1 files changed, 50 insertions, 5 deletions
diff --git a/src/expand/cfg.cpp b/src/expand/cfg.cpp
index 546bb690..d178b9ae 100644
--- a/src/expand/cfg.cpp
+++ b/src/expand/cfg.cpp
@@ -2,6 +2,13 @@
 #include <synext.hpp>
 #include <parse/tokentree.hpp>
 #include <parse/lex.hpp>
+#include <parse/common.hpp>
+
+bool check_cfg(const ::AST::MetaItem& mi) {
+    // TODO: Handle cfg conditions
+    throw ::std::runtime_error("TODO: Handle #[cfg] or cfg! conditions");
+    return true;
+}
 
 class CCfgExpander:
     public ExpandProcMacro
@@ -14,13 +21,51 @@ class CCfgExpander:
             ERROR(sp, E0000, "cfg! doesn't take an identifier");
         }
         
-        DEBUG("cfg!()");
-        
-        // TODO: Handle cfg!()
+        auto lex = TTStreamO(tt);
+        auto attrs = Parse_MetaItem(lex);
+        DEBUG("cfg!() - " << attrs);
         
-        return box$( TTStreamO(TokenTree(TOK_RWORD_FALSE)) );
+        if( check_cfg(attrs) ) {
+            return box$( TTStreamO(TokenTree(TOK_RWORD_TRUE )) );
+        }
+        else {
+            return box$( TTStreamO(TokenTree(TOK_RWORD_FALSE)) );
+        }
+    }
+};
+
+
+class CCfgHandler:
+    public ExpandDecorator
+{
+    AttrStage   stage() const override { return AttrStage::EarlyPre; }
+    
+    
+    void handle(const AST::MetaItem& mi, AST::Crate& crate, AST::MacroInvocation& mac) const override {
+        if( check_cfg(mi) ) {
+            // Leave as is
+        }
+        else {
+            mac.clear();
+        }
+    }
+    void handle(const AST::MetaItem& mi, AST::Crate& crate, const AST::Path& path, AST::Module& mod, AST::Item&i) const override {
+        if( check_cfg(mi) ) {
+            // Leave
+        }
+        else {
+            i = AST::Item::make_None({});
+        }
+    }
+    void handle(const AST::MetaItem& mi, ::std::unique_ptr<AST::ExprNode>& expr) const override {
+        if( check_cfg(mi) ) {
+            // Leave
+        }
+        else {
+            expr.reset();
+        }
     }
 };
 
 STATIC_MACRO("cfg", CCfgExpander);
-//STATIC_DECORATOR("cfg", CCfgHandler);
+STATIC_DECORATOR("cfg", CCfgHandler);