71 lines
2.0 KiB
Go
71 lines
2.0 KiB
Go
// CookieJar - A contestant's algorithm toolbox
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// Copyright (c) 2014 Peter Szilagyi. All rights reserved.
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//
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// CookieJar is dual licensed: use of this source code is governed by a BSD
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// license that can be found in the LICENSE file. Alternatively, the CookieJar
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// toolbox may be used in accordance with the terms and conditions contained
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// in a signed written agreement between you and the author(s).
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package utility
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import (
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"math"
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"gopkg.in/karalabe/cookiejar.v2/collections/bag"
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)
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// Combination utility derived from two other utilities.
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type comboUtility struct {
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combinator Combinator // Curve transformation combinator
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srcA, srcB singleUtility // Base utilities from which to derive this one
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children *bag.Bag // Derived utilities based on the current one
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reset bool // Flag whether the output is not yet calculated
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output float64 // Cached output utility value
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}
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// Creates a new derived utility based on two existing ones.
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func newComboUtility(combinator Combinator) *comboUtility {
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return &comboUtility{
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combinator: combinator,
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children: bag.New(),
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reset: true,
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}
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}
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// Finishes initialization with the two source components.
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func (u *comboUtility) Init(srcA, srcB utility) {
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u.srcA = srcA.(singleUtility)
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u.srcB = srcB.(singleUtility)
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srcA.Dependency(u)
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srcB.Dependency(u)
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}
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// Resets the utility value, forcing it to recalculate when needed again.
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func (u *comboUtility) Reset() {
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if !u.reset {
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u.reset = true
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u.children.Do(func(util interface{}) {
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util.(*comboUtility).Reset()
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})
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}
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}
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// Adds a new dependency to the utility hierarchy.
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func (u *comboUtility) Dependency(util utility) {
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u.children.Insert(util)
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}
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// Evaluates the utility chain and returns the current value.
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func (u *comboUtility) Evaluate() float64 {
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// If the utility was reset, reevaluate it
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if u.reset {
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u.output = math.Min(1, math.Max(0, u.combinator(u.srcA.Evaluate(), u.srcB.Evaluate())))
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u.reset = false
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}
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// Return the currently set value
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return u.output
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}
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