Initial commit; substitutions can be reviewed, no further functionality implemented yet

Pods/SwiftSoup/Sources/Collector.swift

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+//
+//  Collector.swift
+//  SwiftSoup
+//
+//  Created by Nabil Chatbi on 22/10/16.
+//  Copyright © 2016 Nabil Chatbi.. All rights reserved.
+//
+
+import Foundation
+
+/**
+ * Collects a list of elements that match the supplied criteria.
+ *
+ */
+open class Collector {
+
+    private init() {
+    }
+
+    /**
+     Build a list of elements, by visiting root and every descendant of root, and testing it against the evaluator.
+     @param eval Evaluator to test elements against
+     @param root root of tree to descend
+     @return list of matches; empty if none
+     */
+    public static func collect (_ eval: Evaluator, _ root: Element)throws->Elements {
+        let elements: Elements = Elements()
+        try NodeTraversor(Accumulator(root, elements, eval)).traverse(root)
+        return elements
+    }
+
+}
+
+private final class Accumulator: NodeVisitor {
+    private let root: Element
+    private let elements: Elements
+    private let eval: Evaluator
+
+    init(_ root: Element, _ elements: Elements, _ eval: Evaluator) {
+        self.root = root
+        self.elements = elements
+        self.eval = eval
+    }
+
+    public func head(_ node: Node, _ depth: Int) {
+        guard let el = node as? Element else {
+            return
+        }
+        do {
+            if try eval.matches(root, el) {
+                elements.add(el)
+            }
+        } catch {}
+    }
+
+    public func tail(_ node: Node, _ depth: Int) {
+        // void
+    }
+}