actually commit TP2

TP02/demo_files/ex3/Example3.g4

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+//define a tiny grammar with attributes for arith expressions with identifiers
+
+grammar Example3;
+
+full_expr: e0=expr ';' EOF {print($e0.text + " has " + str($e0.count) + " operators!")} ;
+
+expr returns [int count]:  // expr has an integer attribute called count
+    | e0=expr OP e1=expr {$count = $e0.count + $e1.count + 1}  // name sub-parts and access their attributes
+    | ID {$count = 0}
+    | INT {$count = 0}
+    ;
+
+OP : '+'| '*' | '-' | '/' ;
+
+
+INT : '0'..'9'+ ;
+ID : ('a'..'z'|'A'..'Z')+ ;
+WS : [ \t\r\n]+ -> skip ; // skip spaces, tabs, newlines

TP02/demo_files/ex3/Makefile

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+MAINFILE = main
+PACKAGE = Example3
+
+ifndef ANTLR4
+$(error variable ANTLR4 is not set)
+endif
+
+default: $(PACKAGE)Parser.py
+
+$(PACKAGE)Parser.py: $(PACKAGE).g4
+	$(ANTLR4) $^ -Dlanguage=Python3
+
+run: $(MAINFILE).py $(PACKAGE)Parser.py
+	python3 $<
+
+clean:
+	rm -rf *~ $(PACKAGE)*.py $(PACKAGE)*.pyc *.interp *.tokens  __pycache*

TP02/demo_files/ex3/main.py

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+from antlr4 import InputStream
+from antlr4 import CommonTokenStream
+
+# include to use the generated lexer and parser
+from Example3Lexer import Example3Lexer
+from Example3Parser import Example3Parser
+
+import sys
+
+
+def main():
+    input_stream = InputStream(sys.stdin.read())
+    lexer = Example3Lexer(input_stream)
+    stream = CommonTokenStream(lexer)
+    parser = Example3Parser(stream)
+    parser.full_expr()
+    print("Finished")
+
+
+# warns pb if py file is included in others
+if __name__ == '__main__':
+    main()