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use crate::ast::{self, kw};
use crate::parser::{Parse, Parser, Result};
/// A defined WebAssembly memory instance inside of a module.
#[derive(Debug)]
pub struct Memory<'a> {
/// Where this `memory` was defined
pub span: ast::Span,
/// An optional name to refer to this memory by.
pub name: Option<ast::Id<'a>>,
/// If present, inline export annotations which indicate names this
/// definition should be exported under.
pub exports: ast::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 {
module: &'a str,
name: &'a str,
ty: ast::MemoryType,
},
/// A typical memory definition which simply says the limits of the memory
Normal(ast::MemoryType),
/// The data of this memory, starting from 0, explicitly listed
Inline(Vec<&'a [u8]>),
}
impl<'a> Parse<'a> for Memory<'a> {
fn parse(parser: Parser<'a>) -> Result<Self> {
let span = parser.parse::<kw::memory>()?.0;
let name = parser.parse()?;
let exports = parser.parse()?;
// Afterwards figure out which style this is, either:
//
// * `(data ...)`
// * `(import "a" "b") limits`
// * `limits`
let mut l = parser.lookahead1();
let kind = if l.peek::<ast::LParen>() {
enum Which<'a, T> {
Inline(Vec<T>),
Import(&'a str, &'a str),
}
let result = parser.parens(|parser| {
let mut l = parser.lookahead1();
if l.peek::<kw::data>() {
parser.parse::<kw::data>()?;
let mut data = Vec::new();
while !parser.is_empty() {
data.push(parser.parse()?);
}
Ok(Which::Inline(data))
} else if l.peek::<kw::import>() {
parser.parse::<kw::import>()?;
Ok(Which::Import(parser.parse()?, parser.parse()?))
} else {
Err(l.error())
}
})?;
match result {
Which::Inline(data) => MemoryKind::Inline(data),
Which::Import(module, name) => MemoryKind::Import {
module,
name,
ty: parser.parse()?,
},
}
} else if l.peek::<u32>() {
MemoryKind::Normal(parser.parse()?)
} else {
return Err(l.error());
};
Ok(Memory {
span,
name,
exports,
kind,
})
}
}
/// A `data` directive in a WebAssembly module.
#[derive(Debug)]
pub struct Data<'a> {
/// Where this `data` was defined
pub span: ast::Span,
/// The optional name of this data segment
pub name: Option<ast::Id<'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<&'a [u8]>,
}
/// 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: ast::Index<'a>,
/// Initial offset to load this data segment at
offset: ast::Expression<'a>,
},
}
impl<'a> Parse<'a> for Data<'a> {
fn parse(parser: Parser<'a>) -> Result<Self> {
let span = parser.parse::<kw::data>()?.0;
let name = parser.parse()?;
// The `passive` keyword is mentioned in the current spec but isn't
// mentioned in `wabt` tests, so consider it optional for now
let kind = if parser.peek::<kw::passive>() {
parser.parse::<kw::passive>()?;
DataKind::Passive
// If data directly follows then assume this is a passive segment
} else if parser.peek::<&[u8]>() {
DataKind::Passive
// ... and otherwise we must be attached to a particular memory as well
// as having an initialization offset.
} else {
let memory = if parser.peek2::<kw::memory>() {
Some(parser.parens(|p| {
p.parse::<kw::memory>()?;
p.parse()
})?)
} else {
parser.parse()?
};
let offset = parser.parens(|parser| {
if parser.peek::<kw::offset>() {
parser.parse::<kw::offset>()?;
}
parser.parse()
})?;
DataKind::Active {
memory: memory.unwrap_or(ast::Index::Num(0)),
offset,
}
};
let mut data = Vec::new();
while !parser.is_empty() {
data.push(parser.parse()?);
}
Ok(Data {
span,
name,
kind,
data,
})
}
}