76 lines
1.8 KiB
Go
76 lines
1.8 KiB
Go
// Package aghalg contains common generic algorithms and data structures.
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//
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// TODO(a.garipov): Update to use type parameters in Go 1.18.
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package aghalg
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import (
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"fmt"
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"sort"
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)
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// comparable is an alias for interface{}. Values passed as arguments of this
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// type alias must be comparable.
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//
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// TODO(a.garipov): Remove in Go 1.18.
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type comparable = interface{}
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// UniqChecker allows validating uniqueness of comparable items.
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type UniqChecker map[comparable]int64
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// Add adds a value to the validator. v must not be nil.
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func (uc UniqChecker) Add(elems ...comparable) {
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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) Merge(other UniqChecker) (merged UniqChecker) {
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merged = make(UniqChecker, 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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// isBefore is an optional sorting function to make the error message
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// deterministic.
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func (uc UniqChecker) Validate(isBefore func(a, b comparable) (less bool)) (err error) {
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var dup []comparable
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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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if isBefore != nil {
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sort.Slice(dup, func(i, j int) (less bool) {
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return isBefore(dup[i], dup[j])
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})
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}
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return fmt.Errorf("duplicated values: %v", dup)
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}
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// IntIsBefore is a helper sort function for UniqChecker.Validate.
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// a and b must be of type int.
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func IntIsBefore(a, b comparable) (less bool) {
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return a.(int) < b.(int)
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}
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// StringIsBefore is a helper sort function for UniqChecker.Validate.
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// a and b must be of type string.
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func StringIsBefore(a, b comparable) (less bool) {
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return a.(string) < b.(string)
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}
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