libproc_macro: Implement Display for TokenStream

Implement the Display trait for the external rust structure TokenStream.

ChangeLog:

	* librust/proc_macro/rust/bridge/token_stream.rs: Add internal
	TokenStream Display implementation.
	* librust/proc_macro/rust/lib.rs: Add external Display
	implementation for TokenStream.

Signed-off-by: Pierre-Emmanuel Patry <pierre-emmanuel.patry@embecosm.com>

2 files changed, 28 insertions, 2 deletions

diff --git a/librust/proc_macro/rust/bridge/token_stream.rs b/librust/proc_macro/rust/bridge/token_stream.rs
index 027f450..2ddde8e 100644
--- a/librust/proc_macro/rust/bridge/token_stream.rs
+++ b/librust/proc_macro/rust/bridge/token_stream.rs
@@ -1,5 +1,7 @@
 use bridge::{group::Group, ident::Ident, literal::Literal, punct::Punct};
 use std::convert::TryInto;
+use std::fmt;
+use std::slice;
 
 type ExternalTokenTree = crate::TokenTree;
 type ExternalTokenStream = crate::TokenStream;
@@ -17,6 +19,17 @@ pub enum TokenTree {
     Literal(Literal),
 }
 
+impl fmt::Display for TokenTree {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            TokenTree::Group(group) => group.fmt(f),
+            TokenTree::Ident(ident) => ident.fmt(f),
+            TokenTree::Punct(punct) => punct.fmt(f),
+            TokenTree::Literal(literal) => literal.fmt(f),
+        }
+    }
+}
+
 impl From<ExternalTokenTree> for TokenTree {
     fn from(value: ExternalTokenTree) -> Self {
         match value {
@@ -103,3 +116,16 @@ impl Extend<ExternalTokenStream> for TokenStream {
         }
     }
 }
+
+impl fmt::Display for TokenStream {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        for i in unsafe { slice::from_raw_parts(self.data, self.size.try_into().unwrap()) } {
+            i.fmt(f)?;
+            match i {
+                TokenTree::Punct(_) => (),
+                _ => f.write_str(" ")?,
+            }
+        }
+        Ok(())
+    }
+}
diff --git a/librust/proc_macro/rust/lib.rs b/librust/proc_macro/rust/lib.rs
index 13f66f0..aa90a51 100644
--- a/librust/proc_macro/rust/lib.rs
+++ b/librust/proc_macro/rust/lib.rs
@@ -154,8 +154,8 @@ impl TokenStream {
 }
 
 impl fmt::Display for TokenStream {
-    fn fmt(&self, _f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        todo!("Implement this function")
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.0.fmt(f)
     }
 }