32 lines
635 B
Go
32 lines
635 B
Go
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package main
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import (
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"errors"
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"strings"
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)
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// StringService provides operations on strings.
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type StringService interface {
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Uppercase(string) (string, error)
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Count(string) int
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}
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type stringService struct{}
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func (stringService) Uppercase(s string) (string, error) {
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if s == "" {
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return "", ErrEmpty
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}
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return strings.ToUpper(s), nil
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}
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func (stringService) Count(s string) int {
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return len(s)
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}
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// ErrEmpty is returned when an input string is empty.
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var ErrEmpty = errors.New("empty string")
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// ServiceMiddleware is a chainable behavior modifier for StringService.
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type ServiceMiddleware func(StringService) StringService
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