Import 'regex-syntax' package vesion 0.6.17
* Add OWNERS
Bug: 152884384
Test: make
Change-Id: I760a69ffc851039ceaff58980deece308a426aed
diff --git a/src/error.rs b/src/error.rs
new file mode 100644
index 0000000..93c2b0d
--- /dev/null
+++ b/src/error.rs
@@ -0,0 +1,324 @@
+use std::cmp;
+use std::error;
+use std::fmt;
+use std::result;
+
+use ast;
+use 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: '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: 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 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
+"#,
+ );
+ }
+}