Calling Rust from other languages

My lightning talk at PolyConf 2015.

Transcript

1. Zbigniew Siciarz @zsiciarz
   siciarz.net
   

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2. Zbigniew Siciarz @zsiciarz
   siciarz.net
   (mostly) Python developer
   http://rustwarsaw.org/
   http://zsiciarz.github.io/24daysofrust/
   

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3. Zbigniew Siciarz @zsiciarz
   siciarz.net
   

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4. Zbigniew Siciarz @zsiciarz
   siciarz.net
   

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5. fn rust_substrings(value: &str, substr: &str) -> i32 {
   let mut count = 0;
   let substr_len = substr.len();
   let upper_bound = value.len() - substr_len + 1;
   for c in 0..upper_bound {
   let possible_match = &value[c..c+substr_len];
   if possible_match == substr {
   count += 1;
   }
   }
   count
   }
   Zbigniew Siciarz @zsiciarz
   siciarz.net
   

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6. Zbigniew Siciarz @zsiciarz
   siciarz.net
   

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7. #[no_mangle]
   pub extern "C" fn count_substrings(
   value: *const c_char, substr: *const c_char) -> i32 {
   let c_value = unsafe {
   CStr::from_ptr(value).to_bytes()
   };
   let c_substr = unsafe {
   CStr::from_ptr(substr).to_bytes()
   };
   match str::from_utf8(c_value) {
   Ok(value) => match str::from_utf8(c_substr) {
   Ok(substr) => rust_substrings(value, substr),
   Err(_) => -1,
   },
   Err(_) => -1,
   }
   }
   Zbigniew Siciarz @zsiciarz
   siciarz.net
   

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8. #include
   #include
   int32_t count_substrings(const char* value, const char*
   substr);
   int main() {
   printf("%d\n", count_substrings("banana", "na"));
   return 0;
   }s
   Zbigniew Siciarz @zsiciarz
   siciarz.net
   

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9. import ctypes
   library_name = "../target/debug/libstringtools.so"
   stringtools = ctypes.CDLL(library_name)
   print(stringtools.count_substrings(b"banana", b"na"))
   Zbigniew Siciarz @zsiciarz
   siciarz.net
   

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10. require 'ffi'
    module StringTools
    extend FFI::Library
    ffi_lib "../target/debug/libstringtools.so"
    attach_function :count_substrings, [:string, :string], :int
    end
    puts StringTools.count_substrings("banana", "na")
    Zbigniew Siciarz @zsiciarz
    siciarz.net
    

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11. using System;
    using System.Runtime.InteropServices;
    public class StringTools
    {
    [DllImport("../target/debug/libstringtools.so")]
    public static extern Int32 count_substrings(string value,
    string substr);
    static public void Main()
    {
    Console.WriteLine(count_substrings("banana", "na"));
    }
    }
    Zbigniew Siciarz @zsiciarz
    siciarz.net
    

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12. {-# LANGUAGE ForeignFunctionInterface #-}
    import Foreign.C.String (CString, newCString)
    foreign import ccall "count_substrings"
    count_substrings :: CString -> CString -> IO Int
    main :: IO ()
    main = do
    value <- newCString "banana"
    substr <- newCString "na"
    count_substrings value substr >>= print
    Zbigniew Siciarz @zsiciarz
    siciarz.net
    

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13. package main
    // #cgo LDFLAGS: -L../target/debug -lstringtools
    // int count_substrings(const char* value, const char*
    substr);
    import "C"
    import "fmt"
    func main() {
    value := C.CString("banana")
    substr := C.CString("na")
    fmt.Println(C.count_substrings(value, substr))
    }
    Zbigniew Siciarz @zsiciarz
    siciarz.net
    

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14. // sorry, code too long :(
    Zbigniew Siciarz @zsiciarz
    siciarz.net
    

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15. Zbigniew Siciarz @zsiciarz
    siciarz.net
    http://jakegoulding.com/rust-ffi-omnibus/
    https://github.com/zsiciarz/rust-ffi-stringtools
    https://github.com/alexcrichton/rust-ffi-examples
    https://doc.rust-lang.org/book/ffi.html
    

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