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Diffstat (limited to 'third_party/rust/regex-syntax/src/error.rs')
| -rw-r--r-- | third_party/rust/regex-syntax/src/error.rs | 324 |
1 files changed, 324 insertions, 0 deletions
diff --git a/third_party/rust/regex-syntax/src/error.rs b/third_party/rust/regex-syntax/src/error.rs new file mode 100644 index 0000000000..1230d2fc5d --- /dev/null +++ b/third_party/rust/regex-syntax/src/error.rs @@ -0,0 +1,324 @@ +use std::cmp; +use std::error; +use std::fmt; +use std::result; + +use crate::ast; +use crate::hir; + +/// A type alias for dealing with errors returned by this crate. +pub type Result<T> = result::Result<T, Error>; + +/// This error type encompasses any error that can be returned by this crate. +#[derive(Clone, Debug, Eq, PartialEq)] +pub enum Error { + /// An error that occurred while translating concrete syntax into abstract + /// syntax (AST). + Parse(ast::Error), + /// An error that occurred while translating abstract syntax into a high + /// level intermediate representation (HIR). + Translate(hir::Error), + /// Hints that destructuring should not be exhaustive. + /// + /// This enum may grow additional variants, so this makes sure clients + /// don't count on exhaustive matching. (Otherwise, adding a new variant + /// could break existing code.) + #[doc(hidden)] + __Nonexhaustive, +} + +impl From<ast::Error> for Error { + fn from(err: ast::Error) -> Error { + Error::Parse(err) + } +} + +impl From<hir::Error> for Error { + fn from(err: hir::Error) -> Error { + Error::Translate(err) + } +} + +impl error::Error for Error { + // TODO: Remove this method entirely on the next breaking semver release. + #[allow(deprecated)] + fn description(&self) -> &str { + match *self { + Error::Parse(ref x) => x.description(), + Error::Translate(ref x) => x.description(), + _ => unreachable!(), + } + } +} + +impl fmt::Display for Error { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + match *self { + Error::Parse(ref x) => x.fmt(f), + Error::Translate(ref x) => x.fmt(f), + _ => unreachable!(), + } + } +} + +/// A helper type for formatting nice error messages. +/// +/// This type is responsible for reporting regex parse errors in a nice human +/// readable format. Most of its complexity is from interspersing notational +/// markers pointing out the position where an error occurred. +#[derive(Debug)] +pub struct Formatter<'e, E> { + /// The original regex pattern in which the error occurred. + pattern: &'e str, + /// The error kind. It must impl fmt::Display. + err: &'e E, + /// The primary span of the error. + span: &'e ast::Span, + /// An auxiliary and optional span, in case the error needs to point to + /// two locations (e.g., when reporting a duplicate capture group name). + aux_span: Option<&'e ast::Span>, +} + +impl<'e> From<&'e ast::Error> for Formatter<'e, ast::ErrorKind> { + fn from(err: &'e ast::Error) -> Self { + Formatter { + pattern: err.pattern(), + err: err.kind(), + span: err.span(), + aux_span: err.auxiliary_span(), + } + } +} + +impl<'e> From<&'e hir::Error> for Formatter<'e, hir::ErrorKind> { + fn from(err: &'e hir::Error) -> Self { + Formatter { + pattern: err.pattern(), + err: err.kind(), + span: err.span(), + aux_span: None, + } + } +} + +impl<'e, E: fmt::Display> fmt::Display for Formatter<'e, E> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + let spans = Spans::from_formatter(self); + if self.pattern.contains('\n') { + let divider = repeat_char('~', 79); + + writeln!(f, "regex parse error:")?; + writeln!(f, "{}", divider)?; + let notated = spans.notate(); + write!(f, "{}", notated)?; + writeln!(f, "{}", divider)?; + // If we have error spans that cover multiple lines, then we just + // note the line numbers. + if !spans.multi_line.is_empty() { + let mut notes = vec![]; + for span in &spans.multi_line { + notes.push(format!( + "on line {} (column {}) through line {} (column {})", + span.start.line, + span.start.column, + span.end.line, + span.end.column - 1 + )); + } + writeln!(f, "{}", notes.join("\n"))?; + } + write!(f, "error: {}", self.err)?; + } else { + writeln!(f, "regex parse error:")?; + let notated = Spans::from_formatter(self).notate(); + write!(f, "{}", notated)?; + write!(f, "error: {}", self.err)?; + } + Ok(()) + } +} + +/// This type represents an arbitrary number of error spans in a way that makes +/// it convenient to notate the regex pattern. ("Notate" means "point out +/// exactly where the error occurred in the regex pattern.") +/// +/// Technically, we can only ever have two spans given our current error +/// structure. However, after toiling with a specific algorithm for handling +/// two spans, it became obvious that an algorithm to handle an arbitrary +/// number of spans was actually much simpler. +struct Spans<'p> { + /// The original regex pattern string. + pattern: &'p str, + /// The total width that should be used for line numbers. The width is + /// used for left padding the line numbers for alignment. + /// + /// A value of `0` means line numbers should not be displayed. That is, + /// the pattern is itself only one line. + line_number_width: usize, + /// All error spans that occur on a single line. This sequence always has + /// length equivalent to the number of lines in `pattern`, where the index + /// of the sequence represents a line number, starting at `0`. The spans + /// in each line are sorted in ascending order. + by_line: Vec<Vec<ast::Span>>, + /// All error spans that occur over one or more lines. That is, the start + /// and end position of the span have different line numbers. The spans are + /// sorted in ascending order. + multi_line: Vec<ast::Span>, +} + +impl<'p> Spans<'p> { + /// Build a sequence of spans from a formatter. + fn from_formatter<'e, E: fmt::Display>( + fmter: &'p Formatter<'e, E>, + ) -> Spans<'p> { + let mut line_count = fmter.pattern.lines().count(); + // If the pattern ends with a `\n` literal, then our line count is + // off by one, since a span can occur immediately after the last `\n`, + // which is consider to be an additional line. + if fmter.pattern.ends_with('\n') { + line_count += 1; + } + let line_number_width = + if line_count <= 1 { 0 } else { line_count.to_string().len() }; + let mut spans = Spans { + pattern: &fmter.pattern, + line_number_width, + by_line: vec![vec![]; line_count], + multi_line: vec![], + }; + spans.add(fmter.span.clone()); + if let Some(span) = fmter.aux_span { + spans.add(span.clone()); + } + spans + } + + /// Add the given span to this sequence, putting it in the right place. + fn add(&mut self, span: ast::Span) { + // This is grossly inefficient since we sort after each add, but right + // now, we only ever add two spans at most. + if span.is_one_line() { + let i = span.start.line - 1; // because lines are 1-indexed + self.by_line[i].push(span); + self.by_line[i].sort(); + } else { + self.multi_line.push(span); + self.multi_line.sort(); + } + } + + /// Notate the pattern string with carents (`^`) pointing at each span + /// location. This only applies to spans that occur within a single line. + fn notate(&self) -> String { + let mut notated = String::new(); + for (i, line) in self.pattern.lines().enumerate() { + if self.line_number_width > 0 { + notated.push_str(&self.left_pad_line_number(i + 1)); + notated.push_str(": "); + } else { + notated.push_str(" "); + } + notated.push_str(line); + notated.push('\n'); + if let Some(notes) = self.notate_line(i) { + notated.push_str(¬es); + notated.push('\n'); + } + } + notated + } + + /// Return notes for the line indexed at `i` (zero-based). If there are no + /// spans for the given line, then `None` is returned. Otherwise, an + /// appropriately space padded string with correctly positioned `^` is + /// returned, accounting for line numbers. + fn notate_line(&self, i: usize) -> Option<String> { + let spans = &self.by_line[i]; + if spans.is_empty() { + return None; + } + let mut notes = String::new(); + for _ in 0..self.line_number_padding() { + notes.push(' '); + } + let mut pos = 0; + for span in spans { + for _ in pos..(span.start.column - 1) { + notes.push(' '); + pos += 1; + } + let note_len = span.end.column.saturating_sub(span.start.column); + for _ in 0..cmp::max(1, note_len) { + notes.push('^'); + pos += 1; + } + } + Some(notes) + } + + /// Left pad the given line number with spaces such that it is aligned with + /// other line numbers. + fn left_pad_line_number(&self, n: usize) -> String { + let n = n.to_string(); + let pad = self.line_number_width.checked_sub(n.len()).unwrap(); + let mut result = repeat_char(' ', pad); + result.push_str(&n); + result + } + + /// Return the line number padding beginning at the start of each line of + /// the pattern. + /// + /// If the pattern is only one line, then this returns a fixed padding + /// for visual indentation. + fn line_number_padding(&self) -> usize { + if self.line_number_width == 0 { + 4 + } else { + 2 + self.line_number_width + } + } +} + +fn repeat_char(c: char, count: usize) -> String { + ::std::iter::repeat(c).take(count).collect() +} + +#[cfg(test)] +mod tests { + use crate::ast::parse::Parser; + + fn assert_panic_message(pattern: &str, expected_msg: &str) { + let result = Parser::new().parse(pattern); + match result { + Ok(_) => { + panic!("regex should not have parsed"); + } + Err(err) => { + assert_eq!(err.to_string(), expected_msg.trim()); + } + } + } + + // See: https://github.com/rust-lang/regex/issues/464 + #[test] + fn regression_464() { + let err = Parser::new().parse("a{\n").unwrap_err(); + // This test checks that the error formatter doesn't panic. + assert!(!err.to_string().is_empty()); + } + + // See: https://github.com/rust-lang/regex/issues/545 + #[test] + fn repetition_quantifier_expects_a_valid_decimal() { + assert_panic_message( + r"\\u{[^}]*}", + r#" +regex parse error: + \\u{[^}]*} + ^ +error: repetition quantifier expects a valid decimal +"#, + ); + } +} |