rocksgraph 0.1.0

A Gremlin-inspired property graph query engine written in Rust, backed by RocksDB
Documentation 
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// Copyright (c) 2026 Austin Han <austinhan1024@gmail.com>
//
// This file is part of RocksGraph.
//
// RocksGraph is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 2 of the License, or
// (at your option) any later version.
//
// RocksGraph 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 General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with RocksGraph.  If not, see <https://www.gnu.org/licenses/>.

// ── Existence ────────────────────────────────────────────────────────────────
//
/// Mutation kind for a dirty graph element within a `LogicalGraph`.
///
/// Only dirty elements appear in the `dirty` map; absence means `Clean`.
///
/// **Note**: How to handle delete -> add on the same element within a single query?
/// This is currently treated as `New`, but it might be beneficial to distinguish it
///     from a pure create for better conflict detection.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub(crate) enum Existence {
    /// Props were mutated on an existing element.
    Modified,
    /// Only the vertex edge counts changed.
    CounterOnly,
    /// Props and vertex edge counts both changed.
    ModifiedWithCounter,
    /// Created in this query; not yet persisted.
    New,
    /// Deleted in this query.
    Tombstone,
}

impl Existence {
    /// Merges two dirty states for the same element within a single transaction.
    ///
    /// This defines the state machine for consecutive operations. For example:
    /// - Any operation followed by a deletion (`Tombstone`) results in a `Tombstone`.
    /// - Modifying properties (`Modified`) and changing edge counts (`CounterOnly`) combines into
    ///   `ModifiedWithCounter`.
    #[inline]
    pub(crate) fn merge(self, other: Existence) -> Existence {
        use Existence::*;
        match (self, other) {
            (Tombstone, _) | (_, Tombstone) => Tombstone,
            (New, _) | (_, New) => New,
            (ModifiedWithCounter, _) | (_, ModifiedWithCounter) => ModifiedWithCounter,
            (Modified, CounterOnly) | (CounterOnly, Modified) => ModifiedWithCounter,
            (Modified, Modified) => Modified,
            (CounterOnly, CounterOnly) => CounterOnly,
        }
    }
}