src/libstd/sys/wasm/args.rs

   1 // Copyright 2017 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 use ffi::OsString;
  12 use marker::PhantomData;
  13 use mem;
  14 use vec;
  15
  16 pub unsafe fn init(_argc: isize, _argv: *const *const u8) {
  17     // On wasm these should always be null, so there's nothing for us to do here
  18 }
  19
  20 pub unsafe fn cleanup() {
  21 }
  22
  23 pub fn args() -> Args {
  24     // When the runtime debugging is enabled we'll link to some extra runtime
  25     // functions to actually implement this. These are for now just implemented
  26     // in a node.js script but they're off by default as they're sort of weird
  27     // in a web-wasm world.
  28     if !super::DEBUG {
  29         return Args {
  30             iter: Vec::new().into_iter(),
  31             _dont_send_or_sync_me: PhantomData,
  32         }
  33     }
  34
  35     // You'll find the definitions of these in `src/etc/wasm32-shim.js`. These
  36     // are just meant for debugging and should not be relied on.
  37     extern {
  38         fn rust_wasm_args_count() -> usize;
  39         fn rust_wasm_args_arg_size(a: usize) -> usize;
  40         fn rust_wasm_args_arg_fill(a: usize, ptr: *mut u8);
  41     }
  42
  43     unsafe {
  44         let cnt = rust_wasm_args_count();
  45         let mut v = Vec::with_capacity(cnt);
  46         for i in 0..cnt {
  47             let n = rust_wasm_args_arg_size(i);
  48             let mut data = vec![0; n];
  49             rust_wasm_args_arg_fill(i, data.as_mut_ptr());
  50             v.push(mem::transmute::<Vec<u8>, OsString>(data));
  51         }
  52         Args {
  53             iter: v.into_iter(),
  54             _dont_send_or_sync_me: PhantomData,
  55         }
  56     }
  57 }
  58
  59 pub struct Args {
  60     iter: vec::IntoIter<OsString>,
  61     _dont_send_or_sync_me: PhantomData<*mut ()>,
  62 }
  63
  64 impl Args {
  65     pub fn inner_debug(&self) -> &[OsString] {
  66         self.iter.as_slice()
  67     }
  68 }
  69
  70 impl Iterator for Args {
  71     type Item = OsString;
  72     fn next(&mut self) -> Option<OsString> {
  73         self.iter.next()
  74     }
  75     fn size_hint(&self) -> (usize, Option<usize>) {
  76         self.iter.size_hint()
  77     }
  78 }
  79
  80 impl ExactSizeIterator for Args {
  81     fn len(&self) -> usize {
  82         self.iter.len()
  83     }
  84 }
  85
  86 impl DoubleEndedIterator for Args {
  87     fn next_back(&mut self) -> Option<OsString> {
  88         self.iter.next_back()
  89     }
  90 }