vendor/regex-syntax-0.8.4/src/parser.rs - toolchain/rustc - Git at Google

 use crate::{ast, hir, Error};

 /// A convenience routine for parsing a regex using default options.
 ///
 /// This is equivalent to `Parser::new().parse(pattern)`.
 ///
 /// If you need to set non-default options, then use a [`ParserBuilder`].
 ///
 /// This routine returns an [`Hir`](hir::Hir) value. Namely, it automatically
 /// parses the pattern as an [`Ast`](ast::Ast) and then invokes the translator
 /// to convert the `Ast` into an `Hir`. If you need access to the `Ast`, then
 /// you should use a [`ast::parse::Parser`].
 pub fn parse(pattern: &str) -> Result<hir::Hir, Error> {
     Parser::new().parse(pattern)
 }

 /// A builder for a regular expression parser.
 ///
 /// This builder permits modifying configuration options for the parser.
 ///
 /// This type combines the builder options for both the [AST
 /// `ParserBuilder`](ast::parse::ParserBuilder) and the [HIR
 /// `TranslatorBuilder`](hir::translate::TranslatorBuilder).
 #[derive(Clone, Debug, Default)]
 pub struct ParserBuilder {
     ast: ast::parse::ParserBuilder,
     hir: hir::translate::TranslatorBuilder,
 }

 impl ParserBuilder {
     /// Create a new parser builder with a default configuration.
     pub fn new() -> ParserBuilder {
         ParserBuilder::default()
     }

     /// Build a parser from this configuration with the given pattern.
     pub fn build(&self) -> Parser {
         Parser { ast: self.ast.build(), hir: self.hir.build() }
     }

     /// Set the nesting limit for this 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 for consumers that do structural induction on an `Ast` using
     /// explicit recursion. While this crate never does this (instead using
     /// constant stack space and moving the call stack to the heap), other
     /// crates may.
     ///
     /// 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 this parser
     /// implementation 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, 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) -> &mut ParserBuilder {
         self.ast.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 `\0` 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) -> &mut ParserBuilder {
         self.ast.octal(yes);
         self
     }

     /// When disabled, translation will permit the construction of a regular
     /// expression that may match invalid UTF-8.
     ///
     /// When enabled (the default), the translator is guaranteed to produce an
     /// expression that, for non-empty matches, will only ever produce spans
     /// that are entirely valid UTF-8 (otherwise, the translator will return an
     /// error).
     ///
     /// Perhaps surprisingly, when UTF-8 is enabled, an empty regex or even
     /// a negated ASCII word boundary (uttered as `(?-u:\B)` in the concrete
     /// syntax) will be allowed even though they can produce matches that split
     /// a UTF-8 encoded codepoint. This only applies to zero-width or "empty"
     /// matches, and it is expected that the regex engine itself must handle
     /// these cases if necessary (perhaps by suppressing any zero-width matches
     /// that split a codepoint).
     pub fn utf8(&mut self, yes: bool) -> &mut ParserBuilder {
         self.hir.utf8(yes);
         self
     }

     /// Enable verbose mode in the regular expression.
     ///
     /// When enabled, verbose mode permits insignificant 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) -> &mut ParserBuilder {
         self.ast.ignore_whitespace(yes);
         self
     }

     /// Enable or disable the case insensitive flag by default.
     ///
     /// 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) -> &mut ParserBuilder {
         self.hir.case_insensitive(yes);
         self
     }

     /// Enable or disable the multi-line matching flag by default.
     ///
     /// 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) -> &mut ParserBuilder {
         self.hir.multi_line(yes);
         self
     }

     /// Enable or disable the "dot matches any character" flag by default.
     ///
     /// 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) -> &mut ParserBuilder {
         self.hir.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) -> &mut ParserBuilder {
         self.hir.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) -> &mut ParserBuilder {
         self.hir.line_terminator(byte);
         self
     }

     /// Enable or disable the "swap greed" flag by default.
     ///
     /// 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) -> &mut ParserBuilder {
         self.hir.swap_greed(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 `utf8` is disabled (it's enabled by default), a
     /// regular expression will fail to parse if Unicode mode is disabled and a
     /// sub-expression could possibly match invalid UTF-8.
     pub fn unicode(&mut self, yes: bool) -> &mut ParserBuilder {
         self.hir.unicode(yes);
         self
     }
 }

 /// A convenience parser for regular expressions.
 ///
 /// This parser takes as input a regular expression pattern string (the
 /// "concrete syntax") and returns a high-level intermediate representation
 /// (the HIR) suitable for most types of analysis. In particular, this parser
 /// hides the intermediate state of producing an AST (the "abstract syntax").
 /// The AST is itself far more complex than the HIR, so this parser serves as a
 /// convenience for never having to deal with it at all.
 ///
 /// If callers have more fine grained use cases that need an AST, then please
 /// see the [`ast::parse`] module.
 ///
 /// A `Parser` can be configured in more detail via a [`ParserBuilder`].
 #[derive(Clone, Debug)]
 pub struct Parser {
     ast: ast::parse::Parser,
     hir: hir::translate::Translator,
 }

 impl Parser {
     /// Create a new parser with a default configuration.
     ///
     /// The parser can be run with `parse` method. The parse method returns
     /// a high level intermediate representation of the given regular
     /// expression.
     ///
     /// To set configuration options on the parser, use [`ParserBuilder`].
     pub fn new() -> Parser {
         ParserBuilder::new().build()
     }

     /// Parse the regular expression into a high level intermediate
     /// representation.
     pub fn parse(&mut self, pattern: &str) -> Result<hir::Hir, Error> {
         let ast = self.ast.parse(pattern)?;
         let hir = self.hir.translate(pattern, &ast)?;
         Ok(hir)
     }
 }
	use crate::{ast, hir, Error};

	/// A convenience routine for parsing a regex using default options.
	///
	/// This is equivalent to `Parser::new().parse(pattern)`.
	///
	/// If you need to set non-default options, then use a [`ParserBuilder`].
	///
	/// This routine returns an [`Hir`](hir::Hir) value. Namely, it automatically
	/// parses the pattern as an [`Ast`](ast::Ast) and then invokes the translator
	/// to convert the `Ast` into an `Hir`. If you need access to the `Ast`, then
	/// you should use a [`ast::parse::Parser`].
	pub fn parse(pattern: &str) -> Result<hir::Hir, Error> {
	Parser::new().parse(pattern)
	}

	/// A builder for a regular expression parser.
	///
	/// This builder permits modifying configuration options for the parser.
	///
	/// This type combines the builder options for both the [AST
	/// `ParserBuilder`](ast::parse::ParserBuilder) and the [HIR
	/// `TranslatorBuilder`](hir::translate::TranslatorBuilder).
	#[derive(Clone, Debug, Default)]
	pub struct ParserBuilder {
	ast: ast::parse::ParserBuilder,
	hir: hir::translate::TranslatorBuilder,
	}

	impl ParserBuilder {
	/// Create a new parser builder with a default configuration.
	pub fn new() -> ParserBuilder {
	ParserBuilder::default()
	}

	/// Build a parser from this configuration with the given pattern.
	pub fn build(&self) -> Parser {
	Parser { ast: self.ast.build(), hir: self.hir.build() }
	}

	/// Set the nesting limit for this 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 for consumers that do structural induction on an `Ast` using
	/// explicit recursion. While this crate never does this (instead using
	/// constant stack space and moving the call stack to the heap), other
	/// crates may.
	///
	/// 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 this parser
	/// implementation 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, 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) -> &mut ParserBuilder {
	self.ast.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 `\0` 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) -> &mut ParserBuilder {
	self.ast.octal(yes);
	self
	}

	/// When disabled, translation will permit the construction of a regular
	/// expression that may match invalid UTF-8.
	///
	/// When enabled (the default), the translator is guaranteed to produce an
	/// expression that, for non-empty matches, will only ever produce spans
	/// that are entirely valid UTF-8 (otherwise, the translator will return an
	/// error).
	///
	/// Perhaps surprisingly, when UTF-8 is enabled, an empty regex or even
	/// a negated ASCII word boundary (uttered as `(?-u:\B)` in the concrete
	/// syntax) will be allowed even though they can produce matches that split
	/// a UTF-8 encoded codepoint. This only applies to zero-width or "empty"
	/// matches, and it is expected that the regex engine itself must handle
	/// these cases if necessary (perhaps by suppressing any zero-width matches
	/// that split a codepoint).
	pub fn utf8(&mut self, yes: bool) -> &mut ParserBuilder {
	self.hir.utf8(yes);
	self
	}

	/// Enable verbose mode in the regular expression.
	///
	/// When enabled, verbose mode permits insignificant 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) -> &mut ParserBuilder {
	self.ast.ignore_whitespace(yes);
	self
	}

	/// Enable or disable the case insensitive flag by default.
	///
	/// 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) -> &mut ParserBuilder {
	self.hir.case_insensitive(yes);
	self
	}

	/// Enable or disable the multi-line matching flag by default.
	///
	/// 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) -> &mut ParserBuilder {
	self.hir.multi_line(yes);
	self
	}

	/// Enable or disable the "dot matches any character" flag by default.
	///
	/// 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) -> &mut ParserBuilder {
	self.hir.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) -> &mut ParserBuilder {
	self.hir.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) -> &mut ParserBuilder {
	self.hir.line_terminator(byte);
	self
	}

	/// Enable or disable the "swap greed" flag by default.
	///
	/// 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) -> &mut ParserBuilder {
	self.hir.swap_greed(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 `utf8` is disabled (it's enabled by default), a
	/// regular expression will fail to parse if Unicode mode is disabled and a
	/// sub-expression could possibly match invalid UTF-8.
	pub fn unicode(&mut self, yes: bool) -> &mut ParserBuilder {
	self.hir.unicode(yes);
	self
	}
	}

	/// A convenience parser for regular expressions.
	///
	/// This parser takes as input a regular expression pattern string (the
	/// "concrete syntax") and returns a high-level intermediate representation
	/// (the HIR) suitable for most types of analysis. In particular, this parser
	/// hides the intermediate state of producing an AST (the "abstract syntax").
	/// The AST is itself far more complex than the HIR, so this parser serves as a
	/// convenience for never having to deal with it at all.
	///
	/// If callers have more fine grained use cases that need an AST, then please
	/// see the [`ast::parse`] module.
	///
	/// A `Parser` can be configured in more detail via a [`ParserBuilder`].
	#[derive(Clone, Debug)]
	pub struct Parser {
	ast: ast::parse::Parser,
	hir: hir::translate::Translator,
	}

	impl Parser {
	/// Create a new parser with a default configuration.
	///
	/// The parser can be run with `parse` method. The parse method returns
	/// a high level intermediate representation of the given regular
	/// expression.
	///
	/// To set configuration options on the parser, use [`ParserBuilder`].
	pub fn new() -> Parser {
	ParserBuilder::new().build()
	}

	/// Parse the regular expression into a high level intermediate
	/// representation.
	pub fn parse(&mut self, pattern: &str) -> Result<hir::Hir, Error> {
	let ast = self.ast.parse(pattern)?;
	let hir = self.hir.translate(pattern, &ast)?;
	Ok(hir)
	}
	}