narwhal-core 1.2.0

Core traits and types for narwhal
Documentation 
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use serde::{Deserialize, Serialize};

/// Static description of features a driver supports.
///
/// The UI inspects [`Capabilities`] to enable or disable commands without
/// hard-coding driver names. New flags are added by extending this struct;
/// existing drivers default to `false` for unknown features.
#[derive(Debug, Clone, Copy, Default, PartialEq, Eq, Serialize, Deserialize)]
#[non_exhaustive]
pub struct Capabilities {
    /// Driver supports explicit transactions (`BEGIN`/`COMMIT`/`ROLLBACK`).
    pub transactions: bool,
    /// Driver can request asynchronous cancellation of an in-flight query.
    pub cancellation: bool,
    /// Driver exposes more than one logical schema/namespace.
    pub multiple_schemas: bool,
    /// Driver supports server-side prepared statements with parameter binding.
    pub prepared_statements: bool,
    /// Driver supports nested transactions via savepoints.
    pub savepoints: bool,
    /// Driver can report row counts for `UPDATE`/`DELETE` statements.
    pub rows_affected: bool,
    /// Driver returns rows progressively from [`crate::Connection::stream`] —
    /// i.e. the stream yields rows as the server produces them, without
    /// materialising the entire result set in memory first.
    ///
    /// Drivers that currently buffer the full result before exposing the
    /// stream (notably `MySQL`, which is awaiting a real `stream_and_drop`
    /// implementation) must leave this `false` so the UI can warn the
    /// user and refuse to launch open-ended streams over large tables.
    pub streaming: bool,
    /// Driver supports row-level DML through the standard
    /// `INSERT`/`UPDATE`/`DELETE` grammar that
    /// [`crate::Connection::execute`] accepts.
    ///
    /// Most engines do; the notable exception is `ClickHouse`, where
    /// row-level changes have to go through `ALTER TABLE ... UPDATE`
    /// or `ALTER TABLE ... DELETE` async mutations. The pending-changes
    /// pipeline gates `o`/`O`/`d`/cell-edit on this flag so it never
    /// emits a statement the driver cannot consume. Defaults to
    /// `false`; drivers opt in explicitly via
    /// [`Self::with_row_level_dml`].
    pub row_level_dml: bool,
}

impl Capabilities {
    /// Builder-style mutation used by drivers to assemble their capability set.
    #[must_use]
    pub const fn with_transactions(mut self, value: bool) -> Self {
        self.transactions = value;
        self
    }

    #[must_use]
    pub const fn with_cancellation(mut self, value: bool) -> Self {
        self.cancellation = value;
        self
    }

    #[must_use]
    pub const fn with_multiple_schemas(mut self, value: bool) -> Self {
        self.multiple_schemas = value;
        self
    }

    #[must_use]
    pub const fn with_prepared_statements(mut self, value: bool) -> Self {
        self.prepared_statements = value;
        self
    }

    #[must_use]
    pub const fn with_savepoints(mut self, value: bool) -> Self {
        self.savepoints = value;
        self
    }

    #[must_use]
    pub const fn with_rows_affected(mut self, value: bool) -> Self {
        self.rows_affected = value;
        self
    }

    #[must_use]
    pub const fn with_streaming(mut self, value: bool) -> Self {
        self.streaming = value;
        self
    }

    #[must_use]
    pub const fn with_row_level_dml(mut self, value: bool) -> Self {
        self.row_level_dml = value;
        self
    }
}