Allow constructing Scopes from a string

src/scopes.rs

@@ -3,10 +3,13 @@ use std::{
     collections::HashSet,
     fmt,
     ops::BitOr,
+    str::FromStr,
 };
 
 use serde::ser::{Serialize, Serializer};
 
+use errors::Error;
+
 /// Represents a set of OAuth scopes
 ///
 /// # Example
@@ -24,6 +27,21 @@ pub struct Scopes {
     scopes: HashSet<Scope>,
 }
 
+impl FromStr for Scopes {
+    type Err = Error;
+
+    fn from_str(s: &str) -> Result<Scopes, Self::Err> {
+        let mut set = HashSet::new();
+        for scope in s.split_whitespace() {
+            let scope = Scope::from_str(&scope)?;
+            set.insert(scope);
+        }
+        Ok(Scopes {
+            scopes: set,
+        })
+    }
+}
+
 impl Serialize for Scopes {
     fn serialize<S>(&self, serializer: S) -> ::std::result::Result<S::Ok, S::Error>
     where
@@ -250,7 +268,7 @@ impl fmt::Display for Scopes {
 /// Permission scope of the application.
 /// [Details on what each permission provides][1]
 /// [1]: https://github.com/tootsuite/documentation/blob/master/Using-the-API/OAuth-details.md)
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize)]
+#[derive(Debug, Clone, Copy, PartialEq, PartialOrd, Eq, Hash, Serialize)]
 enum Scope {
     /// Read only permissions.
     #[serde(rename = "read")]
@@ -266,9 +284,25 @@ enum Scope {
     Push,
 }
 
-impl PartialOrd for Scope {
+impl FromStr for Scope {
-    fn partial_cmp(&self, other: &Scope) -> Option<Ordering> {
+    type Err = Error;
-        Some(self.cmp(other))
+
+    fn from_str(s: &str) -> Result<Scope, Self::Err> {
+        Ok(match s {
+            "read" => Scope::Read(None),
+            "write" => Scope::Write(None),
+            "follow" => Scope::Follow,
+            "push" => Scope::Push,
+            read if read.starts_with("read:") => {
+                let r: Read = Read::from_str(&read[5..])?;
+                Scope::Read(Some(r))
+            },
+            write if write.starts_with("write:") => {
+                let w: Write = Write::from_str(&write[6..])?;
+                Scope::Write(Some(w))
+            },
+            _ => return Err(Error::Other("Unknown scope".to_string())),
+        })
     }
 }
 
@@ -363,6 +397,27 @@ pub enum Read {
     Statuses,
 }
 
+impl FromStr for Read {
+    type Err = Error;
+
+    fn from_str(s: &str) -> Result<Read, Self::Err> {
+        Ok(match s {
+            "accounts" => Read::Accounts,
+            "blocks" => Read::Blocks,
+            "favourites" => Read::Favourites,
+            "filters" => Read::Filters,
+            "follows" => Read::Follows,
+            "lists" => Read::Lists,
+            "mutes" => Read::Mutes,
+            "notifications" => Read::Notifications,
+            "reports" => Read::Reports,
+            "search" => Read::Search,
+            "statuses" => Read::Statuses,
+            _ => return Err(Error::Other("Unknown 'read' subcategory".to_string())),
+        })
+    }
+}
+
 impl PartialOrd for Read {
     fn partial_cmp(&self, other: &Read) -> Option<Ordering> {
         Some(self.cmp(other))
@@ -437,6 +492,27 @@ pub enum Write {
     Statuses,
 }
 
+impl FromStr for Write {
+    type Err = Error;
+
+    fn from_str(s: &str) -> Result<Write, Self::Err> {
+        Ok(match s {
+            "accounts" => Write::Accounts,
+            "blocks" => Write::Blocks,
+            "favourites" => Write::Favourites,
+            "filters" => Write::Filters,
+            "follows" => Write::Follows,
+            "lists" => Write::Lists,
+            "media" => Write::Media,
+            "mutes" => Write::Mutes,
+            "notifications" => Write::Notifications,
+            "reports" => Write::Reports,
+            "statuses" => Write::Statuses,
+            _ => return Err(Error::Other("Unknown 'write' subcategory".to_string())),
+        })
+    }
+}
+
 impl PartialOrd for Write {
     fn partial_cmp(&self, other: &Write) -> Option<Ordering> {
         Some(self.cmp(other))
@@ -664,4 +740,51 @@ mod tests {
             assert_eq!(&ser, &expected);
         }
     }
+
+    #[test]
+    fn test_scope_from_str() {
+        let tests = [
+            ("read", Scope::Read(None)),
+            ("read:accounts", Scope::Read(Some(Read::Accounts))),
+            ("read:blocks", Scope::Read(Some(Read::Blocks))),
+            ("read:favourites", Scope::Read(Some(Read::Favourites))),
+            ("read:filters", Scope::Read(Some(Read::Filters))),
+            ("read:follows", Scope::Read(Some(Read::Follows))),
+            ("read:lists", Scope::Read(Some(Read::Lists))),
+            ("read:mutes", Scope::Read(Some(Read::Mutes))),
+            ("read:notifications", Scope::Read(Some(Read::Notifications))),
+            ("read:reports", Scope::Read(Some(Read::Reports))),
+            ("read:search", Scope::Read(Some(Read::Search))),
+            ("read:statuses", Scope::Read(Some(Read::Statuses))),
+            ("write", Scope::Write(None)),
+            ("write:accounts", Scope::Write(Some(Write::Accounts))),
+            ("write:blocks", Scope::Write(Some(Write::Blocks))),
+            ("write:favourites", Scope::Write(Some(Write::Favourites))),
+            ("write:filters", Scope::Write(Some(Write::Filters))),
+            ("write:follows", Scope::Write(Some(Write::Follows))),
+            ("write:lists", Scope::Write(Some(Write::Lists))),
+            ("write:media", Scope::Write(Some(Write::Media))),
+            ("write:mutes", Scope::Write(Some(Write::Mutes))),
+            (
+                "write:notifications",
+                Scope::Write(Some(Write::Notifications)),
+            ),
+            ("write:reports", Scope::Write(Some(Write::Reports))),
+            ("write:statuses", Scope::Write(Some(Write::Statuses))),
+            ("follow", Scope::Follow),
+            ("push", Scope::Push),
+        ];
+        for (source, expected) in &tests {
+            let result = Scope::from_str(source).expect(&format!("Couldn't parse '{}'", &source));
+            assert_eq!(result, *expected);
+        }
+    }
+
+    #[test]
+    fn test_scopes_str_round_trip() {
+        let original = "read write follow push";
+        let scopes = Scopes::from_str(original).expect("Couldn't convert to Scopes");
+        let result = format!("{}", scopes);
+        assert_eq!(original, result);
+    }
 }