Add a simple example of library use.

Specifically for internment without any static values.

Author: Richard Dodd

examples/simple.rs

@@ -0,0 +1,26 @@
+extern crate string_cache;
+
+use string_cache::{DefaultAtom, Atom};
+
+fn main() {
+
+    let mut interned_stuff = Vec::new();
+    let text = "here is a sentence of text that will be tokenised and interned and some repeated \
+                tokens is of text and";
+    for word in text.split_whitespace() {
+        let seen_before = interned_stuff.iter()
+            // We can use impl PartialEq<T> where T is anything string-like to compare to
+            // interned strings to either other interned strings, or actual strings  Comparing two
+            // interned strings is very fast (normally a single cpu operation).
+            .filter(|interned_word| interned_word == &word)
+            .count();
+        if seen_before > 0 {
+            println!(r#"Seen the word "{}" {} times"#, word, seen_before);
+        } else {
+            println!(r#"Not seen the word "{}" before"#, word);
+        }
+        // We use the impl From<(Cow<'a, str>, or &'a str, or String) for Atom<Static> to intern a
+        // new string
+        interned_stuff.push(DefaultAtom::from(word));
+    }
+}