From 8e12f4a4ac15287c953f846ca00d7e15be37f7bc Mon Sep 17 00:00:00 2001
From: "Ryan C. Gordon" <icculus@icculus.org>
Date: Mon, 8 Feb 2010 04:42:51 -0500
Subject: [PATCH] Free the parse tree once we're done with it.

--HG--
branch : calculator-experiment
---
 calculator.c     | 34 +++++++++++++++++++++++++++++++++-
 calculator.lemon |  2 +-
 2 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/calculator.c b/calculator.c
index 57fddb1d..c94bd67a 100644
--- a/calculator.c
+++ b/calculator.c
@@ -497,10 +497,42 @@ static double run_expr(const Expression *expr)
     return 0.0;  // oh well.
 } // run_expr
 
-static void parse_complete(const Expression *expr)
+static void free_expr(Context *ctx, Expression *expr)
+{
+    if (operator_is_unary(expr->op))
+    {
+        const ExpressionUnary *unary = (const ExpressionUnary *) expr;
+        free_expr(ctx, unary->operand);
+    } // if
+    else if (operator_is_binary(expr->op))
+    {
+        const ExpressionBinary *binary = (const ExpressionBinary *) expr;
+        free_expr(ctx, binary->left);
+        free_expr(ctx, binary->right);
+    } // else if
+    else if (operator_is_ternary(expr->op))
+    {
+        const ExpressionTernary *ternary = (const ExpressionTernary *) expr;
+        free_expr(ctx, ternary->left);
+        free_expr(ctx, ternary->center);
+        free_expr(ctx, ternary->right);
+    } // else if
+    else if (expr->op == OP_STRING_LITERAL)
+    {
+        Free(ctx, (void *) ((ExpressionStringLiteral *)expr)->string);
+    } // else if
+    else if (expr->op == OP_IDENTIFIER)
+    {
+        Free(ctx, (void *) ((ExpressionIdentifier *)expr)->identifier);
+    } // else if
+    Free(ctx, expr);
+} // free_expr
+
+static void parse_complete(Context *ctx, Expression *expr)
 {
     print_expr(expr, 0);
     printf("Result: %lf\n\n", run_expr(expr));
+    free_expr(ctx, expr);
 } // parse_complete
 
 
diff --git a/calculator.lemon b/calculator.lemon
index 2d8a154c..329b3920 100644
--- a/calculator.lemon
+++ b/calculator.lemon
@@ -72,7 +72,7 @@
 
 // The rules...
 
-calculator ::= expression(B). { parse_complete(B); }
+calculator ::= expression(B). { parse_complete(ctx, B); }
 
 %type identifier { const char * }
 %destructor identifier { (void) ctx; }  // !!! FIXME: remove this later, it's just to shut up the compiler for now.