Struct BranchId 

pub struct BranchId(/* private fields */);

A validated lineage name.

This is not ModelName’s reason, and the rule

is deliberately different

ModelName exists because a model name is spliced into a table identifier and SQLite cannot bind an identifier as a parameter, so the validation is what makes the splice safe. None of that applies here. A branch_id reaches SQL as a bound value at every one of its call sites; there is no splice to protect. Copying ModelName’s [a-z][a-z0-9_]* rule would be borrowing a justification that does not hold, and it would reject the two name shapes the use case in §15.5 actually produces — a hyphenated UUID and a path-like turn id.

What this type is for is narrower and has nothing to do with SQL:

• branch_id is a primary key that four ledger tables hold a foreign key into, and branches is append-only under two unconditional triggers (CREATE_BRANCHES_GUARD_UPDATE). A name is therefore written once and can never be corrected — not by the crate, not by raw SQL. Validation has one chance, and this is it.
• A name that differs from the caller’s intent by a trailing space is not a typo, it is a second lineage that reads as the first. Every subsequent on_branch("release ") resolves to a different ancestry than on_branch("release"), both succeed, and neither reports anything. That is the failure shape this wave keeps finding, and it is cheapest to refuse at D-034’s boundary.

So the rule is: non-empty, at most MAX_BRANCH_ID bytes, no ASCII control characters, and no leading or trailing whitespace. Refused rather than trimmed, on §4.1’s principle — a silent repair here becomes two lineages sharing one intent later.

main is constructible and not forkable

Database::branches returns the trunk and every read may name it, so BranchId::new("main") must succeed. What is refused is creating it a second time, and that refusal belongs to Database::fork rather than to this type: the trunk is a lineage like any other to a reader, and only a writer has cause to care that it already exists.

Implementations

impl BranchId

pub fn new(raw: impl AsRef<str>) -> Result<Self>

Validate raw as a lineage name, or explain why it is not one.

pub fn main() -> Self

The trunk, which every database has from its first migration.

pub fn as_str(&self) -> &str

The name, as it is stored.

pub fn is_main(&self) -> bool

Whether this names the trunk.

Trait Implementations

impl AsRef<str> for BranchId

fn as_ref(&self) -> &str

Converts this type into a shared reference of the (usually inferred) input type.

impl Clone for BranchId

fn clone(&self) -> BranchId

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for BranchId

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

Formats the value using the given formatter.

impl Display for BranchId

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

Formats the value using the given formatter.

impl Eq for BranchId

impl From<BranchId> for String

So a BranchId can be handed straight to the 0.14.4 read surface.

TraversalBuilder::on_branch and query_as_of_edges_on take impl Into<String>, and they shipped two releases before this type existed. This impl is what makes on_branch(id) compile rather than on_branch(id.as_str()) — additive, and cheaper than widening four signatures that are already public.

fn from(id: BranchId) -> Self

Converts to this type from the input type.

impl Hash for BranchId

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl Ord for BranchId

fn cmp(&self, other: &BranchId) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

fn clamp_to<R>(self, range: R) -> Self

where Self: Sized, R: ClampBounds<Self>,

🔬This is a nightly-only experimental API. (clamp_to)

Restrict a value to a certain range.

impl PartialEq for BranchId

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

Equality operator ==.

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

Inequality operator !=.

impl PartialOrd for BranchId

fn partial_cmp(&self, other: &BranchId) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

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

Tests less than (for self and other) and is used by the < operator.

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

Tests less than or equal to (for self and other) and is used by the <= operator.

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

Tests greater than (for self and other) and is used by the > operator.

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

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl StructuralPartialEq for BranchId