Add List::empty() to allow creating an empty list

Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "publicsuffix"
-description = "A robust and reliable library for parsing domain names"
-version = "1.3.1"
+description = "Robust domain name parsing and RFC compliant email address validation"
+version = "1.3.2"
 license = "MIT/Apache-2.0"
 repository = "https://github.com/rushmorem/publicsuffix"
 documentation = "https://docs.rs/publicsuffix"

README.md

@@ -1,8 +1,8 @@
-# A Rust library for robust domain name parsing
+# Robust domain name parsing and RFC compliant email address validation
 
 [![Build Status](https://travis-ci.org/rushmorem/publicsuffix.svg?branch=master)](https://travis-ci.org/rushmorem/publicsuffix) [![Latest Version](https://img.shields.io/crates/v/publicsuffix.svg)](https://crates.io/crates/publicsuffix) [![Docs](https://docs.rs/publicsuffix/badge.svg)](https://docs.rs/publicsuffix)
 
-This library uses Mozilla's [Public Suffix List](https://publicsuffix.org) to reliably parse domain names in [Rust](https://www.rust-lang.org). Though parsing domain names is it's primary goal, it also fully exposes the list allowing you to use convenient methods like `list.all()` to get all known domain extensions or `list.icann()` to get only ICANN extensions.
+This library uses Mozilla's [Public Suffix List](https://publicsuffix.org) to reliably parse domain names and email addresses in [Rust](https://www.rust-lang.org). Though parsing domain names is it's primary goal, it also fully exposes the list allowing you to use convenient methods like `list.all()` to get all known domain extensions or `list.icann()` to get only ICANN extensions.
 
 If all you need is to check whether a domain is syntactically correct and do not need to utilise the list you can just use `Domain::has_valid_syntax` method. This method will reliably tell you if a domain has valid syntax whether or not it is an internationalised domain name (IDN). It also checks the length restrictions for each label, total number of labels and full length of domain name.
 

src/lib.rs

@@ -266,9 +266,7 @@ impl List {
 
     fn build(res: String) -> Result<List> {
         let mut typ = None;
-        let mut list = List {
-            rules: HashMap::new(),
-        };
+        let mut list = List::empty();
         for line in res.lines() {
             match line {
                 line if line.contains("BEGIN ICANN DOMAINS") => { typ = Some(Type::Icann); }
@@ -294,6 +292,17 @@ impl List {
         Ok(list)
     }
 
+    /// Creates an empty List without any rules
+    ///
+    /// Sometimes all you want is to do syntax checks. If you don't really care whether
+    /// the domain has a known suffix or not you can just create an empty list and use
+    /// that to parse domain names and email addresses.
+    pub fn empty() -> List {
+        List {
+            rules: HashMap::new(),
+        }
+    }
+
     /// Pull the list from a URL
     #[cfg(feature = "remote_list")]
     pub fn from_url<U: IntoUrl>(url: U) -> Result<List> {