parser not to remove trailing white-spaces from the keys.
 
+## DisableTrimKeys
+
+Disables the trim at the start and end of the keys:
+```cs
+new EnvLoader()
+    .DisableTrimKeys()
+    .Load();
+```
+This method will tell the parser not to remove leading and trailing white-spaces from the keys.
+
 ## DisableTrimStartValues
 
 Disable the trim at the beginning of the values:
@@ -42,6 +52,16 @@ new EnvLoader()
 ```
 This method will tell the parser not to remove trailing white-spaces from the values.
 
+## DisableTrimValues
+
+Disables the trim at the start and end of the values:
+```cs
+new EnvLoader()
+    .DisableTrimValues()
+    .Load();
+```
+This method will tell the parser not to remove leading and trailing white-spaces from the values.
+
 ## DisableTrimStartComments
 
 Disable the trim at the beginning of the comments:
@@ -62,4 +82,71 @@ new EnvLoader()
 ```
 Imagine that if there is an environment variable called `KEY1` whose value is `1`, then in an .env file there can be a key named `KEY1` whose value is `2`, if this option is enabled, then, when the parser reads `KEY1` from the .env file, it will overwrite the value of `KEY1` by `2`.
 
+## AllowConcatDuplicateKeys
+
+Allows to concatenate the values of the duplicate keys:
+```cs
+new EnvLoader()
+    .AllowConcatDuplicateKeys()
+    .Load();
+```
+This method will by default concatenate to the end of the value, for example, imagine you have the following .env file:
+```
+KEY1 = Hello
+KEY1 = World
+KEY1 = !
+```
+The parser will concatenate the duplicate keys in this way:
+```
+KEY1 = HelloWorld!
+```
+But we can also tell the parser to concatenate at the beginning of the value using `ConcatKeysOptions` enum:
+```cs
+new EnvLoader()
+    .AllowConcatDuplicateKeys(ConcatKeysOptions.Start)
+    .Load();
+```
+So if we follow the above example, the parser will concatenate the duplicate keys in this way:
+```
+KEY1 = !WorldHello
+```
+
+## IgnoreParserExceptions
+
+Ignores parser exceptions. By calling this method the parser will not throw any exceptions when it encounters an error:
+```cs
+new EnvLoader()
+    .IgnoreParserExceptions()
+    .Load();
+```
+
+## SetCommentChar
+
+Sets the character that will define the beginning of a comment:
+```cs
+new EnvLoader()
+    .SetCommentChar(';')
+    .Load();
+```
+So the .env file could look like this:
+```
+; comment (1)
+KEY1=VAL1
+; comment (2)
+```
+
+## SetDelimiterKeyValuePair
+
+Sets the delimiter that separates an assigment of a value to a key:
+```cs
+new EnvLoader()
+    .SetDelimiterKeyValuePair(':')
+    .Load();
+```
+So the .env file could look like this:
+```
+KEY1: VAL1
+KEY2: VAL2
+```
+
 **As a side note**, the `EnvLoader` class has a parameterized constructor in which you can specify a custom parser. You can inherit from `EnvParser` and inject the instance into the constructor.

docs/articles/using_parser.md

@@ -45,7 +45,7 @@ Don't forget to look up in the [API documentation](xref:DotEnv.Core.EnvParserOpt
 
 ## Customizing the parser algorithm
 
-You can also create a class that inherits from `EnvParser` and then you can override its methods:
+You can also create a class that inherits from `EnvParser` and then you can override its methods (each of these methods are used by the [parser algorithm](xref:DotEnv.Core.EnvParser.Parse(System.String))):
 ```cs
 class CustomEnvParser : EnvParser
 {
@@ -73,6 +73,16 @@ class CustomEnvParser : EnvParser
     {
         // Here you can add your own implementation.
     }
+
+    protected override string ConcatValues(string currentValue, string value)
+    {
+        // Here you can add your own implementation.
+    }
+
+    protected override string ExpandEnvironmentVariables(string value, int lineNumber)
+    {
+        // Here you can add your own implementation.
+    }
 }
 ```
 This is useful when you need to customize the parser and change its internal behavior.