Improve Ctrl key labels for Serbian Cyrillic layout

Add the ':char' syntax for defining character keys with a different
symbol.
This new kind of keys is used to implement Ctrl combinations in the
Serbian Cyrillic layout without showing latin letters while the Ctrl
modifier is activated.

doc/Possible-key-values.md

@@ -161,8 +161,8 @@ Where `<kind>` is one of the kinds documented below and `<attributes>` is a
 space separated list of attributes. `<payload>` depends on the `<kind>`.
 
 Attributes are:
-- `symbol='Sym'` is the symbol to be shown on the keyboard.
-- `flags='<flags>'` is a collection of flags that change the behavior of the key.
+- `symbol='Sym'` specifies the symbol to be shown on the keyboard.
+- `flags='<flags>'` changes the behavior of the key.
   `<flags>` is a coma separated list of:
   + `dim`: Make the symbol dimmer.
   + `small`: Make the symbol smaller.
@@ -172,4 +172,18 @@ Attributes are:
 Defines a key that outputs an arbitrary string. `<payload>` is a string wrapped
 in single-quotes (`'`), escaping of other single quotes is allowed with `\'`.
 
-For example: `:str symbol='Sym':'Output string'`
+For example:
+- `:str:'Arbitrary string with a \' inside'`
+- `:str symbol='Symbol':'Output string'`
+
+### Kind `char`
+
+Defines a key that outputs a single character. `<payload>` is the character to
+output, unquoted.
+This kind of key can be used to define a character key with a different symbol
+on it. `char` keys can be modified by `ctrl` and other modifiers, unlike `str`
+keys.
+
+For example:
+- `:char symbol='q':љ`, which is used to implement `ctrl` shortcuts in cyrillic
+  layouts.

srcs/juloo.keyboard2/KeyValue.java

@@ -393,7 +393,14 @@ public final class KeyValue implements Comparable<KeyValue>
 
   public static KeyValue makeCharKey(char c)
   {
-    return new KeyValue(String.valueOf(c), Kind.Char, c, 0);
+    return makeCharKey(c, null, 0);
+  }
+
+  public static KeyValue makeCharKey(char c, String symbol, int flags)
+  {
+    if (symbol == null)
+      symbol = String.valueOf(c);
+    return new KeyValue(symbol, Kind.Char, c, flags);
   }
 
   public static KeyValue makeComposePending(String symbol, int state, int flags)

srcs/juloo.keyboard2/KeyValueParser.java

@@ -9,21 +9,7 @@ Parse a key definition. The syntax for a key definition is:
 - If [str] doesn't start with a [:] character, it is interpreted as an
   arbitrary string key.
 
-[(kind)] specifies the kind of the key, it can be:
-- [str]: An arbitrary string key. The payload is the string to output when
-  typed and is quoted by single quotes ([']). The payload can contain single
-  quotes if they are escaped with a backslash ([\']).
-
-The [(attributes)] part is a space-separated list of attributes, all optional,
-of the form: [attrname='attrvalue'].
-
-Attributes can be:
-- [flags]: Add flags that change the behavior of the key.
-  Value is a coma separated list of:
-  - [dim]: Make the symbol dimmer on the keyboard.
-  - [small]: Make the symbol smaller on the keyboard.
-- [symbol]: Specify the symbol that is rendered on the keyboard.
-  It can contain single quotes if they are escaped: ([\']).
+For the different kinds and attributes, see doc/Possible-key-values.md.
 
 Examples:
 - [:str flags=dim,small symbol='MyKey':'My arbitrary string'].
@@ -36,6 +22,7 @@ public final class KeyValueParser
   static Pattern ATTR_PAT;
   static Pattern QUOTED_PAT;
   static Pattern PAYLOAD_START_PAT;
+  static Pattern SINGLE_CHAR_PAT;
 
   static public KeyValue parse(String str) throws ParseError
   {
@@ -73,11 +60,14 @@ public final class KeyValueParser
     switch (kind)
     {
       case "str":
-        String payload = parseSingleQuotedString(m);
+        String str_payload = parseSingleQuotedString(m);
         if (symbol == null)
-          return KeyValue.makeStringKey(payload, flags);
-        return KeyValue.makeStringKeyWithSymbol(payload, symbol, flags);
+          return KeyValue.makeStringKey(str_payload, flags);
+        return KeyValue.makeStringKeyWithSymbol(str_payload, symbol, flags);
 
+      case "char":
+        char char_payload = parseOneChar(m);
+        return KeyValue.makeCharKey(char_payload, symbol, flags);
       default: break;
     }
     parseError("Unknown kind '"+kind+"'", m, 1);
@@ -91,6 +81,13 @@ public final class KeyValueParser
     return m.group(1).replace("\\'", "'");
   }
 
+  static char parseOneChar(Matcher m) throws ParseError
+  {
+    if (!match(m, SINGLE_CHAR_PAT))
+      parseError("Expected a character", m);
+    return m.group(0).charAt(0);
+  }
+
   static int parseFlags(String s, Matcher m) throws ParseError
   {
     int flags = 0;
@@ -121,6 +118,7 @@ public final class KeyValueParser
     ATTR_PAT = Pattern.compile("\\s*(\\w+)\\s*=");
     QUOTED_PAT = Pattern.compile("'(([^'\\\\]+|\\\\')*)'");
     PAYLOAD_START_PAT = Pattern.compile("\\s*:");
+    SINGLE_CHAR_PAT = Pattern.compile(".");
   }
 
   static void parseError(String msg, Matcher m) throws ParseError

srcs/layouts/cyrl_lynyertz_sr.xml

@@ -8,32 +8,32 @@
     <fn a="у" b="у̂" />
     <fn a="cursor_left" b="home" />
     <fn a="cursor_right" b="end" />
-    <ctrl a="љ" b="q" />
-    <ctrl a="њ" b="w" />
-    <ctrl a="е" b="e" />
-    <ctrl a="р" b="r" />
-    <ctrl a="т" b="t" />
-    <ctrl a="ж" b="y" />
-    <ctrl a="у" b="u" />
-    <ctrl a="и" b="i" />
-    <ctrl a="о" b="o" />
-    <ctrl a="п" b="p" />
-    <ctrl a="а" b="a" />
-    <ctrl a="с" b="s" />
-    <ctrl a="д" b="d" />
-    <ctrl a="ф" b="f" />
-    <ctrl a="г" b="g" />
-    <ctrl a="х" b="h" />
-    <ctrl a="ј" b="j" />
-    <ctrl a="к" b="k" />
-    <ctrl a="л" b="l" />
-    <ctrl a="з" b="z" />
-    <ctrl a="џ" b="x" />
-    <ctrl a="ц" b="c" />
-    <ctrl a="в" b="v" />
-    <ctrl a="б" b="b" />
-    <ctrl a="н" b="n" />
-    <ctrl a="м" b="m" />
+    <ctrl a="љ" b=":char symbol='љ':q" />
+    <ctrl a="њ" b=":char symbol='њ':w" />
+    <ctrl a="е" b=":char symbol='е':e" />
+    <ctrl a="р" b=":char symbol='р':r" />
+    <ctrl a="т" b=":char symbol='т':t" />
+    <ctrl a="ж" b=":char symbol='ж':y" />
+    <ctrl a="у" b=":char symbol='у':u" />
+    <ctrl a="и" b=":char symbol='и':i" />
+    <ctrl a="о" b=":char symbol='о':o" />
+    <ctrl a="п" b=":char symbol='п':p" />
+    <ctrl a="а" b=":char symbol='а':a" />
+    <ctrl a="с" b=":char symbol='с':s" />
+    <ctrl a="д" b=":char symbol='д':d" />
+    <ctrl a="ф" b=":char symbol='ф':f" />
+    <ctrl a="г" b=":char symbol='г':g" />
+    <ctrl a="х" b=":char symbol='х':h" />
+    <ctrl a="ј" b=":char symbol='ј':j" />
+    <ctrl a="к" b=":char symbol='к':k" />
+    <ctrl a="л" b=":char symbol='л':l" />
+    <ctrl a="з" b=":char symbol='з':z" />
+    <ctrl a="џ" b=":char symbol='џ':x" />
+    <ctrl a="ц" b=":char symbol='ц':c" />
+    <ctrl a="в" b=":char symbol='в':v" />
+    <ctrl a="б" b=":char symbol='б':b" />
+    <ctrl a="н" b=":char symbol='н':n" />
+    <ctrl a="м" b=":char symbol='м':m" />
   </modmap>
   <row>
     <key key0="љ" ne="1" se="loc esc"/>

test/juloo.keyboard2/KeyValueParserTest.java

@@ -10,7 +10,7 @@ public class KeyValueParserTest
   public KeyValueParserTest() {}
 
   @Test
-  public void parse() throws Exception
+  public void parseStr() throws Exception
   {
     Utils.parse(":str:'Foo'", KeyValue.makeStringKey("Foo"));
     Utils.parse(":str flags='dim':'Foo'", KeyValue.makeStringKey("Foo", KeyValue.FLAG_SECONDARY));
@@ -34,6 +34,13 @@ public class KeyValueParserTest
     Utils.expect_error(":str flags='':'");
   }
 
+  @Test
+  public void parseChar() throws Exception
+  {
+    Utils.parse(":char symbol='a':b", KeyValue.makeCharKey('b', "a", 0));
+    Utils.parse(":char:b", KeyValue.makeCharKey('b', "b", 0));
+  }
+
   /** JUnit removes these functions from stacktraces. */
   static class Utils
   {