rpn(1): rewrote parser for the second time
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parent
4cb5e8e2b0
commit
fb2a164507
67
src/rpn.rs
67
src/rpn.rs
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@ -67,7 +67,7 @@ enum CalcType {
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Floor,
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Modulo,
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Val(f64),
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Empty,
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Invalid,
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}
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impl From<&str> for CalcType {
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@ -83,7 +83,7 @@ impl From<&str> for CalcType {
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_ => {
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match value.parse::<f64>() {
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Ok(x) => Val(x),
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Err(_) => Empty,
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Err(_) => Invalid,
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}
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},
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}
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@ -104,7 +104,7 @@ impl Display for CalcType {
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Val(x) => {
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y = x.to_string(); &y
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},
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Empty => "",
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Invalid => "",
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})
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}
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}
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@ -122,6 +122,7 @@ impl Display for EvaluationError {
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// repeating and it seems this can give it to me
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const PRECISION_MOD: f64 = 0.9 + f64::EPSILON * 100.0;
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fn eval(
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input: &str,
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initial_stack: VecDeque<f64>,
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@ -135,54 +136,30 @@ fn eval(
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}
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// Split the input into tokens.
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let toks = input.split(' ').collect::<Vec<&str>>();
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let mut toks: VecDeque<CalcType> = input
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.split(' ')
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.map(|t| CalcType::from(t))
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.collect();
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let mut ops: VecDeque<CalcType> = VecDeque::new();
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for tok in toks {
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let x: CalcType = match CalcType::from(tok) {
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Empty => {
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return Err(EvaluationError {
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message: format!("{}: Invalid token", tok),
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})
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},
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x => x,
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};
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match x {
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while let Some(n) = toks.pop_back() {
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match n {
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Val(v) => stack.push_back(v),
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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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Val(_) => {
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return Err(EvaluationError { message: format!(
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"{}: Unexpected value in the operator stack.",
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op,
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)});
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},
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_ => {
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if stack.len() < 2 {
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Invalid => {
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return Err(EvaluationError {
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message: format!("{}: Unexpected operation.", op)
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message: format!("{}: Invalid token", n)
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})
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}
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if stack.len() > ops.len() + 1 {
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return Err(
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EvaluationError { message: format!("Syntax error.")}
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);
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}
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},
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op => {
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ops.push_back(op);
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oper = true;
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let (x, y) = (
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stack.pop_back().unwrap(),
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stack.pop_back().unwrap(),
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let vals = (
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stack.pop_back(),
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stack.pop_back(),
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);
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if let (Some(x), Some(y)) = vals {
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match op {
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Add => stack.push_back(y + x),
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Subtract => stack.push_back(y - x),
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@ -193,6 +170,11 @@ fn eval(
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Modulo => stack.push_back(y % x),
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_ => {},
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};
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} else {
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return Err(EvaluationError {
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message: format!("{}: Unexpected operation.", op)
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})
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}
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},
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};
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}
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@ -240,6 +222,7 @@ fn main() -> ExitCode {
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let input = argv
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.iter()
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.skip(1)
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.rev()
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.map(|x| x.to_owned())
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.collect::<Vec<String>>()
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.join(" ");
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