// Transform is used to transform the input when --with-nth option is given
func Transform(tokens []Token, withNth []Range) []Token {
transTokens := make([]Token, len(withNth))
numTokens := len(tokens)
for idx, r := range withNth {
part := []rune{}
minIdx := 0
if r.begin == r.end {
idx := r.begin
if idx == rangeEllipsis {
part = append(part, joinTokensAsRunes(tokens)...)
} else {
if idx < 0 {
idx += numTokens + 1
}
if idx >= 1 && idx <= numTokens {
minIdx = idx - 1
part = append(part, tokens[idx-1].text...)
}
}
} else {
var begin, end int
if r.begin == rangeEllipsis { // ..N
begin, end = 1, r.end
if end < 0 {
end += numTokens + 1
}
} else if r.end == rangeEllipsis { // N..
begin, end = r.begin, numTokens
if begin < 0 {
begin += numTokens + 1
}
} else {
begin, end = r.begin, r.end
if begin < 0 {
begin += numTokens + 1
}
if end < 0 {
end += numTokens + 1
}
}
minIdx = util.Max(0, begin-1)
for idx := begin; idx <= end; idx++ {
if idx >= 1 && idx <= numTokens {
part = append(part, tokens[idx-1].text...)
}
}
}
var prefixLength int
if minIdx < numTokens {
prefixLength = tokens[minIdx].prefixLength
} else {
prefixLength = 0
}
transTokens[idx] = Token{part, prefixLength, util.TrimLen(part)}
}
return transTokens
}
func withPrefixLengths(tokens [][]rune, begin int) []Token {
ret := make([]Token, len(tokens))
prefixLength := begin
for idx, token := range tokens {
// Need to define a new local variable instead of the reused token to take
// the pointer to it
ret[idx] = Token{token, prefixLength, util.TrimLen(token)}
prefixLength += len(token)
}
return ret
}
func (p *Pattern) prepareInput(item *Item) []Token {
if item.transformed != nil {
return item.transformed
}
var ret []Token
if len(p.nth) > 0 {
tokens := Tokenize(item.text, p.delimiter)
ret = Transform(tokens, p.nth)
} else {
ret = []Token{Token{text: item.text, prefixLength: 0, trimLength: util.TrimLen(item.text)}}
}
item.transformed = ret
return ret
}