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// Copyright 2003-2009 The RE2 Authors. All Rights Reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
#ifndef RE2_RE2_H_
#define RE2_RE2_H_
// C++ interface to the re2 regular-expression library.
// RE2 supports Perl-style regular expressions (with extensions like
// \d, \w, \s, ...).
// -----------------------------------------------------------------------
// This module uses the re2 library and hence supports
// its syntax for regular expressions, which is similar to Perl's with
// some of the more complicated things thrown away. In particular,
// backreferences and generalized assertions are not available, nor is \Z.
// See for the syntax
// supported by RE2, and a comparison with PCRE and PERL regexps.
// For those not familiar with Perl's regular expressions,
// here are some examples of the most commonly used extensions:
// "hello (\\w+) world" -- \w matches a "word" character
// "version (\\d+)" -- \d matches a digit
// "hello\\s+world" -- \s matches any whitespace character
// "\\b(\\w+)\\b" -- \b matches non-empty string at word boundary
// "(?i)hello" -- (?i) turns on case-insensitive matching
// "/\\*(.*?)\\*/" -- .*? matches . minimum no. of times possible
// The double backslashes are needed when writing C++ string literals.
// However, they should NOT be used when writing C++11 raw string literals:
// R"(hello (\w+) world)" -- \w matches a "word" character
// R"(version (\d+))" -- \d matches a digit
// R"(hello\s+world)" -- \s matches any whitespace character
// R"(\b(\w+)\b)" -- \b matches non-empty string at word boundary
// R"((?i)hello)" -- (?i) turns on case-insensitive matching
// R"(/\*(.*?)\*/)" -- .*? matches . minimum no. of times possible
// When using UTF-8 encoding, case-insensitive matching will perform
// simple case folding, not full case folding.
// -----------------------------------------------------------------------
// The "FullMatch" operation checks that supplied text matches a
// supplied pattern exactly.
// Example: successful match
// CHECK(RE2::FullMatch("hello", "h.*o"));
// Example: unsuccessful match (requires full match):
// CHECK(!RE2::FullMatch("hello", "e"));
// -----------------------------------------------------------------------
// By default, the pattern and input text are interpreted as UTF-8.
// The RE2::Latin1 option causes them to be interpreted as Latin-1.
// Example:
// CHECK(RE2::FullMatch(utf8_string, RE2(utf8_pattern)));
// CHECK(RE2::FullMatch(latin1_string, RE2(latin1_pattern, RE2::Latin1)));
// -----------------------------------------------------------------------
// You can supply extra pointer arguments to extract submatches.
// On match failure, none of the pointees will have been modified.
// On match success, the submatches will be converted (as necessary) and
// their values will be assigned to their pointees until all conversions
// have succeeded or one conversion has failed.
// On conversion failure, the pointees will be in an indeterminate state
// because the caller has no way of knowing which conversion failed.
// However, conversion cannot fail for types like string and string_view
// that do not inspect the submatch contents. Hence, in the common case
// where all of the pointees are of such types, failure is always due to
// match failure and thus none of the pointees will have been modified.
// Example: extracts "ruby" into "s" and 1234 into "i"
// int i;
// std::string s;
// CHECK(RE2::FullMatch("ruby:1234", "(\\w+):(\\d+)", &s, &i));
// Example: fails because string cannot be stored in integer
// CHECK(!RE2::FullMatch("ruby", "(.*)", &i));
// Example: fails because there aren't enough sub-patterns
// CHECK(!RE2::FullMatch("ruby:1234", "\\w+:\\d+", &s));
// Example: does not try to extract any extra sub-patterns
// CHECK(RE2::FullMatch("ruby:1234", "(\\w+):(\\d+)", &s));
// Example: does not try to extract into NULL
// CHECK(RE2::FullMatch("ruby:1234", "(\\w+):(\\d+)", NULL, &i));
// Example: integer overflow causes failure
// CHECK(!RE2::FullMatch("ruby:1234567891234", "\\w+:(\\d+)", &i));
// NOTE(rsc): Asking for submatches slows successful matches quite a bit.
// This may get a little faster in the future, but right now is slower
// than PCRE. On the other hand, failed matches run *very* fast (faster
// than PCRE), as do matches without submatch extraction.
// -----------------------------------------------------------------------
// You can use the "PartialMatch" operation when you want the pattern
// to match any substring of the text.
// Example: simple search for a string:
// CHECK(RE2::PartialMatch("hello", "ell"));
// Example: find first number in a string
// int number;
// CHECK(RE2::PartialMatch("x*100 + 20", "(\\d+)", &number));
// CHECK_EQ(number, 100);
// -----------------------------------------------------------------------
// RE2 makes it easy to use any string as a regular expression, without
// requiring a separate compilation step.
// If speed is of the essence, you can create a pre-compiled "RE2"
// object from the pattern and use it multiple times. If you do so,
// you can typically parse text faster than with sscanf.
// Example: precompile pattern for faster matching:
// RE2 pattern("h.*o");
// while (ReadLine(&str)) {
// if (RE2::FullMatch(str, pattern)) ...;
// }
// -----------------------------------------------------------------------
// The "Consume" operation may be useful if you want to repeatedly
// match regular expressions at the front of a string and skip over
// them as they match. This requires use of the string_view type,
// which represents a sub-range of a real string.
// Example: read lines of the form "var = value" from a string.
// std::string contents = ...; // Fill string somehow
// absl::string_view input(contents); // Wrap a string_view around it
// std::string var;
// int value;
// while (RE2::Consume(&input, "(\\w+) = (\\d+)\n", &var, &value)) {
// ...;
// }
// Each successful call to "Consume" will set "var/value", and also
// advance "input" so it points past the matched text. Note that if the
// regular expression matches an empty string, input will advance
// by 0 bytes. If the regular expression being used might match
// an empty string, the loop body must check for this case and either
// advance the string or break out of the loop.
// The "FindAndConsume" operation is similar to "Consume" but does not
// anchor your match at the beginning of the string. For example, you
// could extract all words from a string by repeatedly calling
// RE2::FindAndConsume(&input, "(\\w+)", &word)
// -----------------------------------------------------------------------
// The above operations require you to know the number of arguments
// when you write the code. This is not always possible or easy (for
// example, the regular expression may be calculated at run time).
// You can use the "N" version of the operations when the number of
// match arguments are determined at run time.
// Example:
// const RE2::Arg* args[10];
// int n;
// // ... populate args with pointers to RE2::Arg values ...
// // ... set n to the number of RE2::Arg objects ...
// bool match = RE2::FullMatchN(input, pattern, args, n);
// The last statement is equivalent to
// bool match = RE2::FullMatch(input, pattern,
// *args[0], *args[1], ..., *args[n - 1]);
// -----------------------------------------------------------------------
// By default, if you pass a pointer to a numeric value, the
// corresponding text is interpreted as a base-10 number. You can
// instead wrap the pointer with a call to one of the operators Hex(),
// Octal(), or CRadix() to interpret the text in another base. The
// CRadix operator interprets C-style "0" (base-8) and "0x" (base-16)
// prefixes, but defaults to base-10.
// Example:
// int a, b, c, d;
// CHECK(RE2::FullMatch("100 40 0100 0x40", "(.*) (.*) (.*) (.*)",
// RE2::Octal(&a), RE2::Hex(&b), RE2::CRadix(&c), RE2::CRadix(&d));
// will leave 64 in a, b, c, and d.
#include <stddef.h>
#include <stdint.h>
#include <algorithm>
#include <map>
#include <string>
#include <type_traits>
#include <vector>
#if defined(__APPLE__)
#include <TargetConditionals.h>
#include "absl/base/call_once.h"
#include "absl/strings/string_view.h"
#include "absl/types/optional.h"
#include "re2/stringpiece.h"
namespace re2 {
class Prog;
class Regexp;
} // namespace re2
namespace re2 {
// Interface for regular expression matching. Also corresponds to a
// pre-compiled regular expression. An "RE2" object is safe for
// concurrent use by multiple threads.
class RE2 {
// We convert user-passed pointers into special Arg objects
class Arg;
class Options;
// Defined in set.h.
class Set;
enum ErrorCode {
NoError = 0,
// Unexpected error
// Parse errors
ErrorBadEscape, // bad escape sequence
ErrorBadCharClass, // bad character class
ErrorBadCharRange, // bad character class range
ErrorMissingBracket, // missing closing ]
ErrorMissingParen, // missing closing )
ErrorUnexpectedParen, // unexpected closing )
ErrorTrailingBackslash, // trailing \ at end of regexp
ErrorRepeatArgument, // repeat argument missing, e.g. "*"
ErrorRepeatSize, // bad repetition argument
ErrorRepeatOp, // bad repetition operator
ErrorBadPerlOp, // bad perl operator
ErrorBadUTF8, // invalid UTF-8 in regexp
ErrorBadNamedCapture, // bad named capture group
ErrorPatternTooLarge // pattern too large (compile failed)
// Predefined common options.
// If you need more complicated things, instantiate
// an Option class, possibly passing one of these to
// the Option constructor, change the settings, and pass that
// Option class to the RE2 constructor.
enum CannedOptions {
DefaultOptions = 0,
Latin1, // treat input as Latin-1 (default UTF-8)
POSIX, // POSIX syntax, leftmost-longest match
Quiet // do not log about regexp parse errors
// Need to have the const char* and const std::string& forms for implicit
// conversions when passing string literals to FullMatch and PartialMatch.
// Otherwise the absl::string_view form would be sufficient.
RE2(const char* pattern);
RE2(const std::string& pattern);
RE2(absl::string_view pattern);
RE2(absl::string_view pattern, const Options& options);
// Not copyable.
// RE2 objects are expensive. You should probably use std::shared_ptr<RE2>
// instead. If you really must copy, RE2(first.pattern(), first.options())
// effectively does so: it produces a second object that mimics the first.
RE2(const RE2&) = delete;
RE2& operator=(const RE2&) = delete;
// Not movable.
// RE2 objects are thread-safe and logically immutable. You should probably
// use std::unique_ptr<RE2> instead. Otherwise, consider std::deque<RE2> if
// direct emplacement into a container is desired. If you really must move,
// be prepared to submit a design document along with your feature request.
RE2(RE2&&) = delete;
RE2& operator=(RE2&&) = delete;
// Returns whether RE2 was created properly.
bool ok() const { return error_code() == NoError; }
// The string specification for this RE2. E.g.
// RE2 re("ab*c?d+");
// re.pattern(); // "ab*c?d+"
const std::string& pattern() const { return *pattern_; }
// If RE2 could not be created properly, returns an error string.
// Else returns the empty string.
const std::string& error() const { return *error_; }
// If RE2 could not be created properly, returns an error code.
// Else returns RE2::NoError (== 0).
ErrorCode error_code() const { return error_code_; }
// If RE2 could not be created properly, returns the offending
// portion of the regexp.
const std::string& error_arg() const { return *error_arg_; }
// Returns the program size, a very approximate measure of a regexp's "cost".
// Larger numbers are more expensive than smaller numbers.
int ProgramSize() const;
int ReverseProgramSize() const;
// If histogram is not null, outputs the program fanout
// as a histogram bucketed by powers of 2.
// Returns the number of the largest non-empty bucket.
int ProgramFanout(std::vector<int>* histogram) const;
int ReverseProgramFanout(std::vector<int>* histogram) const;
// Returns the underlying Regexp; not for general use.
// Returns entire_regexp_ so that callers don't need
// to know about prefix_ and prefix_foldcase_.
re2::Regexp* Regexp() const { return entire_regexp_; }
/***** The array-based matching interface ******/
// The functions here have names ending in 'N' and are used to implement
// the functions whose names are the prefix before the 'N'. It is sometimes
// useful to invoke them directly, but the syntax is awkward, so the 'N'-less
// versions should be preferred.
static bool FullMatchN(absl::string_view text, const RE2& re,
const Arg* const args[], int n);
static bool PartialMatchN(absl::string_view text, const RE2& re,
const Arg* const args[], int n);
static bool ConsumeN(absl::string_view* input, const RE2& re,
const Arg* const args[], int n);
static bool FindAndConsumeN(absl::string_view* input, const RE2& re,
const Arg* const args[], int n);
template <typename F, typename SP>
static inline bool Apply(F f, SP sp, const RE2& re) {
return f(sp, re, NULL, 0);
template <typename F, typename SP, typename... A>
static inline bool Apply(F f, SP sp, const RE2& re, const A&... a) {
const Arg* const args[] = {&a...};
const int n = sizeof...(a);
return f(sp, re, args, n);
// In order to allow FullMatch() et al. to be called with a varying number
// of arguments of varying types, we use two layers of variadic templates.
// The first layer constructs the temporary Arg objects. The second layer
// (above) constructs the array of pointers to the temporary Arg objects.
/***** The useful part: the matching interface *****/
// Matches "text" against "re". If pointer arguments are
// supplied, copies matched sub-patterns into them.
// You can pass in a "const char*" or a "std::string" for "text".
// You can pass in a "const char*" or a "std::string" or a "RE2" for "re".
// The provided pointer arguments can be pointers to any scalar numeric
// type, or one of:
// std::string (matched piece is copied to string)
// absl::string_view (string_view is mutated to point to matched piece)
// T ("bool T::ParseFrom(const char*, size_t)" must exist)
// (void*)NULL (the corresponding matched sub-pattern is not copied)
// Returns true iff all of the following conditions are satisfied:
// a. "text" matches "re" fully - from the beginning to the end of "text".
// b. The number of matched sub-patterns is >= number of supplied pointers.
// c. The "i"th argument has a suitable type for holding the
// string captured as the "i"th sub-pattern. If you pass in
// NULL for the "i"th argument, or pass fewer arguments than
// number of sub-patterns, the "i"th captured sub-pattern is
// ignored.
// CAVEAT: An optional sub-pattern that does not exist in the
// matched string is assigned the empty string. Therefore, the
// following will return false (because the empty string is not a
// valid number):
// int number;
// RE2::FullMatch("abc", "[a-z]+(\\d+)?", &number);
template <typename... A>
static bool FullMatch(absl::string_view text, const RE2& re, A&&... a) {
return Apply(FullMatchN, text, re, Arg(std::forward<A>(a))...);
// Like FullMatch(), except that "re" is allowed to match a substring
// of "text".
// Returns true iff all of the following conditions are satisfied:
// a. "text" matches "re" partially - for some substring of "text".
// b. The number of matched sub-patterns is >= number of supplied pointers.
// c. The "i"th argument has a suitable type for holding the
// string captured as the "i"th sub-pattern. If you pass in
// NULL for the "i"th argument, or pass fewer arguments than
// number of sub-patterns, the "i"th captured sub-pattern is
// ignored.
template <typename... A>
static bool PartialMatch(absl::string_view text, const RE2& re, A&&... a) {
return Apply(PartialMatchN, text, re, Arg(std::forward<A>(a))...);
// Like FullMatch() and PartialMatch(), except that "re" has to match
// a prefix of the text, and "input" is advanced past the matched
// text. Note: "input" is modified iff this routine returns true
// and "re" matched a non-empty substring of "input".
// Returns true iff all of the following conditions are satisfied:
// a. "input" matches "re" partially - for some prefix of "input".
// b. The number of matched sub-patterns is >= number of supplied pointers.
// c. The "i"th argument has a suitable type for holding the
// string captured as the "i"th sub-pattern. If you pass in
// NULL for the "i"th argument, or pass fewer arguments than
// number of sub-patterns, the "i"th captured sub-pattern is
// ignored.
template <typename... A>
static bool Consume(absl::string_view* input, const RE2& re, A&&... a) {
return Apply(ConsumeN, input, re, Arg(std::forward<A>(a))...);
// Like Consume(), but does not anchor the match at the beginning of
// the text. That is, "re" need not start its match at the beginning
// of "input". For example, "FindAndConsume(s, "(\\w+)", &word)" finds
// the next word in "s" and stores it in "word".
// Returns true iff all of the following conditions are satisfied:
// a. "input" matches "re" partially - for some substring of "input".
// b. The number of matched sub-patterns is >= number of supplied pointers.
// c. The "i"th argument has a suitable type for holding the
// string captured as the "i"th sub-pattern. If you pass in
// NULL for the "i"th argument, or pass fewer arguments than
// number of sub-patterns, the "i"th captured sub-pattern is
// ignored.
template <typename... A>
static bool FindAndConsume(absl::string_view* input, const RE2& re, A&&... a) {
return Apply(FindAndConsumeN, input, re, Arg(std::forward<A>(a))...);
// Replace the first match of "re" in "str" with "rewrite".
// Within "rewrite", backslash-escaped digits (\1 to \9) can be
// used to insert text matching corresponding parenthesized group
// from the pattern. \0 in "rewrite" refers to the entire matching
// text. E.g.,
// std::string s = "yabba dabba doo";
// CHECK(RE2::Replace(&s, "b+", "d"));
// will leave "s" containing "yada dabba doo"
// Returns true if the pattern matches and a replacement occurs,
// false otherwise.
static bool Replace(std::string* str,
const RE2& re,
absl::string_view rewrite);
// Like Replace(), except replaces successive non-overlapping occurrences
// of the pattern in the string with the rewrite. E.g.
// std::string s = "yabba dabba doo";
// CHECK(RE2::GlobalReplace(&s, "b+", "d"));
// will leave "s" containing "yada dada doo"
// Replacements are not subject to re-matching.
// Because GlobalReplace only replaces non-overlapping matches,
// replacing "ana" within "banana" makes only one replacement, not two.
// Returns the number of replacements made.
static int GlobalReplace(std::string* str,
const RE2& re,
absl::string_view rewrite);
// Like Replace, except that if the pattern matches, "rewrite"
// is copied into "out" with substitutions. The non-matching
// portions of "text" are ignored.
// Returns true iff a match occurred and the extraction happened
// successfully; if no match occurs, the string is left unaffected.
// REQUIRES: "text" must not alias any part of "*out".
static bool Extract(absl::string_view text,
const RE2& re,
absl::string_view rewrite,
std::string* out);
// Escapes all potentially meaningful regexp characters in
// 'unquoted'. The returned string, used as a regular expression,
// will match exactly the original string. For example,
// 1.5-2.0?
// may become:
// 1\.5\-2\.0\?
static std::string QuoteMeta(absl::string_view unquoted);
// Computes range for any strings matching regexp. The min and max can in
// some cases be arbitrarily precise, so the caller gets to specify the
// maximum desired length of string returned.
// Assuming PossibleMatchRange(&min, &max, N) returns successfully, any
// string s that is an anchored match for this regexp satisfies
// min <= s && s <= max.
// Note that PossibleMatchRange() will only consider the first copy of an
// infinitely repeated element (i.e., any regexp element followed by a '*' or
// '+' operator). Regexps with "{N}" constructions are not affected, as those
// do not compile down to infinite repetitions.
// Returns true on success, false on error.
bool PossibleMatchRange(std::string* min, std::string* max,
int maxlen) const;
// Generic matching interface
// Type of match.
enum Anchor {
UNANCHORED, // No anchoring
ANCHOR_START, // Anchor at start only
ANCHOR_BOTH // Anchor at start and end
// Return the number of capturing subpatterns, or -1 if the
// regexp wasn't valid on construction. The overall match ($0)
// does not count: if the regexp is "(a)(b)", returns 2.
int NumberOfCapturingGroups() const { return num_captures_; }
// Return a map from names to capturing indices.
// The map records the index of the leftmost group
// with the given name.
// Only valid until the re is deleted.
const std::map<std::string, int>& NamedCapturingGroups() const;
// Return a map from capturing indices to names.
// The map has no entries for unnamed groups.
// Only valid until the re is deleted.
const std::map<int, std::string>& CapturingGroupNames() const;
// General matching routine.
// Match against text starting at offset startpos
// and stopping the search at offset endpos.
// Returns true if match found, false if not.
// On a successful match, fills in submatch[] (up to nsubmatch entries)
// with information about submatches.
// I.e. matching RE2("(foo)|(bar)baz") on "barbazbla" will return true, with
// submatch[0] = "barbaz", submatch[1].data() = NULL, submatch[2] = "bar",
// submatch[3].data() = NULL, ..., up to submatch[nsubmatch-1].data() = NULL.
// Caveat: submatch[] may be clobbered even on match failure.
// Don't ask for more match information than you will use:
// runs much faster with nsubmatch == 1 than nsubmatch > 1, and
// runs even faster if nsubmatch == 0.
// Doesn't make sense to use nsubmatch > 1 + NumberOfCapturingGroups(),
// but will be handled correctly.
// Passing text == absl::string_view() will be handled like any other
// empty string, but note that on return, it will not be possible to tell
// whether submatch i matched the empty string or did not match:
// either way, submatch[i].data() == NULL.
bool Match(absl::string_view text,
size_t startpos,
size_t endpos,
Anchor re_anchor,
absl::string_view* submatch,
int nsubmatch) const;
// Check that the given rewrite string is suitable for use with this
// regular expression. It checks that:
// * The regular expression has enough parenthesized subexpressions
// to satisfy all of the \N tokens in rewrite
// * The rewrite string doesn't have any syntax errors. E.g.,
// '\' followed by anything other than a digit or '\'.
// A true return value guarantees that Replace() and Extract() won't
// fail because of a bad rewrite string.
bool CheckRewriteString(absl::string_view rewrite,
std::string* error) const;
// Returns the maximum submatch needed for the rewrite to be done by
// Replace(). E.g. if rewrite == "foo \\2,\\1", returns 2.
static int MaxSubmatch(absl::string_view rewrite);
// Append the "rewrite" string, with backslash substitutions from "vec",
// to string "out".
// Returns true on success. This method can fail because of a malformed
// rewrite string. CheckRewriteString guarantees that the rewrite will
// be sucessful.
bool Rewrite(std::string* out,
absl::string_view rewrite,
const absl::string_view* vec,
int veclen) const;
// Constructor options
class Options {
// The options are (defaults in parentheses):
// utf8 (true) text and pattern are UTF-8; otherwise Latin-1
// posix_syntax (false) restrict regexps to POSIX egrep syntax
// longest_match (false) search for longest match, not first match
// log_errors (true) log syntax and execution errors to ERROR
// max_mem (see below) approx. max memory footprint of RE2
// literal (false) interpret string as literal, not regexp
// never_nl (false) never match \n, even if it is in regexp
// dot_nl (false) dot matches everything including new line
// never_capture (false) parse all parens as non-capturing
// case_sensitive (true) match is case-sensitive (regexp can override
// with (?i) unless in posix_syntax mode)
// The following options are only consulted when posix_syntax == true.
// When posix_syntax == false, these features are always enabled and
// cannot be turned off; to perform multi-line matching in that case,
// begin the regexp with (?m).
// perl_classes (false) allow Perl's \d \s \w \D \S \W
// word_boundary (false) allow Perl's \b \B (word boundary and not)
// one_line (false) ^ and $ only match beginning and end of text
// The max_mem option controls how much memory can be used
// to hold the compiled form of the regexp (the Prog) and
// its cached DFA graphs. Code Search placed limits on the number
// of Prog instructions and DFA states: 10,000 for both.
// In RE2, those limits would translate to about 240 KB per Prog
// and perhaps 2.5 MB per DFA (DFA state sizes vary by regexp; RE2 does a
// better job of keeping them small than Code Search did).
// Each RE2 has two Progs (one forward, one reverse), and each Prog
// can have two DFAs (one first match, one longest match).
// That makes 4 DFAs:
// forward, first-match - used for UNANCHORED or ANCHOR_START searches
// if opt.longest_match() == false
// forward, longest-match - used for all ANCHOR_BOTH searches,
// and the other two kinds if
// opt.longest_match() == true
// reverse, first-match - never used
// reverse, longest-match - used as second phase for unanchored searches
// The RE2 memory budget is statically divided between the two
// Progs and then the DFAs: two thirds to the forward Prog
// and one third to the reverse Prog. The forward Prog gives half
// of what it has left over to each of its DFAs. The reverse Prog
// gives it all to its longest-match DFA.
// Once a DFA fills its budget, it flushes its cache and starts over.
// If this happens too often, RE2 falls back on the NFA implementation.
// For now, make the default budget something close to Code Search.
static const int kDefaultMaxMem = 8<<20;
enum Encoding {
EncodingUTF8 = 1,
Options() :
one_line_(false) {
/*implicit*/ Options(CannedOptions);
int64_t max_mem() const { return max_mem_; }
void set_max_mem(int64_t m) { max_mem_ = m; }
Encoding encoding() const { return encoding_; }
void set_encoding(Encoding encoding) { encoding_ = encoding; }
bool posix_syntax() const { return posix_syntax_; }
void set_posix_syntax(bool b) { posix_syntax_ = b; }
bool longest_match() const { return longest_match_; }
void set_longest_match(bool b) { longest_match_ = b; }
bool log_errors() const { return log_errors_; }
void set_log_errors(bool b) { log_errors_ = b; }
bool literal() const { return literal_; }
void set_literal(bool b) { literal_ = b; }
bool never_nl() const { return never_nl_; }
void set_never_nl(bool b) { never_nl_ = b; }
bool dot_nl() const { return dot_nl_; }
void set_dot_nl(bool b) { dot_nl_ = b; }
bool never_capture() const { return never_capture_; }
void set_never_capture(bool b) { never_capture_ = b; }
bool case_sensitive() const { return case_sensitive_; }
void set_case_sensitive(bool b) { case_sensitive_ = b; }
bool perl_classes() const { return perl_classes_; }
void set_perl_classes(bool b) { perl_classes_ = b; }
bool word_boundary() const { return word_boundary_; }
void set_word_boundary(bool b) { word_boundary_ = b; }
bool one_line() const { return one_line_; }
void set_one_line(bool b) { one_line_ = b; }
void Copy(const Options& src) {
*this = src;
int ParseFlags() const;
int64_t max_mem_;
Encoding encoding_;
bool posix_syntax_;
bool longest_match_;
bool log_errors_;
bool literal_;
bool never_nl_;
bool dot_nl_;
bool never_capture_;
bool case_sensitive_;
bool perl_classes_;
bool word_boundary_;
bool one_line_;
// Returns the options set in the constructor.
const Options& options() const { return options_; }
// Argument converters; see below.
template <typename T>
static Arg CRadix(T* ptr);
template <typename T>
static Arg Hex(T* ptr);
template <typename T>
static Arg Octal(T* ptr);
// Controls the maximum count permitted by GlobalReplace(); -1 is unlimited.
static void FUZZING_ONLY_set_maximum_global_replace_count(int i);
void Init(absl::string_view pattern, const Options& options);
bool DoMatch(absl::string_view text,
Anchor re_anchor,
size_t* consumed,
const Arg* const args[],
int n) const;
re2::Prog* ReverseProg() const;
// First cache line is relatively cold fields.
const std::string* pattern_; // string regular expression
Options options_; // option flags
re2::Regexp* entire_regexp_; // parsed regular expression
re2::Regexp* suffix_regexp_; // parsed regular expression, prefix_ removed
const std::string* error_; // error indicator (or points to empty string)
const std::string* error_arg_; // fragment of regexp showing error (or ditto)
// Second cache line is relatively hot fields.
// These are ordered oddly to pack everything.
int num_captures_; // number of capturing groups
ErrorCode error_code_ : 29; // error code (29 bits is more than enough)
bool longest_match_ : 1; // cached copy of options_.longest_match()
bool is_one_pass_ : 1; // can use prog_->SearchOnePass?
bool prefix_foldcase_ : 1; // prefix_ is ASCII case-insensitive
std::string prefix_; // required prefix (before suffix_regexp_)
re2::Prog* prog_; // compiled program for regexp
// Reverse Prog for DFA execution only
mutable re2::Prog* rprog_;
// Map from capture names to indices
mutable const std::map<std::string, int>* named_groups_;
// Map from capture indices to names
mutable const std::map<int, std::string>* group_names_;
mutable absl::once_flag rprog_once_;
mutable absl::once_flag named_groups_once_;
mutable absl::once_flag group_names_once_;
/***** Implementation details *****/
namespace re2_internal {
// Types for which the 3-ary Parse() function template has specializations.
template <typename T> struct Parse3ary : public std::false_type {};
template <> struct Parse3ary<void> : public std::true_type {};
template <> struct Parse3ary<std::string> : public std::true_type {};
template <> struct Parse3ary<absl::string_view> : public std::true_type {};
template <> struct Parse3ary<char> : public std::true_type {};
template <> struct Parse3ary<signed char> : public std::true_type {};
template <> struct Parse3ary<unsigned char> : public std::true_type {};
template <> struct Parse3ary<float> : public std::true_type {};
template <> struct Parse3ary<double> : public std::true_type {};
template <typename T>
bool Parse(const char* str, size_t n, T* dest);
// Types for which the 4-ary Parse() function template has specializations.
template <typename T> struct Parse4ary : public std::false_type {};
template <> struct Parse4ary<long> : public std::true_type {};
template <> struct Parse4ary<unsigned long> : public std::true_type {};
template <> struct Parse4ary<short> : public std::true_type {};
template <> struct Parse4ary<unsigned short> : public std::true_type {};
template <> struct Parse4ary<int> : public std::true_type {};
template <> struct Parse4ary<unsigned int> : public std::true_type {};
template <> struct Parse4ary<long long> : public std::true_type {};
template <> struct Parse4ary<unsigned long long> : public std::true_type {};
template <typename T>
bool Parse(const char* str, size_t n, T* dest, int radix);
// Support absl::optional<T> for all T with a stock parser.
template <typename T> struct Parse3ary<absl::optional<T>> : public Parse3ary<T> {};
template <typename T> struct Parse4ary<absl::optional<T>> : public Parse4ary<T> {};
template <typename T>
bool Parse(const char* str, size_t n, absl::optional<T>* dest) {
if (str == NULL) {
if (dest != NULL)
return true;
T tmp;
if (Parse(str, n, &tmp)) {
if (dest != NULL)
return true;
return false;
template <typename T>
bool Parse(const char* str, size_t n, absl::optional<T>* dest, int radix) {
if (str == NULL) {
if (dest != NULL)
return true;
T tmp;
if (Parse(str, n, &tmp, radix)) {
if (dest != NULL)
return true;
return false;
} // namespace re2_internal
class RE2::Arg {
template <typename T>
using CanParse3ary = typename std::enable_if<
template <typename T>
using CanParse4ary = typename std::enable_if<
#if !defined(_MSC_VER)
template <typename T>
using CanParseFrom = typename std::enable_if<
decltype(static_cast<bool (T::*)(const char*, size_t)>(
Arg() : Arg(nullptr) {}
Arg(std::nullptr_t ptr) : arg_(ptr), parser_(DoNothing) {}
template <typename T, CanParse3ary<T> = 0>
Arg(T* ptr) : arg_(ptr), parser_(DoParse3ary<T>) {}
template <typename T, CanParse4ary<T> = 0>
Arg(T* ptr) : arg_(ptr), parser_(DoParse4ary<T>) {}
#if !defined(_MSC_VER)
template <typename T, CanParseFrom<T> = 0>
Arg(T* ptr) : arg_(ptr), parser_(DoParseFrom<T>) {}
typedef bool (*Parser)(const char* str, size_t n, void* dest);
template <typename T>
Arg(T* ptr, Parser parser) : arg_(ptr), parser_(parser) {}
bool Parse(const char* str, size_t n) const {
return (*parser_)(str, n, arg_);
static bool DoNothing(const char* /*str*/, size_t /*n*/, void* /*dest*/) {
return true;
template <typename T>
static bool DoParse3ary(const char* str, size_t n, void* dest) {
return re2_internal::Parse(str, n, reinterpret_cast<T*>(dest));
template <typename T>
static bool DoParse4ary(const char* str, size_t n, void* dest) {
return re2_internal::Parse(str, n, reinterpret_cast<T*>(dest), 10);
#if !defined(_MSC_VER)
template <typename T>
static bool DoParseFrom(const char* str, size_t n, void* dest) {
if (dest == NULL) return true;
return reinterpret_cast<T*>(dest)->ParseFrom(str, n);
void* arg_;
Parser parser_;
template <typename T>
inline RE2::Arg RE2::CRadix(T* ptr) {
return RE2::Arg(ptr, [](const char* str, size_t n, void* dest) -> bool {
return re2_internal::Parse(str, n, reinterpret_cast<T*>(dest), 0);
template <typename T>
inline RE2::Arg RE2::Hex(T* ptr) {
return RE2::Arg(ptr, [](const char* str, size_t n, void* dest) -> bool {
return re2_internal::Parse(str, n, reinterpret_cast<T*>(dest), 16);
template <typename T>
inline RE2::Arg RE2::Octal(T* ptr) {
return RE2::Arg(ptr, [](const char* str, size_t n, void* dest) -> bool {
return re2_internal::Parse(str, n, reinterpret_cast<T*>(dest), 8);
// Silence warnings about missing initializers for members of LazyRE2.
#if !defined(__clang__) && defined(__GNUC__)
#pragma GCC diagnostic ignored "-Wmissing-field-initializers"
// Helper for writing global or static RE2s safely.
// Write
// static LazyRE2 re = {".*"};
// and then use *re instead of writing
// static RE2 re(".*");
// The former is more careful about multithreaded
// situations than the latter.
// N.B. This class never deletes the RE2 object that
// it constructs: that's a feature, so that it can be used
// for global and function static variables.
class LazyRE2 {
struct NoArg {};
typedef RE2 element_type; // support std::pointer_traits
// Constructor omitted to preserve braced initialization in C++98.
// Pretend to be a pointer to Type (never NULL due to on-demand creation):
RE2& operator*() const { return *get(); }
RE2* operator->() const { return get(); }
// Named accessor/initializer:
RE2* get() const {
absl::call_once(once_, &LazyRE2::Init, this);
return ptr_;
// All data fields must be public to support {"foo"} initialization.
const char* pattern_;
RE2::CannedOptions options_;
NoArg barrier_against_excess_initializers_;
mutable RE2* ptr_;
mutable absl::once_flag once_;
static void Init(const LazyRE2* lazy_re2) {
lazy_re2->ptr_ = new RE2(lazy_re2->pattern_, lazy_re2->options_);
void operator=(const LazyRE2&); // disallowed
namespace hooks {
// Most platforms support thread_local. Older versions of iOS don't support
// thread_local, but for the sake of brevity, we lump together all versions
// of Apple platforms that aren't macOS. If an iOS application really needs
// the context pointee someday, we can get more specific then...
// As per, thread_local support in
// MinGW seems to be buggy. (FWIW, Abseil folks also avoid it.)
#if (defined(__APPLE__) && !(defined(TARGET_OS_OSX) && TARGET_OS_OSX)) || defined(__MINGW32__)
// A hook must not make any assumptions regarding the lifetime of the context
// pointee beyond the current invocation of the hook. Pointers and references
// obtained via the context pointee should be considered invalidated when the
// hook returns. Hence, any data about the context pointee (e.g. its pattern)
// would have to be copied in order for it to be kept for an indefinite time.
// A hook must not use RE2 for matching. Control flow reentering RE2::Match()
// could result in infinite mutual recursion. To discourage that possibility,
// RE2 will not maintain the context pointer correctly when used in that way.
extern thread_local const RE2* context;
struct DFAStateCacheReset {
int64_t state_budget;
size_t state_cache_size;
struct DFASearchFailure {
// Nothing yet...
#define DECLARE_HOOK(type) \
using type##Callback = void(const type&); \
void Set##type##Hook(type##Callback* cb); \
type##Callback* Get##type##Hook();
} // namespace hooks
} // namespace re2
using re2::RE2;
using re2::LazyRE2;
#endif // RE2_RE2_H_