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93 lines
2.6 KiB
Go
93 lines
2.6 KiB
Go
package monday
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import (
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"strings"
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"unicode"
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"unicode/utf8"
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)
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// dateStringLayoutItem represents one word or set of delimiters between words.
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// This is an abstraction level above date raw character string of date representation.
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//
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// Example: "1 February / 2013" ->
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// dateStringLayoutItem { item: "1", isWord: true }
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// dateStringLayoutItem { item: " ", isWord: false }
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// dateStringLayoutItem { item: "February", isWord: true }
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// dateStringLayoutItem { item: " / ", isWord: false }
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// dateStringLayoutItem { item: "2013", isWord: true }
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type dateStringLayoutItem struct {
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item string
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isWord bool // true if this is a sequence of letters/digits (as opposed to a sequence of non-letters like delimiters)
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isDigit bool // true if this is a sequence only containing digits
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}
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// extractLetterSequence extracts first word (sequence of letters ending with a non-letter)
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// starting with the specified index and wraps it to dateStringLayoutItem according to the type
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// of the word.
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func extractLetterSequence(originalStr string, index int) (it dateStringLayoutItem) {
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letters := &strings.Builder{}
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bytesToParse := []byte(originalStr[index:])
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runeCount := utf8.RuneCount(bytesToParse)
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var isWord bool
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var isDigit bool
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letters.Grow(runeCount)
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for i := 0; i < runeCount; i++ {
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rne, runeSize := utf8.DecodeRune(bytesToParse)
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bytesToParse = bytesToParse[runeSize:]
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if i == 0 {
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isWord = unicode.IsLetter(rne)
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isDigit = unicode.IsDigit(rne)
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} else {
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if (isWord && (!unicode.IsLetter(rne) && !unicode.IsDigit(rne))) ||
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(isDigit && !unicode.IsDigit(rne)) ||
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(!isWord && unicode.IsLetter(rne)) ||
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(!isDigit && unicode.IsDigit(rne)) {
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break
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}
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}
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letters.WriteRune(rne)
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}
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it.item = letters.String()
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it.isWord = isWord
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it.isDigit = isDigit
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return
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}
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// stringToLayoutItems transforms raw date string (like "2 Mar 2012") into
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// a set of dateStringLayoutItems, which are more convenient to work with
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// in other analysis modules.
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func stringToLayoutItems(dateStr string) (seqs []dateStringLayoutItem) {
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i := 0
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for i < len(dateStr) {
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seq := extractLetterSequence(dateStr, i)
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i += len(seq.item)
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seqs = append(seqs, seq)
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}
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return
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}
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func layoutToString(li []dateStringLayoutItem) string {
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// This function is expensive enough to be worth counting
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// bytes and allocating all in one go.
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numChars := 0
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for _, v := range li {
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numChars += len(v.item)
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}
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sb := &strings.Builder{}
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sb.Grow(numChars)
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for _, v := range li {
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sb.WriteString(v.item)
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}
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return sb.String()
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}
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