uregex

Documentation

Overview

Package uregex compiles user-supplied regular expressions for the operations that accept them. It prefers Go's RE2 engine for its linear-time guarantee and falls back to regexp2 in ECMAScript (JavaScript-compatible) mode only when a pattern uses a feature RE2 lacks — lookahead, lookbehind, backreferences, or JavaScript named-group syntax. The regexp2 path is bounded by a match timeout, since it can backtrack.

Both engines are presented through a small Regexp interface that mirrors the two shapes the operations need from the standard library: a list of matches with their capture-group text, and the same with byte offsets.

Index

• type Regexp
  • func Compile(pattern string) (Regexp, error)

Types

type Regexp

type Regexp interface {
	// MatchString reports whether the pattern matches anywhere in s.
	MatchString(s string) bool
	// ReplaceAll replaces every match with repl, expanding $-group references.
	ReplaceAll(src, repl string) string
	// ReplaceFirst replaces only the first match with repl.
	ReplaceFirst(src, repl string) string
	// FindStringSubmatch returns the first match: element 0 is the whole match
	// and later elements are the capture groups (empty string if a group did not
	// participate). It returns nil when there is no match.
	FindStringSubmatch(s string) []string
	// FindAllStringSubmatch returns every non-overlapping match. In each result,
	// element 0 is the whole match and later elements are the capture groups; a
	// group that did not participate is the empty string.
	FindAllStringSubmatch(s string) [][]string
	// FindAllStringSubmatchIndex returns the same matches as byte-offset pairs:
	// [start,end] of the whole match followed by [start,end] of each group, with
	// -1,-1 for a group that did not participate.
	FindAllStringSubmatchIndex(s string) [][]int
}

Regexp is the behavior the operations need from a compiled user pattern.

func Compile

func Compile(pattern string) (Regexp, error)

Compile builds a Regexp from a user pattern (which may already carry an inline flag prefix such as "(?ims)"). RE2 is tried first; a pattern it cannot compile is retried under regexp2's ECMAScript mode.