sqlite-diff-rs 0.2.0

Build SQLite changeset and patchset binary formats programmatically, without SQLite
Documentation 
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//! [`Decoder`]: per-(source, semantic) conversion from a payload into
//! [`Value`](crate::encoding::Value), plus every built-in decoder unit
//! type the crate ships.

use super::error::DecodeError;
use super::source::WireSource;
use crate::encoding::Value;

/// Converts a per-column payload into a [`Value`].
///
/// Zero-sized unit-struct implementations (the crate's built-ins) cover
/// the common cases. User-defined stateful decoders carry their own
/// fields (lookup tables, compiled regexes, per-adapter configuration)
/// and implement the same trait shape.
pub trait Decoder<Src: WireSource, S, B> {
    /// Decode one payload.
    ///
    /// # Errors
    ///
    /// Returns a [`DecodeError`] variant describing the failure. Every
    /// variant carries the offending column name so the outer
    /// [`WireAdapter`](super::adapter::WireAdapter) impl does not have to wrap.
    fn decode(&self, payload: Src::Payload<'_>) -> Result<Value<S, B>, DecodeError>;
}

// ------------------------------------------------------------------
// Built-in decoder unit types. Every one is a zero-sized marker whose
// `impl Decoder<Src, S, B>` for each supported `Src` lives in the format
// module (`pg_walstream`, `wal2json`, `maxwell`).
// ------------------------------------------------------------------

/// Decoder producing `Value::Null` regardless of the payload's non-null
/// contents. Registered internally when the payload's null discriminator
/// is set. Users normally do not register this directly.
#[derive(Debug, Clone, Copy, Default)]
pub struct NullDecoder;

/// Decoder for boolean columns.
#[derive(Debug, Clone, Copy, Default)]
pub struct BoolDecoder;

/// Decoder for integer columns fitting in `i64`.
#[derive(Debug, Clone, Copy, Default)]
pub struct IntDecoder;

/// Decoder for integer columns whose wire values may exceed `i64`. Values
/// fitting `i64` produce `Value::Integer`, values above produce
/// `Value::Text` with the base-10 digits preserved.
#[derive(Debug, Clone, Copy, Default)]
pub struct Int64OverflowToTextDecoder;

/// Decoder for floating-point columns.
#[derive(Debug, Clone, Copy, Default)]
pub struct RealDecoder;

/// Decoder for text-affinity columns.
#[derive(Debug, Clone, Copy, Default)]
pub struct TextDecoder;

/// Decoder for pg_walstream binary-mode BYTEA.
#[derive(Debug, Clone, Copy, Default)]
pub struct PgByteaBinaryDecoder;

/// Decoder for pg_walstream text-mode BYTEA (`\xHEX` form).
#[derive(Debug, Clone, Copy, Default)]
pub struct PgByteaTextModeDecoder;

/// Decoder for MySQL binary-family columns (base64 on the wire).
#[derive(Debug, Clone, Copy, Default)]
pub struct MySqlBinaryDecoder;

/// Decoder rendering UUID wire text into a 16-byte `Value::Blob`.
#[derive(Debug, Clone, Copy, Default)]
pub struct UuidBlob16Decoder;

/// Decoder rendering UUID wire text into a verbatim `Value::Text(36)`.
#[derive(Debug, Clone, Copy, Default)]
pub struct UuidText36Decoder;

/// Decoder for `numeric`/`decimal` columns, preserving precision as
/// `Value::Text`.
#[derive(Debug, Clone, Copy, Default)]
pub struct DecimalTextDecoder;

/// Decoder for `timestamp` (without time zone). Preserves the wire text
/// verbatim.
#[derive(Debug, Clone, Copy, Default)]
pub struct TimestampVerbatimDecoder;

/// Decoder for `timestamptz`. Preserves the wire text verbatim.
#[derive(Debug, Clone, Copy, Default)]
pub struct TimestampTzVerbatimDecoder;

/// Decoder for `date`. Preserves the wire text verbatim.
#[derive(Debug, Clone, Copy, Default)]
pub struct DateVerbatimDecoder;

/// Decoder for `time`/`timetz`. Preserves the wire text verbatim.
#[derive(Debug, Clone, Copy, Default)]
pub struct TimeVerbatimDecoder;

/// Decoder for `interval`. Preserves the wire text verbatim.
#[derive(Debug, Clone, Copy, Default)]
pub struct IntervalVerbatimDecoder;

/// Decoder for `json`/`jsonb`. Preserves the wire form verbatim as
/// `Value::Text`.
#[derive(Debug, Clone, Copy, Default)]
pub struct JsonVerbatimDecoder;

/// Decoder for `json`/`jsonb` that canonicalizes into sorted-key compact
/// JSON text.
#[derive(Debug, Clone, Copy, Default)]
pub struct JsonCanonicalDecoder;