_ Git - rust-lightning/blob - c-bindings-gen/src/blocks.rs

   1 //! Printing logic for basic blocks of Rust-mapped code - parts of functions and declarations but
   2 //! not the full mapping logic.
   3
   4 use std::fs::File;
   5 use std::io::Write;
   6 use proc_macro2::{TokenTree, Span};
   7
   8 use crate::types::*;
   9
  10 /// Writes out a C++ wrapper class for the given type, which contains various utilities to access
  11 /// the underlying C-mapped type safely avoiding some common memory management issues by handling
  12 /// resource-freeing and prevending accidental raw copies.
  13 pub fn write_cpp_wrapper(cpp_header_file: &mut File, ty: &str, has_destructor: bool) {
  14         writeln!(cpp_header_file, "class {} {{", ty).unwrap();
  15         writeln!(cpp_header_file, "private:").unwrap();
  16         writeln!(cpp_header_file, "\tLDK{} self;", ty).unwrap();
  17         writeln!(cpp_header_file, "public:").unwrap();
  18         writeln!(cpp_header_file, "\t{}(const {}&) = delete;", ty, ty).unwrap();
  19         writeln!(cpp_header_file, "\t{}({}&& o) : self(o.self) {{ memset(&o, 0, sizeof({})); }}", ty, ty, ty).unwrap();
  20         writeln!(cpp_header_file, "\t{}(LDK{}&& m_self) : self(m_self) {{ memset(&m_self, 0, sizeof(LDK{})); }}", ty, ty, ty).unwrap();
  21         writeln!(cpp_header_file, "\toperator LDK{}() && {{ LDK{} res = self; memset(&self, 0, sizeof(LDK{})); return res; }}", ty, ty, ty).unwrap();
  22         if has_destructor {
  23                 writeln!(cpp_header_file, "\t~{}() {{ {}_free(self); }}", ty, ty).unwrap();
  24                 writeln!(cpp_header_file, "\t{}& operator=({}&& o) {{ {}_free(self); self = o.self; memset(&o, 0, sizeof({})); return *this; }}", ty, ty, ty, ty).unwrap();
  25         } else {
  26                 writeln!(cpp_header_file, "\t{}& operator=({}&& o) {{ self = o.self; memset(&o, 0, sizeof({})); return *this; }}", ty, ty, ty).unwrap();
  27         }
  28         writeln!(cpp_header_file, "\tLDK{}* operator &() {{ return &self; }}", ty).unwrap();
  29         writeln!(cpp_header_file, "\tLDK{}* operator ->() {{ return &self; }}", ty).unwrap();
  30         writeln!(cpp_header_file, "\tconst LDK{}* operator &() const {{ return &self; }}", ty).unwrap();
  31         writeln!(cpp_header_file, "\tconst LDK{}* operator ->() const {{ return &self; }}", ty).unwrap();
  32         writeln!(cpp_header_file, "}};").unwrap();
  33 }
  34
  35 /// Writes out a C-callable concrete Result<A, B> struct and utility methods
  36 pub fn write_result_block<W: std::io::Write>(w: &mut W, mangled_container: &str, ok_type: &str, err_type: &str) {
  37         writeln!(w, "#[repr(C)]").unwrap();
  38         writeln!(w, "pub union {}Ptr {{", mangled_container).unwrap();
  39         if ok_type != "()" {
  40                 writeln!(w, "\tpub result: *mut {},", ok_type).unwrap();
  41         } else {
  42                 writeln!(w, "\t/// Note that this value is always NULL, as there are no contents in the OK variant").unwrap();
  43                 writeln!(w, "\tpub result: *mut std::ffi::c_void,").unwrap();
  44         }
  45         if err_type != "()" {
  46                 writeln!(w, "\tpub err: *mut {},", err_type).unwrap();
  47         } else {
  48                 writeln!(w, "\t/// Note that this value is always NULL, as there are no contents in the Err variant").unwrap();
  49                 writeln!(w, "\tpub err: *mut std::ffi::c_void,").unwrap();
  50         }
  51         writeln!(w, "}}").unwrap();
  52         writeln!(w, "#[repr(C)]").unwrap();
  53         writeln!(w, "pub struct {} {{", mangled_container).unwrap();
  54         writeln!(w, "\tpub contents: {}Ptr,", mangled_container).unwrap();
  55         writeln!(w, "\tpub result_ok: bool,").unwrap();
  56         writeln!(w, "}}").unwrap();
  57
  58         writeln!(w, "#[no_mangle]").unwrap();
  59         if ok_type != "()" {
  60                 writeln!(w, "pub extern \"C\" fn {}_ok(o: {}) -> {} {{", mangled_container, ok_type, mangled_container).unwrap();
  61         } else {
  62                 writeln!(w, "pub extern \"C\" fn {}_ok() -> {} {{", mangled_container, mangled_container).unwrap();
  63         }
  64         writeln!(w, "\t{} {{", mangled_container).unwrap();
  65         writeln!(w, "\t\tcontents: {}Ptr {{", mangled_container).unwrap();
  66         if ok_type != "()" {
  67                 writeln!(w, "\t\t\tresult: Box::into_raw(Box::new(o)),").unwrap();
  68         } else {
  69                 writeln!(w, "\t\t\tresult: std::ptr::null_mut(),").unwrap();
  70         }
  71         writeln!(w, "\t\t}},").unwrap();
  72         writeln!(w, "\t\tresult_ok: true,").unwrap();
  73         writeln!(w, "\t}}").unwrap();
  74         writeln!(w, "}}").unwrap();
  75
  76         writeln!(w, "#[no_mangle]").unwrap();
  77         if err_type != "()" {
  78                 writeln!(w, "pub extern \"C\" fn {}_err(e: {}) -> {} {{", mangled_container, err_type, mangled_container).unwrap();
  79         } else {
  80                 writeln!(w, "pub extern \"C\" fn {}_err() -> {} {{", mangled_container, mangled_container).unwrap();
  81         }
  82         writeln!(w, "\t{} {{", mangled_container).unwrap();
  83         writeln!(w, "\t\tcontents: {}Ptr {{", mangled_container).unwrap();
  84         if err_type != "()" {
  85                 writeln!(w, "\t\t\terr: Box::into_raw(Box::new(e)),").unwrap();
  86         } else {
  87                 writeln!(w, "\t\t\terr: std::ptr::null_mut(),").unwrap();
  88         }
  89         writeln!(w, "\t\t}},").unwrap();
  90         writeln!(w, "\t\tresult_ok: false,").unwrap();
  91         writeln!(w, "\t}}").unwrap();
  92         writeln!(w, "}}").unwrap();
  93
  94         writeln!(w, "#[no_mangle]").unwrap();
  95         writeln!(w, "pub extern \"C\" fn {}_free(_res: {}) {{ }}", mangled_container, mangled_container).unwrap();
  96         writeln!(w, "impl Drop for {} {{", mangled_container).unwrap();
  97         writeln!(w, "\tfn drop(&mut self) {{").unwrap();
  98         writeln!(w, "\t\tif self.result_ok {{").unwrap();
  99         if ok_type != "()" {
 100                 writeln!(w, "\t\t\tif unsafe {{ !(self.contents.result as *mut ()).is_null() }} {{").unwrap();
 101                 writeln!(w, "\t\t\t\tlet _ = unsafe {{ Box::from_raw(self.contents.result) }};").unwrap();
 102                 writeln!(w, "\t\t\t}}").unwrap();
 103         }
 104         writeln!(w, "\t\t}} else {{").unwrap();
 105         if err_type != "()" {
 106                 writeln!(w, "\t\t\tif unsafe {{ !(self.contents.err as *mut ()).is_null() }} {{").unwrap();
 107                 writeln!(w, "\t\t\t\tlet _ = unsafe {{ Box::from_raw(self.contents.err) }};").unwrap();
 108                 writeln!(w, "\t\t\t}}").unwrap();
 109         }
 110         writeln!(w, "\t\t}}").unwrap();
 111         writeln!(w, "\t}}").unwrap();
 112         writeln!(w, "}}").unwrap();
 113
 114         // TODO: Templates should use () now that they can, too
 115         let templ_ok_type = if ok_type != "()" { ok_type } else { "u8" };
 116         let templ_err_type = if err_type != "()" { err_type } else { "u8" };
 117
 118         writeln!(w, "impl From<crate::c_types::CResultTempl<{}, {}>> for {} {{", templ_ok_type, templ_err_type, mangled_container).unwrap();
 119         writeln!(w, "\tfn from(mut o: crate::c_types::CResultTempl<{}, {}>) -> Self {{", templ_ok_type, templ_err_type).unwrap();
 120         writeln!(w, "\t\tlet contents = if o.result_ok {{").unwrap();
 121         if ok_type != "()" {
 122                 writeln!(w, "\t\t\tlet result = unsafe {{ o.contents.result }};").unwrap();
 123                 writeln!(w, "\t\t\tunsafe {{ o.contents.result = std::ptr::null_mut() }};").unwrap();
 124                 writeln!(w, "\t\t\t{}Ptr {{ result }}", mangled_container).unwrap();
 125         } else {
 126                 writeln!(w, "\t\t\tlet _ = unsafe {{ Box::from_raw(o.contents.result) }};").unwrap();
 127                 writeln!(w, "\t\t\to.contents.result = std::ptr::null_mut();").unwrap();
 128                 writeln!(w, "\t\t\t{}Ptr {{ result: std::ptr::null_mut() }}", mangled_container).unwrap();
 129         }
 130         writeln!(w, "\t\t}} else {{").unwrap();
 131         if err_type != "()" {
 132                 writeln!(w, "\t\t\tlet err = unsafe {{ o.contents.err }};").unwrap();
 133                 writeln!(w, "\t\t\tunsafe {{ o.contents.err = std::ptr::null_mut(); }}").unwrap();
 134                 writeln!(w, "\t\t\t{}Ptr {{ err }}", mangled_container).unwrap();
 135         } else {
 136                 writeln!(w, "\t\t\tlet _ = unsafe {{ Box::from_raw(o.contents.err) }};").unwrap();
 137                 writeln!(w, "\t\t\to.contents.err = std::ptr::null_mut();").unwrap();
 138                 writeln!(w, "\t\t\t{}Ptr {{ err: std::ptr::null_mut() }}", mangled_container).unwrap();
 139         }
 140         writeln!(w, "\t\t}};").unwrap();
 141         writeln!(w, "\t\tSelf {{").unwrap();
 142         writeln!(w, "\t\t\tcontents,").unwrap();
 143         writeln!(w, "\t\t\tresult_ok: o.result_ok,").unwrap();
 144         writeln!(w, "\t\t}}").unwrap();
 145         writeln!(w, "\t}}").unwrap();
 146         writeln!(w, "}}").unwrap();
 147 }
 148
 149 /// Writes out a C-callable concrete Vec<A> struct and utility methods
 150 pub fn write_vec_block<W: std::io::Write>(w: &mut W, mangled_container: &str, inner_type: &str) {
 151         writeln!(w, "#[repr(C)]").unwrap();
 152         writeln!(w, "pub struct {} {{", mangled_container).unwrap();
 153         writeln!(w, "\tpub data: *mut {},", inner_type).unwrap();
 154         writeln!(w, "\tpub datalen: usize").unwrap();
 155         writeln!(w, "}}").unwrap();
 156
 157         writeln!(w, "impl {} {{", mangled_container).unwrap();
 158         writeln!(w, "\t#[allow(unused)] pub(crate) fn into_rust(&mut self) -> Vec<{}> {{", inner_type).unwrap();
 159         writeln!(w, "\t\tif self.datalen == 0 {{ return Vec::new(); }}").unwrap();
 160         writeln!(w, "\t\tlet ret = unsafe {{ Box::from_raw(std::slice::from_raw_parts_mut(self.data, self.datalen)) }}.into();").unwrap();
 161         writeln!(w, "\t\tself.data = std::ptr::null_mut();").unwrap();
 162         writeln!(w, "\t\tself.datalen = 0;").unwrap();
 163         writeln!(w, "\t\tret").unwrap();
 164         writeln!(w, "\t}}").unwrap();
 165         writeln!(w, "\t#[allow(unused)] pub(crate) fn as_slice(&self) -> &[{}] {{", inner_type).unwrap();
 166         writeln!(w, "\t\tunsafe {{ std::slice::from_raw_parts_mut(self.data, self.datalen) }}").unwrap();
 167         writeln!(w, "\t}}").unwrap();
 168         writeln!(w, "}}").unwrap();
 169
 170         writeln!(w, "impl From<Vec<{}>> for {} {{", inner_type, mangled_container).unwrap();
 171         writeln!(w, "\tfn from(v: Vec<{}>) -> Self {{", inner_type).unwrap();
 172         writeln!(w, "\t\tlet datalen = v.len();").unwrap();
 173         writeln!(w, "\t\tlet data = Box::into_raw(v.into_boxed_slice());").unwrap();
 174         writeln!(w, "\t\tSelf {{ datalen, data: unsafe {{ (*data).as_mut_ptr() }} }}").unwrap();
 175         writeln!(w, "\t}}").unwrap();
 176         writeln!(w, "}}").unwrap();
 177
 178         writeln!(w, "#[no_mangle]").unwrap();
 179         writeln!(w, "pub extern \"C\" fn {}_free(_res: {}) {{ }}", mangled_container, mangled_container).unwrap();
 180         writeln!(w, "impl Drop for {} {{", mangled_container).unwrap();
 181         writeln!(w, "\tfn drop(&mut self) {{").unwrap();
 182         writeln!(w, "\t\tif self.datalen == 0 {{ return; }}").unwrap();
 183         writeln!(w, "\t\tunsafe {{ Box::from_raw(std::slice::from_raw_parts_mut(self.data, self.datalen)) }};").unwrap();
 184         writeln!(w, "\t}}").unwrap();
 185         writeln!(w, "}}").unwrap();
 186         if inner_type == "u8" || mangled_container == "CVec_SpendableOutputDescriptorZ" { // XXX
 187                 writeln!(w, "impl Clone for {} {{", mangled_container).unwrap();
 188                 writeln!(w, "\tfn clone(&self) -> Self {{").unwrap();
 189                 writeln!(w, "\t\tlet mut res = Vec::new();").unwrap();
 190                 writeln!(w, "\t\tif self.datalen == 0 {{ return Self::from(res); }}").unwrap();
 191                 writeln!(w, "\t\tres.extend_from_slice(unsafe {{ std::slice::from_raw_parts_mut(self.data, self.datalen) }});").unwrap();
 192                 writeln!(w, "\t\tSelf::from(res)").unwrap();
 193                 writeln!(w, "\t}}").unwrap();
 194                 writeln!(w, "}}").unwrap();
 195         }
 196 }
 197
 198 /// Writes out a C-callable concrete (A, B, ...) struct and utility methods
 199 pub fn write_tuple_block<W: std::io::Write>(w: &mut W, mangled_container: &str, types: &[String]) {
 200         writeln!(w, "#[repr(C)]").unwrap();
 201         writeln!(w, "pub struct {} {{", mangled_container).unwrap();
 202         for (idx, ty) in types.iter().enumerate() {
 203                 writeln!(w, "\tpub {}: {},", ('a' as u8 + idx as u8) as char, ty).unwrap();
 204         }
 205         writeln!(w, "}}").unwrap();
 206
 207         let mut needs_clone = true;
 208         let mut tuple_str = "(".to_owned();
 209         for (idx, ty) in types.iter().enumerate() {
 210                 if idx != 0 { tuple_str += ", "; }
 211                 tuple_str += ty;
 212                 if !ty.starts_with("u") ||
 213                         ty.len() > 3 || ty.len() < 2 ||
 214                         ty.as_bytes()[1] < '0' as u8 || ty.as_bytes()[1] > '9' as u8 ||
 215                         (ty.len() == 3 && (ty.as_bytes()[2] < '0' as u8 || ty.as_bytes()[2] > '9' as u8)) {
 216                                 // For non-uXX types, we don't implement clone
 217                                 needs_clone = false;
 218                 }
 219         }
 220         tuple_str += ")";
 221
 222         writeln!(w, "impl From<{}> for {} {{", tuple_str, mangled_container).unwrap();
 223         writeln!(w, "\tfn from (tup: {}) -> Self {{", tuple_str).unwrap();
 224         writeln!(w, "\t\tSelf {{").unwrap();
 225         for idx in 0..types.len() {
 226                 writeln!(w, "\t\t\t{}: tup.{},", ('a' as u8 + idx as u8) as char, idx).unwrap();
 227         }
 228         writeln!(w, "\t\t}}").unwrap();
 229         writeln!(w, "\t}}").unwrap();
 230         writeln!(w, "}}").unwrap();
 231         writeln!(w, "impl {} {{", mangled_container).unwrap();
 232         writeln!(w, "\t#[allow(unused)] pub(crate) fn to_rust(mut self) -> {} {{", tuple_str).unwrap();
 233         write!(w, "\t\t(").unwrap();
 234         for idx in 0..types.len() {
 235                 write!(w, "{}self.{}", if idx != 0 {", "} else {""}, ('a' as u8 + idx as u8) as char).unwrap();
 236         }
 237         writeln!(w, ")").unwrap();
 238         writeln!(w, "\t}}").unwrap();
 239         writeln!(w, "}}").unwrap();
 240
 241         if needs_clone {
 242                 writeln!(w, "impl Clone for {} {{", mangled_container).unwrap();
 243                 writeln!(w, "\tfn clone(&self) -> Self {{").unwrap();
 244                 writeln!(w, "\t\tSelf {{").unwrap();
 245                 for idx in 0..types.len() {
 246                         writeln!(w, "\t\t\t{}: self.{}.clone(),", ('a' as u8 + idx as u8) as char, ('a' as u8 + idx as u8) as char).unwrap();
 247                 }
 248                 writeln!(w, "\t\t}}").unwrap();
 249                 writeln!(w, "\t}}").unwrap();
 250                 writeln!(w, "}}").unwrap();
 251         }
 252
 253         writeln!(w, "#[no_mangle]").unwrap();
 254         writeln!(w, "pub extern \"C\" fn {}_free(_res: {}) {{ }}", mangled_container, mangled_container).unwrap();
 255 }
 256
 257 /// Prints the docs from a given attribute list unless its tagged no export
 258 pub fn writeln_docs<W: std::io::Write>(w: &mut W, attrs: &[syn::Attribute], prefix: &str) {
 259         for attr in attrs.iter() {
 260                 let tokens_clone = attr.tokens.clone();
 261                 let mut token_iter = tokens_clone.into_iter();
 262                 if let Some(token) = token_iter.next() {
 263                         match token {
 264                                 TokenTree::Punct(c) if c.as_char() == '=' => {
 265                                         // syn gets '=' from '///' or '//!' as it is syntax for #[doc = ""]
 266                                 },
 267                                 TokenTree::Group(_) => continue, // eg #[derive()]
 268                                 _ => unimplemented!(),
 269                         }
 270                 } else { continue; }
 271                 match attr.style {
 272                         syn::AttrStyle::Inner(_) => {
 273                                 match token_iter.next().unwrap() {
 274                                         TokenTree::Literal(lit) => {
 275                                                 // Drop the first and last chars from lit as they are always "
 276                                                 let doc = format!("{}", lit);
 277                                                 writeln!(w, "{}//!{}", prefix, &doc[1..doc.len() - 1]).unwrap();
 278                                         },
 279                                         _ => unimplemented!(),
 280                                 }
 281                         },
 282                         syn::AttrStyle::Outer => {
 283                                 match token_iter.next().unwrap() {
 284                                         TokenTree::Literal(lit) => {
 285                                                 // Drop the first and last chars from lit as they are always "
 286                                                 let doc = format!("{}", lit);
 287                                                 writeln!(w, "{}///{}", prefix, &doc[1..doc.len() - 1]).unwrap();
 288                                         },
 289                                         _ => unimplemented!(),
 290                                 }
 291                         },
 292                 }
 293         }
 294 }
 295
 296 /// Print the parameters in a method declaration, starting after the open parenthesis, through and
 297 /// including the closing parenthesis and return value, but not including the open bracket or any
 298 /// trailing semicolons.
 299 ///
 300 /// Usable both for a function definition and declaration.
 301 ///
 302 /// this_param is used when returning Self or accepting a self parameter, and should be the
 303 /// concrete, mapped type.
 304 pub fn write_method_params<W: std::io::Write>(w: &mut W, sig: &syn::Signature, this_param: &str, types: &mut TypeResolver, generics: Option<&GenericTypes>, self_ptr: bool, fn_decl: bool) {
 305         if sig.constness.is_some() || sig.asyncness.is_some() || sig.unsafety.is_some() ||
 306                         sig.abi.is_some() || sig.variadic.is_some() {
 307                 unimplemented!();
 308         }
 309         if sig.generics.lt_token.is_some() {
 310                 for generic in sig.generics.params.iter() {
 311                         match generic {
 312                                 syn::GenericParam::Type(_)|syn::GenericParam::Lifetime(_) => {
 313                                         // We ignore these, if they're not on skipped args, we'll blow up
 314                                         // later, and lifetimes we just hope the C client enforces.
 315                                 },
 316                                 _ => unimplemented!(),
 317                         }
 318                 }
 319         }
 320
 321         let mut first_arg = true;
 322         let mut num_unused = 0;
 323         for inp in sig.inputs.iter() {
 324                 match inp {
 325                         syn::FnArg::Receiver(recv) => {
 326                                 if !recv.attrs.is_empty() || recv.reference.is_none() { unimplemented!(); }
 327                                 write!(w, "this_arg: {}{}",
 328                                         match (self_ptr, recv.mutability.is_some()) {
 329                                                 (true, true) => "*mut ",
 330                                                 (true, false) => "*const ",
 331                                                 (false, true) => "&mut ",
 332                                                 (false, false) => "&",
 333                                         }, this_param).unwrap();
 334                                 assert!(first_arg);
 335                                 first_arg = false;
 336                         },
 337                         syn::FnArg::Typed(arg) => {
 338                                 if types.skip_arg(&*arg.ty, generics) { continue; }
 339                                 if !arg.attrs.is_empty() { unimplemented!(); }
 340                                 // First get the c type so that we can check if it ends up being a reference:
 341                                 let mut c_type = Vec::new();
 342                                 types.write_c_type(&mut c_type, &*arg.ty, generics, false);
 343                                 match &*arg.pat {
 344                                         syn::Pat::Ident(ident) => {
 345                                                 if !ident.attrs.is_empty() || ident.subpat.is_some() {
 346                                                         unimplemented!();
 347                                                 }
 348                                                 write!(w, "{}{}{}: ", if first_arg { "" } else { ", " }, if !fn_decl || c_type[0] == '&' as u8 || c_type[0] == '*' as u8 { "" } else { "mut " }, ident.ident).unwrap();
 349                                                 first_arg = false;
 350                                         },
 351                                         syn::Pat::Wild(wild) => {
 352                                                 if !wild.attrs.is_empty() { unimplemented!(); }
 353                                                 write!(w, "{}unused_{}: ", if first_arg { "" } else { ", " }, num_unused).unwrap();
 354                                                 num_unused += 1;
 355                                         },
 356                                         _ => unimplemented!(),
 357                                 }
 358                                 w.write(&c_type).unwrap();
 359                         }
 360                 }
 361         }
 362         write!(w, ")").unwrap();
 363         match &sig.output {
 364                 syn::ReturnType::Type(_, rtype) => {
 365                         write!(w, " -> ").unwrap();
 366                         if let Some(mut remaining_path) = first_seg_self(&*rtype) {
 367                                 if remaining_path.next().is_none() {
 368                                         write!(w, "{}", this_param).unwrap();
 369                                         return;
 370                                 }
 371                         }
 372                         if let syn::Type::Reference(r) = &**rtype {
 373                                 // We can't return a reference, cause we allocate things on the stack.
 374                                 types.write_c_type(w, &*r.elem, generics, true);
 375                         } else {
 376                                 types.write_c_type(w, &*rtype, generics, true);
 377                         }
 378                 },
 379                 _ => {},
 380         }
 381 }
 382
 383 /// Print the main part of a method declaration body, starting with a newline after the function
 384 /// open bracket and converting each function parameter to or from C-mapped types. Ends with "let
 385 /// mut ret = " assuming the next print will be the unmapped Rust function to call followed by the
 386 /// parameters we mapped to/from C here.
 387 pub fn write_method_var_decl_body<W: std::io::Write>(w: &mut W, sig: &syn::Signature, extra_indent: &str, types: &TypeResolver, generics: Option<&GenericTypes>, to_c: bool) {
 388         let mut num_unused = 0;
 389         for inp in sig.inputs.iter() {
 390                 match inp {
 391                         syn::FnArg::Receiver(_) => {},
 392                         syn::FnArg::Typed(arg) => {
 393                                 if types.skip_arg(&*arg.ty, generics) { continue; }
 394                                 if !arg.attrs.is_empty() { unimplemented!(); }
 395                                 macro_rules! write_new_var {
 396                                         ($ident: expr, $ty: expr) => {
 397                                                 if to_c {
 398                                                         if types.write_to_c_conversion_new_var(w, &$ident, &$ty, generics, false) {
 399                                                                 write!(w, "\n\t{}", extra_indent).unwrap();
 400                                                         }
 401                                                 } else {
 402                                                         if types.write_from_c_conversion_new_var(w, &$ident, &$ty, generics) {
 403                                                                 write!(w, "\n\t{}", extra_indent).unwrap();
 404                                                         }
 405                                                 }
 406                                         }
 407                                 }
 408                                 match &*arg.pat {
 409                                         syn::Pat::Ident(ident) => {
 410                                                 if !ident.attrs.is_empty() || ident.subpat.is_some() {
 411                                                         unimplemented!();
 412                                                 }
 413                                                 write_new_var!(ident.ident, *arg.ty);
 414                                         },
 415                                         syn::Pat::Wild(w) => {
 416                                                 if !w.attrs.is_empty() { unimplemented!(); }
 417                                                 write_new_var!(syn::Ident::new(&format!("unused_{}", num_unused), Span::call_site()), *arg.ty);
 418                                                 num_unused += 1;
 419                                         },
 420                                         _ => unimplemented!(),
 421                                 }
 422                         }
 423                 }
 424         }
 425         match &sig.output {
 426                 syn::ReturnType::Type(_, _) => {
 427                         write!(w, "let mut ret = ").unwrap();
 428                 },
 429                 _ => {},
 430         }
 431 }
 432
 433 /// Prints the parameters in a method call, starting after the open parenthesis and ending with a
 434 /// final return statement returning the method's result. Should be followed by a single closing
 435 /// bracket.
 436 ///
 437 /// The return value is expected to be bound to a variable named `ret` which is available after a
 438 /// method-call-ending semicolon.
 439 pub fn write_method_call_params<W: std::io::Write>(w: &mut W, sig: &syn::Signature, extra_indent: &str, types: &TypeResolver, generics: Option<&GenericTypes>, this_type: &str, to_c: bool) {
 440         let mut first_arg = true;
 441         let mut num_unused = 0;
 442         for inp in sig.inputs.iter() {
 443                 match inp {
 444                         syn::FnArg::Receiver(recv) => {
 445                                 if !recv.attrs.is_empty() || recv.reference.is_none() { unimplemented!(); }
 446                                 if to_c {
 447                                         write!(w, "self.this_arg").unwrap();
 448                                         first_arg = false;
 449                                 }
 450                         },
 451                         syn::FnArg::Typed(arg) => {
 452                                 if types.skip_arg(&*arg.ty, generics) {
 453                                         if !to_c {
 454                                                 if !first_arg {
 455                                                         write!(w, ", ").unwrap();
 456                                                 }
 457                                                 first_arg = false;
 458                                                 types.no_arg_to_rust(w, &*arg.ty, generics);
 459                                         }
 460                                         continue;
 461                                 }
 462                                 if !arg.attrs.is_empty() { unimplemented!(); }
 463                                 macro_rules! write_ident {
 464                                         ($ident: expr) => {
 465                                                 if !first_arg {
 466                                                         write!(w, ", ").unwrap();
 467                                                 }
 468                                                 first_arg = false;
 469                                                 if to_c {
 470                                                         types.write_to_c_conversion_inline_prefix(w, &*arg.ty, generics, false);
 471                                                         write!(w, "{}", $ident).unwrap();
 472                                                         types.write_to_c_conversion_inline_suffix(w, &*arg.ty, generics, false);
 473                                                 } else {
 474                                                         types.write_from_c_conversion_prefix(w, &*arg.ty, generics);
 475                                                         write!(w, "{}", $ident).unwrap();
 476                                                         types.write_from_c_conversion_suffix(w, &*arg.ty, generics);
 477                                                 }
 478                                         }
 479                                 }
 480                                 match &*arg.pat {
 481                                         syn::Pat::Ident(ident) => {
 482                                                 if !ident.attrs.is_empty() || ident.subpat.is_some() {
 483                                                         unimplemented!();
 484                                                 }
 485                                                 write_ident!(ident.ident);
 486                                         },
 487                                         syn::Pat::Wild(w) => {
 488                                                 if !w.attrs.is_empty() { unimplemented!(); }
 489                                                 write_ident!(format!("unused_{}", num_unused));
 490                                                 num_unused += 1;
 491                                         },
 492                                         _ => unimplemented!(),
 493                                 }
 494                         }
 495                 }
 496         }
 497         write!(w, ")").unwrap();
 498         match &sig.output {
 499                 syn::ReturnType::Type(_, rtype) => {
 500                         write!(w, ";\n\t{}", extra_indent).unwrap();
 501
 502                         let self_segs_iter = first_seg_self(&*rtype);
 503                         if to_c && first_seg_self(&*rtype).is_some() {
 504                                 // Assume rather blindly that we're returning an associated trait from a C fn call to a Rust trait object.
 505                                 write!(w, "ret").unwrap();
 506                         } else if !to_c && self_segs_iter.is_some() && self_segs_iter.unwrap().next().is_none() {
 507                                 // If we're returning "Self" (and not "Self::X"), just do it manually
 508                                 write!(w, "{} {{ inner: Box::into_raw(Box::new(ret)), is_owned: true }}", this_type).unwrap();
 509                         } else if to_c {
 510                                 let new_var = types.write_from_c_conversion_new_var(w, &syn::Ident::new("ret", Span::call_site()), rtype, generics);
 511                                 if new_var {
 512                                         write!(w, "\n\t{}", extra_indent).unwrap();
 513                                 }
 514                                 types.write_from_c_conversion_prefix(w, &*rtype, generics);
 515                                 write!(w, "ret").unwrap();
 516                                 types.write_from_c_conversion_suffix(w, &*rtype, generics);
 517                         } else {
 518                                 let ret_returned = if let syn::Type::Reference(_) = &**rtype { true } else { false };
 519                                 let new_var = types.write_to_c_conversion_new_var(w, &syn::Ident::new("ret", Span::call_site()), &rtype, generics, true);
 520                                 if new_var {
 521                                         write!(w, "\n\t{}", extra_indent).unwrap();
 522                                 }
 523                                 types.write_to_c_conversion_inline_prefix(w, &rtype, generics, true);
 524                                 write!(w, "{}ret", if ret_returned && !new_var { "*" } else { "" }).unwrap();
 525                                 types.write_to_c_conversion_inline_suffix(w, &rtype, generics, true);
 526                         }
 527                 }
 528                 _ => {},
 529         }
 530 }
 531
 532 /// Prints concrete generic parameters for a struct/trait/function, including the less-than and
 533 /// greater-than symbols, if any generic parameters are defined.
 534 pub fn maybe_write_generics<W: std::io::Write>(w: &mut W, generics: &syn::Generics, types: &TypeResolver, concrete_lifetimes: bool) {
 535         let mut gen_types = GenericTypes::new();
 536         assert!(gen_types.learn_generics(generics, types));
 537         if !generics.params.is_empty() {
 538                 write!(w, "<").unwrap();
 539                 for (idx, generic) in generics.params.iter().enumerate() {
 540                         match generic {
 541                                 syn::GenericParam::Type(type_param) => {
 542                                         let mut printed_param = false;
 543                                         for bound in type_param.bounds.iter() {
 544                                                 if let syn::TypeParamBound::Trait(trait_bound) = bound {
 545                                                         assert_simple_bound(&trait_bound);
 546                                                         write!(w, "{}{}", if idx != 0 { ", " } else { "" }, gen_types.maybe_resolve_ident(&type_param.ident).unwrap()).unwrap();
 547                                                         if printed_param {
 548                                                                 unimplemented!("Can't print generic params that have multiple non-lifetime bounds");
 549                                                         }
 550                                                         printed_param = true;
 551                                                 }
 552                                         }
 553                                 },
 554                                 syn::GenericParam::Lifetime(lt) => {
 555                                         if concrete_lifetimes {
 556                                                 write!(w, "'static").unwrap();
 557                                         } else {
 558                                                 write!(w, "{}'{}", if idx != 0 { ", " } else { "" }, lt.lifetime.ident).unwrap();
 559                                         }
 560                                 },
 561                                 _ => unimplemented!(),
 562                         }
 563                 }
 564                 write!(w, ">").unwrap();
 565         }
 566 }
 567
 568