Struct HunkPatch 

pub struct HunkPatch {
    pub header: Vec<String>,
    pub hunk: Vec<String>,
    pub header_line: usize,
    pub end_line: usize,
}

One hunk, plus the file header needed to apply it on its own.

Fields

header: Vec<String>

Verbatim file-header lines: diff --git through +++.

hunk: Vec<String>

The @@ line and its body, verbatim.

header_line: usize

Buffer line of the @@ header, for cursor restoration.

end_line: usize

Buffer line one past the hunk’s last body line.

Implementations

impl HunkPatch

pub fn display_location(&self) -> String

path:line naming this hunk’s position in the file — the @@ header’s new-side start, not a buffer row. Prompts and echoes use it, so Discard hunk at src/main.rs:42? points at something the user can find after the buffer is rebuilt.

Falls back to the path alone, then to "hunk", so a header this cannot parse still yields a sentence.

pub fn file_path(&self) -> Option<&str>

The file this hunk belongs to, for finding it again after the buffer is rebuilt (MG.18d).

Prefers the +++ b/ side and falls back to --- a/, so a deletion — whose +++ is /dev/null — still names its file. Self::display_path deliberately does not: a prompt saying “discard hunk at /dev/null” would be worse than one that omits the path, while a cursor restore that skipped deletions would silently lose the user’s place on exactly the rows that are hardest to find again.

pub fn display_path(&self) -> Option<&str>

The path from the +++ b/… line, for prompts and messages. None for a deletion (+++ /dev/null) or a malformed header.

Display only — Self::to_patch never consults it, so a path this cannot parse still stages correctly.

pub fn to_patch(&self) -> String

A standalone patch: the file header, then this hunk alone.

Always ends in a newline — git apply rejects a patch whose final line is unterminated.

impl HunkPatch

pub fn restrict_to_rows( &self, selected: RangeInclusive<usize>, direction: ApplyDirection, ) -> Option<HunkPatch>

MG.18e: rewrite this hunk to carry only the changes on the buffer rows in selected.

Region staging is not “a smaller hunk” — the body has to be rewritten, because a patch must still describe a complete transformation of the region it covers:

Line	Selected	Unselected (Forward)	Unselected (Reverse)
+added	stays +	dropped	becomes context
-removed	stays -	becomes context	dropped
context	context	context	context

The asymmetry is not a convention, it is what the target contains. Applying forward, the target holds the old side: an unselected + is not there and must not appear at all, while an unselected - is there and survives — i.e. context. Reversed, the target holds the new side and the roles swap exactly.

Both counts are recounted from the rewritten body; git apply validates them against it and rejects the patch outright if they disagree (“corrupt patch”). The two start lines are kept verbatim: whichever side the target matches is preserved line-for-line by the rules above, so its start is still correct, and the other side’s start is not something git checks.

None when the selection contains no +/- line at all — a body of pure context is a patch that does nothing, and telling the user “nothing to stage there” beats handing git a no-op.

Trait Implementations

impl Clone for HunkPatch

fn clone(&self) -> HunkPatch

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for HunkPatch

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

Formats the value using the given formatter.

impl Eq for HunkPatch

impl PartialEq for HunkPatch

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for HunkPatch