Add project files

examples/split/CalcParser.g4

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+parser grammar CalcParser;
+
+options { tokenVocab = CalcLexer; }
+
+program   : statement* EOF ;
+
+statement : IDENT ASSIGN expression SEMI ;
+
+expression
+    : expression (STAR | SLASH) expression
+    | expression (PLUS | MINUS) expression
+    | LPAREN expression RPAREN
+    | NUMBER
+    | IDENT
+    ;