Moved BindingGenerator from gen html project. It makes more sense here.

Sources/BindingGenerator/Internal/String+Escaping.swift

@@ -0,0 +1,171 @@
+/**
+*  Plot
+*  Copyright (c) John Sundell 2019
+*  MIT license, see LICENSE file for details
+*/
+
+import Foundation
+
+/// let someUrl:URL = try URL("hello") ?! AppError("What")
+infix operator ?!: NilCoalescingPrecedence
+
+public func ?!<T>(value: T?, error: @autoclosure () -> Error) throws -> T {
+    if let value = value { return value }
+    throw error()
+}
+
+
+internal extension String {
+    func asSubstring() -> Substring {
+        return self[self.startIndex..<self.endIndex]
+    }
+    func escaped() -> String {
+        var pendingAmpersandString: String?
+
+        func flushPendingAmpersandString(
+            withSuffix suffix: String? = nil,
+            resettingTo newValue: String? = nil
+        ) -> String {
+            let pending = pendingAmpersandString
+            pendingAmpersandString = newValue
+            return pending.map { "&amp;\($0)\(suffix ?? "")" } ?? suffix ?? ""
+        }
+
+        return String(flatMap { character -> String in
+            switch character {
+            case "<":
+                return flushPendingAmpersandString(withSuffix: "&lt;")
+            case ">":
+                return flushPendingAmpersandString(withSuffix: "&gt;")
+            case "&":
+                return flushPendingAmpersandString(resettingTo: "")
+            case ";":
+                let pending = pendingAmpersandString.map { "&\($0);" }
+                pendingAmpersandString = nil
+                return pending ?? ";"
+            case "#" where pendingAmpersandString?.isEmpty == true:
+                pendingAmpersandString = "#"
+                return ""
+            default:
+                if let pending = pendingAmpersandString {
+                    guard character.isLetter || character.isNumber else {
+                        return flushPendingAmpersandString(withSuffix: String(character))
+                    }
+
+                    pendingAmpersandString = "\(pending)\(character)"
+                    return ""
+                }
+
+                return "\(character)"
+            }
+        }) + flushPendingAmpersandString()
+    }
+    
+    static func parseList(_ value:String?, _ separator:String = " ") throws -> [String] {
+        guard let value = value else { return [] }
+        var iterator = value.componentsIterator(separatedBy: separator)
+        return iterator.map({String($0)})
+    }
+    
+}
+
+extension Array where Element: RawRepresentable, Element.RawValue == String {
+    /// Converts an array of String-backed enums to an array of their raw string values.
+    func toStringList(_ seperator:String) -> String {
+        let strList = self.map { $0.rawValue }
+        return strList.joined(separator: seperator)
+    }
+}
+
+extension Array where Element == String {
+    /// Converts an array of String-backed enums to an array of their raw string values.
+    func toStringList(_ seperator:String) -> String {
+        let strList = self.map { $0 }
+        return strList.joined(separator: seperator)
+    }
+}
+
+extension Array where Element == URL {
+    /// Converts an array of String-backed enums to an array of their raw string values.
+    func toStringList(_ seperator:String) -> String {
+        let strList = self.map { $0.absoluteString }
+        return strList.joined(separator: seperator)
+    }
+}
+
+extension Array where Element == Float {
+    /// Converts an array of String-backed enums to an array of their raw string values.
+    func toStringList(_ seperator:String) -> String {
+        let strList = self.map { String($0) }
+        return strList.joined(separator: seperator)
+    }
+}
+
+extension Set where Element: RawRepresentable, Element.RawValue == String {
+    /// Converts an array of String-backed enums to an array of their raw string values.
+    func toStringList(_ seperator:String) -> String {
+        let strList = self.map { $0.rawValue }
+        return strList.joined(separator: seperator)
+    }
+}
+
+extension Float {
+    static func parseList(_ value:String?, _ separator:String = " ") throws -> [Float] {
+        guard let value = value else { return [] }
+        var iterator = value.componentsIterator(separatedBy: separator)
+        return try iterator.map({ try Float.expect($0) })
+    }
+    
+    static func expect(_ value:String) throws -> Float {
+        if let result = Float(value) {
+            return result
+        }
+        throw AppError("Unable to map value to float")
+    }
+    
+    static func expect(_ value:Substring) throws -> Float {
+        if let result = Float(value) {
+            return result
+        }
+        throw AppError("Unable to map value to float")
+    }
+}
+
+extension URL {
+    static func parseList(_ value:String?, _ separator:String = " ") throws -> [URL] {
+        guard let value = value else { return [] }
+        var iterator = value.componentsIterator(separatedBy: separator)
+        return try iterator.map({
+            guard let result = URL(string:String($0)) else {
+                throw AppError("Invalid URL: \(String($0))")
+            }
+            return result
+        })
+    }
+}
+
+extension Bool {
+    public init(expect: String) throws {
+        if (expect == "true") {
+            self = true
+            return
+        }
+        if (expect == "false") {
+            self = false
+            return
+        }
+        throw AppError("Unexpected value for bool: \(expect)")
+    }
+    
+    public init(expectYesOrNo: String) throws {
+        if (expectYesOrNo == "yes") {
+            self = true
+            return
+        }
+        if (expectYesOrNo == "no") {
+            self = false
+            return
+        }
+        throw AppError("Unexpected value for bool: \(expectYesOrNo)")
+    }
+}