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use crate::bfic::BfCode;
use crate::celltype::BfCell;
use crate::error::*;
impl<T> BfCode<T>
where
T: BfCell,
{
/// Parse the brainfuck code.
///
/// Parse the brainfuck code, convert it into BfCode intermediate code.
///
/// # Failures
///
/// The function will return a `ParseError` if:
/// 1. An error occurs during an IO operation.
/// 2. A syntax error in the brainfuck code (such as mismatched brackets).
///
/// # Examples
/// ```rust
/// use std::io::BufReader;
/// use crain::bfir::BfCode::{self, *};
/// use crain::celltype::Cell8;
///
/// let code = BufReader::new("+-<>,.[]".as_bytes());
/// let ic = BfCode::<Cell8>::parse(code)?;
///
/// assert_eq!(
/// ic,
/// vec![AddCell(1), SubCell(1), LeftShift(1), RightShift(1),
/// Input, Output, Jz(7), Jnz(6)]
/// );
/// # Ok::<(), crain::ParseError>(())
/// ```
pub fn parse(source_codes: impl std::io::BufRead) -> Result<Vec<BfCode<T>>, ParseError> {
let mut codes = vec![];
let mut stack: Vec<(usize, usize, usize)> = vec![];
let mut line = 1usize;
let mut row = 0usize;
macro_rules! wrapping_push {
($vector:expr, $code:path) => {
if let Some($code(n)) = $vector.last() {
let mut new_n = n.clone();
let last = $vector.last_mut().unwrap();
new_n.add(T::ONE);
*last = $code(new_n);
} else {
$vector.push($code(T::ONE));
}
};
}
macro_rules! unwrapping_push {
($vector:expr, $code:path) => {
if let Some($code(n)) = $vector.last() {
// Pre dereference reference "n" to end the lifetime of immutable
// reference and avoid conflicts with mutable reference "last"
let n = *n;
if n == usize::MAX {
$vector.push($code(1usize));
} else {
let last = $vector.last_mut().unwrap();
*last = $code(n + 1);
}
} else {
$vector.push($code(1usize));
}
};
}
for byte in source_codes.bytes() {
let byte = byte.map_err(|e| ParseError::IO { source: e })?;
if byte == b'\n' {
line += 1;
row = 0;
continue;
}
row += 1;
match byte {
b'+' => wrapping_push!(codes, BfCode::<T>::AddCell),
b'-' => wrapping_push!(codes, BfCode::<T>::SubCell),
b'<' => unwrapping_push!(codes, BfCode::<T>::LeftShift),
b'>' => unwrapping_push!(codes, BfCode::<T>::RightShift),
b',' => codes.push(BfCode::<T>::Input),
b'.' => codes.push(BfCode::<T>::Output),
b'[' => {
stack.push((codes.len(), line, row));
codes.push(BfCode::<T>::Jz(usize::MAX));
}
b']' => {
if let Some(left_bracket_data) = stack.pop() {
codes[left_bracket_data.0] = BfCode::<T>::Jz(codes.len());
codes.push(BfCode::<T>::Jnz(left_bracket_data.0));
} else {
return Err(ParseError::MismatchedBracket {
bracket: ']',
line,
row,
});
}
}
_ => {}
}
}
if let Some(left_bracket_data) = stack.pop() {
return Err(ParseError::MismatchedBracket {
bracket: '[',
line: left_bracket_data.1,
row: left_bracket_data.2,
});
}
Ok(codes)
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::bfic::BfCode::*;
use crate::celltype::Cell8;
use std::io::BufReader;
#[test]
fn test_bfcode_parse() {
let error_func = |e| panic!("Parse Error: {}", e);
let ok_func = |v| v;
let new_frame = |s: &str| {
BfCode::<Cell8>::parse(BufReader::new(s.as_bytes())).map_or_else(error_func, ok_func)
};
assert_eq!(
new_frame("+-<>,.[]"),
vec![
AddCell(1),
SubCell(1),
LeftShift(1),
RightShift(1),
Input,
Output,
Jz(7),
Jnz(6),
]
);
assert_eq!(
new_frame("-<<<+++--><++>>>"),
vec![
SubCell(1),
LeftShift(3),
AddCell(3),
SubCell(2),
RightShift(1),
LeftShift(1),
AddCell(2),
RightShift(3),
]
);
assert_eq!(
new_frame("[[][[[][[]][]]]]"),
vec![
Jz(15), // 0
Jz(2), // 1
Jnz(1), // 2
Jz(14), // 3
Jz(13), // 4
Jz(6), // 5
Jnz(5), // 6
Jz(10), // 7
Jz(9), // 8
Jnz(8), // 9
Jnz(7), // 10
Jz(12), // 11
Jnz(11), // 12
Jnz(4), // 13
Jnz(3), // 14
Jnz(0), // 15
]
);
}
}