feat: setting value may be null/empty

Based on https://stackoverflow.com/a/9491779/152142 it seems like
a empty/null value is allowed.

close #9

Author: justinmk

README.md

@@ -1,37 +1,45 @@
 tree-sitter-ini
 ==================
 
-This grammar implements the INI format.
+This grammar implements the [INI format](https://en.wikipedia.org/wiki/INI_file).
 
 Overview
 --------
 
 Example INI file:
 
-    [section name]
-    some_key = some_value
-    another-key = another value
+```ini
+[section name]
+some_key = some_value
+# a comment
+another-key=another value
 
-    [another section]
-    # a comment
-    some_key = some_value
-    another-key = another value
+[another section]
+# Keys may contain whitespace.
+key 1 =
+# Value may be empty.
+key 2 =
+```
 
 See [test/corpus/](./test/corpus/) for more examples.
 
-### Notes
+Notes
+-----
 
-- Comments must start at column 1. Trailing comments are not supported. (Should they be?)
-
-Known issues
-------------
-
-- `setting_value` [includes whitespace](https://github.com/justinmk/tree-sitter-ini/issues/3).
+- Comments (`;` or `#`) must start at column 1. Trailing comments are not supported yet. [#13](https://github.com/justinmk/tree-sitter-ini/issues/13)
+- Equals sign (=) and semicolon (;) are reserved characters and cannot appear in the key. Any whitespace surrounding the key is stripped by the parser. [ref](https://en.wikipedia.org/wiki/INI_file#Key-value_pairs)
+- Section name must appear on a line by itself.
+- Duplicate names are not checked.
+- Line continuations (`\`) are not supported.
+- `setting_value` includes whitespace. [#3](https://github.com/justinmk/tree-sitter-ini/issues/3).
   Should values exclude surrounding whitespace?
+- [Quoted keys/values](https://en.wikipedia.org/wiki/INI_file#Quoted_values) are not supported yet.
+- Escape sequences are not supported.
 
 Reference
 ---------
 
+- https://en.wikipedia.org/wiki/INI_file
 - https://github.com/textmate/ini.tmbundle
 
 Release

grammar.js

@@ -34,7 +34,7 @@ module.exports = grammar({
     setting: $ => seq(
       alias(/[^;#=\s\[]+( *[^;#=\s\[])*/, $.setting_name),
       '=',
-      alias(/.+/, $.setting_value),
+      optional(alias(/.+/, $.setting_value)),
       /\r?\n/,
     ),
 

test/corpus/main.txt

@@ -15,6 +15,44 @@ foo = bar
       (setting_name)
       (setting_value))))
 
+================================================================================
+setting value may be null/empty #9
+================================================================================
+
+[section 1]
+setting 1 =
+setting 2 = x
+setting 3 =
+# comment
+setting 4 = y
+setting-5 =
+
+[section 2]
+
+--------------------------------------------------------------------------------
+
+(document
+  (section
+    (section_name
+      (text))
+    (setting
+      (setting_name))
+    (setting
+      (setting_name)
+      (setting_value))
+    (setting
+      (setting_name))
+    (comment
+      (text))
+    (setting
+      (setting_name)
+      (setting_value))
+    (setting
+      (setting_name)))
+  (section
+    (section_name
+      (text))))
+
 ================================================================================
 weird key names
 ================================================================================