diff options
Diffstat (limited to 'third_party/rust/regex-automata/src/util/syntax.rs')
| -rw-r--r-- | third_party/rust/regex-automata/src/util/syntax.rs | 482 |
1 files changed, 482 insertions, 0 deletions
diff --git a/third_party/rust/regex-automata/src/util/syntax.rs b/third_party/rust/regex-automata/src/util/syntax.rs new file mode 100644 index 0000000000..78e3cf9a11 --- /dev/null +++ b/third_party/rust/regex-automata/src/util/syntax.rs @@ -0,0 +1,482 @@ +/*! +Utilities for dealing with the syntax of a regular expression. + +This module currently only exposes a [`Config`] type that +itself represents a wrapper around the configuration for a +[`regex-syntax::ParserBuilder`](regex_syntax::ParserBuilder). The purpose of +this wrapper is to make configuring syntax options very similar to how other +configuration is done throughout this crate. Namely, instead of duplicating +syntax options across every builder (of which there are many), we instead +create small config objects like this one that can be passed around and +composed. +*/ + +use alloc::{vec, vec::Vec}; + +use regex_syntax::{ + ast, + hir::{self, Hir}, + Error, ParserBuilder, +}; + +/// A convenience routine for parsing a pattern into an HIR value with the +/// default configuration. +/// +/// # Example +/// +/// This shows how to parse a pattern into an HIR value: +/// +/// ``` +/// use regex_automata::util::syntax; +/// +/// let hir = syntax::parse(r"([a-z]+)|([0-9]+)")?; +/// assert_eq!(Some(1), hir.properties().static_explicit_captures_len()); +/// +/// # Ok::<(), Box<dyn std::error::Error>>(()) +/// ``` +pub fn parse(pattern: &str) -> Result<Hir, Error> { + parse_with(pattern, &Config::default()) +} + +/// A convenience routine for parsing many patterns into HIR value with the +/// default configuration. +/// +/// # Example +/// +/// This shows how to parse many patterns into an corresponding HIR values: +/// +/// ``` +/// use { +/// regex_automata::util::syntax, +/// regex_syntax::hir::Properties, +/// }; +/// +/// let hirs = syntax::parse_many(&[ +/// r"([a-z]+)|([0-9]+)", +/// r"foo(A-Z]+)bar", +/// ])?; +/// let props = Properties::union(hirs.iter().map(|h| h.properties())); +/// assert_eq!(Some(1), props.static_explicit_captures_len()); +/// +/// # Ok::<(), Box<dyn std::error::Error>>(()) +/// ``` +pub fn parse_many<P: AsRef<str>>(patterns: &[P]) -> Result<Vec<Hir>, Error> { + parse_many_with(patterns, &Config::default()) +} + +/// A convenience routine for parsing a pattern into an HIR value using a +/// `Config`. +/// +/// # Example +/// +/// This shows how to parse a pattern into an HIR value with a non-default +/// configuration: +/// +/// ``` +/// use regex_automata::util::syntax; +/// +/// let hir = syntax::parse_with( +/// r"^[a-z]+$", +/// &syntax::Config::new().multi_line(true).crlf(true), +/// )?; +/// assert!(hir.properties().look_set().contains_anchor_crlf()); +/// +/// # Ok::<(), Box<dyn std::error::Error>>(()) +/// ``` +pub fn parse_with(pattern: &str, config: &Config) -> Result<Hir, Error> { + let mut builder = ParserBuilder::new(); + config.apply(&mut builder); + builder.build().parse(pattern) +} + +/// A convenience routine for parsing many patterns into HIR values using a +/// `Config`. +/// +/// # Example +/// +/// This shows how to parse many patterns into an corresponding HIR values +/// with a non-default configuration: +/// +/// ``` +/// use { +/// regex_automata::util::syntax, +/// regex_syntax::hir::Properties, +/// }; +/// +/// let patterns = &[ +/// r"([a-z]+)|([0-9]+)", +/// r"\W", +/// r"foo(A-Z]+)bar", +/// ]; +/// let config = syntax::Config::new().unicode(false).utf8(false); +/// let hirs = syntax::parse_many_with(patterns, &config)?; +/// let props = Properties::union(hirs.iter().map(|h| h.properties())); +/// assert!(!props.is_utf8()); +/// +/// # Ok::<(), Box<dyn std::error::Error>>(()) +/// ``` +pub fn parse_many_with<P: AsRef<str>>( + patterns: &[P], + config: &Config, +) -> Result<Vec<Hir>, Error> { + let mut builder = ParserBuilder::new(); + config.apply(&mut builder); + let mut hirs = vec![]; + for p in patterns.iter() { + hirs.push(builder.build().parse(p.as_ref())?); + } + Ok(hirs) +} + +/// A common set of configuration options that apply to the syntax of a regex. +/// +/// This represents a group of configuration options that specifically apply +/// to how the concrete syntax of a regular expression is interpreted. In +/// particular, they are generally forwarded to the +/// [`ParserBuilder`](https://docs.rs/regex-syntax/*/regex_syntax/struct.ParserBuilder.html) +/// in the +/// [`regex-syntax`](https://docs.rs/regex-syntax) +/// crate when building a regex from its concrete syntax directly. +/// +/// These options are defined as a group since they apply to every regex engine +/// in this crate. Instead of re-defining them on every engine's builder, they +/// are instead provided here as one cohesive unit. +#[derive(Clone, Copy, Debug)] +pub struct Config { + case_insensitive: bool, + multi_line: bool, + dot_matches_new_line: bool, + crlf: bool, + line_terminator: u8, + swap_greed: bool, + ignore_whitespace: bool, + unicode: bool, + utf8: bool, + nest_limit: u32, + octal: bool, +} + +impl Config { + /// Return a new default syntax configuration. + pub fn new() -> Config { + // These defaults match the ones used in regex-syntax. + Config { + case_insensitive: false, + multi_line: false, + dot_matches_new_line: false, + crlf: false, + line_terminator: b'\n', + swap_greed: false, + ignore_whitespace: false, + unicode: true, + utf8: true, + nest_limit: 250, + octal: false, + } + } + + /// Enable or disable the case insensitive flag by default. + /// + /// When Unicode mode is enabled, case insensitivity is Unicode-aware. + /// Specifically, it will apply the "simple" case folding rules as + /// specified by Unicode. + /// + /// By default this is disabled. It may alternatively be selectively + /// enabled in the regular expression itself via the `i` flag. + pub fn case_insensitive(mut self, yes: bool) -> Config { + self.case_insensitive = yes; + self + } + + /// Enable or disable the multi-line matching flag by default. + /// + /// When this is enabled, the `^` and `$` look-around assertions will + /// match immediately after and immediately before a new line character, + /// respectively. Note that the `\A` and `\z` look-around assertions are + /// unaffected by this setting and always correspond to matching at the + /// beginning and end of the input. + /// + /// By default this is disabled. It may alternatively be selectively + /// enabled in the regular expression itself via the `m` flag. + pub fn multi_line(mut self, yes: bool) -> Config { + self.multi_line = yes; + self + } + + /// Enable or disable the "dot matches any character" flag by default. + /// + /// When this is enabled, `.` will match any character. When it's disabled, + /// then `.` will match any character except for a new line character. + /// + /// Note that `.` is impacted by whether the "unicode" setting is enabled + /// or not. When Unicode is enabled (the default), `.` will match any UTF-8 + /// encoding of any Unicode scalar value (sans a new line, depending on + /// whether this "dot matches new line" option is enabled). When Unicode + /// mode is disabled, `.` will match any byte instead. Because of this, + /// when Unicode mode is disabled, `.` can only be used when the "allow + /// invalid UTF-8" option is enabled, since `.` could otherwise match + /// invalid UTF-8. + /// + /// By default this is disabled. It may alternatively be selectively + /// enabled in the regular expression itself via the `s` flag. + pub fn dot_matches_new_line(mut self, yes: bool) -> Config { + self.dot_matches_new_line = yes; + self + } + + /// Enable or disable the "CRLF mode" flag by default. + /// + /// By default this is disabled. It may alternatively be selectively + /// enabled in the regular expression itself via the `R` flag. + /// + /// When CRLF mode is enabled, the following happens: + /// + /// * Unless `dot_matches_new_line` is enabled, `.` will match any character + /// except for `\r` and `\n`. + /// * When `multi_line` mode is enabled, `^` and `$` will treat `\r\n`, + /// `\r` and `\n` as line terminators. And in particular, neither will + /// match between a `\r` and a `\n`. + pub fn crlf(mut self, yes: bool) -> Config { + self.crlf = yes; + self + } + + /// Sets the line terminator for use with `(?u-s:.)` and `(?-us:.)`. + /// + /// Namely, instead of `.` (by default) matching everything except for `\n`, + /// this will cause `.` to match everything except for the byte given. + /// + /// If `.` is used in a context where Unicode mode is enabled and this byte + /// isn't ASCII, then an error will be returned. When Unicode mode is + /// disabled, then any byte is permitted, but will return an error if UTF-8 + /// mode is enabled and it is a non-ASCII byte. + /// + /// In short, any ASCII value for a line terminator is always okay. But a + /// non-ASCII byte might result in an error depending on whether Unicode + /// mode or UTF-8 mode are enabled. + /// + /// Note that if `R` mode is enabled then it always takes precedence and + /// the line terminator will be treated as `\r` and `\n` simultaneously. + /// + /// Note also that this *doesn't* impact the look-around assertions + /// `(?m:^)` and `(?m:$)`. That's usually controlled by additional + /// configuration in the regex engine itself. + pub fn line_terminator(mut self, byte: u8) -> Config { + self.line_terminator = byte; + self + } + + /// Enable or disable the "swap greed" flag by default. + /// + /// When this is enabled, `.*` (for example) will become ungreedy and `.*?` + /// will become greedy. + /// + /// By default this is disabled. It may alternatively be selectively + /// enabled in the regular expression itself via the `U` flag. + pub fn swap_greed(mut self, yes: bool) -> Config { + self.swap_greed = yes; + self + } + + /// Enable verbose mode in the regular expression. + /// + /// When enabled, verbose mode permits insigificant whitespace in many + /// places in the regular expression, as well as comments. Comments are + /// started using `#` and continue until the end of the line. + /// + /// By default, this is disabled. It may be selectively enabled in the + /// regular expression by using the `x` flag regardless of this setting. + pub fn ignore_whitespace(mut self, yes: bool) -> Config { + self.ignore_whitespace = yes; + self + } + + /// Enable or disable the Unicode flag (`u`) by default. + /// + /// By default this is **enabled**. It may alternatively be selectively + /// disabled in the regular expression itself via the `u` flag. + /// + /// Note that unless "allow invalid UTF-8" is enabled (it's disabled by + /// default), a regular expression will fail to parse if Unicode mode is + /// disabled and a sub-expression could possibly match invalid UTF-8. + /// + /// **WARNING**: Unicode mode can greatly increase the size of the compiled + /// DFA, which can noticeably impact both memory usage and compilation + /// time. This is especially noticeable if your regex contains character + /// classes like `\w` that are impacted by whether Unicode is enabled or + /// not. If Unicode is not necessary, you are encouraged to disable it. + pub fn unicode(mut self, yes: bool) -> Config { + self.unicode = yes; + self + } + + /// When disabled, the builder will permit the construction of a regular + /// expression that may match invalid UTF-8. + /// + /// For example, when [`Config::unicode`] is disabled, then + /// expressions like `[^a]` may match invalid UTF-8 since they can match + /// any single byte that is not `a`. By default, these sub-expressions + /// are disallowed to avoid returning offsets that split a UTF-8 + /// encoded codepoint. However, in cases where matching at arbitrary + /// locations is desired, this option can be disabled to permit all such + /// sub-expressions. + /// + /// When enabled (the default), the builder is guaranteed to produce a + /// regex that will only ever match valid UTF-8 (otherwise, the builder + /// will return an error). + pub fn utf8(mut self, yes: bool) -> Config { + self.utf8 = yes; + self + } + + /// Set the nesting limit used for the regular expression parser. + /// + /// The nesting limit controls how deep the abstract syntax tree is allowed + /// to be. If the AST exceeds the given limit (e.g., with too many nested + /// groups), then an error is returned by the parser. + /// + /// The purpose of this limit is to act as a heuristic to prevent stack + /// overflow when building a finite automaton from a regular expression's + /// abstract syntax tree. In particular, construction currently uses + /// recursion. In the future, the implementation may stop using recursion + /// and this option will no longer be necessary. + /// + /// This limit is not checked until the entire AST is parsed. Therefore, + /// if callers want to put a limit on the amount of heap space used, then + /// they should impose a limit on the length, in bytes, of the concrete + /// pattern string. In particular, this is viable since the parser will + /// limit itself to heap space proportional to the length of the pattern + /// string. + /// + /// Note that a nest limit of `0` will return a nest limit error for most + /// patterns but not all. For example, a nest limit of `0` permits `a` but + /// not `ab`, since `ab` requires a concatenation AST item, which results + /// in a nest depth of `1`. In general, a nest limit is not something that + /// manifests in an obvious way in the concrete syntax, therefore, it + /// should not be used in a granular way. + pub fn nest_limit(mut self, limit: u32) -> Config { + self.nest_limit = limit; + self + } + + /// Whether to support octal syntax or not. + /// + /// Octal syntax is a little-known way of uttering Unicode codepoints in + /// a regular expression. For example, `a`, `\x61`, `\u0061` and + /// `\141` are all equivalent regular expressions, where the last example + /// shows octal syntax. + /// + /// While supporting octal syntax isn't in and of itself a problem, it does + /// make good error messages harder. That is, in PCRE based regex engines, + /// syntax like `\1` invokes a backreference, which is explicitly + /// unsupported in Rust's regex engine. However, many users expect it to + /// be supported. Therefore, when octal support is disabled, the error + /// message will explicitly mention that backreferences aren't supported. + /// + /// Octal syntax is disabled by default. + pub fn octal(mut self, yes: bool) -> Config { + self.octal = yes; + self + } + + /// Returns whether "unicode" mode is enabled. + pub fn get_unicode(&self) -> bool { + self.unicode + } + + /// Returns whether "case insensitive" mode is enabled. + pub fn get_case_insensitive(&self) -> bool { + self.case_insensitive + } + + /// Returns whether "multi line" mode is enabled. + pub fn get_multi_line(&self) -> bool { + self.multi_line + } + + /// Returns whether "dot matches new line" mode is enabled. + pub fn get_dot_matches_new_line(&self) -> bool { + self.dot_matches_new_line + } + + /// Returns whether "CRLF" mode is enabled. + pub fn get_crlf(&self) -> bool { + self.crlf + } + + /// Returns the line terminator in this syntax configuration. + pub fn get_line_terminator(&self) -> u8 { + self.line_terminator + } + + /// Returns whether "swap greed" mode is enabled. + pub fn get_swap_greed(&self) -> bool { + self.swap_greed + } + + /// Returns whether "ignore whitespace" mode is enabled. + pub fn get_ignore_whitespace(&self) -> bool { + self.ignore_whitespace + } + + /// Returns whether UTF-8 mode is enabled. + pub fn get_utf8(&self) -> bool { + self.utf8 + } + + /// Returns the "nest limit" setting. + pub fn get_nest_limit(&self) -> u32 { + self.nest_limit + } + + /// Returns whether "octal" mode is enabled. + pub fn get_octal(&self) -> bool { + self.octal + } + + /// Applies this configuration to the given parser. + pub(crate) fn apply(&self, builder: &mut ParserBuilder) { + builder + .unicode(self.unicode) + .case_insensitive(self.case_insensitive) + .multi_line(self.multi_line) + .dot_matches_new_line(self.dot_matches_new_line) + .crlf(self.crlf) + .line_terminator(self.line_terminator) + .swap_greed(self.swap_greed) + .ignore_whitespace(self.ignore_whitespace) + .utf8(self.utf8) + .nest_limit(self.nest_limit) + .octal(self.octal); + } + + /// Applies this configuration to the given AST parser. + pub(crate) fn apply_ast(&self, builder: &mut ast::parse::ParserBuilder) { + builder + .ignore_whitespace(self.ignore_whitespace) + .nest_limit(self.nest_limit) + .octal(self.octal); + } + + /// Applies this configuration to the given AST-to-HIR translator. + pub(crate) fn apply_hir( + &self, + builder: &mut hir::translate::TranslatorBuilder, + ) { + builder + .unicode(self.unicode) + .case_insensitive(self.case_insensitive) + .multi_line(self.multi_line) + .crlf(self.crlf) + .dot_matches_new_line(self.dot_matches_new_line) + .line_terminator(self.line_terminator) + .swap_greed(self.swap_greed) + .utf8(self.utf8); + } +} + +impl Default for Config { + fn default() -> Config { + Config::new() + } +} |