VictoriaMetrics/vendor/github.com/rivo/uniseg/word.go
2022-08-02 09:19:38 +03:00

88 lines
2.5 KiB
Go

package uniseg
import "unicode/utf8"
// FirstWord returns the first word found in the given byte slice according to
// the rules of Unicode Standard Annex #29, Word Boundaries. This function can
// be called continuously to extract all words from a byte slice, as illustrated
// in the example below.
//
// If you don't know the current state, for example when calling the function
// for the first time, you must pass -1. For consecutive calls, pass the state
// and rest slice returned by the previous call.
//
// The "rest" slice is the sub-slice of the original byte slice "b" starting
// after the last byte of the identified word. If the length of the "rest" slice
// is 0, the entire byte slice "b" has been processed. The "word" byte slice is
// the sub-slice of the input slice containing the identified word.
//
// Given an empty byte slice "b", the function returns nil values.
func FirstWord(b []byte, state int) (word, rest []byte, newState int) {
// An empty byte slice returns nothing.
if len(b) == 0 {
return
}
// Extract the first rune.
r, length := utf8.DecodeRune(b)
if len(b) <= length { // If we're already past the end, there is nothing else to parse.
return b, nil, wbAny
}
// If we don't know the state, determine it now.
if state < 0 {
state, _ = transitionWordBreakState(state, r, b[length:], "")
}
// Transition until we find a boundary.
var boundary bool
for {
r, l := utf8.DecodeRune(b[length:])
state, boundary = transitionWordBreakState(state, r, b[length+l:], "")
if boundary {
return b[:length], b[length:], state
}
length += l
if len(b) <= length {
return b, nil, wbAny
}
}
}
// FirstWordInString is like FirstWord() but its input and outputs are strings.
func FirstWordInString(str string, state int) (word, rest string, newState int) {
// An empty byte slice returns nothing.
if len(str) == 0 {
return
}
// Extract the first rune.
r, length := utf8.DecodeRuneInString(str)
if len(str) <= length { // If we're already past the end, there is nothing else to parse.
return str, "", wbAny
}
// If we don't know the state, determine it now.
if state < 0 {
state, _ = transitionWordBreakState(state, r, nil, str[length:])
}
// Transition until we find a boundary.
var boundary bool
for {
r, l := utf8.DecodeRuneInString(str[length:])
state, boundary = transitionWordBreakState(state, r, nil, str[length+l:])
if boundary {
return str[:length], str[length:], state
}
length += l
if len(str) <= length {
return str, "", wbAny
}
}
}