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use std::fmt;
use std::str::FromStr;
use crate::error::ParseError;
use crate::machine::output_receiver::OutputReceiver;
use crate::machine::register::MachineRegister;
pub trait MachineInstruction: Sized + Clone {
fn execute<R: MachineRegister, O: OutputReceiver<R>>(
&self,
register: &mut R,
output_receiver: &mut O,
) -> i64;
fn from_parsed_machine_instruction(
parsed: &ParsedMachineInstruction,
) -> Result<Self, ParseError>;
fn from_str(instruction: &str) -> Result<Self, ParseError> {
let parsed = instruction.parse::<ParsedMachineInstruction>()?;
Self::from_parsed_machine_instruction(&parsed)
}
}
#[derive(Debug, Copy, Clone, Eq, PartialEq)]
pub enum Value {
Raw(i64),
Register(char),
}
impl Value {
pub fn get<T: MachineRegister>(&self, registers: &T) -> i64 {
match self {
Value::Raw(value) => *value,
Value::Register(register) => registers.read(*register),
}
}
}
impl fmt::Display for Value {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
Value::Raw(value) => write!(f, "{}", value),
Value::Register(register) => write!(f, "{}", register),
}
}
}
impl FromStr for Value {
type Err = ParseError;
fn from_str(s: &str) -> Result<Self, Self::Err> {
match s.parse::<i64>() {
Ok(value) => Ok(Value::Raw(value)),
Err(parse_int_error) => match s.parse::<char>() {
Ok(register) => Ok(Value::Register(register)),
Err(parse_char_error) => Err(parse_error!(
"Failed to parse value. Could not parse as int ({}) or as register ({}).",
parse_int_error,
parse_char_error,
)),
},
}
}
}
#[derive(Debug)]
pub struct ParsedMachineInstruction {
command: String,
arguments: Vec<String>,
}
impl ParsedMachineInstruction {
#[cfg(test)]
fn new(command: &str, arguments: &[&str]) -> ParsedMachineInstruction {
ParsedMachineInstruction {
command: command.to_string(),
arguments: arguments.iter().map(|a| a.to_string()).collect(),
}
}
pub fn get_command(&self) -> &str {
self.command.as_str()
}
pub fn get_argument<T: FromStr>(&self, idx: usize) -> Result<T, ParseError>
where
ParseError: From<<T as FromStr>::Err>,
{
match self.arguments.get(idx) {
Some(value) => Ok(value.parse()?),
None => Err(parse_error!(
"Command {} has insufficient arguments ({:?})",
self.command,
self.arguments
)),
}
}
}
impl fmt::Display for ParsedMachineInstruction {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "{}", self.command)?;
for arg in &self.arguments {
write!(f, " {}", arg)?;
}
Ok(())
}
}
impl FromStr for ParsedMachineInstruction {
type Err = ParseError;
fn from_str(s: &str) -> Result<Self, Self::Err> {
if s.is_empty() {
Err(parse_error!("Could not parse empty instruction"))
} else {
let normalized = s.replace(',', " ");
let mut parts = normalized.split_whitespace();
let command = match parts.next() {
Some(cmd) => cmd.to_string(),
None => unreachable!(),
};
let arguments = parts.map(|a| a.to_string()).collect();
Ok(ParsedMachineInstruction { command, arguments })
}
}
}
#[cfg(test)]
mod tests {
use crate::machine::register::HashMapRegister;
use super::*;
#[test]
fn test_get_raw_value() {
let value = Value::Raw(10);
let registers = HashMapRegister::default();
assert_eq!(value.get(®isters), 10);
}
#[test]
fn test_get_register_value() {
let value = Value::Register('a');
let mut registers = HashMapRegister::default();
registers.write('a', 10);
assert_eq!(value.get(®isters), 10);
}
#[test]
fn test_format_raw_value() {
assert_eq!(format!("{}", Value::Raw(10)), "10");
}
#[test]
fn test_format_register_value() {
assert_eq!(format!("{}", Value::Register('a')), "a");
}
#[test]
fn test_parse_invalid_value() {
const ERROR_MESSAGE: &str = "Failed to parse value. Could not parse as int (invalid digit found in string) or as register (too many characters in string).";
assert_eq!("foo".parse::<Value>(), Err(parse_error!(ERROR_MESSAGE)));
}
#[test]
fn test_parse_raw_value() {
assert_eq!("+142".parse::<Value>(), Ok(Value::Raw(142)));
}
#[test]
fn test_parse_register_value() {
assert_eq!("a".parse::<Value>(), Ok(Value::Register('a')));
}
#[test]
fn test_format_instruction() {
let instruction = ParsedMachineInstruction::new("add", &["10", "15"]);
assert_eq!(format!("{}", instruction), "add 10 15");
}
#[test]
fn test_parse_empty_instruction() {
let parsed = "".parse::<ParsedMachineInstruction>().unwrap_err();
assert_eq!(parsed, parse_error!("Could not parse empty instruction"));
}
#[test]
fn test_parse_zero_argument_instruction() {
let parsed = "nop".parse::<ParsedMachineInstruction>().unwrap();
assert_eq!(parsed.command, "nop");
assert_eq!(parsed.arguments.len(), 0);
}
#[test]
fn test_parse_instruction_with_arguments() {
let parsed = "add 5 -10".parse::<ParsedMachineInstruction>().unwrap();
assert_eq!(parsed.get_command(), "add");
assert_eq!(parsed.arguments.len(), 2);
assert_eq!(parsed.get_argument::<i64>(0), Ok(5));
assert_eq!(parsed.get_argument::<i64>(1), Ok(-10));
}
}