Add complex keys (#774)

This allows to add new kinds of keys that need more data without making
KeyValue's footprint bigger for common keys.

This changes the [_symbol] field into [_payload], which holds the same
as the previous field for more common keys but can hold bigger objects
for keys of the new "Complex" kind.

This also adds a complex key: String keys with a symbol different than
the outputted string.

Unit tests are added as the Java language is not helpful in making
robust code.

srcs/juloo.keyboard2/KeyValueParser.java

@@ -0,0 +1,150 @@
+package juloo.keyboard2;
+
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+/**
+Parse a key definition. The syntax for a key definition is:
+- [:(kind) (attributes):(payload)].
+- 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: ([\']).
+
+Examples:
+- [:str flags=dim,small symbol='MyKey':'My arbitrary string'].
+- [:str:'My arbitrary string'].
+
+*/
+public final class KeyValueParser
+{
+  static Pattern START_PAT;
+  static Pattern ATTR_PAT;
+  static Pattern QUOTED_PAT;
+  static Pattern PAYLOAD_START_PAT;
+
+  static public KeyValue parse(String str) throws ParseError
+  {
+    String symbol = null;
+    int flags = 0;
+    init();
+    // Kind
+    Matcher m = START_PAT.matcher(str);
+    if (!m.lookingAt())
+      parseError("Expected kind, for example \":str ...\".", m);
+    String kind = m.group(1);
+    // Attributes
+    while (true)
+    {
+      if (!match(m, ATTR_PAT))
+        break;
+      String attr_name = m.group(1);
+      String attr_value = parseSingleQuotedString(m);
+      switch (attr_name)
+      {
+        case "flags":
+          flags = parseFlags(attr_value, m);
+          break;
+        case "symbol":
+          symbol = attr_value;
+          break;
+
+        default:
+          parseError("Unknown attribute "+attr_name, m);
+      }
+    }
+    // Payload
+    if (!match(m, PAYLOAD_START_PAT))
+      parseError("Unexpected character", m);
+    switch (kind)
+    {
+      case "str":
+        String payload = parseSingleQuotedString(m);
+        if (symbol == null)
+          return KeyValue.makeStringKey(payload, flags);
+        return KeyValue.makeStringKeyWithSymbol(payload, symbol, flags);
+
+      default: break;
+    }
+    parseError("Unknown kind '"+kind+"'", m, 1);
+    return null; // Unreachable
+  }
+
+  static String parseSingleQuotedString(Matcher m) throws ParseError
+  {
+    if (!match(m, QUOTED_PAT))
+      parseError("Expected quoted string", m);
+    return m.group(1).replace("\\'", "'");
+  }
+
+  static int parseFlags(String s, Matcher m) throws ParseError
+  {
+    int flags = 0;
+    for (String f : s.split(","))
+    {
+      switch (f)
+      {
+        case "dim": flags |= KeyValue.FLAG_SECONDARY; break;
+        case "small": flags |= KeyValue.FLAG_SMALLER_FONT; break;
+        default: parseError("Unknown flag "+f, m);
+      }
+    }
+    return flags;
+  }
+
+  static boolean match(Matcher m, Pattern pat)
+  {
+    try { m.region(m.end(), m.regionEnd()); } catch (Exception _e) {}
+    m.usePattern(pat);
+    return m.lookingAt();
+  }
+
+  static void init()
+  {
+    if (START_PAT != null)
+      return;
+    START_PAT = Pattern.compile(":(\\w+)");
+    ATTR_PAT = Pattern.compile("\\s*(\\w+)\\s*=");
+    QUOTED_PAT = Pattern.compile("'(([^'\\\\]+|\\\\')*)'");
+    PAYLOAD_START_PAT = Pattern.compile("\\s*:");
+  }
+
+  static void parseError(String msg, Matcher m) throws ParseError
+  {
+    parseError(msg, m, m.regionStart());
+  }
+
+  static void parseError(String msg, Matcher m, int i) throws ParseError
+  {
+    StringBuilder msg_ = new StringBuilder("Syntax error");
+    try
+    {
+      char c = m.group(0).charAt(0);
+      msg_.append(" at character '").append(c).append("'");
+    } catch (IllegalStateException _e) {}
+    msg_.append(" at position ");
+    msg_.append(i);
+    msg_.append(": ");
+    msg_.append(msg);
+    throw new ParseError(msg_.toString());
+  }
+
+  public static class ParseError extends Exception
+  {
+    public ParseError(String msg) { super(msg); }
+  };
+}