Enum syntree::Error

#[non_exhaustive]
pub enum Error {
    CloseError,
    BuildError,
    CloseAtError,
    Overflow,
    MissingNode(usize),
    // some variants omitted
}

Errors raised while building a tree.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

CloseError

Error raised by Builder::close if there currently is no node being built.

Examples

use syntree::{Builder, Error};

let mut tree = Builder::new();

tree.open("root")?;
tree.close()?;

// Syntax::Root and Syntax::Child is left open.
assert_eq!(tree.close(), Err(Error::CloseError));

BuildError

Error raised by Builder::build if the tree isn’t correctly balanced.

Examples

use syntree::{Builder, Error};

let mut tree = Builder::new();

tree.open("number")?;
tree.token("lit", 3)?;
tree.close()?;

tree.open("number")?;

// Syntax::Number is left open.
assert_eq!(tree.build(), Err(Error::BuildError));

CloseAtError

Error raised by Builder::close_at if we’re not trying to close at a sibling node.

Examples

use syntree::{Builder, Error};

let mut tree = Builder::new();

let c = tree.checkpoint()?;

tree.open("child")?;
tree.token("token", 3)?;

assert_eq!(tree.close_at(&c, "operation"), Err(Error::CloseAtError));

Overflow

Numerical overflow.

This only happens under extreme circumstances or if a feature is enabled which narrows the width of an identifier to the degree that this error is easier to accomplish.

Examples

This is an example where we’re trying to build a really small tree using u8 pointers:

use syntree::{Builder, Error};

let mut tree: Builder<_, u32, u8> = Builder::new_with();

for d in 0..u8::MAX {
    tree.token(d, 1)?;
}

assert_eq!(tree.token(255, 1), Err(Error::Overflow));

MissingNode(usize)

The node of the given id is missing.

Examples

The following showcases what could happen if you mix checkpoints from two compatible trees:

use syntree::{Builder, Error};

let mut a = Builder::new();
let mut b = Builder::new();

b.open("child")?;
b.close()?;

let c = b.checkpoint()?;

assert_eq!(a.close_at(&c, "operation"), Err(Error::MissingNode(0)));

Trait Implementations

impl Clone for Error

fn clone(&self) -> Error

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for Error

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

Formats the value using the given formatter.

impl Display for Error

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

Formats the value using the given formatter.

impl Error for Error

fn source(&self) -> Option<&(dyn Error + 'static)>

The lower-level source of this error, if any.

fn description(&self) -> &str

👎Deprecated since 1.42.0: use the Display impl or to_string()

fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0: replaced by Error::source, which can support downcasting

fn provide<'a>(&'a self, demand: &mut Demand<'a>)

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

Provides type based access to context intended for error reports.

impl PartialEq<Error> for Error

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

This method tests for self and other values to be equal, and is used by ==.

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

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

impl Copy for Error

impl Eq for Error

impl StructuralEq for Error

impl StructuralPartialEq for Error