Add WorkspaceMember

The implementation of WorkspaceMember is almost identical to PackageId in cargo.
The difference is that its deserialization is simplified and it does not use
Arc internally.

Cargo.toml

@@ -8,6 +8,7 @@ license = "MIT"
 readme = "README.md"
 
 [dependencies]
+cargo = "0.23"
 error-chain = "0.11.0"
 serde = "1.0.2"
 serde_derive = "1.0.2"

src/lib.rs

@@ -73,6 +73,7 @@
 //!     cargo_metadata::metadata(matches.value_of("manifest-path").map(Path::new)).unwrap();
 //! ```
 
+extern crate cargo;
 #[macro_use]
 extern crate error_chain;
 extern crate semver;
@@ -87,8 +88,10 @@ use std::path::Path;
 use std::process::Command;
 use std::str::from_utf8;
 
+use cargo::core::source::SourceId;
 pub use errors::{Error, ErrorKind, Result};
 pub use dependency::{Dependency, DependencyKind};
+use serde::de;
 
 mod errors;
 mod dependency;
@@ -99,8 +102,7 @@ pub struct Metadata {
     /// A list of all crates referenced by this crate (and the crate itself)
     pub packages: Vec<Package>,
     /// A list of all workspace members
-    #[serde(default)]
-    pub workspace_members: Vec<String>,
+    pub workspace_members: Vec<WorkspaceMember>,
     /// Dependencies graph
     pub resolve: Option<Resolve>,
     version: usize,
@@ -159,12 +161,44 @@ pub struct Target {
     pub src_path: String,
 }
 
+#[derive(Clone, Debug)]
+/// A workspace member. This is basically identical to `cargo::core::package_id::PackageId`, expect
+/// that this does not use `Arc` internally.
+pub struct WorkspaceMember {
+    /// A name of workspace member.
+    pub name: String,
+    /// A version of workspace member.
+    pub version: semver::Version,
+    /// A source id of workspace member.
+    pub url: SourceId,
+}
+
+impl<'de> de::Deserialize<'de> for WorkspaceMember {
+    fn deserialize<D>(d: D) -> std::result::Result<WorkspaceMember, D::Error>
+    where
+        D: de::Deserializer<'de>,
+    {
+        let string = String::deserialize(d)?;
+        let mut s = string.splitn(3, ' ');
+        let name = s.next().unwrap();
+        let version = s.next().unwrap();
+        let version = semver::Version::parse(&version).map_err(de::Error::custom)?;
+        let url = &s.next().unwrap();
+        let url = &url[1..url.len() - 1];
+        Ok(WorkspaceMember {
+            name: name.to_owned(),
+            version: version,
+            url: SourceId::from_url(&url).unwrap(),
+        })
+    }
+}
+
 /// Obtain metadata only about the root package and don't fetch dependencies
 ///
 /// # Parameters
 ///
 /// - `manifest_path`: Path to the manifest.
-pub fn metadata(manifest_path: Option<&Path>) -> Result<Metadata> {
+pub fn metadata(manifest_path: Option<&Path>) -> errors::Result<Metadata> {
     metadata_deps(manifest_path, false)
 }
 
@@ -174,7 +208,7 @@ pub fn metadata(manifest_path: Option<&Path>) -> Result<Metadata> {
 ///
 /// - `manifest_path`: Path to the manifest.
 /// - `deps`: Whether to include dependencies.
-pub fn metadata_deps(manifest_path: Option<&Path>, deps: bool) -> Result<Metadata> {
+pub fn metadata_deps(manifest_path: Option<&Path>, deps: bool) -> errors::Result<Metadata> {
     let cargo = env::var("CARGO").unwrap_or_else(|_| String::from("cargo"));
     let mut cmd = Command::new(cargo);
     cmd.arg("metadata");