init

src/eval.rs

@@ -0,0 +1,47 @@
+use std::num::ParseIntError;
+
+pub enum EvalError {
+	LeftMissing,
+	RightMissing,
+	I64Conversion(ParseIntError),
+	InvalidOperator(String)
+}
+
+pub struct Input {
+	pub left: i64,
+	pub right: i64
+}
+
+pub struct EvalResult {
+	pub input: Input,
+	pub eval: i64
+}
+
+fn parse(arg: &str) -> Result<i64, EvalError> {
+	match arg {
+		"true" => Ok(1),
+		"false" => Ok(0),
+		arg => arg.parse::<i64>().map_or_else(|e| Err(EvalError::I64Conversion(e)), Ok)
+	}
+}
+
+pub fn eval(expression: Vec<&str>) -> Result<EvalResult, EvalError> {
+	// let left = expression.get(0);
+	let left = parse(expression[0])?;
+	let right = parse(expression[2])?;
+	let wrap_result = |val: i64| -> EvalResult {
+		EvalResult {
+			input: Input { left, right },
+			eval: val,
+		}
+	};
+
+	match expression[1] {
+		">>" | "right" => Ok(wrap_result(left >> right)),
+		"<<" | "left"  => Ok(wrap_result(left << right)),
+		"|"  | "or"    => Ok(wrap_result(left | right)),
+		"&"  | "and"   => Ok(wrap_result(left & right)),
+		"^"  | "xor"   => Ok(wrap_result(left ^ right)),
+		str => Err(EvalError::InvalidOperator(str.to_owned()))
+	}
+}