1 files changed, 62 insertions, 0 deletions
diff --git a/c/env.c b/c/env.c
new file mode 100644
index 0000000..d4b8f32
--- /dev/null
+++ b/c/env.c
@@ -0,0 +1,62 @@
+/*
+#include <stdarg.h>
+#include <stdio.h>
+#include <string.h>
+*/
+#include <stdlib.h>
+#include "types.h"
+
+// Env
+
+Env *new_env(Env *outer, MalVal* binds, MalVal *exprs) {
+    Env *e = malloc(sizeof(Env));
+    e->table = g_hash_table_new(g_str_hash, g_str_equal);
+    e->outer = outer;
+
+    if (binds && exprs) {
+        assert_type(binds, MAL_LIST|MAL_VECTOR,
+                    "new_env called with non-sequential bindings");
+        assert_type(exprs, MAL_LIST|MAL_VECTOR,
+                    "new_env called with non-sequential expressions");
+        int binds_len = _count(binds),
+            exprs_len = _count(exprs),
+            varargs = 0, i;
+        for (i=0; i<binds_len; i++) {
+            if (i > exprs_len) { break; }
+            if (_nth(binds, i)->val.string[0] == '&') {
+                varargs = 1;
+                env_set(e, _nth(binds, i+1)->val.string, _slice(exprs, i, _count(exprs)));
+                break;
+            } else {
+              env_set(e, _nth(binds, i)->val.string, _nth(exprs, i));
+            }
+        }
+        assert(varargs || (binds_len == exprs_len),
+               "Arity mismatch: %d formal params vs %d actual params",
+               binds_len, exprs_len);
+
+    }
+    return e;
+}
+
+Env *env_find(Env *env, char *key) {
+    void *val = g_hash_table_lookup(env->table, key);
+    if (val) {
+        return env;
+    } else if (env->outer) {
+        return env_find(env->outer, key);
+    } else {
+        return NULL;
+    }
+}
+
+MalVal *env_get(Env *env, char *key) {
+    Env *e = env_find(env, key);
+    assert(e, "'%s' not found", key);
+    return g_hash_table_lookup(e->table, key);
+}
+
+Env *env_set(Env *env, char *key, MalVal *val) {
+    g_hash_table_insert(env->table, key, val);
+    return env;
+}