input_parser_grammar.dot

digraph {
  rankdir = "LR";

  ReadElement -> ReadNegativeCoefficient [label = "-"];
  ReadElement -> ReadPositiveCoefficient [label = "0..9"];
  ReadElement -> ReadVariableName [label = "a..z"];

  ReadNegativeCoefficient -> ReadPositiveCoefficient [label = "0..9"];
  ReadNegativeCoefficient -> ReadVariableName [label = "a..z"];

  ReadPositiveCoefficient -> ReadPositiveCoefficient [label = "0..9"];
  ReadPositiveCoefficient -> ReadVariableName [label = "a..z"];
  ReadPositiveCoefficient -> ReadElement [label = "+"];
  ReadPositiveCoefficient -> ReadElement [label = "-"];

  ReadVariableName -> ReadVariableName [label = "a..z, 0..9"];
  ReadVariableName -> ReadNegativeCoefficient [label = "-"];
  ReadVariableName -> ReadPositiveCoefficient [label = "+"];
  ReadVariableName -> ReadFreeMember [label = "="];

  ReadFreeMember -> ReadNegativeFreeMember [label = "-"];
  ReadFreeMember -> ReadPositiveFreeMember [label = "0..9"];

  ReadNegativeFreeMember -> ReadPositiveFreeMember [label = "0..9"];

  ReadPositiveFreeMember -> ReadPositiveFreeMember [label = "0..9"];
}