add parethesis support

1 files changed, 18 insertions, 6 deletions

diff --git a/bu-parser.c b/bu-parser.c
index b077938..df4c2c2 100644
--- a/bu-parser.c
+++ b/bu-parser.c
@@ -2,12 +2,6 @@
 #include "tree.h"
 #include <stdio.h>
 
-void free_node(node *n) {
-  if (n->lhs) free_node(n->lhs);
-  if (n->rhs) free_node(n->rhs);
-  free(n);
-}
-
 void fprint_stack(FILE *stream, struct expr_parser *ep) {
   for (size_t i = 0; i < ep->stack_idx; i++) {
     struct stackmember m = ep->stack[i];
@@ -132,6 +126,20 @@ void unary_expr(struct expr_parser *ep) {
   ep->stack[ep->stack_idx - 1] = newm;
 }
 
+void parens_expr(struct expr_parser *ep) {
+  struct stackmember o, e, c;
+  o = stack_pos(ep, 2);
+  e = stack_pos(ep, 1);
+  c = stack_pos(ep, 0);
+  BAIL_REDUCE_IF(
+    o.id != TOKEN_OPEN_PAREN
+    || e.id != STACKMEMBER_EXPR
+    || c.id != TOKEN_CLOSE_PAREN, "mismatched parenthesis");
+
+  ep->stack_idx -= 2;
+  ep->stack[ep->stack_idx - 1] = e;
+}
+
 int expr_parser_run(struct expr_parser *ep) {
   // prime the look-ahead
   ep->lahead = ep->lex(ep->lex_data);
@@ -167,6 +175,10 @@ int expr_parser_run(struct expr_parser *ep) {
           }
         }
         break;
+      case TOKEN_CLOSE_PAREN:
+        parens_expr(ep);
+        noshift = 1;
+        break;
       default: break;
     }
   }