Struct ChangeSet

Source

pub struct ChangeSet<T, F>where
    T: Copy,
    F: Flavor,
{ /* private fields */ }

Expand description

A recorded set of tree modifications.

You can use ChangeSet::modify to construct a new modified tree from an existing one.

§Examples

use syntree::edit::ChangeSet;

let tree = syntree::tree! {
    "root" => {
        "child" => {
            ("lit", 1),
            ("lit", 2),
        },
        ("whitespace", 3),
    }
};

let child = tree.first().and_then(|n| n.first()).ok_or("missing child")?;

let mut change_set = ChangeSet::new();
change_set.remove(child.id());

assert_eq!(
    change_set.modify(&tree)?,
    syntree::tree! {
        "root" => {
            ("whitespace", 3)
        }
    }
);

let lit = child.first().ok_or("missing lit")?;

let mut change_set = ChangeSet::new();
change_set.remove(lit.id());

assert_eq!(
    change_set.modify(&tree)?,
    syntree::tree! {
        "root" => {
            "child" => {
                ("lit", 2),
            },
            ("whitespace", 3)
        }
    }
);

Implementations§

Source §

impl<T, F> ChangeSet<T, F>
where T: Copy, F: Flavor,

Source

pub fn new() -> Self

Construct a new empty ChangeSet.

Source §

impl<T, F> ChangeSet<T, F>
where T: Copy, F: Flavor,

Source

pub fn remove(&mut self, id: F::Pointer)

Register a node removal in the changeset. Only one kind of modification for a given node will be preserved.

§Examples

use syntree::edit::ChangeSet;

let tree = syntree::tree! {
    "root" => {
        "child" => {
            ("lit", 1),
            ("lit", 2),
        },
        ("whitespace", 3),
    }
};

let child = tree.first().and_then(|n| n.first()).ok_or("missing child")?;

let mut change_set = ChangeSet::new();
change_set.remove(child.id());

assert_eq!(
    change_set.modify(&tree)?,
    syntree::tree! {
        "root" => {
            ("whitespace", 3)
        }
    }
);

Source

pub fn modify( &mut self, tree: &Tree<T, F>, ) -> Result<Tree<T, F>, Error<F::Error>>

Construct a modified tree where the recorded modifications have been applied.

§Errors

Errors with Error::Overflow in case we run out of node identifiers.

§Examples

use syntree::edit::ChangeSet;

let tree = syntree::tree! {
    "root" => {
        "child" => {
            ("lit", 1),
            ("lit", 2),
        },
        ("whitespace", 3),
    }
};

let child = tree.first().and_then(|n| n.first()).ok_or("missing child")?;
let mut change_set = ChangeSet::new();
change_set.remove(child.id());

assert_eq!(
    change_set.modify(&tree)?,
    syntree::tree! {
        "root" => {
            ("whitespace", 3)
        }
    }
);