add CString based search matcher

Author: DivineDominion

SearchExpressionParser/Parsing/Expressions.swift

@@ -1,40 +1,67 @@
 //  Copyright © 2018 Christian Tietze. All rights reserved. Distributed under the MIT License.
 
-public protocol ExpressionSatisfiable {
+/// Literal string matching.
+public protocol StringExpressionSatisfiable {
     func contains(phrase: String) -> Bool
 }
 
-extension String: ExpressionSatisfiable {
+/// The fastest search on earch is `strstr(haystack, needle)` with lowercased string.
+/// This provides the needle as UTF-8, lowercased, precomposed string with canonical mapping.
+public protocol CStringExpressionSatisfiable {
+    func matches(needle: ContainsNode.CString) -> Bool
+}
+
+extension String: StringExpressionSatisfiable {
     public func contains(phrase: String) -> Bool {
         return self.contains(phrase)
     }
 }
 
 public protocol Expression {
-    func isSatisfied(by satisfiable: ExpressionSatisfiable) -> Bool
+    func isSatisfied(by satisfiable: StringExpressionSatisfiable) -> Bool
+    func isSatisfied(by satisfiable: CStringExpressionSatisfiable) -> Bool
 }
 
 /// Wildcard that is satisfied by any string.
 public struct AnythingNode: Expression {
-    public func isSatisfied(by satisfiable: ExpressionSatisfiable) -> Bool {
+    public func isSatisfied(by satisfiable: StringExpressionSatisfiable) -> Bool {
+        return true
+    }
+
+    public func isSatisfied(by satisfiable: CStringExpressionSatisfiable) -> Bool {
         return true
     }
 }
 
 public struct ContainsNode: Expression {
+    public typealias CString = [CChar]
     public let string: String
+    public let cString: CString
+
+    public static var cStringFactory: (String) -> CString = ContainsNode.cString(string:)
+
+    public static func cString(string: String) -> CString {
+        return string.precomposedStringWithCanonicalMapping
+            .lowercased()
+            .cString(using: .utf8) ?? []
+    }
 
     public init(_ string: String) {
         self.string = string
+        self.cString = ContainsNode.cStringFactory(string)
     }
 
     public init(token: Token) {
         self.init(token.string)
     }
 
-    public func isSatisfied(by satisfiable: ExpressionSatisfiable) -> Bool {
+    public func isSatisfied(by satisfiable: StringExpressionSatisfiable) -> Bool {
         return satisfiable.contains(phrase: string)
     }
+
+    public func isSatisfied(by satisfiable: CStringExpressionSatisfiable) -> Bool {
+        return satisfiable.matches(needle: cString)
+    }
 }
 
 public struct NotNode: Expression {
@@ -44,7 +71,11 @@ public struct NotNode: Expression {
         self.expression = expression
     }
 
-    public func isSatisfied(by satisfiable: ExpressionSatisfiable) -> Bool {
+    public func isSatisfied(by satisfiable: StringExpressionSatisfiable) -> Bool {
+        return !expression.isSatisfied(by: satisfiable)
+    }
+
+    public func isSatisfied(by satisfiable: CStringExpressionSatisfiable) -> Bool {
         return !expression.isSatisfied(by: satisfiable)
     }
 }
@@ -58,7 +89,11 @@ public struct AndNode: Expression {
         self.rhs = rhs
     }
 
-    public func isSatisfied(by satisfiable: ExpressionSatisfiable) -> Bool {
+    public func isSatisfied(by satisfiable: StringExpressionSatisfiable) -> Bool {
+        return lhs.isSatisfied(by: satisfiable) && rhs.isSatisfied(by: satisfiable)
+    }
+
+    public func isSatisfied(by satisfiable: CStringExpressionSatisfiable) -> Bool {
         return lhs.isSatisfied(by: satisfiable) && rhs.isSatisfied(by: satisfiable)
     }
 }
@@ -72,7 +107,11 @@ public struct OrNode: Expression {
         self.rhs = rhs
     }
 
-    public func isSatisfied(by satisfiable: ExpressionSatisfiable) -> Bool {
+    public func isSatisfied(by satisfiable: StringExpressionSatisfiable) -> Bool {
+        return lhs.isSatisfied(by: satisfiable) || rhs.isSatisfied(by: satisfiable)
+    }
+
+    public func isSatisfied(by satisfiable: CStringExpressionSatisfiable) -> Bool {
         return lhs.isSatisfied(by: satisfiable) || rhs.isSatisfied(by: satisfiable)
     }
 }

SearchExpressionParserTests/ExpressionTests.swift

@@ -5,7 +5,7 @@ import XCTest
 
 class ExpressionTests: XCTestCase {
 
-    var irrelevant: ExpressionSatisfiable {
+    var irrelevant: StringExpressionSatisfiable {
         return "irrelevant"
     }
 
@@ -52,13 +52,21 @@ class ExpressionTests: XCTestCase {
 }
 
 struct FalsyNode: Expression {
-    func isSatisfied(by satisfiable: ExpressionSatisfiable) -> Bool {
+    func isSatisfied(by satisfiable: StringExpressionSatisfiable) -> Bool {
+        return false
+    }
+
+    func isSatisfied(by satisfiable: CStringExpressionSatisfiable) -> Bool {
         return false
     }
 }
 
 struct TruthyNode: Expression {
-    func isSatisfied(by satisfiable: ExpressionSatisfiable) -> Bool {
+    func isSatisfied(by satisfiable: StringExpressionSatisfiable) -> Bool {
+        return true
+    }
+
+    func isSatisfied(by satisfiable: CStringExpressionSatisfiable) -> Bool {
         return true
     }
 }