Added ANTLR grammar

Author: Bernardo-MG

grammar/DiceNotation.g4

@@ -0,0 +1,62 @@
+/**
+ * Copyright 2014-2019 the original author or authors
+ * 
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy of
+ * the License at
+ * 
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under
+ * the License.
+ */
+
+/** 
+ * Dice notation grammar.
+ * 
+ * This is the notation which RPGs and other tabletop games use to represent operations with dice.
+ */
+grammar DiceNotation;
+
+options { tokenVocab=DiceNotationLexer; }
+
+/**
+ * Rules.
+ */
+ 
+notation
+:
+   dice
+   | number
+   | addOp
+;
+
+addOp
+:
+   multOp (ADDOPERATOR multOp)*
+;
+
+multOp
+:
+   operand (MULTOPERATOR operand)*
+;
+
+operand
+:
+   dice
+   | number
+   | LPAREN notation RPAREN
+;
+
+dice
+:
+   ADDOPERATOR? DIGIT? DSEPARATOR DIGIT
+;
+
+number
+:
+   ADDOPERATOR? DIGIT
+;

grammar/DiceNotationLexer.g4

@@ -0,0 +1,84 @@
+/**
+ * Copyright 2014-2019 the original author or authors
+ * 
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy of
+ * the License at
+ * 
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under
+ * the License.
+ */
+
+/** 
+ * Dice notation lexical rules.
+ */
+lexer grammar DiceNotationLexer;
+
+/**
+ * Tokens.
+ */
+
+// Dice markers
+
+DSEPARATOR
+:
+   ( 'd' | 'D' )
+;
+
+DIGIT
+:
+   ('0'..'9')+
+;
+
+// Operation tokens
+
+ADDOPERATOR
+:
+   ( ADD | SUB )
+;
+
+MULTOPERATOR
+:
+   ( MULT | DIV )
+;
+
+fragment ADD
+:
+   '+'
+;
+
+fragment SUB
+:
+   '-'
+;
+
+fragment MULT
+:
+   '*'
+;
+
+fragment DIV
+:
+   '/'
+;
+
+LPAREN
+:
+   '('
+;
+
+RPAREN
+:
+   ')'
+;
+
+// Skippable tokens
+
+WS:
+   [\t\r\n]+ -> skip
+;