1set/gut

package ystring

import (
    "strings"
    "unicode"
)

// IsEmpty checks if the string is empty.
func IsEmpty(s string) bool {
    return s == ""
}

// IsNotEmpty checks if the string is not empty.
func IsNotEmpty(s string) bool {
    return s != ""
}

// NotEmptyOrDefault returns the string if it is not empty, or returns the fallback.
func NotEmptyOrDefault(s, fallback string) string {
    if s != "" {
        return s
    }
    return fallback
}

// IsBlank checks if the string contains only whitespaces.
func IsBlank(s string) bool {
    return strings.TrimSpace(s) == ""
}

// IsNotBlank checks if the string contains any non-whitespace characters.
func IsNotBlank(s string) bool {
    return strings.TrimSpace(s) != ""
}

// NotBlankOrDefault returns the string if it is not blank, or returns the fallback.
func NotBlankOrDefault(s, fallback string) string {
    if strings.TrimSpace(s) != "" {
        return s
    }
    return fallback
}

// Shrink returns a string that replaces consecutive whitespace characters in s with the sep string.
func Shrink(s, sep string) string {
    sb := strings.Builder{}
    sb.Grow(len(s))

    wFlag := false
    for _, c := range strings.TrimSpace(s) {
        if unicode.IsSpace(c) {
            wFlag = true
        } else {
            if wFlag {
                sb.WriteString(sep)
                wFlag = false
            }
            sb.WriteRune(c)
        }
    }
    return sb.String()
}