package router
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import (
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"regexp"
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"strconv"
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"strings"
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)
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type weightScaler func(value, weight float64) float64
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var numberFinder = regexp.MustCompile(`\d+(\.\d+)?`)
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// NewWeightManager creates a new WeightManager with settings
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func NewWeightManager(s []*StrategyWeight, defaultWeight float64, scaler weightScaler) *WeightManager {
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return &WeightManager{
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settings: s,
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cache: make(map[string]float64),
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scaler: scaler,
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defaultWeight: defaultWeight,
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}
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}
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// WeightManager manages weights for specific settings
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type WeightManager struct {
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settings []*StrategyWeight
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cache map[string]float64
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scaler weightScaler
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defaultWeight float64
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}
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// Get gets the weight of specified tag
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func (s *WeightManager) Get(tag string) float64 {
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weight, ok := s.cache[tag]
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if ok {
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return weight
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}
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weight = s.findValue(tag)
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s.cache[tag] = weight
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return weight
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}
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// Apply applies weight to the value
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func (s *WeightManager) Apply(tag string, value float64) float64 {
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return s.scaler(value, s.Get(tag))
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}
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func (s *WeightManager) findValue(tag string) float64 {
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for _, w := range s.settings {
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matched := s.getMatch(tag, w.Match, w.Regexp)
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if matched == "" {
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continue
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}
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if w.Value > 0 {
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return float64(w.Value)
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}
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// auto weight from matched
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numStr := numberFinder.FindString(matched)
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if numStr == "" {
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return s.defaultWeight
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}
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weight, err := strconv.ParseFloat(numStr, 64)
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if err != nil {
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newError("unexpected error from ParseFloat: ", err).AtError().WriteToLog()
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return s.defaultWeight
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}
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return weight
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}
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return s.defaultWeight
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}
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func (s *WeightManager) getMatch(tag, find string, isRegexp bool) string {
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if !isRegexp {
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idx := strings.Index(tag, find)
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if idx < 0 {
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return ""
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}
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return find
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}
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r, err := regexp.Compile(find)
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if err != nil {
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newError("invalid regexp: ", find, "err: ", err).AtError().WriteToLog()
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return ""
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}
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return r.FindString(tag)
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}
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