72 lines
1.7 KiB
Rust
72 lines
1.7 KiB
Rust
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use std::ops;
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use crate::parser;
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use parser::Atom;
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pub fn eval(ast: &parser::Expr) -> parser::Atom {
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match ast {
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parser::Expr::Atom(a) => a.clone(),
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parser::Expr::UnaryMinus(a) => -eval(&a),
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parser::Expr::Plus(a, b) => eval(&a) + eval(&b),
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parser::Expr::Minus(a, b) => eval(&a) - eval(&b),
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parser::Expr::Mult(a, b) => eval(&a) * eval(&b),
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parser::Expr::Div(a, b) => eval(&a) / eval(&b),
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_ => panic!("Couldn't evalute expression {{ {:?} }}", ast),
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}
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}
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impl ops::Neg for Atom {
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type Output = Self;
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fn neg(self) -> Self {
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match self {
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Atom::Num(a) => Atom::Num(-a),
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_ => panic!("Can't negate non-numeral type!"),
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}
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}
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}
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impl ops::Add for Atom {
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type Output = Self;
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fn add(self, other: Self) -> Self {
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match (self, other) {
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(Atom::Num(a), Atom::Num(b)) => Atom::Num(a + b),
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_ => panic!("Can't add non-numeral types!"),
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}
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}
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}
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impl ops::Sub for Atom {
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type Output = Self;
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fn sub(self, other: Self) -> Self {
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match (self, other) {
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(Atom::Num(a), Atom::Num(b)) => Atom::Num(a - b),
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_ => panic!("Can't subtract non-numeral types!"),
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}
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}
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}
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impl ops::Mul for Atom {
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type Output = Self;
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fn mul(self, other: Self) -> Self {
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match (self, other) {
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(Atom::Num(a), Atom::Num(b)) => Atom::Num(a * b),
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_ => panic!("Can't multiply non-numeral types!"),
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}
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}
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}
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impl ops::Div for Atom {
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type Output = Self;
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fn div(self, other: Self) -> Self {
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match (self, other) {
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(Atom::Num(a), Atom::Num(b)) => Atom::Num(a / b),
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_ => panic!("Can't divide non-numeral types!"),
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}
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}
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}
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