From 482d93619680eb9ea191071041160f4d6d0aae62 Mon Sep 17 00:00:00 2001
From: iska <iska.gp@gmail.com>
Date: Thu, 10 May 2018 23:11:32 +0200
Subject: [PATCH] Add HTML-escaping category method for NSString

Escapes HTML as described in:
https://html.spec.whatwg.org/multipage/parsing.html#escapingString
---
 Sources/NSString+HTMLKit.m                   | 11 +++++++++++
 Sources/include/NSString+HTMLKit.h           |  7 +++++++
 Tests/HTMLKitTests/HTMLStringCategoryTests.m | 17 +++++++++++++++++
 3 files changed, 35 insertions(+)

diff --git a/Sources/NSString+HTMLKit.m b/Sources/NSString+HTMLKit.m
index 2d37ac4..c65bc8f 100644
--- a/Sources/NSString+HTMLKit.m
+++ b/Sources/NSString+HTMLKit.m
@@ -58,4 +58,15 @@ NS_INLINE BOOL isHtmlWhitespaceChar(unichar c)
 	return idx;
 }
 
+- (NSString *)stringByEscapingForHTML
+{
+	NSMutableString *escaped = [self mutableCopy];
+	[escaped replaceOccurrencesOfString:@"&" withString:@"&amp;" options:0 range:NSMakeRange(0, escaped.length)];
+	[escaped replaceOccurrencesOfString:@"0x00A0" withString:@"&nbsp;" options:0 range:NSMakeRange(0, escaped.length)];
+	[escaped replaceOccurrencesOfString:@"\"" withString:@"&quot;" options:0 range:NSMakeRange(0, escaped.length)];
+	[escaped replaceOccurrencesOfString:@"<" withString:@"&lt;" options:0 range:NSMakeRange(0, escaped.length)];
+	[escaped replaceOccurrencesOfString:@">" withString:@"&gt;" options:0 range:NSMakeRange(0, escaped.length)];
+	return escaped;
+}
+
 @end
diff --git a/Sources/include/NSString+HTMLKit.h b/Sources/include/NSString+HTMLKit.h
index b73d0ad..cd532d2 100644
--- a/Sources/include/NSString+HTMLKit.h
+++ b/Sources/include/NSString+HTMLKit.h
@@ -48,6 +48,13 @@ NS_ASSUME_NONNULL_BEGIN
  */
 - (NSUInteger)leadingHTMLWhitespaceLength;
 
+/**
+Escapes this string as specified in `https://html.spec.whatwg.org/multipage/parsing.html#escapingString`
+
+ @return A copy of this string by HTML-escaping this stirng.
+ */
+- (NSString *)stringByEscapingForHTML;
+
 @end
 
 NS_ASSUME_NONNULL_END
diff --git a/Tests/HTMLKitTests/HTMLStringCategoryTests.m b/Tests/HTMLKitTests/HTMLStringCategoryTests.m
index b5d5571..c66e422 100644
--- a/Tests/HTMLKitTests/HTMLStringCategoryTests.m
+++ b/Tests/HTMLKitTests/HTMLStringCategoryTests.m
@@ -8,6 +8,7 @@
 
 #import <XCTest/XCTest.h>
 #import "NSString+HTMLKit.h"
+#import "HTMLDOM.h"
 
 @interface HTMLKitStringCategoryTests : XCTestCase
 
@@ -79,4 +80,20 @@
 	XCTAssertEqual([@"\t\r\n\f\0 " leadingHTMLWhitespaceLength], 4);
 }
 
+- (void)testStringByEscapingForHTML
+{
+	XCTAssertEqualObjects(@"".stringByEscapingForHTML, @"");
+	XCTAssertEqualObjects(@"&".stringByEscapingForHTML, @"&amp;");
+	XCTAssertEqualObjects(@"0x00A0".stringByEscapingForHTML, @"&nbsp;");
+	XCTAssertEqualObjects(@"\"".stringByEscapingForHTML, @"&quot;");
+	XCTAssertEqualObjects(@"<".stringByEscapingForHTML, @"&lt;");
+	XCTAssertEqualObjects(@">".stringByEscapingForHTML, @"&gt;");
+	XCTAssertEqualObjects(@"&0x00A0\"<>".stringByEscapingForHTML, @"&amp;&nbsp;&quot;&lt;&gt;");
+
+	NSString *input = @"This is an <b>email</b>: John Do <john@do.com>";
+	NSString *escaped = input.stringByEscapingForHTML;
+	XCTAssertNotEqual(input, escaped);
+	XCTAssertEqualObjects(escaped, @"This is an &lt;b&gt;email&lt;/b&gt;: John Do &lt;john@do.com&gt;");
+}
+
 @end