From db069ad311cd831a709d8f1598ada81b10d6e635 Mon Sep 17 00:00:00 2001
From: Albert Zhang <albertzhang66@gmail.com>
Date: Sat, 28 Jul 2018 20:27:48 -0500
Subject: [PATCH] Add regex to filter out premature line breaks

This prevents text alignment issues, most visible on iPads, as in #41
---
 Source/AcknowParser.swift | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/Source/AcknowParser.swift b/Source/AcknowParser.swift
index e43edca..0970f85 100644
--- a/Source/AcknowParser.swift
+++ b/Source/AcknowParser.swift
@@ -91,7 +91,24 @@ open class AcknowParser {
                 (preferenceSpecifier: AnyObject) -> Acknow in
                 if let title = preferenceSpecifier["Title"] as! String?,
                     let text = preferenceSpecifier["FooterText"] as! String? {
-                        return Acknow(title: title, text: text, license: preferenceSpecifier["License"] as? String)
+
+                        // This regex replaces single newlines with spaces, while preserving multiple newlines used for formatting.
+                        // This prevents issues such as https://github.com/vtourraine/AcknowList/issues/41
+                        //
+                        // The issue arises when licenses contain premature line breaks in the middle of a sentance, often used
+                        // to limit license texts to 80 characters. When applied on an iPad, the resulting licenses are misaligned.
+                        //
+                        // The expression (?<=.)(\h)*(\R)(\h)*(?=.) can be broken down as:
+                        //
+                        //    (?<=.)  Positive lookbehind matching any non-newline character (matches but does not capture)
+                        //    (\h)*   Matches and captures zero or more horizontal spaces (trailing newlines)
+                        //    (\R)    Matches and captures any single Unicode-compliant newline character
+                        //    (\h)*   Matches and captures zero or more horizontal spaces (leading newlines)
+                        //    (?=.)   Positive lookahead matching any non-newline character (matches but does not capture)
+                        let singleNewLineFinder = try! NSRegularExpression(pattern: "(?<=.)(\\h)*(\\R)(\\h)*(?=.)")
+                        let textWithoutNewlines = singleNewLineFinder.stringByReplacingMatches(in: text, range: NSRange(0..<text.count), withTemplate: " ")
+
+                        return Acknow(title: title, text: textWithoutNewlines, license: preferenceSpecifier["License"] as? String)
                 }
                 else {
                     return Acknow(title: "", text: "", license: nil)