Improve properties file lexer

lexers/embedded/properties.xml

@@ -7,21 +7,39 @@
   </config>
   <rules>
     <state name="root">
-      <rule pattern="\s+">
-        <token type="Text"/>
-      </rule>
-      <rule pattern="^[;#!].*">
-        <token type="CommentSingle"/>
+      <rule pattern="^([ \t\f]*)([#!].*)">
+        <bygroups>
+          <token type="Text"/>
+          <token type="CommentSingle"/>
+        </bygroups>
       </rule>
-      <rule pattern="^(.+?)([ \t]*)([=:])([ \t]*)(.*)">
+      <rule pattern="^([ \t\f]*)(\S+?)([ \t\f]*)([=:])([ \t\f]*)(.*(?:(?&lt;=\\)\n.*)*)">
         <bygroups>
+          <token type="Text"/>
           <token type="NameAttribute"/>
           <token type="Text"/>
           <token type="Operator"/>
           <token type="Text"/>
           <token type="LiteralString"/>
         </bygroups>
       </rule>
+      <rule pattern="^([ \t\f]*)(\S+)([ \t\f]+)(.*(?:(?&lt;=\\)\n.*)*)">
+        <bygroups>
+          <token type="Text"/>
+          <token type="NameAttribute"/>
+          <token type="Text"/>
+          <token type="LiteralString"/>
+        </bygroups>
+      </rule>
+      <rule pattern="^([ \t\f]*)(\w+)$">
+        <bygroups>
+          <token type="Text"/>
+          <token type="NameAttribute"/>
+        </bygroups>
+      </rule>
+       <rule pattern="\n">
+        <token type="Text"/>
+      </rule>
     </state>
   </rules>
-</lexer>
+</lexer>

lexers/testdata/properties.actual

@@ -8,10 +8,19 @@ language : English
 # This means that the following are equivalent (other than for readability).
 hello=hello
 hello = hello
+topic .properties files
+# A word on a line will just create a key with no value.
+empty
 # Keys with the same name will be overwritten by the key that is the furthest in a file.
 # For example the final value for "duplicateKey" will be "second".
 duplicateKey = first
 duplicateKey = second
+# Adding a \ at the end of a line means that the value continues to the next line.
+towLines = This line \
+           continues
+threeLines: This value \
+            has even \
+            three lines
 # If you need to add newlines and carriage returns, they need to be escaped using \n and \r respectively.
 # You can also optionally escape tabs with \t for readability purposes.
 valueWithEscapes = This is a newline\n and a carriage return\r and a tab\t.
@@ -20,3 +29,7 @@ valueWithEscapes = This is a newline\n and a carriage return\r and a tab\t.
 encodedHelloInJapanese = \u3053\u3093\u306b\u3061\u306f
 # But with more modern file encodings like UTF-8, you can directly use supported characters.
 helloInJapanese = こんにちは
+  # Comments and keys can have leading whitespace
+  foo = I have leading whitespace
+# Comments and keys can have trailing whitespace as part of the comment   
+bar = I have trailing whitespace as part of the value  

lexers/testdata/properties.expected

@@ -33,6 +33,14 @@
   {"type":"Text","value":" "},
   {"type":"LiteralString","value":"hello"},
   {"type":"Text","value":"\n"},
+  {"type":"NameAttribute","value":"topic"},
+  {"type":"Text","value":" "},
+  {"type":"LiteralString","value":".properties files"},
+  {"type":"Text","value":"\n"},
+  {"type":"CommentSingle","value":"# A word on a line will just create a key with no value."},
+  {"type":"Text","value":"\n"},
+  {"type":"NameAttribute","value":"empty"},
+  {"type":"Text","value":"\n"},
   {"type":"CommentSingle","value":"# Keys with the same name will be overwritten by the key that is the furthest in a file."},
   {"type":"Text","value":"\n"},
   {"type":"CommentSingle","value":"# For example the final value for \"duplicateKey\" will be \"second\"."},
@@ -49,6 +57,19 @@
   {"type":"Text","value":" "},
   {"type":"LiteralString","value":"second"},
   {"type":"Text","value":"\n"},
+  {"type":"CommentSingle","value":"# Adding a \\ at the end of a line means that the value continues to the next line."},
+  {"type":"Text","value":"\n"},
+  {"type":"NameAttribute","value":"towLines"},
+  {"type":"Text","value":" "},
+  {"type":"Operator","value":"="},
+  {"type":"Text","value":" "},
+  {"type":"LiteralString","value":"This line \\\n           continues"},
+  {"type":"Text","value":"\n"},
+  {"type":"NameAttribute","value":"threeLines"},
+  {"type":"Operator","value":":"},
+  {"type":"Text","value":" "},
+  {"type":"LiteralString","value":"This value \\\n            has even \\\n            three lines"},
+  {"type":"Text","value":"\n"},
   {"type":"CommentSingle","value":"# If you need to add newlines and carriage returns, they need to be escaped using \\n and \\r respectively."},
   {"type":"Text","value":"\n"},
   {"type":"CommentSingle","value":"# You can also optionally escape tabs with \\t for readability purposes."},
@@ -76,5 +97,21 @@
   {"type":"Operator","value":"="},
   {"type":"Text","value":" "},
   {"type":"LiteralString","value":"こんにちは"},
+  {"type":"Text","value":"\n  "},
+  {"type":"CommentSingle","value":"# Comments and keys can have leading whitespace"},
+  {"type":"Text","value":"\n  "},
+  {"type":"NameAttribute","value":"foo"},
+  {"type":"Text","value":" "},
+  {"type":"Operator","value":"="},
+  {"type":"Text","value":" "},
+  {"type":"LiteralString","value":"I have leading whitespace"},
+  {"type":"Text","value":"\n"},
+  {"type":"CommentSingle","value":"# Comments and keys can have trailing whitespace as part of the comment   "},
+  {"type":"Text","value":"\n"},
+  {"type":"NameAttribute","value":"bar"},
+  {"type":"Text","value":" "},
+  {"type":"Operator","value":"="},
+  {"type":"Text","value":" "},
+  {"type":"LiteralString","value":"I have trailing whitespace as part of the value  "},
   {"type":"Text","value":"\n"}
 ]