third_party/rust/regex/src/re_builder.rs
author Dorel Luca <dluca@mozilla.com>
Sat, 12 Jan 2019 03:43:46 +0200
changeset 453620 def9811f03111c1fe26bb578255cc30e56a87414
parent 453619 3c4b8e03e7221c6edc8651a13cd84cc344ce9b76
child 460816 c5e856d5edbad973288a8d3fef108288def87394
permissions -rw-r--r--
Backed out 2 changesets (bug 1516337) for build bustage. CLOSED TREE Backed out changeset 3c4b8e03e722 (bug 1516337) Backed out changeset 4fc377013db5 (bug 1516337)

// Copyright 2014-2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

/// The set of user configurable options for compiling zero or more regexes.
#[derive(Clone, Debug)]
#[allow(missing_docs)]
pub struct RegexOptions {
    pub pats: Vec<String>,
    pub size_limit: usize,
    pub dfa_size_limit: usize,
    pub nest_limit: u32,
    pub case_insensitive: bool,
    pub multi_line: bool,
    pub dot_matches_new_line: bool,
    pub swap_greed: bool,
    pub ignore_whitespace: bool,
    pub unicode: bool,
    pub octal: bool,
}

impl Default for RegexOptions {
    fn default() -> Self {
        RegexOptions {
            pats: vec![],
            size_limit: 10 * (1<<20),
            dfa_size_limit: 2 * (1<<20),
            nest_limit: 250,
            case_insensitive: false,
            multi_line: false,
            dot_matches_new_line: false,
            swap_greed: false,
            ignore_whitespace: false,
            unicode: true,
            octal: false,
        }
    }
}

macro_rules! define_builder {
    ($name:ident, $regex_mod:ident, $only_utf8:expr) => {
        pub mod $name {
            use error::Error;
            use exec::ExecBuilder;
            use super::RegexOptions;

            use $regex_mod::Regex;

/// A configurable builder for a regular expression.
///
/// A builder can be used to configure how the regex is built, for example, by
/// setting the default flags (which can be overridden in the expression
/// itself) or setting various limits.
pub struct RegexBuilder(RegexOptions);

impl RegexBuilder {
    /// Create a new regular expression builder with the given pattern.
    ///
    /// If the pattern is invalid, then an error will be returned when
    /// `build` is called.
    pub fn new(pattern: &str) -> RegexBuilder {
        let mut builder = RegexBuilder(RegexOptions::default());
        builder.0.pats.push(pattern.to_owned());
        builder
    }

    /// Consume the builder and compile the regular expression.
    ///
    /// Note that calling `as_str` on the resulting `Regex` will produce the
    /// pattern given to `new` verbatim. Notably, it will not incorporate any
    /// of the flags set on this builder.
    pub fn build(&self) -> Result<Regex, Error> {
        ExecBuilder::new_options(self.0.clone())
            .only_utf8($only_utf8)
            .build()
            .map(Regex::from)
    }

    /// Set the value for the case insensitive (`i`) flag.
    ///
    /// When enabled, letters in the pattern will match both upper case and
    /// lower case variants.
    pub fn case_insensitive(&mut self, yes: bool) -> &mut RegexBuilder {
        self.0.case_insensitive = yes;
        self
    }

    /// Set the value for the multi-line matching (`m`) flag.
    ///
    /// When enabled, `^` matches the beginning of lines and `$` matches the
    /// end of lines.
    ///
    /// By default, they match beginning/end of the input.
    pub fn multi_line(&mut self, yes: bool) -> &mut RegexBuilder {
        self.0.multi_line = yes;
        self
    }

    /// Set the value for the any character (`s`) flag, where in `.` matches
    /// anything when `s` is set and matches anything except for new line when
    /// it is not set (the default).
    ///
    /// N.B. "matches anything" means "any byte" for `regex::bytes::Regex`
    /// expressions and means "any Unicode scalar value" for `regex::Regex`
    /// expressions.
    pub fn dot_matches_new_line(&mut self, yes: bool) -> &mut RegexBuilder {
        self.0.dot_matches_new_line = yes;
        self
    }

    /// Set the value for the greedy swap (`U`) flag.
    ///
    /// When enabled, a pattern like `a*` is lazy (tries to find shortest
    /// match) and `a*?` is greedy (tries to find longest match).
    ///
    /// By default, `a*` is greedy and `a*?` is lazy.
    pub fn swap_greed(&mut self, yes: bool) -> &mut RegexBuilder {
        self.0.swap_greed = yes;
        self
    }

    /// Set the value for the ignore whitespace (`x`) flag.
    ///
    /// When enabled, whitespace such as new lines and spaces will be ignored
    /// between expressions of the pattern, and `#` can be used to start a
    /// comment until the next new line.
    pub fn ignore_whitespace(&mut self, yes: bool) -> &mut RegexBuilder {
        self.0.ignore_whitespace = yes;
        self
    }

    /// Set the value for the Unicode (`u`) flag.
    ///
    /// Enabled by default. When disabled, character classes such as `\w` only
    /// match ASCII word characters instead of all Unicode word characters.
    pub fn unicode(&mut self, yes: bool) -> &mut RegexBuilder {
        self.0.unicode = yes;
        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 RegexBuilder {
        self.0.octal = yes;
        self
    }

    /// Set the approximate size limit of the compiled regular expression.
    ///
    /// This roughly corresponds to the number of bytes occupied by a single
    /// compiled program. If the program exceeds this number, then a
    /// compilation error is returned.
    pub fn size_limit(&mut self, limit: usize) -> &mut RegexBuilder {
        self.0.size_limit = limit;
        self
    }

    /// Set the approximate size of the cache used by the DFA.
    ///
    /// This roughly corresponds to the number of bytes that the DFA will
    /// use while searching.
    ///
    /// Note that this is a *per thread* limit. There is no way to set a global
    /// limit. In particular, if a regex is used from multiple threads
    /// simultaneously, then each thread may use up to the number of bytes
    /// specified here.
    pub fn dfa_size_limit(&mut self, limit: usize) -> &mut RegexBuilder {
        self.0.dfa_size_limit = limit;
        self
    }

    /// 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
    /// lenth 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 RegexBuilder {
        self.0.nest_limit = limit;
        self
    }
}
        }
    }
}

define_builder!(bytes, re_bytes, false);
define_builder!(unicode, re_unicode, true);

macro_rules! define_set_builder {
    ($name:ident, $regex_mod:ident, $only_utf8:expr) => {
        pub mod $name {
            use error::Error;
            use exec::ExecBuilder;
            use super::RegexOptions;

            use re_set::$regex_mod::RegexSet;

/// A configurable builder for a set of regular expressions.
///
/// A builder can be used to configure how the regexes are built, for example,
/// by setting the default flags (which can be overridden in the expression
/// itself) or setting various limits.
pub struct RegexSetBuilder(RegexOptions);

impl RegexSetBuilder {
    /// Create a new regular expression builder with the given pattern.
    ///
    /// If the pattern is invalid, then an error will be returned when
    /// `build` is called.
    pub fn new<I, S>(patterns: I) -> RegexSetBuilder
            where S: AsRef<str>, I: IntoIterator<Item=S> {
        let mut builder = RegexSetBuilder(RegexOptions::default());
        for pat in patterns {
            builder.0.pats.push(pat.as_ref().to_owned());
        }
        builder
    }

    /// Consume the builder and compile the regular expressions into a set.
    pub fn build(&self) -> Result<RegexSet, Error> {
        ExecBuilder::new_options(self.0.clone())
            .only_utf8($only_utf8)
            .build()
            .map(RegexSet::from)
    }

    /// Set the value for the case insensitive (`i`) flag.
    pub fn case_insensitive(&mut self, yes: bool) -> &mut RegexSetBuilder {
        self.0.case_insensitive = yes;
        self
    }

    /// Set the value for the multi-line matching (`m`) flag.
    pub fn multi_line(&mut self, yes: bool) -> &mut RegexSetBuilder {
        self.0.multi_line = yes;
        self
    }

    /// Set the value for the any character (`s`) flag, where in `.` matches
    /// anything when `s` is set and matches anything except for new line when
    /// it is not set (the default).
    ///
    /// N.B. "matches anything" means "any byte" for `regex::bytes::RegexSet`
    /// expressions and means "any Unicode scalar value" for `regex::RegexSet`
    /// expressions.
    pub fn dot_matches_new_line(&mut self, yes: bool) -> &mut RegexSetBuilder {
        self.0.dot_matches_new_line = yes;
        self
    }

    /// Set the value for the greedy swap (`U`) flag.
    pub fn swap_greed(&mut self, yes: bool) -> &mut RegexSetBuilder {
        self.0.swap_greed = yes;
        self
    }

    /// Set the value for the ignore whitespace (`x`) flag.
    pub fn ignore_whitespace(&mut self, yes: bool) -> &mut RegexSetBuilder {
        self.0.ignore_whitespace = yes;
        self
    }

    /// Set the value for the Unicode (`u`) flag.
    pub fn unicode(&mut self, yes: bool) -> &mut RegexSetBuilder {
        self.0.unicode = yes;
        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 RegexSetBuilder {
        self.0.octal = yes;
        self
    }

    /// Set the approximate size limit of the compiled regular expression.
    ///
    /// This roughly corresponds to the number of bytes occupied by a single
    /// compiled program. If the program exceeds this number, then a
    /// compilation error is returned.
    pub fn size_limit(&mut self, limit: usize) -> &mut RegexSetBuilder {
        self.0.size_limit = limit;
        self
    }

    /// Set the approximate size of the cache used by the DFA.
    ///
    /// This roughly corresponds to the number of bytes that the DFA will
    /// use while searching.
    ///
    /// Note that this is a *per thread* limit. There is no way to set a global
    /// limit. In particular, if a regex is used from multiple threads
    /// simulanteously, then each thread may use up to the number of bytes
    /// specified here.
    pub fn dfa_size_limit(&mut self, limit: usize) -> &mut RegexSetBuilder {
        self.0.dfa_size_limit = limit;
        self
    }

    /// 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
    /// lenth 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 RegexSetBuilder {
        self.0.nest_limit = limit;
        self
    }

}
        }
    }
}

define_set_builder!(set_bytes, bytes, false);
define_set_builder!(set_unicode, unicode, true);