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/environment.c | 72 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 72 insertions(+)
 create mode 100644 src/treewalk/environment.c

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

diff --git a/src/treewalk/environment.c b/src/treewalk/environment.c
new file mode 100644
index 0000000..dd4a648
--- /dev/null
+++ b/src/treewalk/environment.c
@@ -0,0 +1,72 @@
+#include "environment.h"
+#include "gc.h"
+#include "errors.h"
+
+Environment *
+env_create(Environment *parent) {
+    Environment *env = alloc_env();
+    env->parent = parent;
+    env->marked = false;
+    env->table = ht_init();
+    return env;
+}
+
+void
+env_add_symbol(Environment *env, Object *symbol, Object *value) {
+    if (symbol->type != OBJ_TYPE_SYMBOL) {
+        error_push((Error){
+            .type = ERR_TYPE_RUNTIME,
+            .value = ERR_NOT_A_SYMBOL,
+            .line = 0,
+            .col = 0,
+        });
+        return;
+    }
+    ht_insert(env->table, symbol, value);
+}
+
+Object *
+env_lookup(Environment *env, Object *symbol) {
+    while (env != NULL) {
+        Object *obj = ht_lookup(env->table, symbol);
+        if (obj != NULL) {
+            return obj;
+        }
+        env = env->parent;
+    }
+    return obj_err;
+}
+
+Object *
+env_update(Environment *env, Object *symbol, Object *value) {
+    while (env != NULL) {
+        Object *obj = ht_lookup(env->table, symbol);
+        if (obj != NULL) {
+            ht_insert(env->table, symbol, value);
+            return obj_nil;
+        }
+        env = env->parent;
+    }
+    error_push((Error){
+        .type = ERR_TYPE_RUNTIME,
+        .value = ERR_SYMBOL_NOT_FOUND,
+    });
+    return obj_err;
+}
+
+void
+env_add_or_update_current(Environment *env, Object *symbol, Object *value) {
+    ht_insert(env->table, symbol, value);
+}
+
+Environment *
+env_extend(Environment *parent, Environment *extra) {
+    Environment *env = parent;
+    HashTablePair *pairs = extra->table->pairs;
+    for (size_t i = 0; i < array_cap(pairs); i++) {
+        if (pairs[i].key != NULL) {
+            ht_insert(env->table, pairs[i].key, pairs[i].value);
+        }
+    }
+    return env;
+}
-- 
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