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use std::{
fmt::{self, Display},
fs::read_to_string,
};
pub fn run(arg: &str) -> String {
let content = read_to_string(arg).unwrap();
let result = interpret(&content.to_string());
result.to_string()
}
#[derive(Debug, PartialEq)]
pub enum Value {
Num(i32),
Bool(bool),
Sym(String),
}
impl Display for Value {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
Value::Num(i) => write!(f, "{}", i),
Value::Bool(b) => write!(f, "{}", b),
Value::Sym(s) => write!(f, "{}", s),
}
}
}
fn interpret(arg: &str) -> Value {
let token = arg.trim();
token
.parse::<i32>()
.map(Value::Num)
.or(token.parse::<bool>().map(Value::Bool))
.unwrap_or(Value::Sym(token.to_string()))
}
#[cfg(test)]
mod tests {
use super::interpret;
use super::Value::*;
use proptest::prelude::*;
proptest! {
#[test]
fn interpret_integer_as_number(i in -1000i32..1000) {
let result = interpret(&i.to_string());
assert_eq!(Num(i), result);
}
}
#[test]
fn interpret_truth_values_as_booleans() {
assert_eq!(Bool(true), interpret("true"));
assert_eq!(Bool(false), interpret("false"));
}
#[test]
fn interpret_identifiers_values_as_symbols() {
assert_eq!(Sym("foo".to_string()), interpret("foo"));
}
#[test]
fn ignores_whitespace() {
assert_eq!(Sym("foo".to_string()), interpret(" foo \n\r"));
assert_eq!(Num(-42), interpret("\n-42"));
}
}
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