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regexp.go
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regexp.go
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// Package regexp implements extended regular expression search.
package regexp
// This package provides extended regular expression syntax.
// The implementation does NOT guarantee linear processing time.
//
// If you don't use extended syntax, the golang built-in regex engine will be used transparently.
import (
"fmt"
"regexp"
"strings"
"github.com/skybet/goback/regexp/syntax"
)
// Regexp is the representation of a compiled regular expression.
// A Regexp is safe for concurrent use by multiple goroutines.
type Regexp interface {
// Match reports whether the Regexp matches the byte slice b.
Match(b []byte) bool
// MatchString reports whether the Regexp matches the string s.
MatchString(s string) bool
// Find returns a slice holding the text of the leftmost match in b of the regular expression.
// A return value of nil indicates no match.
Find(b []byte) []byte
// FindIndex returns a two-element slice of integers defining the location of
// the leftmost match in b of the regular expression. The match itself is at
// b[loc[0]:loc[1]].
// A return value of nil indicates no match.
FindIndex(b []byte) []int
// FindSubmatch returns a slice of slices holding the text of the leftmost
// match of the regular expression in b and the matches, if any, of its
// subexpressions, as defined by the 'Submatch' descriptions in the package
// comment.
// A return value of nil indicates no match.
FindSubmatch(b []byte) [][]byte
// FindSubmatchIndex returns a slice holding the index pairs identifying the
// leftmost match of the regular expression in b and the matches, if any, of
// its subexpressions, as defined by the 'Submatch' and 'Index' descriptions
// in the package comment.
// A return value of nil indicates no match.
FindSubmatchIndex(b []byte) []int
// FindString returns a string holding the text of the leftmost match in s of the regular
// expression. If there is no match, the return value is an empty string,
// but it will also be empty if the regular expression successfully matches
// an empty string. Use FindStringIndex or FindStringSubmatch if it is
// necessary to distinguish these cases.
FindString(s string) string
// FindStringIndex returns a two-element slice of integers defining the
// location of the leftmost match in s of the regular expression. The match
// itself is at s[loc[0]:loc[1]].
// A return value of nil indicates no match.
FindStringIndex(s string) []int
// FindStringSubmatch returns a slice of strings holding the text of the
// leftmost match of the regular expression in s and the matches, if any, of
// its subexpressions, as defined by the 'Submatch' description in the
// package comment.
// A return value of nil indicates no match.
FindStringSubmatch(s string) []string
// FindStringSubmatchIndex returns a slice holding the index pairs
// identifying the leftmost match of the regular expression in s and the
// matches, if any, of its subexpressions, as defined by the 'Submatch' and
// 'Index' descriptions in the package comment.
// A return value of nil indicates no match.
FindStringSubmatchIndex(s string) []int
// FindAll is the 'All' version of Find; it returns a slice of all successive
// matches of the expression, as defined by the 'All' description in the
// package comment.
// A return value of nil indicates no match.
FindAll(b []byte, n int) [][]byte
// FindAllIndex is the 'All' version of FindIndex; it returns a slice of all
// successive matches of the expression, as defined by the 'All' description
// in the package comment.
// A return value of nil indicates no match.
FindAllIndex(b []byte, n int) [][]int
// FindAllSubmatchIndex is the 'All' version of FindSubmatchIndex; it returns
// a slice of all successive matches of the expression, as defined by the
// 'All' description in the package comment.
// A return value of nil indicates no match.
FindAllSubmatchIndex(b []byte, n int) [][]int
// FindAllSubmatch is the 'All' version of FindSubmatch; it returns a slice
// of all successive matches of the expression, as defined by the 'All'
// description in the package comment.
// A return value of nil indicates no match.
FindAllSubmatch(b []byte, n int) [][][]byte
// FindAllString is the 'All' version of FindString; it returns a slice of all
// successive matches of the expression, as defined by the 'All' description
// in the package comment.
// A return value of nil indicates no match.
FindAllString(s string, n int) []string
// FindAllStringIndex is the 'All' version of FindStringIndex; it returns a
// slice of all successive matches of the expression, as defined by the 'All'
// description in the package comment.
// A return value of nil indicates no match.
FindAllStringIndex(s string, n int) [][]int
// FindAllStringSubmatch is the 'All' version of FindStringSubmatch; it
// returns a slice of all successive matches of the expression, as defined by
// the 'All' description in the package comment.
// A return value of nil indicates no match.
FindAllStringSubmatch(s string, n int) [][]string
// FindAllStringSubmatchIndex is the 'All' version of
// FindStringSubmatchIndex; it returns a slice of all successive matches of
// the expression, as defined by the 'All' description in the package
// comment.
// A return value of nil indicates no match.
FindAllStringSubmatchIndex(s string, n int) [][]int
// ReplaceAllFunc returns a copy of src in which all matches of the
// Regexp have been replaced by the return value of function repl applied
// to the matched byte slice. The replacement returned by repl is substituted
// directly, without using Expand.
ReplaceAllFunc(src []byte, repl func([]byte) []byte) []byte
// ReplaceAllStringFunc returns a copy of src in which all matches of the
// Regexp have been replaced by the return value of function repl applied
// to the matched substring. The replacement returned by repl is substituted
// directly, without using Expand.
ReplaceAllStringFunc(src string, repl func(string) string) string
// ReplaceAll returns a copy of src, replacing matches of the Regexp
// with the replacement text repl. Inside repl, $ signs are interpreted as
// in Expand, so for instance $1 represents the text of the first submatch.
ReplaceAll(src, repl []byte) []byte
// ReplaceAllString returns a copy of src, replacing matches of the Regexp
// with the replacement string repl. Inside repl, $ signs are interpreted as
// in Expand, so for instance $1 represents the text of the first submatch.
ReplaceAllString(src, repl string) string
// ReplaceAllLiteral returns a copy of src, replacing matches of the Regexp
// with the replacement bytes repl. The replacement repl is substituted directly,
// without using Expand.
ReplaceAllLiteral(src, repl []byte) []byte
// ReplaceAllLiteralString returns a copy of src, replacing matches of the Regexp
// with the replacement string repl. The replacement repl is substituted directly,
// without using Expand.
ReplaceAllLiteralString(src, repl string) string
// Expand appends template to dst and returns the result; during the
// append, Expand replaces variables in the template with corresponding
// matches drawn from src. The match slice should have been returned by
// FindSubmatchIndex.
//
// In the template, a variable is denoted by a substring of the form
// $name or ${name}, where name is a non-empty sequence of letters,
// digits, and underscores. A purely numeric name like $1 refers to
// the submatch with the corresponding index; other names refer to
// capturing parentheses named with the (?P<name>...) syntax. A
// reference to an out of range or unmatched index or a name that is not
// present in the regular expression is replaced with an empty slice.
//
// In the $name form, name is taken to be as long as possible: $1x is
// equivalent to ${1x}, not ${1}x, and, $10 is equivalent to ${10}, not ${1}0.
//
// To insert a literal $ in the output, use $$ in the template.
Expand(dst []byte, template []byte, src []byte, match []int) []byte
// ExpandString is like Expand but the template and source are strings.
// It appends to and returns a byte slice in order to give the calling
// code control over allocation.
ExpandString(dst []byte, template string, src string, match []int) []byte
// Split slices s into substrings separated by the expression and returns a slice of
// the substrings between those expression matches.
//
// The slice returned by this method consists of all the substrings of s
// not contained in the slice returned by FindAllString. When called on an expression
// that contains no metacharacters, it is equivalent to strings.SplitN.
//
// Example:
// s := regexp.MustCompile("a*").Split("abaabaccadaaae", 5)
// // s: ["", "b", "b", "c", "cadaaae"]
//
// The count determines the number of substrings to return:
// n > 0: at most n substrings; the last substring will be the unsplit remainder.
// n == 0: the result is nil (zero substrings)
// n < 0: all substrings
Split(s string, n int) []string
// LiteralPrefix returns a literal string that must begin any match
// of the regular expression re. It returns the boolean true if the
// literal string comprises the entire regular expression.
LiteralPrefix() (prefix string, complete bool)
// NumSubexp returns the number of parenthesized subexpressions in this Regexp.
NumSubexp() int
// SubexpNames returns the names of the parenthesized subexpressions
// in this Regexp. The name for the first sub-expression is names[1],
// so that if m is a match slice, the name for m[i] is SubexpNames()[i].
// Since the Regexp as a whole cannot be named, names[0] is always
// the empty string. The slice should not be modified.
SubexpNames() []string
// Longest makes future searches prefer the leftmost-longest match.
// That is, when matching against text, the regexp returns a match that
// begins as early as possible in the input (leftmost), and among those
// it chooses a match that is as long as possible.
Longest()
// String returns the source text used to compile the regular expression.
String() string
// Funcs adds the elements of the argument map to the template's function map.
Funcs(funcMap syntax.FuncMap)
}
type reg struct {
*regexp.Regexp
}
func (r *reg) Funcs(funcMap syntax.FuncMap) {}
// Compile parses a regular expression and returns, if successful,
// a Regexp object that can be used to match against text.
func Compile(expr string) (Regexp, error) {
r, ext, err := syntax.Compile(expr)
if err != nil {
return nil, err
}
if ext {
return r, nil
}
re, err := regexp.Compile(ignoreComments(expr))
return ®{
Regexp: re,
}, err
}
// CompileFreeSpacing parses a regular expression like Compile,
// but whitespace characters are ignored and # is parsed as the beggining of a line comment.
func CompileFreeSpacing(expr string) (Regexp, error) {
r, ext, err := syntax.Compile(ignoreCommentsAndSpaces(expr))
if err != nil {
return nil, err
}
if ext {
return r, nil
}
re, err := regexp.Compile(ignoreComments(ignoreCommentsAndSpaces(expr)))
return ®{
Regexp: re,
}, err
}
func compile(expr string) (Regexp, error) {
r, _, err := syntax.Compile(expr)
if err != nil {
return nil, err
}
return r, nil
}
// MustCompileFreeSpacing parses a regular expression like MustCompile,
// but whitespace characters are ignored and # is parsed as the beggining of a line comment.
func MustCompileFreeSpacing(str string) Regexp {
r, err := CompileFreeSpacing(str)
if err != nil {
panic(err)
}
return r
}
// MustCompile is like Compile but panics if the expression cannot be parsed.
// It simplifies safe initialization of global variables holding compiled regular
// expressions.
func MustCompile(str string) Regexp {
r, err := Compile(str)
if err != nil {
panic(err)
}
return r
}
func mustCompile(expr string) Regexp {
r, err := compile(expr)
if err != nil {
panic(err)
}
return r
}
// Match checks whether a textual regular expression
// matches a byte slice. More complicated queries need
// to use Compile and the full Regexp interface.
func Match(pattern string, b []byte) (matched bool, err error) {
re, err := Compile(pattern)
if err != nil {
return false, err
}
return re.Match(b), nil
}
// MatchString checks whether a textual regular expression
// matches a string. More complicated queries need
// to use Compile and the full Regexp interface.
func MatchString(pattern string, s string) (matched bool, err error) {
re, err := Compile(pattern)
if err != nil {
return false, err
}
return re.MatchString(s), nil
}
// QuoteMeta returns a string that quotes all regular expression metacharacters
// inside the argument text; the returned string is a regular expression matching
// the literal text. For example, QuoteMeta(`[foo]`) returns `\[foo\]`.
func QuoteMeta(s string) string {
return regexp.QuoteMeta(s)
}
var commentRegexp = regexp.MustCompile(`(^|[^\\]|\\\\)(\(\?#[^)]*\))`)
func ignoreComments(expr string) string {
return commentRegexp.ReplaceAllString(expr, "$1")
}
var lineCommentRegexp = regexp.MustCompile(`(?m)(?:\\#)|(\#)|(?:#.*$)`)
var spaceRegexp = regexp.MustCompile(`( )|(?:)`)
func ignoreCommentsAndSpaces(expr string) string {
var res string
loop:
for _, line := range strings.Split(expr, "\n") {
meta := false
charClass := false
for _, c := range line {
if meta {
charClass = false
switch c {
case '\\':
res += "\\"
case '#':
res += "#"
case ' ':
res += " "
default:
res += fmt.Sprintf("\\%c", c)
}
meta = false
} else {
if charClass {
if c == ' ' {
res += fmt.Sprintf("%c", c)
}
charClass = false
} else {
if c == '[' {
charClass = true
}
}
switch c {
case '\\':
meta = true
case ' ':
case '\v':
case '\t':
case '\f':
case '\r':
case '[':
res += "["
case '#':
continue loop
default:
res += fmt.Sprintf("%c", c)
}
}
}
}
return res
}