Initial code commit.

src/value.c

@@ -0,0 +1,92 @@
+#include "value.h"
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+
+Value make_int(int64_t v) {
+    Value val;
+    val.type = VAL_INT;
+    val.i = v;
+    return val;
+}
+
+Value make_string(const char *s) {
+    Value val;
+    val.type = VAL_STRING;
+    if (s) val.s = strdup(s);
+    else val.s = strdup("");
+    return val;
+}
+
+Value make_function(struct Bytecode *fn) {
+    Value val;
+    val.type = VAL_FUNCTION;
+    val.fn = fn;
+    return val;
+}
+
+Value make_nil(void) {
+    Value v;
+    v.type = VAL_NIL;
+    return v;
+}
+
+Value copy_value(const Value *v) {
+    Value out;
+    out.type = v->type;
+    switch (v->type) {
+        case VAL_INT:
+            out.i = v->i;
+            break;
+        case VAL_STRING:
+            out.s = v->s ? strdup(v->s) : strdup("");
+            break;
+        case VAL_FUNCTION:
+            out.fn = v->fn; /* shallow copy pointer */
+            break;
+        case VAL_NIL:
+        default:
+            break;
+    }
+    return out;
+}
+
+void free_value(Value v) {
+    if (v.type == VAL_STRING && v.s) {
+        free(v.s);
+    }
+    /* VAL_FUNCTION: we *do not* free the Bytecode here (caller frees it) */
+}
+
+void print_value(const Value *v) {
+    switch (v->type) {
+        case VAL_INT:
+            printf("%" PRId64, v->i);
+            break;
+        case VAL_STRING:
+            printf("%s", v->s ? v->s : "");
+            break;
+        case VAL_FUNCTION:
+            printf("<function@%p>", (void*)v->fn);
+            break;
+        case VAL_NIL:
+        default:
+            printf("nil");
+            break;
+    }
+}
+
+int value_is_truthy(const Value *v) {
+    switch (v->type) {
+        case VAL_INT:
+            return v->i != 0;
+        case VAL_STRING:
+            return v->s && v->s[0] != '\0';
+        case VAL_FUNCTION:
+            return 1;
+        case VAL_NIL:
+        default:
+            return 0;
+    }
+}
+