Fix padded code (text) in mdast

Closes GH-122.
Closes GH-123.

Reviewed-by: Titus Wormer <tituswormer@gmail.com>

src/to_mdast.rs

@@ -1080,6 +1080,16 @@ fn on_exit_raw_text(context: &mut CompileContext) -> Result<(), message::Message
         }
     }
 
+    let value_bytes = value.as_bytes();
+    if value.len() > 2
+        && value_bytes[0] == b' '
+        && value_bytes[value.len() - 1] == b' '
+        && !value_bytes.iter().all(|b| *b == b' ')
+    {
+        value.remove(0);
+        value.pop();
+    }
+
     match context.tail_mut() {
         Node::InlineCode(node) => node.value = value,
         Node::InlineMath(node) => node.value = value,

tests/code_text.rs

@@ -205,5 +205,35 @@ fn code_text() -> Result<(), message::Message> {
         "should support code (text) as `InlineCode`s in mdast"
     );
 
+    assert_eq!(
+        to_mdast("`  alpha `", &Default::default())?,
+        Node::Root(Root {
+            children: vec![Node::Paragraph(Paragraph {
+                children: vec![Node::InlineCode(InlineCode {
+                    value: " alpha".into(),
+                    position: Some(Position::new(1, 1, 0, 1, 11, 10))
+                }),],
+                position: Some(Position::new(1, 1, 0, 1, 11, 10))
+            })],
+            position: Some(Position::new(1, 1, 0, 1, 11, 10))
+        }),
+        "should strip one space from each side of `InlineCode` if the value starts and ends with space"
+    );
+
+    assert_eq!(
+        to_mdast("`   `", &Default::default())?,
+        Node::Root(Root {
+            children: vec![Node::Paragraph(Paragraph {
+                children: vec![Node::InlineCode(InlineCode {
+                    value: "   ".into(),
+                    position: Some(Position::new(1, 1, 0, 1, 6, 5))
+                }),],
+                position: Some(Position::new(1, 1, 0, 1, 6, 5))
+            })],
+            position: Some(Position::new(1, 1, 0, 1, 6, 5))
+        }),
+        "should not strip any whitespace if `InlineCode` is all whitespace"
+    );
+
     Ok(())
 }