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use crate::core::*;
use crate::kw;
use crate::parser::{Lookahead1, Parse, Parser, Peek, Result};
use crate::token::*;
/// A defined WebAssembly memory instance inside of a module.
#[derive(Debug)]
pub struct Memory<'a> {
/// Where this `memory` was defined
pub span: Span,
/// An optional name to refer to this memory by.
pub id: Option<Id<'a>>,
/// An optional name for this function stored in the custom `name` section.
pub name: Option<NameAnnotation<'a>>,
/// If present, inline export annotations which indicate names this
/// definition should be exported under.
pub exports: InlineExport<'a>,
/// How this memory is defined in the module.
pub kind: MemoryKind<'a>,
}
/// Different syntactical ways a memory can be defined in a module.
#[derive(Debug)]
pub enum MemoryKind<'a> {
/// This memory is actually an inlined import definition.
#[allow(missing_docs)]
Import {
import: InlineImport<'a>,
ty: MemoryType,
},
/// A typical memory definition which simply says the limits of the memory
Normal(MemoryType),
/// The data of this memory, starting from 0, explicitly listed
Inline {
/// Whether or not this will be creating a 64-bit memory
is64: bool,
/// The inline data specified for this memory
data: Vec<DataVal<'a>>,
},
}
impl<'a> Parse<'a> for Memory<'a> {
fn parse(parser: Parser<'a>) -> Result<Self> {
let span = parser.parse::<kw::memory>()?.0;
let id = parser.parse()?;
let name = parser.parse()?;
let exports = parser.parse()?;
// Afterwards figure out which style this is, either:
//
// * `(import "a" "b") limits`
// * `(data ...)`
// * `limits`
let mut l = parser.lookahead1();
let kind = if let Some(import) = parser.parse()? {
MemoryKind::Import {
import,
ty: parser.parse()?,
}
} else if l.peek::<LParen>()?
|| ((parser.peek::<kw::i32>()? || parser.peek::<kw::i64>()?)
&& parser.peek2::<LParen>()?)
{
let is64 = if parser.parse::<Option<kw::i32>>()?.is_some() {
false
} else {
parser.parse::<Option<kw::i64>>()?.is_some()
};
let data = parser.parens(|parser| {
parser.parse::<kw::data>()?;
let mut data = Vec::new();
while !parser.is_empty() {
data.push(parser.parse()?);
}
Ok(data)
})?;
MemoryKind::Inline { data, is64 }
} else if l.peek::<u32>()? || l.peek::<kw::i32>()? || l.peek::<kw::i64>()? {
MemoryKind::Normal(parser.parse()?)
} else {
return Err(l.error());
};
Ok(Memory {
span,
id,
name,
exports,
kind,
})
}
}
/// A `data` directive in a WebAssembly module.
#[derive(Debug)]
pub struct Data<'a> {
/// Where this `data` was defined
pub span: Span,
/// The optional name of this data segment
pub id: Option<Id<'a>>,
/// An optional name for this data stored in the custom `name` section.
pub name: Option<NameAnnotation<'a>>,
/// Whether this data segment is passive or active
pub kind: DataKind<'a>,
/// Bytes for this `Data` segment, viewed as the concatenation of all the
/// contained slices.
pub data: Vec<DataVal<'a>>,
}
/// Different kinds of data segments, either passive or active.
#[derive(Debug)]
pub enum DataKind<'a> {
/// A passive data segment which isn't associated with a memory and is
/// referenced from various instructions.
Passive,
/// An active data segment which is associated and loaded into a particular
/// memory on module instantiation.
Active {
/// The memory that this `Data` will be associated with.
memory: Index<'a>,
/// Initial offset to load this data segment at
offset: Expression<'a>,
},
}
impl<'a> Parse<'a> for Data<'a> {
fn parse(parser: Parser<'a>) -> Result<Self> {
let span = parser.parse::<kw::data>()?.0;
let id = parser.parse()?;
let name = parser.parse()?;
let kind = if parser.peek::<&[u8]>()? || parser.peek::<RParen>()? {
DataKind::Passive
// ... and otherwise we must be attached to a particular memory as well
// as having an initialization offset.
} else {
let memory = if parser.peek::<u32>()? {
// FIXME: this is only here to accomodate
// proposals/threads/imports.wast at this current moment in
// time, this probably should get removed when the threads
// proposal is rebased on the current spec.
Index::Num(parser.parse()?, span)
} else if parser.peek2::<kw::memory>()? {
parser.parens(|p| {
p.parse::<kw::memory>()?;
p.parse()
})?
} else {
Index::Num(0, span)
};
let offset = parser.parens(|parser| {
if parser.peek::<kw::offset>()? {
parser.parse::<kw::offset>()?;
parser.parse()
} else {
// This is all that the spec allows, which is that if
// `offset` isn't present then this is "sugar" for a
// single-instruction expression.
let insn = parser.parse()?;
if parser.is_empty() {
return Ok(Expression::one(insn));
}
// This is support for what is currently invalid syntax
// according to the strict specification but is otherwise
// present in the spec test suite:
//
// (data (i32.add (i32.const 0) (i32.const 0)))
//
// Technically the spec says this should be:
//
// (data (offset ...))
//
// but alas
let mut expr: Expression = parser.parse()?;
let mut instrs = Vec::from(expr.instrs);
instrs.push(insn);
expr.instrs = instrs.into();
Ok(expr)
}
})?;
DataKind::Active { memory, offset }
};
let mut data = Vec::new();
while !parser.is_empty() {
data.push(parser.parse()?);
}
Ok(Data {
span,
id,
name,
kind,
data,
})
}
}
/// Differnet ways the value of a data segment can be defined.
#[derive(Debug)]
#[allow(missing_docs)]
pub enum DataVal<'a> {
String(&'a [u8]),
Integral(Vec<u8>),
}
impl DataVal<'_> {
/// Returns the length, in bytes, of the memory used to represent this data
/// value.
pub fn len(&self) -> usize {
match self {
DataVal::String(s) => s.len(),
DataVal::Integral(s) => s.len(),
}
}
/// Pushes the value of this data value onto the provided list of bytes.
pub fn push_onto(&self, dst: &mut Vec<u8>) {
match self {
DataVal::String(s) => dst.extend_from_slice(s),
DataVal::Integral(s) => dst.extend_from_slice(s),
}
}
}
impl<'a> Parse<'a> for DataVal<'a> {
fn parse(parser: Parser<'a>) -> Result<Self> {
if !parser.peek::<LParen>()? {
return Ok(DataVal::String(parser.parse()?));
}
return parser.parens(|p| {
let mut result = Vec::new();
let mut lookahead = p.lookahead1();
let l = &mut lookahead;
let r = &mut result;
if consume::<kw::i8, i8, _>(p, l, r, |u, v| v.push(u as u8))?
|| consume::<kw::i16, i16, _>(p, l, r, |u, v| v.extend(&u.to_le_bytes()))?
|| consume::<kw::i32, i32, _>(p, l, r, |u, v| v.extend(&u.to_le_bytes()))?
|| consume::<kw::i64, i64, _>(p, l, r, |u, v| v.extend(&u.to_le_bytes()))?
|| consume::<kw::f32, F32, _>(p, l, r, |u, v| v.extend(&u.bits.to_le_bytes()))?
|| consume::<kw::f64, F64, _>(p, l, r, |u, v| v.extend(&u.bits.to_le_bytes()))?
|| consume::<kw::v128, V128Const, _>(p, l, r, |u, v| v.extend(&u.to_le_bytes()))?
{
Ok(DataVal::Integral(result))
} else {
Err(lookahead.error())
}
});
fn consume<'a, T: Peek + Parse<'a>, U: Parse<'a>, F>(
parser: Parser<'a>,
lookahead: &mut Lookahead1<'a>,
dst: &mut Vec<u8>,
push: F,
) -> Result<bool>
where
F: Fn(U, &mut Vec<u8>),
{
if !lookahead.peek::<T>()? {
return Ok(false);
}
parser.parse::<T>()?;
while !parser.is_empty() {
let val = parser.parse::<U>()?;
push(val, dst);
}
Ok(true)
}
}
}