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// use std::env; // TODO: Get args from here
use std::collections::HashMap;
use rust_decimal::prelude::*;
use rust_decimal_macros::dec;
#[derive(Debug)]
enum Value {
Str(String),
Num(Decimal),
}
enum Mode {
Integer,
Decimal,
Str,
Command
}
fn main() {
let mut state = RPState {
registers: HashMap::new(),
stack: Vec::new(),
mode: Mode::Command,
wip_str: String::from(""),
num: dec!(0.0),
decimal_offset: dec!(1),
};
let result = eval(String::from("123 456 7.89+"), &mut state);
match result {
Ok(()) => println!("{:?}", state.stack),
Err(msg) => println!("Error: {}", msg),
}
}
const RADIX: u32 = 10;
const INTEGER_RADIX: Decimal = dec!(10);
fn to_decimal(input: u32) -> Decimal {
<u32 as Into<Decimal>>::into(input)
}
struct RPState {
registers: HashMap<String, Value>,
stack: Vec<Value>,
mode: Mode,
wip_str: String,
num: Decimal,
decimal_offset: Decimal
}
fn command(c: char, state: &mut RPState) -> Result<(), String> {
if c.is_digit(RADIX) {
state.mode = Mode::Integer;
state.num = dec!(0);
state.num += to_decimal(c.to_digit(10).ok_or_else(|| format!("{} isn't a digit", c))?);
Ok(())
} else if c == ' ' {
// do nothing
Ok(())
} else if c == '+' {
let a = state.stack.pop().ok_or_else(|| "Data underflow!")?;
let b = state.stack.pop().ok_or_else(|| "Data underflow!")?;
match (a, b) {
(Value::Num(c), Value::Num(d)) => {
state.stack.push(Value::Num(c + d));
}
_ => return Err("Invalid operation + on non-numbers!".to_string())
}
Ok(())
} else {
panic!("{} isn't implemented yet!", c)
}
}
fn integer(c: char, state: &mut RPState) -> Result<(), String> {
if c.is_digit(RADIX) {
state.num *= INTEGER_RADIX;
state.num += to_decimal(c.to_digit(10).unwrap());
} else if c == '.' {
state.decimal_offset = dec!(1);
state.mode = Mode::Decimal;
}
else {
state.stack.push(Value::Num(state.num));
state.mode = Mode::Command;
return command(c, state);
}
return Ok(());
}
fn decimal(c: char, state: &mut RPState) -> Result<(), String> {
if c.is_digit(RADIX) {
state.decimal_offset *= dec!(0.1);
state.num += to_decimal(c.to_digit(10).unwrap()) * state.decimal_offset;
} else {
state.stack.push(Value::Num(state.num));
state.mode = Mode::Command;
return command(c, state);
}
return Ok(());
}
fn eval(input: String, state: &mut RPState) -> Result<(), String> {
for (_cpos, c) in input.char_indices() {
let res = match state.mode {
Mode::Command => command(c, state),
Mode::Integer => integer(c, state),
Mode::Decimal => decimal(c, state),
Mode::Str => {
panic!("Strings not implemented yet");
}
};
if res.is_err() {
return res
}
}
match state.mode {
Mode::Integer | Mode::Decimal => {
state.stack.push(Value::Num(state.num));
state.mode = Mode::Command;
},
_ => {}
};
return Ok(());
}
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