maps.h

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/* -*- C -*-
 * Serene programming language
 * Copyright (C) 2019-2026 Sameer Rahmani <[email protected]>
 *
 * This library is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this library.  If not, see <https://www.gnu.org/licenses/>.
 */
#pragma once
 
#include "serene/rt/core.h"
#include "serene/rt/impl/hashmap.h"
#include "serene/rt/protocols.h"
#include "serene/utils.h"
 
typedef struct srn_context_t srn_context_t;
 
/// A persistent, immutable map. Backed by the CHAMT in
/// serene/rt/impl/hashmap.h. Keys and values are both srn_value_t*.
typedef struct srn_map_t {
  hmap_t inner;
} srn_map_t;
 
// ---------------------------------------------------------------------------
// Lifetime contract for keys and values
//
// srn_map_assoc does NOT copy `key` or `value`. The underlying hmap stores
// the caller-supplied srn_value_t* directly: the key sits inside an
// hmap_key_t.data pointer, and the value occupies the entry's value slot.
// Both pointers must remain valid for at least as long as the map itself.
//
// In practice this means: every key and value placed in a map must live in
// a memory chain whose lifetime is equal to or longer than the chain that
// holds the map. Interned values (keywords, namespaces) live in
// engine immortal memory and are always safe. Values allocated inside a
// short lived chain (per form, per call) must not be stored in a map whose
// chain outlasts them, or the map will dangle.
//
// The runtime does not detect violations of this rule. A dangling key or
// value silently corrupts later lookups and iterations.
// ---------------------------------------------------------------------------
 
[[gnu::nonnull(1)]] srn_value_t *srn_map_empty(srn_context_t *ctx,
                                               srn_metadata_t *metadata);
 
[[gnu::nonnull(1, 3, 4, 5)]] srn_value_t *
srn_map_assoc(srn_context_t *ctx, srn_metadata_t *metadata, srn_value_t *map,
              srn_value_t *key, srn_value_t *value);