added truth table and expression evaluatorHEADmaster

1 files changed, 23 insertions, 0 deletions

diff --git a/tree.c b/tree.c
index fbb561a..00d5eb9 100644
--- a/tree.c
+++ b/tree.c
@@ -1,5 +1,6 @@
 #include <stdio.h>
 #include <stdlib.h>
+#include <stdint.h>
 #include "tree.h"
 
 int strichar(const char *str, char c){
@@ -69,3 +70,25 @@ void free_node(node *n) {
   free(n);
 }
 
+char eval_tree(node *root, uint32_t alph_bools) {
+  switch (root->type) {
+    case BIOP: {
+      char lhs = eval_tree(root->lhs, alph_bools);
+      char rhs = eval_tree(root->rhs, alph_bools);
+      switch (root->el) {
+        case '+': return lhs || rhs;
+        case '*': return lhs && rhs;
+        default: fprintf(stderr, "%s: unknown binary operation \"%c\"\n", __func__, root->el);
+      }
+    }
+    case UNOP: {
+      // We only have the not, FIXME if more are added
+      return !eval_tree(root->value, alph_bools);
+    }
+    case LTTR: {
+      char alph_pos = root->el - 'a';
+      return (alph_bools & (1 << alph_pos)) > 0;
+    }
+  }
+}
+