8000 feat: add ToMap for stream by ppd324 · Pull Request #301 · duke-git/lancet · GitHub
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feat: add ToMap for stream #301

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Merged
merged 3 commits into from
Apr 14, 2025
Merged

feat: add ToMap for stream #301

merged 3 commits into from
Apr 14, 2025

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ppd324
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@ppd324 ppd324 commented Apr 2, 2025

add ToMap for stream

@cannian1
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cannian1 commented Apr 6, 2025

@ppd324 main branch was frozen, merge into rc branch.

@ppd324 ppd324 changed the base branch from main to rc April 7, 2025 02:15
cannian1
cannian1 previously approved these changes Apr 7, 2025
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ppd324 commented Apr 7, 2025 •
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Is it necessary to add a merge function to the ToMap method to merge key conflicts?
like this:

func ToMap[T any, K comparable, V any](s Stream[T], mapper func(item T) (K, V), mergeFunc func(existing, new V) V) map[K]V {
	m := make(map[K]V, len(s.source))
	for _, v := range s.source {
		key, value := mapper(v)
		if existing, ok := m[key]; ok {
			if mergeFunc != nil {
				m[key] = mergeFunc(existing, value)
				continue
			}
		}
		m[key] = value
	}
	return m
}

@cannian1
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func ToMap[T any, K comparable, V any](s Stream[T], mapper func(item T) (K, V), mergeFunc func(existing, new V) V) map[K]V {
	m := make(map[K]V, len(s.source))
	for _, v := range s.source {
		key, value := mapper(v)
		if existing, ok := m[key]; ok {
			if mergeFunc != nil {
				m[key] = mergeFunc(existing, value)
				continue
			}
		}
		m[key] = value
	}
	return m
}

I think it's better to split this into two functions

Simpler API for common cases

func ToMap[T any, K comparable, V any](s Stream[T], mapper func(item T) (K, V)) map[K]V {
	return ToMapWithMerge(s, mapper, nil)
}

func ToMapWithMerge[T any, K comparable, V any](s Stream[T], mapper func(item T) (K, V), mergeFunc func(existing, new V) V) map[K]V

@ppd324 ppd324 requested a review from cannian1 April 14, 2025 02:27
@cannian1 cannian1 merged commit c841a5b into duke-git:rc Apr 14, 2025
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