Start work on symbol table lookup by type name

schala-lang/language/src/symbol_table.rs

@@ -28,14 +28,16 @@ enum ScopeSegmentKind {
 
 //cf. p. 150 or so of Language Implementation Patterns
 pub struct SymbolTable {
-  values: HashMap<PathToSymbol, Symbol>,
+  symbol_path_to_symbol: HashMap<PathToSymbol, Symbol>,
+  type_name_to_symbol: HashMap<Rc<String>, PathToSymbol>
 }
 
 //TODO add various types of lookups here, maybe multiple hash tables internally?
 impl SymbolTable {
   pub fn new() -> SymbolTable {
     SymbolTable {
-      values: HashMap::new(),
+      symbol_path_to_symbol: HashMap::new(),
+      type_name_to_symbol: HashMap::new(),
     }
   }
 
@@ -44,7 +46,7 @@ impl SymbolTable {
     vec.push(name.clone());
     let symbol_path = PathToSymbol(vec);
     let symbol = Symbol { name: name.clone(), scopes: scope_path.to_vec(), spec };
-    self.values.insert(symbol_path, symbol);
+    self.symbol_path_to_symbol.insert(symbol_path, symbol);
   }
 
   pub fn lookup_by_name(&self, name: &Rc<String>) -> Option<&Symbol> {
@@ -55,7 +57,11 @@ impl SymbolTable {
     let mut vec = path.clone();
     vec.push(name.clone());
     let symbol_path = PathToSymbol(vec);
-    self.values.get(&symbol_path)
+    self.symbol_path_to_symbol.get(&symbol_path)
+  }
+
+  pub fn lookup_by_type_and_tag(&self, type_name: &Rc<String>, tag: usize) -> Option<&Symbol> {
+    unimplemented!()
   }
 }
 
@@ -163,7 +169,7 @@ impl SymbolTable {
   }
   pub fn debug_symbol_table(&self) -> String {
     let mut output = format!("Symbol table\n");
-    for (name, sym) in &self.values {
+    for (name, sym) in &self.symbol_path_to_symbol {
       write!(output, "{:?} -> {}\n", name, sym).unwrap();
     }
     output