From b8bad3bf5af3261f25780a8cd8b90a659fe29bab Mon Sep 17 00:00:00 2001
From: Bad Diode <bd@badd10de.dev>
Date: Wed, 13 Oct 2021 14:19:32 +0200
Subject: Add support for environments and recursive evaluation

---
 src/bootstrap/environment.c | 106 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 106 insertions(+)
 create mode 100644 src/bootstrap/environment.c

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

diff --git a/src/bootstrap/environment.c b/src/bootstrap/environment.c
new file mode 100644
index 0000000..1bbe844
--- /dev/null
+++ b/src/bootstrap/environment.c
@@ -0,0 +1,106 @@
+//
+// Environment.
+//
+
+typedef struct EnvEntry {
+    Object *symbol;
+    Object *value;
+} EnvEntry;
+
+typedef struct Environment {
+    struct Environment *parent;
+    EnvEntry *buf;
+    size_t size;
+    size_t cap;
+} Environment;
+
+static Environment *global_env;
+
+#define ENV_BUF_CAP 8
+
+Environment *
+env_create(Environment *parent) {
+    Environment *env = malloc(sizeof(Environment));
+    env->parent = parent;
+    env->buf = NULL;
+    env->size = 0;
+    env->cap = ENV_BUF_CAP;
+    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;
+    }
+    if (env->buf == NULL) {
+        env->size = 0;
+        env->cap = ENV_BUF_CAP;
+        env->buf = malloc(env->cap * sizeof(EnvEntry));
+    } else if (env->size == env->cap) {
+        env->cap *= 2;
+        env->buf = realloc(env->buf, env->cap * sizeof(EnvEntry));
+    }
+    env->buf[env->size++] = (EnvEntry){symbol, value};
+}
+
+bool
+obj_eq(Object *a, 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 (a->string_n != b->string_n) {
+                return false;
+            }
+            for (size_t i = 0; i < a->string_n; i++) {
+                if (a->string[i] != b->string[i]) {
+                    return false;
+                }
+            }
+        } break;
+        case OBJ_TYPE_SYMBOL: {
+            if (a->symbol_n != b->symbol_n) {
+                return false;
+            }
+            for (size_t i = 0; i < a->symbol_n; i++) {
+                if (a->symbol[i] != b->symbol[i]) {
+                    return false;
+                }
+            }
+        } break;
+        case OBJ_TYPE_PAIR: {
+            // TODO: needs evaluation of parameters...
+        } break;
+        default: {
+            return a == b;
+        } break;
+    }
+    return true;
+}
+
+Object *
+env_lookup(Environment *env, Object *symbol) {
+    while (env != NULL) {
+        for (size_t i = 0; i < env->size; i++) {
+            EnvEntry entry = env->buf[i];
+            if (obj_eq(symbol, entry.symbol)) {
+                return entry.value;
+            }
+        }
+        env = env->parent;
+    }
+    return obj_err;
+}
+
+// TODO: Free env function.
-- 
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