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49 lines
1.3 KiB
49 lines
1.3 KiB
use std::{fmt};
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use super::SourcePosition;
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use position::get_line_and_column;
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/// The representation of an s-expression parse error.
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pub struct Error {
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/// The error message.
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pub message: &'static str,
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/// Position in the source string where the error was detected
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pub pos: SourcePosition,
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}
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/// Since errors are the uncommon case, they're boxed. This keeps the size of
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/// structs down, which helps performance in the common case.
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///
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/// For example, an `ERes<()>` becomes 8 bytes, instead of the 24 bytes it would
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/// be if `Err` were unboxed.
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type Err = Box<Error>;
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/// Helps clean up type signatures, but shouldn't be exposed to the outside
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/// world.
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pub(crate) type ERes<T> = Result<T, Err>;
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impl fmt::Display for Error {
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fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
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write!(f, "{}: {}", self.pos, self.message)
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}
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}
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impl fmt::Debug for Error {
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fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
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write!(f, "{}", self)
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}
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}
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impl std::error::Error for Error {}
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#[cold]
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fn err_impl(message: &'static str, s: &str, pos: usize) -> Err {
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Box::new(Error {
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message,
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pos: get_line_and_column(s, pos),
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})
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}
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/// Build an error with span information
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pub(crate) fn err<T>(message: &'static str, s: &str, pos: usize) -> ERes<T> {
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Err(err_impl(message, s, pos))
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}
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