Remove constant duplication on compile time

2 files changed, 44 insertions, 8 deletions

diff --git a/src/bytecode/chunk.h b/src/bytecode/chunk.h
index aafa0ec..5fbc000 100755
--- a/src/bytecode/chunk.h
+++ b/src/bytecode/chunk.h
@@ -34,9 +34,7 @@ chunk_free(Chunk *chunk) {
     array_free(chunk->code);
     for (size_t i = 0; i < array_size(chunk->constants); i++) {
         Object obj = chunk->constants[i];
-        if (IS_STRING(obj) || IS_SYMBOL(obj)) {
-            array_free(obj.text);
-        }
+        object_free(obj);
     }
     array_free(chunk->constants);
     array_free(chunk->lines);
@@ -52,12 +50,12 @@ add_code(Chunk *chunk, u8 byte, size_t line, size_t col) {
 
 size_t
 add_constant(Chunk *chunk, Object obj) {
-    // FIXME?: Since we are using a single byte to store constant indices, we
-    // can only have 256 stored constants. If we need more we may need to add
-    // another instruction OP_CONSTANT_16 to have at least two bytes for
-    // constants. Alternatively, we could make that the default. Either way, for
-    // now it's fine.
     size_t pos = array_size(chunk->constants);
+    for (size_t i = 0; i < pos; i++) {
+        if (object_equal(obj, chunk->constants[i])) {
+            return i;
+        }
+    }
     array_push(chunk->constants, obj);
     return pos;
 }
diff --git a/src/bytecode/objects.h b/src/bytecode/objects.h
index 17809d5..fc5e069 100755
--- a/src/bytecode/objects.h
+++ b/src/bytecode/objects.h
@@ -121,4 +121,42 @@ display(Object obj) {
     return;
 }
 
+void
+object_free(Object obj) {
+    if (IS_STRING(obj) || IS_SYMBOL(obj)) {
+        array_free(obj.text);
+    }
+}
+
+bool
+object_equal(Object a, Object b) {
+    if (a.type != b.type) {
+        return false;
+    }
+    switch (a.type) {
+        case OBJ_TYPE_TRUE:
+        case OBJ_TYPE_FALSE: {
+            return true;
+        } break;
+        case OBJ_TYPE_FIXNUM: {
+            return a.fixnum == b.fixnum;
+        } break;
+        case OBJ_TYPE_SYMBOL:
+        case OBJ_TYPE_STRING: {
+            if (array_size(a.text) != array_size(b.text)) {
+                return false;
+            }
+            for (size_t i = 0; i < array_size(a.text); i++) {
+                if (a.text[i] != b.text[i]) {
+                    return false;
+                }
+            }
+        } break;
+        default: {
+            return false;
+        } break;
+    }
+    return true;
+}
+
 #endif // BDL_OBJECTS_H