Struct PriorSnapshot 

pub struct PriorSnapshot { /* private fields */ }

A read-only, page-addressable image of the database AS IT WAS BEFORE the last transaction (design §4/§5). The temporal inverse of CommitSnapshot: prior[pgno] is the rollback-journal image where present, else the live main page. Diffing this against the current database yields the last transaction’s deletions (rowid present here, absent now) and modifications (present in both, values differ — the journal carries the OLD value).

Returned by Database::rollback_prior as a DISTINCT type, never a Database, so prior/deleted rows can never be read as “live” (secure-by-design). Shares ONE b-tree/overflow walk with the live and commit-snapshot reads via the internal PageSource seam.

Implementations

impl PriorSnapshot

pub fn tables(&self) -> Vec<SnapshotTable>

The user tables AS OF the prior state, parsed from the snapshot’s OWN page 1 (the prior sqlite_master), NOT the live database — so a DROP/CREATE in the last transaction is interpreted against the prior schema. Best-effort and panic-free: an unreadable page-1 schema yields an empty vector.

pub fn schema_sql(&self) -> BTreeMap<String, String>

The PRIOR sqlite_master as a name -> CREATE SQL map for every user table, parsed from the snapshot’s OWN page 1 — the prior-schema half of the Detector-B sidecar schema-change comparison (docs/design/drop-recreate-attribution.md).

The counterpart to Database::schema_sql read against the pre-transaction state the -journal preserves, so a DROP/CREATE/ALTER in the last transaction is interpreted against the prior schema. Best-effort and panic-free: an unreadable prior page-1 schema yields an empty map.

pub fn read_table( &self, rootpage: u32, column_count: usize, ) -> Result<Vec<(i64, Vec<Value>)>, Error>

Read every row of the table b-tree rooted at rootpage AS OF the prior state, in rowid order, resolving overflow chains through the snapshot’s OWN pages. The snapshot-scoped counterpart to Database::read_table: a typed Error (never a panic) on a cyclic/over-deep b-tree or overflow chain.

pub fn grew_db(&self) -> bool

Whether the last transaction GREW the database (a journal page number exceeded the current main-db page count). Pages beyond the prior size are new — their pre-images were not journaled — which bounds what rolls back.

pub fn read_table_with_pages( &self, rootpage: u32, column_count: usize, ) -> Result<Vec<(i64, Vec<Value>, u32)>, Error>

Read the table rooted at rootpage AS OF the prior state, returning each row’s rowid, values, AND the 1-based LEAF page it was decoded from — the per-row page provenance the forensic diff attaches to a recovered prior row. Shares decode_leaf_cell with the standard read; a typed Error (never a panic) on a cyclic/over-deep b-tree.

Trait Implementations

impl Clone for PriorSnapshot

fn clone(&self) -> PriorSnapshot

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for PriorSnapshot

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for PriorSnapshot

impl PartialEq for PriorSnapshot

fn eq(&self, other: &PriorSnapshot) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for PriorSnapshot