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//! ImlProgram glues ImlParselets, ImlOps and ImlValues together to produce a VM program.
use super::*;
use crate::value::Parselet;
use crate::vm::Program;
use crate::Error;
use crate::{Object, RefValue};
use indexmap::IndexMap;
use std::cell::RefCell;
use std::collections::{HashMap, HashSet};
use std::rc::Rc;
#[derive(Debug)]
pub(in crate::compiler) struct ImlProgram {
statics: IndexMap<ImlValue, Option<Parselet>>, // static values with optional final parselet replacement
pub errors: Vec<Error>, // errors collected during finalization (at least these are unresolved symbols)
}
impl ImlProgram {
pub fn new(main: ImlValue) -> Self {
let mut statics = IndexMap::new();
statics.insert(main, None);
ImlProgram {
statics,
errors: Vec::new(),
}
}
/** Registers an ImlValue in the ImlProgram's statics map and returns its index.
In case *value* already exists inside of the current statics, the existing index will be returned,
otherwiese the value is cloned and put into the statics table. */
pub fn register(&mut self, value: &ImlValue) -> usize {
if let ImlValue::Shared(value) = value {
return self.register(&*value.borrow());
}
match self.statics.get_index_of(value) {
None => self.statics.insert_full(value.clone(), None).0,
Some(idx) => idx,
}
}
/** Turns the ImlProgram and its intermediate values into a final VM program ready for execution.
The finalization is done according to a grammar's point of view, as this is one of Tokays core features.
This closure algorithm runs until no more changes on any parselet configurations regarding left-recursive
and nullable parselet detection occurs.
*/
pub fn compile(mut self) -> Result<Program, Vec<Error>> {
let mut finalize = Vec::new(); // list of consuming parselets required to be finalized
// Loop until end of statics is reached
let mut i = 0;
while i < self.statics.len() {
// Pick only intermediate parselets, other static values are directly moved
let outer = {
match self.statics.get_index(i).unwrap() {
(_, Some(_)) => unreachable!(), // may not exist!
(ImlValue::Parselet(parselet), None) => parselet.clone(),
_ => {
i += 1;
continue;
}
}
};
let parselet = outer.borrow();
// Memoize parselets required to be finalized (needs a general rework later...)
if parselet.consuming {
finalize.push(outer.clone());
}
// Compile parselet from intermediate parselet
let parselet = Parselet::new(
parselet.name.clone(),
None,
parselet.severity,
parselet
.signature
.iter()
.map(|var_value| {
(
// Copy parameter name
var_value.0.clone(),
// Register default value, if any
match &var_value.1 {
ImlValue::Void => None,
value => Some(self.register(value)),
},
)
})
.collect(),
parselet.locals,
parselet.begin.compile_to_vec(&mut self),
parselet.end.compile_to_vec(&mut self),
parselet.body.compile_to_vec(&mut self),
);
*self.statics.get_index_mut(i).unwrap().1 = Some(parselet);
i += 1;
}
let leftrec = self.finalize(finalize);
// Stop on any raised error
if !self.errors.is_empty() {
return Err(self.errors);
}
// Assemble all statics to be transferred into a Program
let statics: Vec<RefValue> = self
.statics
.into_iter()
.map(|(iml, parselet)| {
if let Some(mut parselet) = parselet {
if let ImlValue::Parselet(imlparselet) = iml {
parselet.consuming = leftrec
.get(&imlparselet.borrow().id())
.map_or(None, |leftrec| Some(*leftrec));
//println!("{:?} => {:?}", imlparselet.borrow().name, parselet.consuming);
}
RefValue::from(parselet)
} else {
iml.into_refvalue()
}
})
.collect();
/*
for (i, value) in statics.iter().enumerate() {
println!("{} : {:?}", i, value.borrow());
}
*/
Ok(Program::new(statics))
}
/** Internal function to finalize a program on a grammar's point of view.
The finalization performs a closure algorithm on every parselet to detect
- nullable parselets
- left-recursive parselets
until no more changes occur.
It can only be run on a previously compiled program without any unresolved usages.
*/
fn finalize(&mut self, parselets: Vec<Rc<RefCell<ImlParselet>>>) -> HashMap<usize, bool> {
#[derive(Debug, Clone, Copy, PartialEq, PartialOrd)]
struct Consumable {
leftrec: bool,
nullable: bool,
}
// Finalize ImlValue
fn finalize_value(
value: &ImlValue,
visited: &mut HashSet<usize>,
configs: &mut HashMap<usize, Consumable>,
) -> Option<Consumable> {
match value {
ImlValue::Shared(value) => finalize_value(&*value.borrow(), visited, configs),
ImlValue::Parselet(parselet) => {
match parselet.try_borrow() {
// In case the parselet cannot be borrowed, it is left-recursive!
Err(_) => Some(Consumable {
leftrec: true,
nullable: false,
}),
// Otherwise dive into this parselet...
Ok(parselet) => finalize_parselet(&parselet, visited, configs),
}
}
ImlValue::Value(callee) => {
if callee.is_consuming() {
//println!("{:?} called, which is nullable={:?}", callee, callee.is_nullable());
Some(Consumable {
leftrec: false,
nullable: callee.is_nullable(),
})
} else {
None
}
}
_ => None,
}
}
// Finalize ImlOp
fn finalize_op(
op: &ImlOp,
visited: &mut HashSet<usize>,
configs: &mut HashMap<usize, Consumable>,
) -> Option<Consumable> {
match op {
ImlOp::Call { target, .. } => finalize_value(target, visited, configs),
ImlOp::Alt { alts } => {
let mut leftrec = false;
let mut nullable = false;
let mut consumes = false;
for alt in alts {
if let Some(consumable) = finalize_op(alt, visited, configs) {
leftrec |= consumable.leftrec;
nullable |= consumable.nullable;
consumes = true;
}
}
if consumes {
Some(Consumable { leftrec, nullable })
} else {
None
}
}
ImlOp::Seq { seq, .. } => {
let mut leftrec = false;
let mut nullable = true;
let mut consumes = false;
for item in seq {
if !nullable {
break;
}
if let Some(consumable) = finalize_op(item, visited, configs) {
leftrec |= consumable.leftrec;
nullable = consumable.nullable;
consumes = true;
}
}
if consumes {
Some(Consumable { leftrec, nullable })
} else {
None
}
}
ImlOp::If { then, else_, .. } => {
let then = finalize_op(then, visited, configs);
if let Some(else_) = finalize_op(else_, visited, configs) {
if let Some(then) = then {
Some(Consumable {
leftrec: then.leftrec || else_.leftrec,
nullable: then.nullable || else_.nullable,
})
} else {
Some(else_)
}
} else {
then
}
}
ImlOp::Loop {
initial,
condition,
body,
..
} => {
let mut ret: Option<Consumable> = None;
for part in [initial, condition, body] {
let part = finalize_op(part, visited, configs);
if let Some(part) = part {
ret = if let Some(ret) = ret {
Some(Consumable {
leftrec: ret.leftrec || part.leftrec,
nullable: ret.nullable || part.nullable,
})
} else {
Some(part)
}
}
}
ret
}
// DEPRECATED BELOW!!!
ImlOp::Expect { body, .. } => finalize_op(body, visited, configs),
ImlOp::Not { body } | ImlOp::Peek { body } => finalize_op(body, visited, configs),
ImlOp::Repeat { body, min, .. } => {
if let Some(consumable) = finalize_op(body, visited, configs) {
if *min == 0 {
Some(Consumable {
leftrec: consumable.leftrec,
nullable: true,
})
} else {
Some(consumable)
}
} else {
None
}
}
// default case
_ => None,
}
}
// Finalize ImlParselet
fn finalize_parselet(
parselet: &ImlParselet,
visited: &mut HashSet<usize>,
configs: &mut HashMap<usize, Consumable>,
) -> Option<Consumable> {
// ... only if it's generally flagged to be consuming.
if !parselet.consuming {
return None;
}
let id = parselet.id();
if visited.contains(&id) {
Some(Consumable {
leftrec: false,
nullable: configs[&id].nullable,
})
} else {
visited.insert(id);
if !configs.contains_key(&id) {
configs.insert(
id,
Consumable {
leftrec: false,
nullable: false,
},
);
}
for part in [&parselet.begin, &parselet.body, &parselet.end] {
if let Some(result) = finalize_op(part, visited, configs) {
if configs[&id] < result {
configs.insert(id, result);
}
}
}
visited.remove(&id);
Some(Consumable {
leftrec: false,
nullable: configs[&id].nullable,
})
}
}
// Now, start the closure algorithm with left-recursive and nullable configurations for all parselets
// put into the finalize list.
let mut changes = true;
let mut configs = HashMap::new();
while changes {
changes = false;
for parselet in &parselets {
let parselet = parselet.borrow_mut(); // parselet is locked for left-recursion detection
changes = finalize_parselet(&*parselet, &mut HashSet::new(), &mut configs)
> configs.get(&parselet.id()).cloned();
}
}
/*
for parselet in parselets {
let parselet = parselet.borrow();
println!(
"{} consuming={:?}",
parselet.name.as_deref().unwrap_or("(unnamed)"),
configs[&parselet.id()]
);
}
*/
configs.into_iter().map(|(k, v)| (k, v.leftrec)).collect()
}
}