Enum ContentsShape 

pub enum ContentsShape {
    Absent,
    Single(ObjRef),
    Array(Vec<ObjRef>),
}

Where a regenerated element lands in the page’s /Contents.

The /Contents entry is a stream, an array of streams, or absent, and adding or removing an element moves it between those shapes. The rules are not symmetric, which is the point of naming them:

• absent gaining an element becomes a lone stream at index 0;
• a lone stream gaining a second becomes an array [old new], and the new one is index 1;
• an array gaining one appends, at len - 1;
• a lone stream losing index 0 loses the /Contents key entirely;
• an array losing elements keeps being an array — even down to one element, and even down to none. Collapsing a one-element array back to a bare stream would be tidier and is deliberately not done: a second stream may well be added next, and every object’s recorded index would have to move again.

Variants

Absent

No /Contents at all.

Single(ObjRef)

One stream, reached through /Contents directly.

Array(Vec<ObjRef>)

An array of stream references.

Implementations

impl ContentsShape

pub fn read(page_dict: &Dict, r: &impl Resolve) -> Self

Read the shape out of a page dictionary.

Anything that is neither a stream nor an array of streams — a dangling reference, a number, a name — reads as ContentsShape::Absent, which is how a page with unusable contents behaves everywhere else.

pub fn with_added(&self, added: ObjRef) -> (usize, Self)

The index a newly added element takes, and the shape afterwards.

pub fn with_removed( &self, removed: &BTreeSet<usize>, ) -> (Self, BTreeMap<usize, usize>)

The shape after removed elements are dropped, and the map from each surviving element’s old index to its new one.

Every object whose index is not in the map — one whose own element was removed, and one that was still streamless — collapses to index 0. That is the C++’s default-inserting map read literally, and it is deliberate: those objects were not written by this regeneration and their recorded index has to point somewhere.

Both halves of the map are usize: a /Contents index is a position in an array, and there is no negative sentinel.

pub fn to_object(&self, array_ref: Option<ObjRef>) -> Option<Object>

The /Contents value this shape writes, given the object number a fresh array would take.

None for ContentsShape::Absent, which removes the key.

pub fn elements(&self) -> &[ObjRef]

The element references, in order.

Trait Implementations

impl Clone for ContentsShape

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for ContentsShape

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

Formats the value using the given formatter.

impl Eq for ContentsShape

impl PartialEq for ContentsShape

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for ContentsShape