2016-12-27 08:10:47 -08:00

607 lines
23 KiB
Rust

// -------------------------------------------------------------------------------------------------
// Rick, a Rust intercal compiler. Save your souls!
//
// Copyright (c) 2015 Georg Brandl
//
// This program is free software; you can redistribute it and/or modify it under the terms of the
// GNU General Public License as published by the Free Software Foundation; either version 2 of the
// License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without
// even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// General Public License for more details.
//
// You should have received a copy of the GNU General Public License along with this program;
// if not, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
// -------------------------------------------------------------------------------------------------
/// Interprets INTERCAL source.
///
/// The evaluator is used when rick is called with `-i`, or when the compiler generates
/// the output while compiling (in the constant-output case).
use std::fmt::{ Debug, Display };
use std::io::Write;
use std::u16;
use err::{ Res, IE123, IE129, IE252, IE275, IE555, IE633, IE774, IE994 };
use ast::{ self, Program, Stmt, StmtBody, ComeFrom, Expr, Var, VType };
use stdops::{ Bind, Array, write_number, read_number, check_chance, check_ovf, pop_jumps,
get_random_seed, mingle, select, and_16, and_32, or_16, or_32, xor_16, xor_32 };
/// Represents a value (either 16-bit or 32-bit) at runtime.
#[derive(Clone, PartialEq, Eq, Debug)]
pub enum Val {
I16(u16),
I32(u32),
}
impl Val {
/// Cast as a 16-bit value; returns an error if 32-bit and too big.
pub fn as_u16(&self) -> Res<u16> {
match *self {
Val::I16(v) => Ok(v),
Val::I32(v) => {
if v > (u16::MAX as u32) {
return IE275.err();
}
Ok(v as u16)
}
}
}
/// Cast as a 32-bit value; always succeeds.
pub fn as_u32(&self) -> u32 {
match *self {
Val::I16(v) => v as u32,
Val::I32(v) => v
}
}
/// Cast as an usize value; always succeeds.
pub fn as_usize(&self) -> usize {
self.as_u32() as usize
}
/// Create from a 32-bit value; will select the smallest possible type.
pub fn from_u32(v: u32) -> Val {
if v & 0xFFFF == v {
Val::I16(v as u16)
} else {
Val::I32(v)
}
}
}
/// The state of the interpreter's evaluator.
pub struct Eval<'a> {
/// Program to execute.
program: &'a Program,
/// Stream to use for printing output.
stdout: &'a mut Write,
/// Whether to print debugging output during execution.
debug: bool,
/// Variable bindings for the four types of variables.
spot: Vec<Bind<u16>>,
twospot: Vec<Bind<u32>>,
tail: Vec<Bind<Array<u16>>>,
hybrid: Vec<Bind<Array<u32>>>,
/// The infamous NEXT stack, capable of holding 80 elements.
jumps: Vec<ast::LogLine>,
/// Abstain counter for each statement.
abstain: Vec<u32>,
/// Binary I/O "tape" state.
last_in: u8,
last_out: u8,
/// Random number generator state.
rand_st: u32,
/// Counts the number of executed statements.
stmt_ctr: usize,
}
/// Represents the control flow effect of an executed statement.
enum StmtRes {
/// normal execution, next statement
Next,
/// jump around, from DO ... NEXT
Jump(usize),
/// jump back, from RESUME
Back(usize),
/// start from the first statement, from TRY AGAIN
FromTop,
/// end the program, from GIVE UP
End,
}
impl<'a> Eval<'a> {
/// Construct a new evaluator.
pub fn new(program: &'a Program, stdout: &'a mut Write, debug: bool,
random: bool) -> Eval<'a> {
let abs = program.stmts.iter().map(|stmt| stmt.props.disabled as u32).collect();
let nvars = (program.var_info.0.len(),
program.var_info.1.len(),
program.var_info.2.len(),
program.var_info.3.len());
Eval {
program: program,
stdout: stdout,
debug: debug,
spot: vec![Bind::new(0); nvars.0],
twospot: vec![Bind::new(0); nvars.1],
tail: vec![Bind::new(Array::empty()); nvars.2],
hybrid: vec![Bind::new(Array::empty()); nvars.3],
jumps: Vec::with_capacity(80),
rand_st: if random { get_random_seed() } else { 0 },
abstain: abs,
last_in: 0,
last_out: 0,
stmt_ctr: 0,
}
}
/// Interpret the program. Returns either the number of executed statements,
/// or an error (RtError).
pub fn eval(&mut self) -> Res<usize> {
let mut pctr = 0; // index of current statement
let program = self.program.clone();
let nstmts = program.stmts.len();
loop {
// check for falling off the end
if pctr >= nstmts {
// if the last statement was a TRY AGAIN, falling off the end is fine
if let StmtBody::TryAgain = program.stmts[program.stmts.len() - 1].body {
break;
}
return IE633.err();
}
self.stmt_ctr += 1;
let stmt = &program.stmts[pctr];
// execute statement if not abstained
if self.abstain[pctr] == 0 {
// check execution chance
let (passed, rand_st) = check_chance(stmt.props.chance, self.rand_st);
self.rand_st = rand_st;
if passed {
// try to eval this statement
let res = match self.eval_stmt(stmt) {
// on error, set the correct line number and bubble up
Err(mut err) => {
err.set_line(stmt.props.onthewayto);
// special treatment for NEXT
if let StmtBody::DoNext(n) = stmt.body {
if let Some(i) = program.labels.get(&n) {
err.set_line(program.stmts[*i as usize].props.srcline);
}
}
return Err(err);
}
Ok(res) => res
};
// handle control flow effects
match res {
StmtRes::Next => { }
StmtRes::Jump(n) => {
self.jumps.push(pctr as u16); // push the line with the NEXT
pctr = n;
continue; // do not increment or check for COME FROMs
}
StmtRes::Back(n) => {
pctr = n; // will be incremented below after COME FROM check
}
StmtRes::FromTop => {
pctr = 0; // start from the beginning, do not push any stack
continue;
}
StmtRes::End => break,
}
}
}
// if we are on the line with the compiler bug, error out
if pctr == self.program.bugline as usize {
return IE774.err_with(None, stmt.props.onthewayto);
}
// try to determine if we have to go to a COME FROM statement
// (note: in general, program.stmts[pctr] != stmt)
//
// the static COME FROM is always a possibility
let mut maybe_next = program.stmts[pctr].comefrom;
// the complicated case: evaluate all computed-come-from expressions
let my_label = program.stmts[pctr].props.label;
if program.uses_complex_comefrom && my_label > 0 {
for (i, stmt) in program.stmts.iter().enumerate() {
if let StmtBody::ComeFrom(ComeFrom::Expr(ref e)) = stmt.body {
let v = try!(try!(self.eval_expr(e)).as_u16());
if v == my_label {
// as soon as we have multiple candidates, we can bail out
if maybe_next.is_some() {
return IE555.err();
}
maybe_next = Some(i as u16);
}
}
}
}
// check for COME FROMs from this line
if let Some(next) = maybe_next {
let next = next as usize;
// check for abstained COME FROM
if self.abstain[next] == 0 {
// the COME FROM can also have a % chance
let (passed, rand_st) = check_chance(program.stmts[next].props.chance,
self.rand_st);
self.rand_st = rand_st;
if passed {
pctr = next;
continue;
}
}
}
// no COME FROM, normal execution
pctr += 1;
}
Ok(self.stmt_ctr)
}
/// Interpret a single statement.
fn eval_stmt(&mut self, stmt: &Stmt) -> Res<StmtRes> {
if self.debug {
println!("\nExecuting Stmt #{} (state before following)", self.stmt_ctr);
self.dump_state();
println!("{}", stmt);
}
match stmt.body {
StmtBody::Calc(ref var, ref expr) => {
let val = try!(self.eval_expr(expr));
try!(self.assign(var, val));
Ok(StmtRes::Next)
}
StmtBody::Dim(ref var, ref exprs) => {
try!(self.array_dim(var, exprs));
Ok(StmtRes::Next)
}
StmtBody::DoNext(n) => {
match self.program.labels.get(&n) {
// too many jumps on stack already?
Some(_) if self.jumps.len() >= 80 => IE123.err(),
Some(i) => Ok(StmtRes::Jump(*i as usize)),
None => IE129.err(),
}
}
StmtBody::ComeFrom(_) => {
// nothing to do here at runtime
Ok(StmtRes::Next)
}
StmtBody::Resume(ref expr) => {
let n = try!(self.eval_expr(expr)).as_u32();
// this expect() is safe: if the third arg is true, there will
// be no Ok(None) returns
let next = try!(pop_jumps(&mut self.jumps, n, true, 0))
.expect("https://xkcd.com/378/ ?!");
Ok(StmtRes::Back(next as usize))
}
StmtBody::Forget(ref expr) => {
let n = try!(self.eval_expr(expr)).as_u32();
try!(pop_jumps(&mut self.jumps, n, false, 0));
Ok(StmtRes::Next)
}
StmtBody::Ignore(ref vars) => {
for var in vars {
self.set_rw(var, false);
}
Ok(StmtRes::Next)
}
StmtBody::Remember(ref vars) => {
for var in vars {
self.set_rw(var, true);
}
Ok(StmtRes::Next)
}
StmtBody::Stash(ref vars) => {
for var in vars {
self.stash(var);
}
Ok(StmtRes::Next)
}
StmtBody::Retrieve(ref vars) => {
for var in vars {
try!(self.retrieve(var));
}
Ok(StmtRes::Next)
}
StmtBody::Abstain(ref expr, ref whats) => {
let f: Box<Fn(u32) -> u32> = if let Some(ref e) = *expr {
let n = try!(self.eval_expr(e)).as_u32();
box move |v: u32| v.saturating_add(n)
} else {
box |_| 1
};
for what in whats {
self.abstain(what, &*f);
}
Ok(StmtRes::Next)
}
StmtBody::Reinstate(ref whats) => {
for what in whats {
self.abstain(what, &|v: u32| v.saturating_sub(1));
}
Ok(StmtRes::Next)
}
StmtBody::ReadOut(ref vars) => {
for var in vars {
match *var {
// read out whole array
Expr::Var(ref var) if var.is_dim() => {
try!(self.array_readout(var));
}
// read out single var or array element
Expr::Var(ref var) => {
let varval = try!(self.lookup(var));
try!(write_number(self.stdout, varval.as_u32(), 0));
}
// read out constant
Expr::Num(_, v) => try!(write_number(self.stdout, v, 0)),
// others will not be generated
_ => return IE994.err(),
};
}
Ok(StmtRes::Next)
}
StmtBody::WriteIn(ref vars) => {
for var in vars {
if var.is_dim() {
// write in whole array
try!(self.array_writein(var));
} else {
// write in single var or array element
let n = try!(read_number(0));
try!(self.assign(var, Val::from_u32(n)));
}
}
Ok(StmtRes::Next)
}
// this one is only generated by the constant-program optimizer
StmtBody::Print(ref s) => {
if let Err(_) = self.stdout.write(&s) {
return IE252.err();
}
Ok(StmtRes::Next)
}
StmtBody::TryAgain => Ok(StmtRes::FromTop),
StmtBody::GiveUp => Ok(StmtRes::End),
StmtBody::Error(ref e) => Err((*e).clone()),
}
}
/// Evaluate an expression to a value.
fn eval_expr(&self, expr: &Expr) -> Res<Val> {
match *expr {
Expr::Num(vtype, v) => match vtype {
VType::I16 => Ok(Val::I16(v as u16)),
VType::I32 => Ok(Val::I32(v)),
},
Expr::Var(ref var) => self.lookup(var),
Expr::Mingle(ref vx, ref wx) => {
let v = try!(self.eval_expr(vx)).as_u32();
let w = try!(self.eval_expr(wx)).as_u32();
let v = try!(check_ovf(v, 0));
let w = try!(check_ovf(w, 0));
Ok(Val::I32(mingle(v, w)))
}
Expr::Select(vtype, ref vx, ref wx) => {
let v = try!(self.eval_expr(vx));
let w = try!(self.eval_expr(wx));
if vtype == VType::I16 {
Ok(Val::I16(select(v.as_u32(), try!(w.as_u16()) as u32) as u16))
} else {
Ok(Val::I32(select(v.as_u32(), w.as_u32())))
}
}
Expr::And(vtype, ref vx) => {
let v = try!(self.eval_expr(vx));
match vtype {
VType::I16 => Ok(Val::I16(and_16(try!(v.as_u16()) as u32) as u16)),
VType::I32 => Ok(Val::I32(and_32(v.as_u32()))),
}
}
Expr::Or(vtype, ref vx) => {
let v = try!(self.eval_expr(vx));
match vtype {
VType::I16 => Ok(Val::I16(or_16(try!(v.as_u16()) as u32) as u16)),
VType::I32 => Ok(Val::I32(or_32(v.as_u32()))),
}
}
Expr::Xor(vtype, ref vx) => {
let v = try!(self.eval_expr(vx));
match vtype {
VType::I16 => Ok(Val::I16(xor_16(try!(v.as_u16()) as u32) as u16)),
VType::I32 => Ok(Val::I32(xor_32(v.as_u32()))),
}
}
Expr::RsNot(ref vx) => {
let v = try!(self.eval_expr(vx));
Ok(Val::I32(!v.as_u32()))
}
Expr::RsAnd(ref vx, ref wx) => {
let v = try!(self.eval_expr(vx));
let w = try!(self.eval_expr(wx));
Ok(Val::I32(v.as_u32() & w.as_u32()))
}
Expr::RsOr(ref vx, ref wx) => {
let v = try!(self.eval_expr(vx));
let w = try!(self.eval_expr(wx));
Ok(Val::I32(v.as_u32() | w.as_u32()))
}
Expr::RsXor(ref vx, ref wx) => {
let v = try!(self.eval_expr(vx));
let w = try!(self.eval_expr(wx));
Ok(Val::I32(v.as_u32() ^ w.as_u32()))
}
Expr::RsRshift(ref vx, ref wx) => {
let v = try!(self.eval_expr(vx));
let w = try!(self.eval_expr(wx));
Ok(Val::I32(v.as_u32() >> w.as_u32()))
}
Expr::RsLshift(ref vx, ref wx) => {
let v = try!(self.eval_expr(vx));
let w = try!(self.eval_expr(wx));
Ok(Val::I32(v.as_u32() << w.as_u32()))
}
// Expr::RsEqual(ref vx, ref wx) => {
// let v = try!(self.eval_expr(vx));
// let w = try!(self.eval_expr(wx));
// Ok(Val::I32((v.as_u32() == w.as_u32()) as u32))
// }
Expr::RsNotEqual(ref vx, ref wx) => {
let v = try!(self.eval_expr(vx));
let w = try!(self.eval_expr(wx));
Ok(Val::I32((v.as_u32() != w.as_u32()) as u32))
}
Expr::RsPlus(ref vx, ref wx) => {
let v = try!(self.eval_expr(vx));
let w = try!(self.eval_expr(wx));
Ok(Val::I32(v.as_u32() + w.as_u32()))
}
Expr::RsMinus(ref vx, ref wx) => {
let v = try!(self.eval_expr(vx));
let w = try!(self.eval_expr(wx));
Ok(Val::I32(v.as_u32() - w.as_u32()))
}
}
}
#[inline]
fn eval_subs(&self, subs: &Vec<Expr>) -> Res<Vec<usize>> {
subs.iter().map(|v| self.eval_expr(v).map(|w| w.as_usize())).collect()
}
/// Dimension an array.
fn array_dim(&mut self, var: &Var, dims: &Vec<Expr>) -> Res<()> {
let dims = try!(self.eval_subs(dims));
match *var {
Var::A16(n, _) => self.tail[n].dimension(dims, 0),
Var::A32(n, _) => self.hybrid[n].dimension(dims, 0),
_ => return IE994.err(),
}
}
/// Assign to a variable.
fn assign(&mut self, var: &Var, val: Val) -> Res<()> {
match *var {
Var::I16(n) => Ok(self.spot[n].assign(try!(val.as_u16()))),
Var::I32(n) => Ok(self.twospot[n].assign(val.as_u32())),
Var::A16(n, ref subs) => {
let subs = try!(self.eval_subs(subs));
self.tail[n].set_md(subs, try!(val.as_u16()), 0)
}
Var::A32(n, ref subs) => {
let subs = try!(self.eval_subs(subs));
self.hybrid[n].set_md(subs, val.as_u32(), 0)
}
}
}
/// Look up the value of a variable.
fn lookup(&self, var: &Var) -> Res<Val> {
match *var {
Var::I16(n) => Ok(Val::I16(self.spot[n].val)),
Var::I32(n) => Ok(Val::I32(self.twospot[n].val)),
Var::A16(n, ref subs) => {
let subs = try!(self.eval_subs(subs));
self.tail[n].get_md(subs, 0).map(Val::I16)
}
Var::A32(n, ref subs) => {
let subs = try!(self.eval_subs(subs));
self.hybrid[n].get_md(subs, 0).map(Val::I32)
}
}
}
/// Process a STASH statement.
fn stash(&mut self, var: &Var) {
match *var {
Var::I16(n) => self.spot[n].stash(),
Var::I32(n) => self.twospot[n].stash(),
Var::A16(n, _) => self.tail[n].stash(),
Var::A32(n, _) => self.hybrid[n].stash(),
}
}
/// Process a RETRIEVE statement.
fn retrieve(&mut self, var: &Var) -> Res<()> {
match *var {
Var::I16(n) => self.spot[n].retrieve(0),
Var::I32(n) => self.twospot[n].retrieve(0),
Var::A16(n, _) => self.tail[n].retrieve(0),
Var::A32(n, _) => self.hybrid[n].retrieve(0),
}
}
/// Process an IGNORE or REMEMBER statement. Cannot fail.
fn set_rw(&mut self, var: &Var, rw: bool) {
match *var {
Var::I16(n) => self.spot[n].rw = rw,
Var::I32(n) => self.twospot[n].rw = rw,
Var::A16(n, _) => self.tail[n].rw = rw,
Var::A32(n, _) => self.hybrid[n].rw = rw,
}
}
/// P()rocess an ABSTAIN or REINSTATE statement. Cannot fail.
fn abstain(&mut self, what: &ast::Abstain, f: &Fn(u32) -> u32) {
if let &ast::Abstain::Label(lbl) = what {
let idx = self.program.labels[&lbl] as usize;
if self.program.stmts[idx].body != StmtBody::GiveUp {
self.abstain[idx] = f(self.abstain[idx]);
}
} else {
for (i, stype) in self.program.stmt_types.iter().enumerate() {
if stype == what {
self.abstain[i] = f(self.abstain[i]);
}
}
}
}
/// Array readout helper.
fn array_readout(&mut self, var: &Var) -> Res<()> {
let state = &mut self.last_out;
match *var {
Var::A16(n, _) => self.tail[n].readout(self.stdout, state, 0),
Var::A32(n, _) => self.hybrid[n].readout(self.stdout, state, 0),
_ => return IE994.err(),
}
}
/// Array writein helper.
fn array_writein(&mut self, var: &Var) -> Res<()> {
let state = &mut self.last_in;
match *var {
Var::A16(n, _) => self.tail[n].writein(state, 0),
Var::A32(n, _) => self.hybrid[n].writein(state, 0),
_ => return IE994.err(),
}
}
/// Debug helpers.
fn dump_state(&self) {
self.dump_state_one(&self.spot, ".");
self.dump_state_one(&self.twospot, ":");
self.dump_state_one(&self.tail, ",");
self.dump_state_one(&self.hybrid, ";");
if self.jumps.len() > 0 {
println!("Next stack: {:?}", self.jumps);
}
//println!("Abstained: {:?}", self.abstain);
}
fn dump_state_one<T: Debug + Display>(&self, vec: &Vec<Bind<T>>, sigil: &str) {
if vec.len() > 0 {
for (i, v) in vec.iter().enumerate() {
print!("{}{} = {}, ", sigil, i, v);
}
println!("");
}
}
}