rpn(1): code cleanup
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parent
90ca10990f
commit
34b9519e03
45
src/rpn.rs
45
src/rpn.rs
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@ -69,9 +69,7 @@ enum CalcType {
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}
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#[derive(Debug, Clone)]
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struct EvaluationError {
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pub message: String,
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}
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struct EvaluationError { pub message: String }
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impl fmt::Display for EvaluationError {
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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@ -91,9 +89,7 @@ fn str_to_calc_type(string: &str) -> Option<CalcType> {
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Err(_) => None,
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};
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if result.is_some() {
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return result;
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}
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if result.is_some() { return result; }
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match string {
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"+" => Some(Add),
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@ -132,16 +128,20 @@ fn eval(
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};
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match x {
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Add | Divide | Multiply | Power | Subtract | Modulo => {
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ops.push_back(x)
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},
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Val(x_) => stack.push_back(x_),
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_ => ops.push_back(x),
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}
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}
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for op in &ops {
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match op {
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Add | Subtract | Multiply | Divide | Power | Modulo => {
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Val(_) => {
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return Err(EvaluationError {
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message: "Unexpected value in the operator stack."
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.to_string()
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})
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},
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_ => {
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let x = &stack.pop_back().ok_or(EvaluationError {
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message: "Stack is empty.".to_string(),
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})?;
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@ -160,20 +160,13 @@ fn eval(
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_ => &{},
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};
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},
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Val(_) => {
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return Err(
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EvaluationError {
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message: "Unexpected value in the operator stack."
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.to_string()
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}
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)
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},
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};
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}
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Ok(stack)
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}
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// Round a float to the given precision level
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fn round_precise(value: &f64, precision: usize) -> f64 {
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let multiplier = 10_f64.powi(precision as i32);
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(value * multiplier).round() / multiplier
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@ -183,6 +176,8 @@ fn main() -> ExitCode {
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let argv = args().collect::<Vec<String>>();
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let mut stack = VecDeque::new();
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let mut buf = String::new();
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// Set floating-point precision for correcting rounding errors based on
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// machine epsilon
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let precision = (-f64::EPSILON.log10() * PRECISION_MOD).ceil() as usize;
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if argv.get(1).is_none() {
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@ -196,8 +191,7 @@ fn main() -> ExitCode {
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None => break,
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};
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let precise = round_precise(val, precision);
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println!("{}", precise.to_string());
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println!("{}", round_precise(val, precision).to_string());
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buf.clear();
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},
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Err(err) => {
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@ -215,7 +209,16 @@ fn main() -> ExitCode {
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.join(" ");
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match eval(&input, stack) {
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Ok(val) => println!("{}", val.iter().last().unwrap().to_string()),
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Ok(s) => {
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stack = s.clone();
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let val = match stack.iter().last() {
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Some(v) => v,
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None => return ExitCode::from(0),
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};
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println!("{}", round_precise(val, precision).to_string())
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},
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Err(err) => {
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eprintln!("{}: {}", argv[0], err.message);
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return ExitCode::from(EX_DATAERR as u8);
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