Struct Leaf 

pub struct Leaf { /* private fields */ }

A single metadata fence parsed from a Quillmark Markdown document.

A Leaf is the uniform shape for both the document entry (main) fence and composable leaf fences. sentinel distinguishes the two.

Every leaf has:

• sentinel — the QUILL reference (for main) or KIND tag (for composable).
• frontmatter — ordered items parsed from the YAML fence body (with the sentinel key already removed).
• body — the Markdown text that follows the closing fence, up to the next fence (or EOF).

Leaf body absence

If a leaf block has no trailing Markdown content (e.g. the next block or EOF immediately follows the closing fence), body is the empty string "". It is never None; callers that need to distinguish “absent” from “empty” should check leaf.body().is_empty().

Implementations

impl Leaf

pub fn new(tag: impl Into<String>) -> Result<Self, EditError>

Create a new, empty composable leaf with the given tag.

Invariants enforced

tag must match [a-z_][a-z0-9_]*. An invalid tag returns EditError::InvalidTagName.

The new leaf has no fields and an empty body.

pub fn set_field( &mut self, name: &str, value: QuillValue, ) -> Result<(), EditError>

Set a frontmatter field by name. Always clears the !fill marker for that key — the “user filled in” path.

Invariants enforced

• name must not be one of the reserved sentinel names. Returns EditError::ReservedName.
• name must match [a-z_][a-z0-9_]* after NFC normalisation. Returns EditError::InvalidFieldName.

Validity

After a successful call the leaf remains valid: frontmatter contains no reserved key and the value is stored at the correct key.

Warnings

Leaf mutators never modify the parent document’s warnings.

pub fn set_fill( &mut self, name: &str, value: QuillValue, ) -> Result<(), EditError>

Set a frontmatter field AND mark it as a !fill placeholder — the “reset to placeholder” path. A Null value emits as key: !fill; a scalar or sequence value emits as key: !fill <value>.

Invariants enforced

Same as Leaf::set_field.

Warnings

Leaf mutators never modify the parent document’s warnings.

pub fn remove_field( &mut self, name: &str, ) -> Result<Option<QuillValue>, EditError>

Remove a frontmatter field by name, returning the value if it existed.

Invariants enforced

• name must not be one of the reserved sentinel names. Returns EditError::ReservedName.
• name must match [a-z_][a-z0-9_]* after NFC normalisation. Returns EditError::InvalidFieldName.

Absence of an otherwise-valid name returns Ok(None).

Warnings

Leaf mutators never modify the parent document’s warnings.

pub fn replace_body(&mut self, body: impl Into<String>)

Replace the leaf’s Markdown body.

Warnings

Leaf mutators never modify the parent document’s warnings.

impl Leaf

pub fn new_with_sentinel( sentinel: Sentinel, frontmatter: Frontmatter, body: String, ) -> Self

Create a Leaf directly from a sentinel, a typed frontmatter, and a body. Does not validate the sentinel tag or any field names — callers are responsible for providing already-valid data. For user-facing construction of composable leaves use Leaf::new (defined in edit.rs).

pub fn sentinel(&self) -> &Sentinel

The sentinel discriminating this leaf as main or composable.

pub fn tag(&self) -> String

The leaf tag — the KIND: value for composable leaves, or the string form of the quill reference for main leaves.

pub fn frontmatter(&self) -> &Frontmatter

Typed frontmatter (map-keyed view and ordered item list).

pub fn frontmatter_mut(&mut self) -> &mut Frontmatter

Mutable access to the frontmatter.

pub fn body(&self) -> &str

Markdown body that follows this leaf’s closing fence.

Empty string when no trailing content is present.

pub fn is_main(&self) -> bool

Returns true if this is the document entry (main) leaf.

Trait Implementations

impl Clone for Leaf

fn clone(&self) -> Leaf

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Leaf

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

Formats the value using the given formatter.

impl PartialEq for Leaf

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for Leaf