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use crate::ast::*;
use std::mem;
#[derive(Default)]
pub struct Expander<'a> {
to_append: Vec<ModuleField<'a>>,
funcs: u32,
memories: u32,
tables: u32,
globals: u32,
}
fn page_size() -> u32 {
1 << 16
}
impl<'a> Expander<'a> {
/// Process all elements of `fields`, with the specified expansion method.
///
/// This method will handle the `to_append` field of this `Expander`,
/// appending items after processing a `ModuleField` as necessary.
pub fn process(
&mut self,
fields: &mut Vec<ModuleField<'a>>,
mut f: impl FnMut(&mut Self, &mut ModuleField<'a>),
) {
let mut cur = 0;
while cur < fields.len() {
f(self, &mut fields[cur]);
for new in self.to_append.drain(..) {
fields.insert(cur, new);
cur += 1;
}
cur += 1;
}
}
/// Inverts inline `import` descriptions into actual `import` statements.
///
/// In doing so this also takes care of inline `export` statements, if any,
/// since we'll be removing the corresponding `ModuleField` item and
/// replacing it in-place.
///
/// To work right, `Import` field items must be visited first.
///
/// This will replace `item` in-place with an `Import` directive if an
/// inline import is found, and after this pass has been run no more inline
/// import directives should be present.
pub fn deinline_import(&mut self, item: &mut ModuleField<'a>) {
match item {
ModuleField::Func(f) => {
let (module, name) = match f.kind {
FuncKind::Import { module, name } => (module, name),
_ => return,
};
for name in f.exports.names.drain(..) {
self.to_append.push(ModuleField::Export(Export {
name,
kind: ExportKind::Func(Index::Num(self.funcs)),
}));
}
*item = ModuleField::Import(Import {
span: f.span,
module,
name,
id: f.name,
kind: ImportKind::Func(f.ty.clone()),
});
self.funcs += 1;
}
ModuleField::Memory(m) => {
let (module, name, ty) = match m.kind {
MemoryKind::Import { module, name, ty } => (module, name, ty),
_ => return,
};
for name in m.exports.names.drain(..) {
self.to_append.push(ModuleField::Export(Export {
name,
kind: ExportKind::Memory(Index::Num(self.memories)),
}));
}
*item = ModuleField::Import(Import {
span: m.span,
module,
name,
id: m.name,
kind: ImportKind::Memory(ty),
});
self.memories += 1;
}
ModuleField::Table(t) => {
let (module, name, ty) = match t.kind {
TableKind::Import { module, name, ty } => (module, name, ty),
_ => return,
};
for name in t.exports.names.drain(..) {
self.to_append.push(ModuleField::Export(Export {
name,
kind: ExportKind::Table(Index::Num(self.tables)),
}));
}
*item = ModuleField::Import(Import {
span: t.span,
module,
name,
id: t.name,
kind: ImportKind::Table(ty),
});
self.tables += 1;
}
ModuleField::Global(g) => {
let (module, name) = match g.kind {
GlobalKind::Import { module, name } => (module, name),
_ => return,
};
for name in g.exports.names.drain(..) {
self.to_append.push(ModuleField::Export(Export {
name,
kind: ExportKind::Global(Index::Num(self.globals)),
}));
}
*item = ModuleField::Import(Import {
span: g.span,
module,
name,
id: g.name,
kind: ImportKind::Global(g.ty),
});
self.globals += 1;
}
ModuleField::Import(i) => match i.kind {
ImportKind::Func(_) => self.funcs += 1,
ImportKind::Memory(_) => self.memories += 1,
ImportKind::Table(_) => self.tables += 1,
ImportKind::Global(_) => self.globals += 1,
},
_ => {}
}
}
/// Extracts all inline `export` annotations and creates
/// `ModuleField::Export` items.
///
/// Note that this executes after the `deinline_import` pass to ensure
/// indices all line up right.
pub fn deinline_export(&mut self, item: &mut ModuleField<'a>) {
match item {
ModuleField::Func(f) => {
for name in f.exports.names.drain(..) {
self.to_append.push(ModuleField::Export(Export {
name,
kind: ExportKind::Func(Index::Num(self.funcs)),
}));
}
self.funcs += 1;
}
ModuleField::Memory(m) => {
for name in m.exports.names.drain(..) {
self.to_append.push(ModuleField::Export(Export {
name,
kind: ExportKind::Memory(Index::Num(self.memories)),
}));
}
// If data is defined inline insert an explicit `data` module
// field here instead, switching this to a `Normal` memory.
if let MemoryKind::Inline(data) = &mut m.kind {
let len = data.iter().map(|l| l.len()).sum::<usize>() as u32;
let pages = (len + page_size() - 1) / page_size();
let kind = MemoryKind::Normal(MemoryType {
limits: Limits {
min: pages,
max: Some(pages),
},
shared: false,
});
let data = match mem::replace(&mut m.kind, kind) {
MemoryKind::Inline(data) => data,
_ => unreachable!(),
};
self.to_append.push(ModuleField::Data(Data {
span: m.span,
name: None,
kind: DataKind::Active {
memory: Index::Num(self.memories),
offset: Expression {
instrs: vec![Instruction::I32Const(0)],
},
},
data,
}));
}
self.memories += 1;
}
ModuleField::Table(t) => {
for name in t.exports.names.drain(..) {
self.to_append.push(ModuleField::Export(Export {
name,
kind: ExportKind::Table(Index::Num(self.tables)),
}));
}
// If data is defined inline insert an explicit `data` module
// field here instead, switching this to a `Normal` memory.
if let TableKind::Inline { payload, elem } = &mut t.kind {
let len = match payload {
ElemPayload::Indices(v) => v.len(),
ElemPayload::Exprs { exprs, .. } => exprs.len(),
};
let kind = TableKind::Normal(TableType {
limits: Limits {
min: len as u32,
max: Some(len as u32),
},
elem: *elem,
});
let payload = match mem::replace(&mut t.kind, kind) {
TableKind::Inline { payload, .. } => payload,
_ => unreachable!(),
};
self.to_append.push(ModuleField::Elem(Elem {
span: t.span,
name: None,
kind: ElemKind::Active {
table: Index::Num(self.tables),
offset: Expression {
instrs: vec![Instruction::I32Const(0)],
},
},
payload,
}));
}
self.tables += 1;
}
ModuleField::Global(g) => {
for name in g.exports.names.drain(..) {
self.to_append.push(ModuleField::Export(Export {
name,
kind: ExportKind::Global(Index::Num(self.globals)),
}));
}
self.globals += 1;
}
_ => {}
}
}
}