Autocomplete preprocessor macros

src/dreammaker/preprocessor.rs

@@ -1,6 +1,6 @@
 //! The preprocessor.
 use std::collections::{HashMap, VecDeque};
-use std::io;
+use std::{io, fmt};
 use std::fs::File;
 use std::path::{Path, PathBuf};
 
@@ -27,6 +27,22 @@ pub enum Define {
     },
 }
 
+impl fmt::Display for Define {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        let subst = match self {
+            Define::Constant { ref subst, .. } |
+            Define::Function { ref subst, .. } => subst,
+        };
+        if subst.is_empty() {
+            fmt.write_str("(macro)")
+        } else if subst.len() == 1 {
+            write!(fmt, "{}", subst[0])
+        } else {
+            fmt.write_str("(macro...)")
+        }
+    }
+}
+
 /// An interval tree representing historic macro definitions.
 pub type DefineHistory = IntervalTree<Location, (String, Define)>;
 

src/langserver/completion.rs

@@ -342,6 +342,22 @@ impl<'a, R: io::RequestRead, W: io::ResponseWrite> Engine<'a, R, W> {
             }
         }
 
+        // macros
+        if let Some(ref preprocessor) = self.preprocessor {
+            // TODO: verify that the macro is in scope at the location
+            for (_, &(ref name, ref define)) in preprocessor.history().iter() {
+                if contains(name, query) {
+                    results.push(CompletionItem {
+                        label: name.to_owned(),
+                        kind: Some(CompletionItemKind::Constant),
+                        detail: Some(format!("{}", define)),
+                        .. Default::default()
+                    });
+                }
+            }
+        }
+
+        // fields
         let mut next = Some(ty);
         let mut skip = HashSet::new();
         while let Some(ty) = next {