fn import_xform(
    cx: &mut Context,
    id: walrus::ImportId,
    instrs: &mut Vec<InstructionData>,
    params: &mut [AdapterType],
    results: &mut [AdapterType],
) {
    struct Arg {
        idx: usize,
        // Some(false) for a borrowed anyref, Some(true) for an owned one
        anyref: Option<bool>,
    }

    let mut to_delete = Vec::new();
    let mut iter = instrs.iter().enumerate();
    let mut args = Vec::new();
    while let Some((i, instr)) = iter.next() {
        match instr.instr {
            Instruction::CallAdapter(_) => break,
            Instruction::AnyrefLoadOwned | Instruction::TableGet => {
                let owned = match instr.instr {
                    Instruction::TableGet => false,
                    _ => true,
                };
                let mut arg: Arg = match args.pop().unwrap() {
                    Some(arg) => arg,
                    None => panic!("previous instruction must be `arg.get`"),
                };
                arg.anyref = Some(owned);
                match params[arg.idx] {
                    AdapterType::I32 => {}
                    _ => panic!("must be `i32` type"),
                }
                params[arg.idx] = AdapterType::Anyref;
                args.push(Some(arg));
                to_delete.push(i);
            }
            Instruction::Standard(wit_walrus::Instruction::ArgGet(n)) => {
                args.push(Some(Arg {
                    idx: n as usize,
                    anyref: None,
                }));
            }
            _ => match instr.stack_change {
                StackChange::Modified { pushed, popped } => {
                    for _ in 0..popped {
                        args.pop();
                    }
                    for _ in 0..pushed {
                        args.push(None);
                    }
                }
                StackChange::Unknown => {
                    panic!("must have stack change data");
                }
            },
        }
    }

    let mut ret_anyref = false;
    while let Some((i, instr)) = iter.next() {
        match instr.instr {
            Instruction::I32FromAnyrefOwned => {
                assert_eq!(results.len(), 1);
                match results[0] {
                    AdapterType::I32 => {}
                    _ => panic!("must be `i32` type"),
                }
                results[0] = AdapterType::Anyref;
                ret_anyref = true;
                to_delete.push(i);
            }
            _ => {}
        }
    }

    // Delete all unnecessary anyref management insructions
    for idx in to_delete.into_iter().rev() {
        instrs.remove(idx);
    }

    // Filter down our list of arguments to just the ones that are anyref
    // values.
    let args = args
        .iter()
        .filter_map(|arg| arg.as_ref())
        .filter_map(|arg| arg.anyref.map(|owned| (arg.idx, owned)))
        .collect::<Vec<_>>();

    // ... and register this entire transformation with the anyref
    // transformation pass.
    cx.import_xform(id, &args, ret_anyref);
}
/// Adapts the `instrs` given which are an implementation of the import of `id`.
///
/// This function will pattern match outgoing arguments and update the
/// instruction stream to remove any anyref-management instructions since
/// we'll be sinking those into the WebAssembly module.
Adapts the `instrs` given which are an implementation of the import of `id`.
This function will pattern match outgoing arguments and update the
instruction stream to remove any anyref-management instructions since
we'll be sinking those into the WebAssembly module.
Adapts the ` instrs ` given which are an implementation of the import of ` id ` . This function will pattern match outgoing arguments and update the instruction stream to remove any anyref - management instructions since we ' ll be sinking those into the WebAssembly module .
fn import_xform(
    cx: &mut Context,
    id: walrus::ImportId,
    instrs: &mut Vec<InstructionData>,
    params: &mut [AdapterType],
    results: &mut [AdapterType],
) {
    struct Arg {
        idx: usize,
        // Some(false) for a borrowed anyref, Some(true) for an owned one
        anyref: Option<bool>,
    }
    let mut to_delete = Vec::new();
    let mut iter = instrs.iter().enumerate();
    let mut args = Vec::new();
    while let Some((i, instr)) = iter.next() {
        match instr.instr {
            Instruction::CallAdapter(_) => break,
            Instruction::AnyrefLoadOwned | Instruction::TableGet => {
                let owned = match instr.instr {
                    Instruction::TableGet => false,
                    _ => true,
                };
                let mut arg: Arg = match args.pop().unwrap() {
                    Some(arg) => arg,
                    None => panic!("previous instruction must be `arg.get`"),
                };
                arg.anyref = Some(owned);
                match params[arg.idx] {
                    AdapterType::I32 => {}
                    _ => panic!("must be `i32` type"),
                }
                params[arg.idx] = AdapterType::Anyref;
                args.push(Some(arg));
                to_delete.push(i);
            }
            Instruction::Standard(wit_walrus::Instruction::ArgGet(n)) => {
                args.push(Some(Arg {
                    idx: n as usize,
                    anyref: None,
                }));
            }
            _ => match instr.stack_change {
                StackChange::Modified { pushed, popped } => {
                    for _ in 0..popped {
                        args.pop();
                    }
                    for _ in 0..pushed {
                        args.push(None);
                    }
                }
                StackChange::Unknown => {
                    panic!("must have stack change data");
                }
            },
        }
    }
    let mut ret_anyref = false;
    while let Some((i, instr)) = iter.next() {
        match instr.instr {
            Instruction::I32FromAnyrefOwned => {
                assert_eq!(results.len(), 1);
                match results[0] {
                    AdapterType::I32 => {}
                    _ => panic!("must be `i32` type"),
                }
                results[0] = AdapterType::Anyref;
                ret_anyref = true;
                to_delete.push(i);
            }
            _ => {}
        }
    }
    // Delete all unnecessary anyref management insructions
    for idx in to_delete.into_iter().rev() {
        instrs.remove(idx);
    }
    // Filter down our list of arguments to just the ones that are anyref
    // values.
    let args = args
        .iter()
        .filter_map(|arg| arg.as_ref())
        .filter_map(|arg| arg.anyref.map(|owned| (arg.idx, owned)))
        .collect::<Vec<_>>();
    // ... and register this entire transformation with the anyref
    // transformation pass.
    cx.import_xform(id, &args, ret_anyref);
}
fn import_xform ( cx : & mut Context , id : walrus :: ImportId , instrs : & mut Vec < InstructionData > , params : & mut [ AdapterType ] , results : & mut [ AdapterType ] , ) { struct Arg { idx : usize , // Some(false) for a borrowed anyref, Some(true) for an owned one anyref : Option < bool > , } let mut to_delete = Vec :: new ( ) ; let mut iter = instrs . iter ( ) . enumerate ( ) ; let mut args = Vec :: new ( ) ; while let Some ( ( i , instr ) ) = iter . next ( ) { match instr . instr { Instruction :: CallAdapter ( _ ) => break , Instruction :: AnyrefLoadOwned | Instruction :: TableGet => { let owned = match instr . instr { Instruction :: TableGet => false , _ => true , } ; let mut arg : Arg = match args . pop ( ) . unwrap ( ) { Some ( arg ) => arg , None => panic ! ( " " ) , } ; arg . anyref = Some ( owned ) ; match params [ arg . idx ] { AdapterType :: I32 => { } _ => panic ! ( " " ) , } params [ arg . idx ] = AdapterType :: Anyref ; args . push ( Some ( arg ) ) ; to_delete . push ( i ) ; } Instruction :: Standard ( wit_walrus :: Instruction :: ArgGet ( n ) ) => { args . push ( Some ( Arg { idx : n as usize , anyref : None , } ) ) ; } _ => match instr . stack_change { StackChange :: Modified { pushed , popped } => { for _ in 0 .. popped { args . pop ( ) ; } for _ in 0 .. pushed { args . push ( None ) ; } } StackChange :: Unknown => { panic ! ( " " ) ; } } , } } let mut ret_anyref = false ; while let Some ( ( i , instr ) ) = iter . next ( ) { match instr . instr { Instruction :: I32FromAnyrefOwned => { assert_eq ! ( results len ( ) 1 ) ; match results [ 0 ] { AdapterType :: I32 => { } _ => panic ! ( " " ) , } results [ 0 ] = AdapterType :: Anyref ; ret_anyref = true ; to_delete . push ( i ) ; } _ => { } } } // Delete all unnecessary anyref management insructions for idx in to_delete . into_iter ( ) . rev ( ) { instrs . remove ( idx ) ; } // Filter down our list of arguments to just the ones that are anyref // values. let args = args . iter ( ) . filter_map ( | arg | arg . as_ref ( ) ) . filter_map ( | arg | arg . anyref . map ( | owned | ( arg . idx , owned ) ) ) . collect :: < Vec < _ > > ( ) ; // ... and register this entire transformation with the anyref // transformation pass. cx . import_xform ( id , & args , ret_anyref ) ; }
Adapts the `instrs` given which are an implementation of the import of `id`.
Adapts the ` instrs ` given which are an implementation of the import of ` id ` .
cx
&mut Context
id
walrus::ImportId
instrs
&mut Vec<InstructionData>
params
&mut [AdapterType]
results
&mut [AdapterType]
cx
&mut Context
id
walrus::ImportId
instrs
&mut Vec<InstructionData>
params
&mut [AdapterType]
results
&mut [AdapterType]