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use wast::parser::{Parse, Parser, Result};
use crate::{Index, Integer, ValueType};
enum Paren {
None,
Left,
Right,
}
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct Level {
pub expr: Expression,
pub subexprs: Vec<Expression>,
}
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum Expression {
Unfolded(Instruction),
Folded(Instruction),
}
impl Expression {
fn subexprs(&mut self) -> &mut Vec<Expression> {
match self {
Self::Unfolded(i) => i.subexprs(),
Self::Folded(i) => i.subexprs(),
}
}
}
#[derive(Default)]
pub struct ExpressionParser {
exprs: Vec<Expression>,
stack: Vec<Level>,
}
impl ExpressionParser {
pub fn parse(mut self, parser: Parser) -> Result<Vec<Expression>> {
while !parser.is_empty() || !self.stack.is_empty() {
match self.paren(parser)? {
Paren::Left => {
let instr = parser.parse::<Instruction>()?;
self.stack.push(Level {
expr: Expression::Folded(instr),
subexprs: Vec::new(),
});
}
Paren::None => {
let instr = parser.parse::<Instruction>()?;
let expr = Expression::Unfolded(instr);
match self.stack.last_mut() {
Some(level) => level.subexprs.push(expr),
None => self.exprs.push(expr),
}
}
Paren::Right => match self.stack.pop() {
Some(mut level) => {
level.expr.subexprs().append(&mut level.subexprs);
if let Some(top) = self.stack.last_mut() {
top.subexprs.push(level.expr);
} else {
self.exprs.push(level.expr);
}
}
None => {}
},
}
}
Ok(self.exprs.clone())
}
fn paren(&self, parser: Parser) -> Result<Paren> {
parser.step(|cursor| {
Ok(match cursor.lparen() {
Some(rest) => (Paren::Left, rest),
None if self.stack.is_empty() => (Paren::None, cursor),
None => match cursor.rparen() {
Some(rest) => (Paren::Right, rest),
None => (Paren::None, cursor),
},
})
})
}
}
#[macro_export]
macro_rules! instructions {
(pub enum Instruction {
$(
$name:ident : $keyword:tt : $instr:tt {
$($field_name:ident: $field_type:ty),*
},
)*
}) => {
mod kw {
$(
wast::custom_keyword!($keyword = $instr);
)*
}
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum Instruction {
$(
$name($name),
)*
}
impl Instruction {
pub fn subexprs(&mut self) -> &mut Vec<Expression> {
match self {
$(
Self::$name(i) => &mut i.exprs,
)*
}
}
}
impl Parse<'_> for Instruction {
fn parse(parser: Parser<'_>) -> Result<Self> {
let mut l = parser.lookahead1();
$(
if l.peek::<kw::$keyword>() {
return Ok(Self::$name(parser.parse()?));
}
)*
Err(l.error())
}
}
$(
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct $name {
$(
pub $field_name: $field_type,
)*
pub exprs: Vec<Expression>,
}
impl Parse<'_> for $name {
fn parse(parser: Parser<'_>) -> Result<Self> {
parser.parse::<kw::$keyword>()?;
$(
let $field_name = parser.parse::<$field_type>()?;
)*
Ok(Self {
$(
$field_name,
)*
exprs: Vec::new(),
})
}
}
)*
};
}
instructions!(
pub enum Instruction {
Block : block : "block" { id: Option<Index> },
Br : br : "br" { id: Index },
BrIf : br_if : "br_if" { id: Index },
BrTable : br_table : "br_table" { ids: Index },
Call : call : "call" { id: Index },
Drop : drop : "drop" {},
GlobalGet : global_get : "global.get" { id: Index },
GlobalSet : global_set : "global.set" { id: Index },
I32Add : i32_add : "i32.add" {},
I32Const : i32_const : "i32.const" { integer: Integer },
I32Eq : i32_eq : "i32.eq" {},
I32Eqz : i32_eqz : "i32.eqz" {},
I32GtU : i32_gt_u : "i32.gt_u" {},
I32Ne : i32_ne : "i32.ne" {},
I32Sub : i32_sub : "i32.sub" {},
I64Const : i64_const : "i64.const" { integer: Integer },
If : r#if : "if" {},
Local : local : "local" { id: Index, value_type: ValueType },
LocalGet : local_get : "local.get" { id: Index },
LocalSet : local_set : "local.set" { id: Index },
LocalTee : local_tee : "local.tee" { id: Index },
Loop : r#loop : "loop" { id: Option<Index> },
Then : then : "then" {},
}
);