Robot Calculator, v1.0.0-alpha

The electronic calculator.

Implement evaluation of expressions.

Features

• evaluation:
  • number evaluation:
    • support for a whole number;
    • support for a fractional number:
      • support for a fractional number without a whole part;
      • support for a fractional number without a fractional part;
    • ignore duplicated zeros at the beginning of a number;
    • return NaN:
      • return NaN for an incorrect number;
      • return NaN for a number causing overflow;
    • truncate a number longer than the internal buffer;
  • operation evaluation:
    • supported operations:
      • addition;
      • subtraction;
      • multiplication;
      • division;
    • typo processing:
      • support for several operations in a row (only the first operation will be used);
      • support for expression starting with an operation (the leading operation will be ignored);
      • support for expression ending with an operation (the trailing operation will be ignored).

Grammar

Grammar in an EBNF:

expression = addition;

addition = multiplication, {("+" | "-"), multiplication};
multiplication = NUMBER, {("*" | "/"), NUMBER};

NUMBER = ? /(\d+\.\d*)|(\d*\.\d+)|\d+/ ?;

Example of an expression: 1.2+2.3*4.2.