Add Brainfuck functio interpretation
BF functios can now be declared and called from AbleScript code. Function parameters supplied from AbleScript are serialized manually into byte sequences using the `BfWriter` trait, and are available from BF code using the input operator, `,`. At the moment, BF functios simply write output to stdout, and are therefore incapable of communicating results to the rest of the program; this might change in the future if we can get something close to pass-by-reference working.
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@ -1,5 +1,7 @@
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use std::ops::Range;
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use crate::brian::InterpretError;
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#[derive(Debug, Clone)]
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pub struct Error {
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pub kind: ErrorKind,
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@ -16,4 +18,5 @@ pub enum ErrorKind {
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TypeError(String),
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TopLevelBreak,
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ArithmeticError,
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BfInterpretError(InterpretError),
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}
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@ -8,13 +8,16 @@
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#[deny(missing_docs)]
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use std::collections::HashMap;
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use std::convert::TryFrom;
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use std::{
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convert::TryFrom,
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io::{stdout, Write},
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};
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use crate::{
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base_55,
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error::{Error, ErrorKind},
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parser::item::{Expr, Iden, Item, Stmt},
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variables::{Value, Variable},
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variables::{Functio, Value, Variable},
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};
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/// An environment for executing AbleScript code.
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@ -178,29 +181,64 @@ impl ExecEnv {
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None => Value::Nul,
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};
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// There's always at least one stack frame on the
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// stack if we're evaluating something, so we can
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// `unwrap` here.
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self.stack.iter_mut().last().unwrap().variables.insert(
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iden.0.clone(),
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Variable {
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melo: false,
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value: init,
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},
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);
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self.decl_var(&iden.0, init);
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}
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Stmt::FunctionDeclaration {
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iden: _,
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args: _,
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body: _,
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} => todo!(),
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Stmt::BfFDeclaration { iden: _, body: _ } => todo!(),
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Stmt::BfFDeclaration { iden, body } => {
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self.decl_var(
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&iden.0,
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Value::Functio(Functio::BfFunctio(body.as_bytes().into())),
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);
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}
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Stmt::If { cond, body } => {
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if self.eval_expr(cond)?.into() {
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return self.eval_items_hs(body);
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}
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}
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Stmt::FunctionCall { iden: _, args: _ } => todo!(),
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Stmt::FunctionCall { iden, args } => {
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let func = self.get_var(&iden.0)?;
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match func {
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Value::Functio(func) => {
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match func {
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Functio::BfFunctio(body) => {
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use crate::variables::BfWriter;
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let mut input: Vec<u8> = vec![];
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for arg in args {
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input.write_value(&self.eval_expr(arg)?);
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}
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println!("input = {:?}", input);
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let mut output = vec![];
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crate::brian::interpret_with_io(&body, &input as &[_], &mut output)
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.map_err(|e| Error {
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kind: ErrorKind::BfInterpretError(e),
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position: 0..0,
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})?;
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// I guess Brainfuck functions write
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// output to stdout? It's not quite
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// clear to me what else to do. ~~Alex
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stdout()
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.write_all(&output)
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.expect("Failed to write to stdout");
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}
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Functio::AbleFunctio(_) => {
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todo!()
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}
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}
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}
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_ => {
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return Err(Error {
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kind: ErrorKind::TypeError(iden.0.to_owned()),
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position: 0..0,
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})
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}
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}
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}
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Stmt::Loop { body } => loop {
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let res = self.eval_items_hs(body)?;
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match res {
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@ -289,6 +327,16 @@ impl ExecEnv {
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}),
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}
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}
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/// Declares a new variable, with the given initial value.
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fn decl_var(&mut self, name: &str, value: Value) {
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self.stack
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.iter_mut()
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.last()
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.expect("Declaring variable on empty stack")
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.variables
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.insert(name.to_owned(), Variable { melo: false, value });
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}
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}
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#[cfg(test)]
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@ -1,8 +1,11 @@
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use std::{convert::TryFrom, fmt::Display};
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use std::{convert::TryFrom, fmt::Display, io::Write};
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use rand::Rng;
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use crate::error::{Error, ErrorKind};
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use crate::{
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error::{Error, ErrorKind},
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parser::item::Item,
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};
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#[derive(Debug, Clone, PartialEq)]
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pub enum Abool {
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@ -31,23 +34,45 @@ impl From<Abool> for bool {
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}
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}
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#[derive(Debug, Clone, PartialEq)]
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pub enum Functio {
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BfFunctio(Vec<u8>),
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AbleFunctio(Vec<Item>),
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}
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#[derive(Debug, Clone, PartialEq)]
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pub enum Value {
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Nul,
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Str(String),
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Int(i32),
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Bool(bool),
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Abool(Abool),
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Nul,
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Functio(Functio),
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}
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impl Display for Value {
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fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
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match self {
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Value::Nul => write!(f, "nul"),
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Value::Str(v) => write!(f, "{}", v),
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Value::Int(v) => write!(f, "{}", v),
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Value::Bool(v) => write!(f, "{}", v),
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Value::Abool(v) => write!(f, "{}", v),
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Value::Nul => write!(f, "nul"),
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Value::Functio(v) => match v {
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Functio::BfFunctio(source) => {
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write!(
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f,
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"{}",
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String::from_utf8(source.to_owned())
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.expect("Brainfuck functio source should be UTF-8")
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)
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}
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Functio::AbleFunctio(source) => {
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// TODO: what's the proper way to display an
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// AbleScript functio?
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write!(f, "{:?}", source)
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}
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},
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}
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}
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}
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@ -84,6 +109,8 @@ impl From<Value> for bool {
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Value::Str(s) => s.len() != 0,
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// 0 is falsey, nonzero is truthy.
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Value::Int(x) => x != 0,
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// Functios are always truthy.
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Value::Functio(_) => true,
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// And nul is truthy as a symbol of the fact that the
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// deep, fundamental truth of this world is nothing but
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// the eternal void.
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@ -92,6 +119,70 @@ impl From<Value> for bool {
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}
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}
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/// Allows writing AbleScript values to Brainfuck.
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///
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/// This trait is blanket implemented for all `Write`rs, but should
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/// typically only be used for `Write`rs that cannot fail, e.g.,
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/// `Vec<u8>`, because any IO errors will cause a panic.
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///
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/// The mapping from values to encodings is as follows, where all
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/// multi-byte integers are little-endian:
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///
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/// | AbleScript representation | Brainfuck representation |
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/// |---------------------------|-----------------------------------------------------------|
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/// | Nul | 00 |
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/// | Str | 01 [length, 4 bytes] [string, \[LENGTH\] bytes, as UTF-8] |
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/// | Int | 02 [value, 4 bytes] |
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/// | Bool | 03 00 false, 03 01 true. |
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/// | Abool | 04 00 never, 04 01 always, 04 02 sometimes. |
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/// | Brainfuck Functio | 05 00 [length, 4 bytes] [source code, \[LENGTH\] bytes] |
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/// | AbleScript Functio | 05 01 (todo, not yet finalized or implemented) |
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///
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/// The existing mappings should never change, as they are directly
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/// visible from Brainfuck code and modifying them would break a
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/// significant amount of AbleScript code. If more types are added in
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/// the future, they should be assigned the remaining discriminant
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/// bytes from 06..FF.
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pub trait BfWriter {
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/// Write a value. Panic if writing fails for any reason.
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fn write_value(&mut self, value: &Value);
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}
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impl<T: Write> BfWriter for T {
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fn write_value(&mut self, value: &Value) {
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match value {
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Value::Nul => self.write_all(&[0]),
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Value::Str(s) => self
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.write_all(&[1])
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.and_then(|_| self.write_all(&(s.len() as u32).to_le_bytes()))
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.and_then(|_| self.write_all(&s.as_bytes())),
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Value::Int(v) => self
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.write_all(&[2])
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.and_then(|_| self.write_all(&v.to_le_bytes())),
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Value::Bool(b) => self
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.write_all(&[3])
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.and_then(|_| self.write_all(&[*b as _])),
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Value::Abool(a) => self.write_all(&[4]).and_then(|_| {
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self.write_all(&[match *a {
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Abool::Never => 0,
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Abool::Sometimes => 2,
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Abool::Always => 1,
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}])
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}),
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Value::Functio(f) => self.write_all(&[5]).and_then(|_| match f {
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Functio::BfFunctio(f) => self
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.write_all(&[0])
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.and_then(|_| self.write_all(&(f.len() as u32).to_le_bytes()))
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.and_then(|_| self.write_all(&f)),
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Functio::AbleFunctio(_) => {
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todo!()
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}
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}),
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}
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.expect("Failed to write to Brainfuck input");
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}
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}
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#[derive(Debug)]
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pub struct Variable {
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pub melo: bool,
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