69 lines
1.5 KiB
Go
69 lines
1.5 KiB
Go
// Package aghalg contains common generic algorithms and data structures.
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//
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// TODO(a.garipov): Move parts of this into golibs.
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package aghalg
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import (
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"fmt"
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"slices"
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"golang.org/x/exp/constraints"
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)
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// CoalesceSlice returns the first non-zero value. It is named after function
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// COALESCE in SQL. If values or all its elements are empty, it returns nil.
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func CoalesceSlice[E any, S []E](values ...S) (res S) {
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for _, v := range values {
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if v != nil {
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return v
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}
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}
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return nil
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}
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// UniqChecker allows validating uniqueness of comparable items.
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//
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// TODO(a.garipov): The Ordered constraint is only really necessary in Validate.
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// Consider ways of making this constraint comparable instead.
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type UniqChecker[T constraints.Ordered] map[T]int64
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// Add adds a value to the validator. v must not be nil.
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func (uc UniqChecker[T]) Add(elems ...T) {
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for _, e := range elems {
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uc[e]++
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}
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}
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// Merge returns a checker containing data from both uc and other.
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func (uc UniqChecker[T]) Merge(other UniqChecker[T]) (merged UniqChecker[T]) {
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merged = make(UniqChecker[T], len(uc)+len(other))
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for elem, num := range uc {
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merged[elem] += num
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}
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for elem, num := range other {
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merged[elem] += num
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}
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return merged
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}
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// Validate returns an error enumerating all elements that aren't unique.
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func (uc UniqChecker[T]) Validate() (err error) {
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var dup []T
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for elem, num := range uc {
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if num > 1 {
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dup = append(dup, elem)
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}
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}
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if len(dup) == 0 {
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return nil
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}
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slices.Sort(dup)
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return fmt.Errorf("duplicated values: %v", dup)
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}
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