extendr_api/io/
load.rs

1use super::PstreamFormat;
2use crate::{catch_r_error, error::Error, error::Result, robj::Robj, throw_r_error};
3use extendr_ffi::{R_NilValue, R_Unserialize, R_inpstream_st, R_inpstream_t, SEXP};
4use std::io::Read;
5
6pub struct ReadHook {
7    func: Option<unsafe extern "C" fn(arg1: SEXP, arg2: SEXP) -> SEXP>,
8    data: SEXP,
9}
10
11pub trait Load {
12    /// Save an object in the R data format.
13    /// `version` should probably be 3.
14    fn load<P: AsRef<std::path::Path>>(
15        path: &P,
16        format: PstreamFormat,
17        hook: Option<ReadHook>,
18    ) -> Result<Robj> {
19        let mut reader = std::fs::File::open(path)
20            .map_err(|_| Error::Other(format!("could not open file {:?}", path.as_ref())))?;
21        Self::from_reader(&mut reader, format, hook)
22    }
23
24    /// Save an object in the R data format to a `Write` trait.
25    /// `version` should probably be 3.
26    fn from_reader<R: Read>(
27        reader: &mut R,
28        format: PstreamFormat,
29        hook: Option<ReadHook>,
30    ) -> Result<Robj> {
31        unsafe extern "C" fn inchar<R: Read>(arg1: R_inpstream_t) -> ::std::os::raw::c_int {
32            let reader = &mut *((*arg1).data as *mut R);
33            let buf: &mut [u8] = &mut [0_u8];
34            reader.read_exact(buf).map(|_| buf[0].into()).unwrap_or(-1)
35        }
36
37        unsafe extern "C" fn inbytes<R: Read>(
38            arg1: R_inpstream_t,
39            arg2: *mut ::std::os::raw::c_void,
40            arg3: ::std::os::raw::c_int,
41        ) {
42            let reader = &mut *((*arg1).data as *mut R);
43            let buf = std::slice::from_raw_parts_mut(arg2 as *mut u8, arg3 as usize);
44            if let Err(e) = reader.read_exact(buf) {
45                throw_r_error(format!("failed to read R serialization stream: {e}"));
46            }
47        }
48
49        let read_ptr: *mut R = reader as &mut R;
50        let data = read_ptr.cast::<std::ffi::c_void>();
51
52        let (hook_func, hook_data) = if let Some(hook) = hook {
53            (hook.func, hook.data)
54        } else {
55            (None, unsafe { R_NilValue })
56        };
57
58        // let sexp = self.get();
59        // pub type R_inpstream_t = *mut R_inpstream_st;
60        let mut state = R_inpstream_st {
61            data,
62            type_: format,
63            InChar: Some(inchar::<R>),
64            InBytes: Some(inbytes::<R>),
65            InPersistHookFunc: hook_func,
66            InPersistHookData: hook_data,
67            native_encoding: [0; 64],
68            nat2nat_obj: std::ptr::null_mut(),
69            nat2utf8_obj: std::ptr::null_mut(),
70        };
71
72        Ok(unsafe {
73            Robj::from_sexp(catch_r_error(move || {
74                R_Unserialize(&mut state as R_inpstream_t)
75            })?)
76        })
77    }
78}
79
80impl Load for Robj {}
extendr_api/io/load.rs

extendr_api/io/
load.rs
