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#![cfg_attr(test, feature(test))]

#[macro_use]
extern crate decimal;
#[cfg(test)]
extern crate test;

#[cfg(test)]
mod bench;

mod error;
mod token;
pub mod parse;
pub mod value;

pub use value::Value;
pub use error::CalcError;

/// Evalulates a regular mathematical expression.
pub fn eval(input: &str) -> Result<Value, CalcError> {
    let mut env = parse::DefaultEnvironment;
    token::tokenize(input).and_then(|x| parse::parse(&x, &mut env))
}

/// Evalulates a regular mathematical expression, with extra environment
/// variables.
pub fn eval_with_env<E>(input: &str, env: &mut E) -> Result<Value, CalcError>
    where E: parse::Environment
{
    token::tokenize(input).and_then(|x| parse::parse(&x, env))
}

/// Evalulates mathematical expressions that are written in Polish Notation.
///
/// Polish Notation defines that a string of operators are given at the
/// beginning of the
/// expression, as prefixes, and are followed by a string of numbers to apply
/// each operation
/// to. Polish Notation enables writing mathematical expressions that don't
/// require grouping
/// via parenthesis. It's also referred to as Prefix Notation, or Normal Polish
/// Notation (NPN).
///
/// # Examples
///
/// - `+ * 3 4 5` is equivalent to `3 * 4 + 5`
/// - `+ / * 5 3 2 * + 1 3 5` is equivalent to `((5 * 3) / 2) + ((1 + 3) * 5)`
pub fn eval_polish(input: &str) -> Result<Value, CalcError> {
    let mut env = parse::DefaultEnvironment;
    token::tokenize_polish(input).and_then(|x| parse::parse(&x, &mut env))
}

/// Evalulates mathematical expressions that are written in Polish Notation,
/// with extra
/// environment variables.
///
/// Polish Notation defines that a string of operators are given at the
/// beginning of the
/// expression, as prefixes, and are followed by a string of numbers to apply
/// each operation
/// to. Polish Notation enables writing mathematical expressions that don't
/// require grouping
/// via parenthesis. It's also referred to as prefix notation, or Normal Polish
/// Notation (NPN).
///
/// # Examples
///
/// - `+ * 3 4 5` is equivalent to `3 * 4 + 5`
/// - `+ / * 5 3 2 * + 1 3 5` is equivalent to `((5 * 3) / 2) + ((1 + 3) * 5)`
pub fn eval_polish_with_env<E>(
    input: &str,
    env: &mut E,
) -> Result<Value, CalcError>
    where E: parse::Environment
{
    token::tokenize_polish(input).and_then(|x| parse::parse(&x, env))
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn basics() {
        let cases =
            vec![
                ("  1 +   1", Value::Dec(2)),
                (" 4 * 7 - 14", Value::Dec(14)),
                (" 2 << 16 ", Value::Dec(131072)),
                (" ((4 * 18) % 17) / 3", Value::Float(d128!(4.0) / d128!(3.0))),
                ("2²³²", Value::Dec(4096)),
                ("4 ^ 3 ^ 2 ^ 3 ^ 4 ^ 2", Value::Dec(0)),
                ("3 << (4 >> 2)", Value::Dec(6)),
                ("~0", Value::Dec(-1)),
                // ("cos pi + sin (tau * (3 / 4))", Value::Float(d128!(-2.0))),
                ("~~5", Value::Dec(5)),
            ];
        for (input, expected) in cases {
            assert_eq!(eval(input), Ok(expected));
        }
    }

    #[test]
    fn polish() {
        let cases =
            vec![
                (" + 1 1", Value::Dec(2)),
                (" - * 4 7 14", Value::Dec(14)),
                (" << 2 16", Value::Dec(131072)),
                (" / % * 4 18 17 3", Value::Float(d128!(4.0) / d128!(3.0))),
                ("* + 1 3 5", Value::Dec(20)),
                ("+ / * 5 3 2 * + 1 3 5", Value::Float(d128!(27.5))),
                ("^ ^ ^ ^ ^ 4 3 2 3 4 2", Value::Dec(0)),
                ("<< 3 >> 4 2", Value::Dec(6)),
            ];
        for (input, expected) in cases {
            assert_eq!(eval_polish(input), Ok(expected));
        }
    }


    #[test]
    fn random() {
        let cases =
            vec![
                (
                    "((15 * 10) - 26 * 19 - 30 / ((57 * 79 + 93 / 87 / 47))) / 8",
                    Value::Float(d128!(-43.00083277394169075309321854399588))
                ),
                (
                    "(3 << 6) * 7 + (40 / 3)",
                    Value::Float(d128!(1357.333333333333333333333333333333))
                ),
                (
                    "(21 & (5) ^ (20 & 81)) / (25 << 3)",
                    Value::Float(d128!(0.105))
                ),
                (
                    "(79 & 14) * ((3) - 76 + 67 / (62) - (85 ^ (7 - (32) >> 52)))",
                    Value::Float(d128!(197.1290322580645161290322580645161))
                ),
            ];

        for (input, expected) in cases {
            assert_eq!(eval(input), Ok(expected));
        }
    }

}