Fix ASCII/UTF-8 error. (#38)

* Add reproducible test for UTF-8/ASCII error.

* Change encoding according to `xml` tag.

* Add changelog entry.

* Add helper method to parse XML encoding.

CHANGELOG.rdoc

@@ -5,6 +5,7 @@
 https://github.com/patsplat/plist/compare/dece870...HEAD
 
 * Your contribution here!
+* Fix ASCII/UTF-8 error (https://github.com/patsplat/plist/pull/38).
 * Fix Fixnum, Bignum deprecations in Ruby 2.4
 * Fix unused variable `e` warning
 

lib/plist/parser.rb

@@ -73,10 +73,10 @@ def initialize( plist_data_or_file, listener )
     end
 
     TEXT       = /([^<]+)/
-    XMLDECL_PATTERN = /<\?xml\s+(.*?)\?>*/um
-    DOCTYPE_PATTERN = /\s*<!DOCTYPE\s+(.*?)(\[|>)/um
-    COMMENT_START = /\A<!--/u
-    COMMENT_END = /.*?-->/um
+    XMLDECL_PATTERN = /<\?xml\s+(.*?)\?>*/m
+    DOCTYPE_PATTERN = /\s*<!DOCTYPE\s+(.*?)(\[|>)/m
+    COMMENT_START = /\A<!--/
+    COMMENT_END = /.*?-->/m
 
 
     def parse
@@ -91,7 +91,14 @@ def parse
         if @scanner.scan(COMMENT_START)
           @scanner.scan(COMMENT_END)
         elsif @scanner.scan(XMLDECL_PATTERN)
+          encoding = parse_encoding_from_xml_declaration(@scanner[1])
+          next if encoding.nil?
+
+          # use the specified encoding for the rest of the file
+          next unless String.method_defined?(:force_encoding)
+          @scanner.string = @scanner.rest.force_encoding(encoding)
         elsif @scanner.scan(DOCTYPE_PATTERN)
+          next
         elsif @scanner.scan(start_tag)
           @listener.tag_start(@scanner[1], nil)
           if (@scanner[2] =~ /\/$/)
@@ -106,6 +113,22 @@ def parse
         end
       end
     end
+
+    private
+
+    def parse_encoding_from_xml_declaration(xml_declaration)
+      return unless defined?(Encoding)
+
+      xml_encoding = xml_declaration.match(/(?:\A|\s)encoding=(?:"(.*?)"|'(.*?)')(?:\s|\Z)/)
+
+      return if xml_encoding.nil?
+
+      begin
+        Encoding.find(xml_encoding[1])
+      rescue ArgumentError
+        nil
+      end
+    end
   end
 
   class PTag

test/assets/non-ascii-but-utf-8.plist

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>non-ascii-but-utf8-character</key>
+	<string>™</string>
+</dict>
+</plist>

test/test_parser.rb

@@ -90,6 +90,16 @@ def test_filename_or_xml_is_stringio
     assert_nil data
   end
 
-end
+  def test_filename_or_xml_is_encoded_with_ascii_8bit
+    # skip if Ruby version does not support String#force_encoding
+    return unless String.method_defined?(:force_encoding)
+
+    xml = File.read("test/assets/non-ascii-but-utf-8.plist")
+    xml.force_encoding("ASCII-8BIT")
 
-__END__
+    assert_nothing_raised do
+      data = Plist::parse_xml(xml)
+      assert_equal("\u0099", data["non-ascii-but-utf8-character"])
+    end
+  end
+end