Move 'Envrionment' into its own source

3 files changed, 47 insertions, 70 deletions

diff --git a/src/config.rs b/src/config.rs
index 42e6c5c..e5b25f6 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -1,14 +1,11 @@
 use value::Value;
 use source::{Source, SourceBuilder};
 
-use std::env;
 use std::error::Error;
 use std::collections::HashMap;
 
 #[derive(Default)]
 pub struct Config {
-    env_prefix: Option<String>,
-
     defaults: HashMap<String, Value>,
     overrides: HashMap<String, Value>,
     sources: Vec<Box<Source>>,
@@ -28,15 +25,6 @@ impl Config {
         Ok(())
     }
 
-    /// Defines a prefix that environment variables
-    /// must start with to be considered.
-    ///
-    /// By default all environment variables are considered. This can lead to unexpected values
-    /// in configuration (eg. `PATH`).
-    pub fn set_env_prefix(&mut self, prefix: &str) {
-        self.env_prefix = Some(prefix.to_uppercase());
-    }
-
     /// Sets the default value for this key. The default value is only used
     /// when no other value is provided.
     pub fn set_default<T>(&mut self, key: &str, value: T)
@@ -59,23 +47,6 @@ impl Config {
             return Some(value.clone());
         }
 
-        // Check environment
-
-        // Transform key into an env_key which is uppercased
-        // and has the optional prefix applied
-        let mut env_key = String::new();
-
-        if let Some(ref env_prefix) = self.env_prefix {
-            env_key.push_str(env_prefix);
-            env_key.push('_');
-        }
-
-        env_key.push_str(&key.to_uppercase());
-
-        if let Ok(value) = env::var(env_key.clone()) {
-            return Some(Value::from(value));
-        }
-
         // Check sources
 
         for source in &mut self.sources.iter().rev() {
@@ -118,44 +89,11 @@ mod test {
     // Retrieval of a non-existent key
     #[test]
     fn test_not_found() {
-        let mut c = Config::new();
+        let c = Config::new();
 
         assert_eq!(c.get_int("key"), None);
     }
 
-    // // Environment override
-    // #[test]
-    // fn test_env_override() {
-    //     let mut c = Config::new();
-
-    //     c.set_default("key_1", false);
-
-    //     env::set_var("KEY_1", "1");
-
-    //     assert_eq!(c.get_bool("key_1"), Some(true));
-
-    //     // TODO(@rust): Is there a way to easily kill this at the end of a test?
-    //     env::remove_var("KEY_1");
-    // }
-
-    // // Environment prefix
-    // #[test]
-    // fn test_env_prefix() {
-    //     let mut c = Config::new();
-
-    //     env::set_var("KEY_1", "1");
-    //     env::set_var("CFG_KEY_2", "false");
-
-    //     c.set_env_prefix("CFG");
-
-    //     assert_eq!(c.get_bool("key_1"), None);
-    //     assert_eq!(c.get_bool("key_2"), Some(false));
-
-    //     // TODO(@rust): Is there a way to easily kill this at the end of a test?
-    //     env::remove_var("KEY_1");
-    //     env::remove_var("CFG_KEY_2");
-    // }
-
     // Explicit override
     #[test]
     fn test_default_override() {
diff --git a/src/env.rs b/src/env.rs
new file mode 100644
index 0000000..612b97d
--- /dev/null
+++ b/src/env.rs
@@ -0,0 +1,43 @@
+use std::env;
+use std::error::Error;
+
+use source;
+use value::Value;
+
+#[derive(Clone)]
+pub struct Environment {
+    /// Optional prefix that would restrict environment consideration
+    /// to only variables which begin with that prefix.
+    prefix: Option<String>,
+}
+
+impl Environment {
+    pub fn new<'a, T>(prefix: T) -> Environment
+        where T: Into<Option<&'a str>>
+    {
+        Environment { prefix: prefix.into().map(String::from) }
+    }
+}
+
+impl source::SourceBuilder for Environment {
+    fn build(&self) -> Result<Box<source::Source>, Box<Error>> {
+        Ok(Box::new(self.clone()))
+    }
+}
+
+impl source::Source for Environment {
+    fn get(&self, key: &str) -> Option<Value> {
+        let mut env_key = String::new();
+
+        // Apply prefix
+        if let Some(ref prefix) = self.prefix {
+            env_key.push_str(prefix);
+            env_key.push('_');
+        }
+
+        env_key.push_str(&key.to_uppercase());
+
+        // Attempt to retreive environment variable and coerce into a Value
+        env::var(env_key.clone()).ok().map(Value::from)
+    }
+}
diff --git a/src/lib.rs b/src/lib.rs
index 99a6da3..0fa3d70 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -10,6 +10,7 @@ extern crate serde_json;
 mod value;
 mod source;
 mod file;
+mod env;
 mod config;
 
 use std::error::Error;
@@ -17,6 +18,7 @@ use std::sync::{Once, ONCE_INIT};
 
 pub use source::{Source, SourceBuilder};
 pub use file::{File, FileFormat};
+pub use env::Environment;
 
 pub use value::Value;
 
@@ -29,9 +31,7 @@ static CONFIG_INIT: Once = ONCE_INIT;
 // Get the global configuration instance
 fn global() -> &'static mut Config {
     unsafe {
-        CONFIG_INIT.call_once(|| {
-            CONFIG = Some(Default::default());
-        });
+        CONFIG_INIT.call_once(|| { CONFIG = Some(Default::default()); });
 
         CONFIG.as_mut().unwrap()
     }
@@ -43,10 +43,6 @@ pub fn merge<T>(source: T) -> Result<(), Box<Error>>
     global().merge(source)
 }
 
-pub fn set_env_prefix(prefix: &str) {
-    global().set_env_prefix(prefix)
-}
-
 pub fn set_default<T>(key: &str, value: T)
     where T: Into<Value>
 {