From eeff5e273f22aa28e81ab080e9ffdce85ac394b8 Mon Sep 17 00:00:00 2001
From: Bad Diode <bd@badd10de.dev>
Date: Fri, 22 Oct 2021 09:59:31 +0200
Subject: Prepare skeleton for bytecode interpreter

---
 src/treewalk/objects.c | 141 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 141 insertions(+)
 create mode 100644 src/treewalk/objects.c

(limited to 'src/treewalk/objects.c')

diff --git a/src/treewalk/objects.c b/src/treewalk/objects.c
new file mode 100644
index 0000000..c71bc40
--- /dev/null
+++ b/src/treewalk/objects.c
@@ -0,0 +1,141 @@
+#include "gc.h"
+#include "objects.h"
+
+//
+// Constructors.
+//
+
+Object *
+make_fixnum(ssize_t num) {
+    Object *obj = alloc_object(OBJ_TYPE_FIXNUM);
+    obj->fixnum = num;
+    return obj;
+}
+
+Object *
+make_procedure(Object *(*proc)(struct Environment *, struct Object *args)) {
+    Object *obj = alloc_object(OBJ_TYPE_PROCEDURE);
+    obj->proc = proc;
+    return obj;
+}
+
+Object *
+make_pair(Object *car, Object *cdr) {
+    Object *obj = alloc_object(OBJ_TYPE_PAIR);
+    obj->car = car;
+    obj->cdr = cdr;
+    return  obj;
+}
+
+Object *
+make_symbol(StringView sv) {
+    Object *obj = alloc_object(OBJ_TYPE_SYMBOL);
+    obj->symbol = NULL;
+    array_init(obj->symbol, sv.n);
+    array_insert(obj->symbol, sv.start, sv.n);
+    return obj;
+}
+
+Object *
+make_string(void) {
+    Object *obj = alloc_object(OBJ_TYPE_STRING);
+    obj->string = NULL;
+    array_init(obj->string, 0);
+    return obj;
+}
+
+void
+append_string(Object *obj, const StringView sv) {
+    if (sv.n == 0) {
+        return;
+    }
+    array_insert(obj->string, sv.start, sv.n);
+}
+
+void
+display_pair(Object *root) {
+    display(root->car);
+    if (root->cdr->type == OBJ_TYPE_PAIR) {
+        printf(" ");
+        display_pair(root->cdr);
+    } else if (root->cdr == obj_nil) {
+        return;
+    } else {
+        printf(" . ");
+        display(root->cdr);
+    }
+}
+
+void
+display(Object *root) {
+    switch (root->type) {
+        case OBJ_TYPE_FIXNUM: {
+            printf("%zd", root->fixnum);
+        } break;
+        case OBJ_TYPE_BOOL: {
+            if (root == obj_true) {
+                printf("true");
+            } else {
+                printf("false");
+            }
+        } break;
+        case OBJ_TYPE_NIL: {
+            printf("()");
+        } break;
+        case OBJ_TYPE_STRING: {
+            printf("\"%.*s\"", (int)array_size(root->string), root->string);
+        } break;
+        case OBJ_TYPE_SYMBOL: {
+            printf(":%.*s", (int)array_size(root->symbol), root->symbol);
+        } break;
+        case OBJ_TYPE_PAIR: {
+            printf("(");
+            display_pair(root);
+            printf(")");
+        } break;
+        case OBJ_TYPE_LAMBDA:
+        case OBJ_TYPE_PROCEDURE: {
+            printf("#{procedure}");
+        } break;
+        case OBJ_TYPE_ERR: {
+            printf("#{error}");
+        } break;
+    }
+    return;
+}
+
+bool
+obj_eq(const Object *a, const Object* b) {
+    if (a->type != b->type) {
+        return false;
+    }
+    switch (a->type) {
+        case OBJ_TYPE_FIXNUM: {
+            return a->fixnum == b->fixnum;
+        } break;
+        case OBJ_TYPE_STRING: {
+            if (array_size(a->string) != array_size(b->string)) {
+                return false;
+            }
+            for (size_t i = 0; i < array_size(a->string); i++) {
+                if (a->string[i] != b->string[i]) {
+                    return false;
+                }
+            }
+        } break;
+        case OBJ_TYPE_SYMBOL: {
+            if (array_size(a->symbol) != array_size(b->symbol)) {
+                return false;
+            }
+            for (size_t i = 0; i < array_size(a->symbol); i++) {
+                if (a->symbol[i] != b->symbol[i]) {
+                    return false;
+                }
+            }
+        } break;
+        default: {
+            return a == b;
+        } break;
+    }
+    return true;
+}
-- 
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