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use crate::ast::*;
use crate::resolve::gensym;
use std::collections::{hash_map::Entry, HashMap};
pub fn run(fields: &mut Vec<ModuleField>) {
let mut cur = 0;
let mut cx = Expander::default();
// Note that insertion here is somewhat tricky. We're injecting aliases
// which will affect the index spaces for each kind of item being aliased.
// In the final binary aliases will come before all locally defined items,
// notably via the sorting in binary emission of this crate. To account for
// this index space behavior we need to ensure that aliases all appear at
// the right place in the module.
//
// The general algorithm here is that aliases discovered in the "header" of
// the module, e.g. imports/aliases/types/etc, are all inserted preceding
// the field that the alias is found within. After the header, however, the
// position of the header is recorded and all future aliases will be
// inserted at that location.
//
// This ends up meaning that aliases found in globals/functions/tables/etc
// will precede all of those definitions, being positioned at a point that
// should come after all the instances that are defined as well. Overall
// this isn't the cleanest algorithm and probably isn't the final form of
// those. It's hoped that discussion on WebAssembly/module-linking#25 might
// lead to a good solution.
let mut insertion_point = None;
while cur < fields.len() {
let field = &mut fields[cur];
match field {
ModuleField::Alias(_)
| ModuleField::Type(_)
| ModuleField::Import(_)
| ModuleField::NestedModule(_)
| ModuleField::Instance(_) => {}
_ if insertion_point.is_none() => insertion_point = Some(cur),
_ => {}
}
cx.process(field);
if insertion_point.is_none() {
for item in cx.to_prepend.drain(..) {
fields.insert(cur, item);
cur += 1;
}
}
cur += 1;
}
if let Some(mut i) = insertion_point {
for item in cx.to_prepend.drain(..) {
fields.insert(i, item);
i += 1;
}
}
assert!(cx.to_prepend.is_empty());
}
#[derive(Default)]
struct Expander<'a> {
to_prepend: Vec<ModuleField<'a>>,
instances: HashMap<(Index<'a>, &'a str, ExportKind), Index<'a>>,
parents: HashMap<(Index<'a>, Index<'a>, ExportKind), Index<'a>>,
}
impl<'a> Expander<'a> {
fn process(&mut self, field: &mut ModuleField<'a>) {
match field {
ModuleField::Alias(a) => {
let id = gensym::fill(a.span, &mut a.id);
match &mut a.kind {
AliasKind::InstanceExport {
instance,
export,
kind,
} => {
self.expand(instance);
self.instances
.insert((*instance.unwrap_index(), export, *kind), id.into());
}
AliasKind::Outer {
module,
index,
kind,
} => {
self.parents.insert((*module, *index, *kind), id.into());
}
}
}
ModuleField::Instance(i) => {
if let InstanceKind::Inline { module, args } = &mut i.kind {
self.expand(module);
for arg in args {
self.expand(&mut arg.index);
}
}
}
ModuleField::Elem(e) => {
if let ElemKind::Active { table, .. } = &mut e.kind {
self.expand(table);
}
match &mut e.payload {
ElemPayload::Indices(funcs) => {
for func in funcs {
self.expand(func);
}
}
ElemPayload::Exprs { exprs, .. } => {
for func in exprs {
if let Some(func) = func {
self.expand(func);
}
}
}
}
}
ModuleField::Data(e) => {
if let DataKind::Active { memory, .. } = &mut e.kind {
self.expand(memory);
}
}
ModuleField::Export(e) => self.expand(&mut e.index),
ModuleField::Func(f) => {
self.expand_type_use(&mut f.ty);
if let FuncKind::Inline { expression, .. } = &mut f.kind {
self.expand_expr(expression);
}
}
ModuleField::Import(i) => self.expand_item_sig(&mut i.item),
ModuleField::Global(g) => {
if let GlobalKind::Inline(expr) = &mut g.kind {
self.expand_expr(expr);
}
}
ModuleField::Start(s) => self.expand(s),
ModuleField::Event(e) => match &mut e.ty {
EventType::Exception(t) => self.expand_type_use(t),
},
ModuleField::NestedModule(m) => match &mut m.kind {
NestedModuleKind::Import { ty, .. } => self.expand_type_use(ty),
NestedModuleKind::Inline { fields } => run(fields),
},
ModuleField::Custom(_)
| ModuleField::Memory(_)
| ModuleField::Table(_)
| ModuleField::Type(_) => {}
}
}
fn expand_item_sig(&mut self, sig: &mut ItemSig<'a>) {
match &mut sig.kind {
ItemKind::Func(t) => self.expand_type_use(t),
ItemKind::Module(t) => self.expand_type_use(t),
ItemKind::Instance(t) => self.expand_type_use(t),
ItemKind::Table(_) => {}
ItemKind::Memory(_) => {}
ItemKind::Global(_) => {}
ItemKind::Event(_) => {}
}
}
fn expand_type_use<T>(&mut self, ty: &mut TypeUse<'a, T>) {
if let Some(index) = &mut ty.index {
self.expand(index);
}
}
fn expand_expr(&mut self, expr: &mut Expression<'a>) {
for instr in expr.instrs.iter_mut() {
self.expand_instr(instr);
}
}
fn expand_instr(&mut self, instr: &mut Instruction<'a>) {
use Instruction::*;
if let Some(m) = instr.memarg_mut() {
self.expand(&mut m.memory);
}
match instr {
Call(i) | ReturnCall(i) | RefFunc(i) => self.expand(&mut i.0),
CallIndirect(i) | ReturnCallIndirect(i) => {
self.expand(&mut i.table);
self.expand_type_use(&mut i.ty);
}
TableInit(i) => self.expand(&mut i.table),
MemoryInit(i) => self.expand(&mut i.mem),
TableCopy(i) => {
self.expand(&mut i.src);
self.expand(&mut i.dst);
}
MemoryCopy(i) => {
self.expand(&mut i.src);
self.expand(&mut i.dst);
}
GlobalSet(g) | GlobalGet(g) => self.expand(&mut g.0),
TableGet(t) | TableSet(t) | TableFill(t) | TableSize(t) | TableGrow(t) => {
self.expand(&mut t.dst)
}
MemorySize(m) | MemoryGrow(m) | MemoryFill(m) => self.expand(&mut m.mem),
_ => {}
}
}
fn expand<T>(&mut self, item: &mut ItemRef<'a, T>)
where
T: Into<ExportKind> + Copy,
{
match item {
ItemRef::Outer { kind, module, idx } => {
let key = (*module, *idx, (*kind).into());
let idx = match self.parents.entry(key) {
Entry::Occupied(e) => *e.get(),
Entry::Vacant(v) => {
let span = idx.span();
let id = gensym::gen(span);
self.to_prepend.push(ModuleField::Alias(Alias {
span,
id: Some(id),
name: None,
kind: AliasKind::Outer {
module: *module,
index: *idx,
kind: (*kind).into(),
},
}));
*v.insert(Index::Id(id))
}
};
*item = ItemRef::Item {
kind: *kind,
idx,
exports: Vec::new(),
};
}
ItemRef::Item { kind, idx, exports } => {
let mut cur = *idx;
let len = exports.len();
for (i, export) in exports.drain(..).enumerate() {
let kind = if i < len - 1 {
ExportKind::Instance
} else {
(*kind).into()
};
let key = (cur, export, kind);
cur = match self.instances.entry(key) {
Entry::Occupied(e) => *e.get(),
Entry::Vacant(v) => {
let span = idx.span();
let id = gensym::gen(span);
self.to_prepend.push(ModuleField::Alias(Alias {
span,
id: Some(id),
name: None,
kind: AliasKind::InstanceExport {
kind,
instance: ItemRef::Item {
kind: kw::instance(span),
idx: cur,
exports: Vec::new(),
},
export,
},
}));
*v.insert(Index::Id(id))
}
};
}
*idx = cur;
}
}
}
}