From c6f841ec4b44b2481b28f248957bf3a0503f14f5 Mon Sep 17 00:00:00 2001
From: Alexander Ignatov <yalishanda@abv.bg>
Date: Thu, 30 Dec 2021 23:05:03 +0200
Subject: [PATCH] Add LinguisticVariable and new method

---
 Sources/FuzzyLogic/LinguisticVariable.swift   | 39 +++++++++++++++++++
 Sources/FuzzySets/FuzzySetOperations.swift    |  2 +
 .../Implementations/AnyFuzzySet.swift         |  6 ++-
 .../DiscreteMutableFuzzySet.swift             |  6 +++
 .../Implementations/IterableFuzzySet.swift    |  6 +++
 5 files changed, 58 insertions(+), 1 deletion(-)
 create mode 100644 Sources/FuzzyLogic/LinguisticVariable.swift

diff --git a/Sources/FuzzyLogic/LinguisticVariable.swift b/Sources/FuzzyLogic/LinguisticVariable.swift
new file mode 100644
index 0000000..3dd4a19
--- /dev/null
+++ b/Sources/FuzzyLogic/LinguisticVariable.swift
@@ -0,0 +1,39 @@
+import FuzzySets
+
+public struct LinguisticVariable<Universe, TermName: Hashable, Term: FuzzySetOperations, TermModifierName: Hashable> {
+    
+    public typealias TermModifier = (Grade) -> Grade
+    
+    let baseTerms: [TermName: Term]
+    let termModifiers: [TermModifierName: TermModifier]
+    
+    public init(
+        baseTerms: [TermName: Term],
+        termModifiers: [TermModifierName: TermModifier] = [:]
+    ) {
+        self.baseTerms = baseTerms
+        self.termModifiers = termModifiers
+    }
+    
+    public func term(_ name: TermName) -> Term? {
+        baseTerms[name]
+    }
+    
+    public subscript(_ termName: TermName) -> Term? {
+        term(termName)
+    }
+    
+    public subscript(_ termName: TermName, applyModifier modifierName: TermModifierName) -> Term? {
+        applyModifier(modifierName, to: termName)
+    }
+    
+    public func applyModifier(_ modifierName: TermModifierName, to termName: TermName) -> Term? {
+        guard let term = term(termName) else { return nil }
+        return applyModifier(modifierName, to: term)
+    }
+    
+    public func applyModifier(_ modifierName: TermModifierName, to term: Term) -> Term? {
+        guard let modifier = termModifiers[modifierName] else { return nil }
+        return term.appliedCustomFunction(modifier)
+    }
+}
diff --git a/Sources/FuzzySets/FuzzySetOperations.swift b/Sources/FuzzySets/FuzzySetOperations.swift
index e0c38ba..2658599 100644
--- a/Sources/FuzzySets/FuzzySetOperations.swift
+++ b/Sources/FuzzySets/FuzzySetOperations.swift
@@ -13,4 +13,6 @@ public protocol FuzzySetOperations: FuzzySet {
     func symmetricDifference(_ other: Self, method: SymmetricDifferenceFunction) -> Self
     
     func power(_ n: Double) -> Self
+    
+    func appliedCustomFunction(_ function: @escaping (Grade) -> Grade) -> Self
 }
diff --git a/Sources/FuzzySets/Implementations/AnyFuzzySet.swift b/Sources/FuzzySets/Implementations/AnyFuzzySet.swift
index 05d20cf..1c8be41 100644
--- a/Sources/FuzzySets/Implementations/AnyFuzzySet.swift
+++ b/Sources/FuzzySets/Implementations/AnyFuzzySet.swift
@@ -48,7 +48,11 @@ extension AnyFuzzySet: FuzzySetOperations {
     }
     
     public func power(_ n: Double) -> Self {
-        return .init { Double.pow(membershipFunction($0), n) }
+        .init { Double.pow(membershipFunction($0), n) }
+    }
+    
+    public func appliedCustomFunction(_ function: @escaping (Grade) -> Grade) -> Self {
+        .init { function(membershipFunction($0)) }
     }
 }
 
diff --git a/Sources/FuzzySets/Implementations/DiscreteMutableFuzzySet.swift b/Sources/FuzzySets/Implementations/DiscreteMutableFuzzySet.swift
index 334ecce..c72755e 100644
--- a/Sources/FuzzySets/Implementations/DiscreteMutableFuzzySet.swift
+++ b/Sources/FuzzySets/Implementations/DiscreteMutableFuzzySet.swift
@@ -62,6 +62,12 @@ extension DiscreteMutableFuzzySet: FuzzySetOperations {
         result.applyPower(n)
         return result
     }
+    
+    public func appliedCustomFunction(_ function: @escaping (Grade) -> Grade) -> Self {
+        var result = self
+        result.applyFunction(function)
+        return result
+    }
 }
 
 // MARK: - Mutability
diff --git a/Sources/FuzzySets/Implementations/IterableFuzzySet.swift b/Sources/FuzzySets/Implementations/IterableFuzzySet.swift
index 46aeebb..ebc84ac 100644
--- a/Sources/FuzzySets/Implementations/IterableFuzzySet.swift
+++ b/Sources/FuzzySets/Implementations/IterableFuzzySet.swift
@@ -91,6 +91,12 @@ extension IterableFuzzySet: FuzzySetOperations {
             Double.pow(function($0), n)
         }
     }
+    
+    public func appliedCustomFunction(_ function: @escaping (Grade) -> Grade) -> IterableFuzzySet<Universe, S> {
+        .init(sequence) {
+            function(self.function($0))
+        }
+    }
 }
 
 // MARK: - Sequence