mirror of
https://github.com/matrix-construct/construct
synced 2024-11-05 13:28:54 +01:00
222 lines
9.4 KiB
C++
222 lines
9.4 KiB
C++
// Matrix Construct
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//
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// Copyright (C) Matrix Construct Developers, Authors & Contributors
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// Copyright (C) 2016-2018 Jason Volk <jason@zemos.net>
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//
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// Permission to use, copy, modify, and/or distribute this software for any
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// purpose with or without fee is hereby granted, provided that the above
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// copyright notice and this permission notice is present in all copies. The
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// full license for this software is available in the LICENSE file.
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#pragma once
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#define HAVE_IRCD_M_STATE_H
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/// Matrix machine state unit and bus.
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///
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/// !!! note: This is actually a really low-level interface. If you don't
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/// know that you are almost certainly looking for the room::state interface
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/// and not this.
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///
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/// This section deals specifically with the aspect of Matrix called "state"
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/// providing tools and utilities as well as local databasing. IO is done for
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/// reads, and indirect into db::txn's for writes. No network activities are
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/// conducted here.
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///
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/// These tools allow the user to query aspects of the "state" of a room at
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/// the point of any event. Composed out of these queries are a suite of more
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/// utilities to efficiently aid the Matrix virtual machine with the rest of
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/// its tasks.
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///
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namespace ircd::m::state
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{
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struct node;
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constexpr size_t ID_MAX_SZ { 64 };
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constexpr size_t KEY_MAX_SZ { 256 + 256 + 16 };
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constexpr size_t VAL_MAX_SZ { 256 + 16 };
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constexpr size_t NODE_MAX_SZ { 4_KiB };
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constexpr size_t NODE_MAX_KEY { 2 }; // tmp for now
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constexpr size_t NODE_MAX_VAL { NODE_MAX_KEY };
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constexpr size_t NODE_MAX_DEG { NODE_MAX_KEY + 1 }; // tmp for now
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constexpr int8_t MAX_HEIGHT { 16 }; // good for few mil at any degree :)
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using id = string_view;
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using id_buffer = fixed_buffer<mutable_buffer, ID_MAX_SZ>;
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using id_closure = std::function<void (const id &)>;
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using val_closure = std::function<void (const string_view &)>;
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using node_closure = std::function<void (const json::object &)>;
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using search_closure = std::function<bool (const json::array &, const string_view &, const uint &, const uint &)>;
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using iter_closure = std::function<void (const json::array &, const string_view &)>;
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using iter_bool_closure = std::function<bool (const json::array &, const string_view &)>;
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int keycmp(const json::array &a, const json::array &b);
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bool prefix_eq(const json::array &a, const json::array &b);
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json::array make_key(const mutable_buffer &out, const string_view &type, const string_view &state_key);
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json::array make_key(const mutable_buffer &out, const string_view &type);
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id set_node(db::txn &txn, const mutable_buffer &id, const json::object &node);
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bool get_node(const std::nothrow_t, const string_view &id, const node_closure &);
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void get_node(const string_view &id, const node_closure &);
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id remove(db::txn &, const mutable_buffer &rootout, const id &rootin, const json::array &key);
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id remove(db::txn &, const mutable_buffer &rootout, const id &rootin, const string_view &type, const string_view &state_key);
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id remove(db::txn &, const mutable_buffer &rootout, const id &rootin, const event &);
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id insert(db::txn &, const mutable_buffer &rootout, const id &rootin, const json::array &key, const m::id::event &);
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id insert(db::txn &, const mutable_buffer &rootout, const id &rootin, const string_view &type, const string_view &state_key, const m::id::event &);
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id insert(db::txn &, const mutable_buffer &rootout, const id &rootin, const event &);
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bool dfs(const id &root, const json::array &key, const search_closure &);
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bool dfs(const id &root, const search_closure &);
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size_t count(const id &root, const string_view &type);
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size_t count(const id &root);
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bool test(const id &root, const iter_bool_closure &);
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bool test(const id &root, const string_view &type, const iter_bool_closure &);
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bool test(const id &root, const string_view &type, const string_view &state_key_lb, const iter_bool_closure &);
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void for_each(const id &root, const iter_closure &);
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void for_each(const id &root, const string_view &type, const iter_closure &);
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size_t accumulate(const id &root, const iter_bool_closure &);
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bool get(std::nothrow_t, const id &root, const json::array &key, const val_closure &);
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void get(const id &root, const json::array &key, const val_closure &);
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bool get(std::nothrow_t, const id &root, const string_view &type, const string_view &state_key, const val_closure &);
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void get(const id &root, const string_view &type, const string_view &state_key, const val_closure &);
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}
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/// JSON property name strings specifically for use in m::state
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namespace ircd::m::state::name
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{
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constexpr const char *const key {"k"};
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constexpr const char *const val {"v"};
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constexpr const char *const child {"c"};
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constexpr const char *const count {"n"};
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}
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#pragma GCC diagnostic push
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#pragma GCC diagnostic ignored "-Wsubobject-linkage"
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/// Format for node: Node is plaintext and not binary at this time. In fact,
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/// *evil chuckle*, node might as well be JSON and can easily become content
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/// of another event sent to other rooms over network *snorts*. (important:
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/// database is well compressed).
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///
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/// { ;
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/// "k": ; Key array
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/// [ ;
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/// ["m.room.member", "@ar4an:matrix.org"], ; Left key
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/// ["m.room.member", "@jzk:matrix.org"] ; Right key
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/// ], ;
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/// "v": ; Value array
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/// [ ;
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/// "$14961836116kXQRA:matrix.org", ; Left accept
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/// "$15018692261xPQDB:matrix.org", ; Right accept
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/// ] ;
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/// "c": ; Child array
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/// [ ;
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/// "nPKN9twTF9a8k5dD7AApFcaraHTX", ; Left child
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/// "PcxAAACvkvyUMz19AZcCfrC3S84s", ; Center child
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/// "2jVYKIMKErJ6w6BLMhfVjsXearhB", ; Right child
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/// ] ;
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/// "n": ; Counting array
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/// [ ;
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/// 15, ; Left child value count
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/// 12, ; Center child value count
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/// 19, ; Right child value count
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/// ] ;
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/// } ;
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///
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/// Elements are ordered based on type+state_key lexical sort. The type and
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/// the state_key strings are literally concatenated to this effect. They're
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/// not hashed. We can have some more control over data locality this way. Any
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/// number of values may be in a key array, not just type+state_key. The
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/// concatenation involves the string with its surrounding quotes as to not
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/// allow the user to mess about conflicting values:
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/// ```
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/// "m.room.member""@jzk" > "m.room.create"""
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/// ```
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/// Unlike traditional trees of such variety, the number of elements is not
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/// really well defined and not even fixed. There just can be one more value
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/// in the "child" list than there are keys in the "key" list. We have an
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/// opportunity to vary the degree for different levels in different areas.
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struct ircd::m::state::node
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:json::tuple
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<
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json::property<name::key, json::array>,
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json::property<name::val, json::array>,
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json::property<name::child, json::array>,
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json::property<name::count, json::array>
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>
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{
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struct rep;
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size_t keys() const;
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size_t vals() const;
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size_t childs() const;
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size_t counts() const;
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size_t totals() const;
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json::array key(const size_t &) const;
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string_view val(const size_t &) const;
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state::id child(const size_t &) const;
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size_t count(const size_t &) const;
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size_t keys(json::array *const &out, const size_t &max) const;
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size_t vals(string_view *const &out, const size_t &max) const;
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size_t childs(state::id *const &out, const size_t &max) const;
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size_t counts(size_t *const &out, const size_t &max) const;
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size_t find(const json::array &key) const;
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bool has_key(const json::array &key) const;
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bool has_child(const size_t &) const;
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using super_type::tuple;
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using super_type::operator=;
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};
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#pragma GCC diagnostic pop
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/// Internal representation of a node for manipulation purposes. This is
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/// because json::tuple's (like most of json::) are oriented around the
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/// dominant use-case of reading const datas. These arrays could be
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/// vectors optimized with a local allocator but the size_t members are
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/// used to count active elements instead. One more element than the node
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/// maximum is provided so that insertions and sorts can safely take place
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/// before splits.
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struct ircd::m::state::node::rep
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{
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std::array<json::array, NODE_MAX_KEY + 1> keys;
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std::array<string_view, NODE_MAX_VAL + 1> vals;
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std::array<state::id, NODE_MAX_DEG + 1> chld;
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std::array<size_t, NODE_MAX_DEG + 1> cnts;
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size_t kn {0};
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size_t vn {0};
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size_t cn {0};
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size_t nn {0};
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bool full() const;
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bool last() const;
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bool overfull() const;
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bool duplicates() const;
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size_t childs() const;
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size_t counts() const;
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size_t totals() const;
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size_t find(const json::array &key) const;
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void shl(const size_t &pos);
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void shr(const size_t &pos);
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json::object write(const mutable_buffer &out);
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state::id write(db::txn &, const mutable_buffer &id);
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rep(const node &node);
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rep() = default;
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};
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static_assert
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(
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ircd::m::state::NODE_MAX_KEY == ircd::m::state::NODE_MAX_VAL
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);
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