git.bitcoin.ninja 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::collections::HashMap;
   5 use std::fs::File;
   6 use std::io::Write;
   7 use proc_macro2::{TokenTree, Span};
   8
   9 use crate::types::*;
  10
  11 /// Writes out a C++ wrapper class for the given type, which contains various utilities to access
  12 /// the underlying C-mapped type safely avoiding some common memory management issues by handling
  13 /// resource-freeing and prevending accidental raw copies.
  14 pub fn write_cpp_wrapper(cpp_header_file: &mut File, ty: &str, has_destructor: bool) {
  15         writeln!(cpp_header_file, "class {} {{", ty).unwrap();
  16         writeln!(cpp_header_file, "private:").unwrap();
  17         writeln!(cpp_header_file, "\tLDK{} self;", ty).unwrap();
  18         writeln!(cpp_header_file, "public:").unwrap();
  19         writeln!(cpp_header_file, "\t{}(const {}&) = delete;", ty, ty).unwrap();
  20         if has_destructor {
  21                 writeln!(cpp_header_file, "\t~{}() {{ {}_free(self); }}", ty, ty).unwrap();
  22         }
  23         writeln!(cpp_header_file, "\t{}({}&& o) : self(o.self) {{ memset(&o, 0, sizeof({})); }}", ty, ty, ty).unwrap();
  24         writeln!(cpp_header_file, "\t{}(LDK{}&& m_self) : self(m_self) {{ memset(&m_self, 0, sizeof(LDK{})); }}", ty, ty, ty).unwrap();
  25         writeln!(cpp_header_file, "\toperator LDK{}() {{ LDK{} res = self; memset(&self, 0, sizeof(LDK{})); return res; }}", ty, ty, ty).unwrap();
  26         writeln!(cpp_header_file, "\tLDK{}* operator &() {{ return &self; }}", ty).unwrap();
  27         writeln!(cpp_header_file, "\tLDK{}* operator ->() {{ return &self; }}", ty).unwrap();
  28         writeln!(cpp_header_file, "\tconst LDK{}* operator &() const {{ return &self; }}", ty).unwrap();
  29         writeln!(cpp_header_file, "\tconst LDK{}* operator ->() const {{ return &self; }}", ty).unwrap();
  30         writeln!(cpp_header_file, "}};").unwrap();
  31 }
  32
  33 /// Prints the docs from a given attribute list unless its tagged no export
  34 pub fn writeln_docs<W: std::io::Write>(w: &mut W, attrs: &[syn::Attribute], prefix: &str) {
  35         for attr in attrs.iter() {
  36                 let tokens_clone = attr.tokens.clone();
  37                 let mut token_iter = tokens_clone.into_iter();
  38                 if let Some(token) = token_iter.next() {
  39                         match token {
  40                                 TokenTree::Punct(c) if c.as_char() == '=' => {
  41                                         // syn gets '=' from '///' or '//!' as it is syntax for #[doc = ""]
  42                                 },
  43                                 TokenTree::Group(_) => continue, // eg #[derive()]
  44                                 _ => unimplemented!(),
  45                         }
  46                 } else { continue; }
  47                 match attr.style {
  48                         syn::AttrStyle::Inner(_) => {
  49                                 match token_iter.next().unwrap() {
  50                                         TokenTree::Literal(lit) => {
  51                                                 // Drop the first and last chars from lit as they are always "
  52                                                 let doc = format!("{}", lit);
  53                                                 writeln!(w, "{}//!{}", prefix, &doc[1..doc.len() - 1]).unwrap();
  54                                         },
  55                                         _ => unimplemented!(),
  56                                 }
  57                         },
  58                         syn::AttrStyle::Outer => {
  59                                 match token_iter.next().unwrap() {
  60                                         TokenTree::Literal(lit) => {
  61                                                 // Drop the first and last chars from lit as they are always "
  62                                                 let doc = format!("{}", lit);
  63                                                 writeln!(w, "{}///{}", prefix, &doc[1..doc.len() - 1]).unwrap();
  64                                         },
  65                                         _ => unimplemented!(),
  66                                 }
  67                         },
  68                 }
  69         }
  70 }
  71
  72 /// Print the parameters in a method declaration, starting after the open parenthesis, through and
  73 /// including the closing parenthesis and return value, but not including the open bracket or any
  74 /// trailing semicolons.
  75 ///
  76 /// Usable both for a function definition and declaration.
  77 ///
  78 /// this_param is used when returning Self or accepting a self parameter, and should be the
  79 /// concrete, mapped type.
  80 pub fn write_method_params<W: std::io::Write>(w: &mut W, sig: &syn::Signature, associated_types: &HashMap<&syn::Ident, &syn::Ident>, this_param: &str, types: &mut TypeResolver, generics: Option<&GenericTypes>, self_ptr: bool, fn_decl: bool) {
  81         if sig.constness.is_some() || sig.asyncness.is_some() || sig.unsafety.is_some() ||
  82                         sig.abi.is_some() || sig.variadic.is_some() {
  83                 unimplemented!();
  84         }
  85         if sig.generics.lt_token.is_some() {
  86                 for generic in sig.generics.params.iter() {
  87                         match generic {
  88                                 syn::GenericParam::Type(_)|syn::GenericParam::Lifetime(_) => {
  89                                         // We ignore these, if they're not on skipped args, we'll blow up
  90                                         // later, and lifetimes we just hope the C client enforces.
  91                                 },
  92                                 _ => unimplemented!(),
  93                         }
  94                 }
  95         }
  96
  97         let mut first_arg = true;
  98         let mut num_unused = 0;
  99         for inp in sig.inputs.iter() {
 100                 match inp {
 101                         syn::FnArg::Receiver(recv) => {
 102                                 if !recv.attrs.is_empty() || recv.reference.is_none() { unimplemented!(); }
 103                                 write!(w, "this_arg: {}{}",
 104                                         match (self_ptr, recv.mutability.is_some()) {
 105                                                 (true, true) => "*mut ",
 106                                                 (true, false) => "*const ",
 107                                                 (false, true) => "&mut ",
 108                                                 (false, false) => "&",
 109                                         }, this_param).unwrap();
 110                                 assert!(first_arg);
 111                                 first_arg = false;
 112                         },
 113                         syn::FnArg::Typed(arg) => {
 114                                 if types.skip_arg(&*arg.ty, generics) { continue; }
 115                                 if !arg.attrs.is_empty() { unimplemented!(); }
 116                                 let mut is_ref = if let syn::Type::Reference(_) = *arg.ty { true } else { false };
 117                                 if let syn::Type::Reference(syn::TypeReference { ref elem, .. }) = *arg.ty {
 118                                         if let syn::Type::Slice(_) = &**elem {
 119                                                 // Slices are mapped to non-ref Vec types, so we want them to be mut
 120                                                 // letting us drain(..) the underlying Vec.
 121                                                 is_ref = false;
 122                                         }
 123                                 }
 124                                 match &*arg.pat {
 125                                         syn::Pat::Ident(ident) => {
 126                                                 if !ident.attrs.is_empty() || ident.subpat.is_some() {
 127                                                         unimplemented!();
 128                                                 }
 129                                                 write!(w, "{}{}{}: ", if first_arg { "" } else { ", " }, if is_ref || !fn_decl { "" } else { "mut " }, ident.ident).unwrap();
 130                                                 first_arg = false;
 131                                         },
 132                                         syn::Pat::Wild(wild) => {
 133                                                 if !wild.attrs.is_empty() { unimplemented!(); }
 134                                                 write!(w, "{}unused_{}: ", if first_arg { "" } else { ", " }, num_unused).unwrap();
 135                                                 num_unused += 1;
 136                                         },
 137                                         _ => unimplemented!(),
 138                                 }
 139                                 types.write_c_type(w, &*arg.ty, generics, false);
 140                         }
 141                 }
 142         }
 143         write!(w, ")").unwrap();
 144         match &sig.output {
 145                 syn::ReturnType::Type(_, rtype) => {
 146                         write!(w, " -> ").unwrap();
 147                         if let Some(mut remaining_path) = first_seg_self(&*rtype) {
 148                                 if let Some(associated_seg) = get_single_remaining_path_seg(&mut remaining_path) {
 149                                         // We're returning an associated type in a trait impl. Its probably a safe bet
 150                                         // that its also a trait, so just return the trait type.
 151                                         let real_type = associated_types.get(associated_seg).unwrap();
 152                                         types.write_c_type(w, &syn::Type::Path(syn::TypePath { qself: None,
 153                                                 path: syn::PathSegment {
 154                                                         ident: (*real_type).clone(),
 155                                                         arguments: syn::PathArguments::None
 156                                                 }.into()
 157                                         }), generics, true);
 158                                 } else {
 159                                         write!(w, "{}", this_param).unwrap();
 160                                 }
 161                         } else {
 162                                 if let syn::Type::Reference(r) = &**rtype {
 163                                         // We can't return a reference, cause we allocate things on the stack.
 164                                         types.write_c_type(w, &*r.elem, generics, true);
 165                                 } else {
 166                                         types.write_c_type(w, &*rtype, generics, true);
 167                                 }
 168                         }
 169                 },
 170                 _ => {},
 171         }
 172 }
 173
 174 /// Print the main part of a method declaration body, starting with a newline after the function
 175 /// open bracket and converting each function parameter to or from C-mapped types. Ends with "let
 176 /// mut ret = " assuming the next print will be the unmapped Rust function to call followed by the
 177 /// parameters we mapped to/from C here.
 178 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) {
 179         let mut num_unused = 0;
 180         for inp in sig.inputs.iter() {
 181                 match inp {
 182                         syn::FnArg::Receiver(_) => {},
 183                         syn::FnArg::Typed(arg) => {
 184                                 if types.skip_arg(&*arg.ty, generics) { continue; }
 185                                 if !arg.attrs.is_empty() { unimplemented!(); }
 186                                 macro_rules! write_new_var {
 187                                         ($ident: expr, $ty: expr) => {
 188                                                 if to_c {
 189                                                         if types.write_to_c_conversion_new_var(w, &$ident, &$ty, generics, false) {
 190                                                                 write!(w, "\n\t{}", extra_indent).unwrap();
 191                                                         }
 192                                                 } else {
 193                                                         if types.write_from_c_conversion_new_var(w, &$ident, &$ty, generics) {
 194                                                                 write!(w, "\n\t{}", extra_indent).unwrap();
 195                                                         }
 196                                                 }
 197                                         }
 198                                 }
 199                                 match &*arg.pat {
 200                                         syn::Pat::Ident(ident) => {
 201                                                 if !ident.attrs.is_empty() || ident.subpat.is_some() {
 202                                                         unimplemented!();
 203                                                 }
 204                                                 write_new_var!(ident.ident, *arg.ty);
 205                                         },
 206                                         syn::Pat::Wild(w) => {
 207                                                 if !w.attrs.is_empty() { unimplemented!(); }
 208                                                 write_new_var!(syn::Ident::new(&format!("unused_{}", num_unused), Span::call_site()), *arg.ty);
 209                                                 num_unused += 1;
 210                                         },
 211                                         _ => unimplemented!(),
 212                                 }
 213                         }
 214                 }
 215         }
 216         match &sig.output {
 217                 syn::ReturnType::Type(_, _) => {
 218                         write!(w, "let mut ret = ").unwrap();
 219                 },
 220                 _ => {},
 221         }
 222 }
 223
 224 /// Prints the parameters in a method call, starting after the open parenthesis and ending with a
 225 /// final return statement returning the method's result. Should be followed by a single closing
 226 /// bracket.
 227 ///
 228 /// The return value is expected to be bound to a variable named `ret` which is available after a
 229 /// method-call-ending semicolon.
 230 pub fn write_method_call_params<W: std::io::Write>(w: &mut W, sig: &syn::Signature, associated_types: &HashMap<&syn::Ident, &syn::Ident>, extra_indent: &str, types: &TypeResolver, generics: Option<&GenericTypes>, this_type: &str, to_c: bool) {
 231         let mut first_arg = true;
 232         let mut num_unused = 0;
 233         for inp in sig.inputs.iter() {
 234                 match inp {
 235                         syn::FnArg::Receiver(recv) => {
 236                                 if !recv.attrs.is_empty() || recv.reference.is_none() { unimplemented!(); }
 237                                 if to_c {
 238                                         write!(w, "self.this_arg").unwrap();
 239                                         first_arg = false;
 240                                 }
 241                         },
 242                         syn::FnArg::Typed(arg) => {
 243                                 if types.skip_arg(&*arg.ty, generics) {
 244                                         if !to_c {
 245                                                 if !first_arg {
 246                                                         write!(w, ", ").unwrap();
 247                                                 }
 248                                                 first_arg = false;
 249                                                 types.no_arg_to_rust(w, &*arg.ty, generics);
 250                                         }
 251                                         continue;
 252                                 }
 253                                 if !arg.attrs.is_empty() { unimplemented!(); }
 254                                 macro_rules! write_ident {
 255                                         ($ident: expr) => {
 256                                                 if !first_arg {
 257                                                         write!(w, ", ").unwrap();
 258                                                 }
 259                                                 first_arg = false;
 260                                                 if to_c {
 261                                                         types.write_to_c_conversion_inline_prefix(w, &*arg.ty, generics, false);
 262                                                         write!(w, "{}", $ident).unwrap();
 263                                                         types.write_to_c_conversion_inline_suffix(w, &*arg.ty, generics, false);
 264                                                 } else {
 265                                                         types.write_from_c_conversion_prefix(w, &*arg.ty, generics);
 266                                                         write!(w, "{}", $ident).unwrap();
 267                                                         types.write_from_c_conversion_suffix(w, &*arg.ty, generics);
 268                                                 }
 269                                         }
 270                                 }
 271                                 match &*arg.pat {
 272                                         syn::Pat::Ident(ident) => {
 273                                                 if !ident.attrs.is_empty() || ident.subpat.is_some() {
 274                                                         unimplemented!();
 275                                                 }
 276                                                 write_ident!(ident.ident);
 277                                         },
 278                                         syn::Pat::Wild(w) => {
 279                                                 if !w.attrs.is_empty() { unimplemented!(); }
 280                                                 write_ident!(format!("unused_{}", num_unused));
 281                                                 num_unused += 1;
 282                                         },
 283                                         _ => unimplemented!(),
 284                                 }
 285                         }
 286                 }
 287         }
 288         write!(w, ")").unwrap();
 289         match &sig.output {
 290                 syn::ReturnType::Type(_, rtype) => {
 291                         write!(w, ";\n\t{}", extra_indent).unwrap();
 292
 293                         if to_c && first_seg_self(&*rtype).is_some() {
 294                                 // Assume rather blindly that we're returning an associated trait from a C fn call to a Rust trait object.
 295                                 write!(w, "ret").unwrap();
 296                         } else if !to_c && first_seg_self(&*rtype).is_some() {
 297                                 if let Some(mut remaining_path) = first_seg_self(&*rtype) {
 298                                         if let Some(associated_seg) = get_single_remaining_path_seg(&mut remaining_path) {
 299                                                 let real_type = associated_types.get(associated_seg).unwrap();
 300                                                 if let Some(t) = types.crate_types.traits.get(&types.maybe_resolve_ident(&real_type).unwrap()) {
 301                                                         // We're returning an associated trait from a Rust fn call to a C trait
 302                                                         // object.
 303                                                         writeln!(w, "let mut rust_obj = {} {{ inner: Box::into_raw(Box::new(ret)), is_owned: true }};", this_type).unwrap();
 304                                                         writeln!(w, "\t{}let mut ret = {}_as_{}(&rust_obj);", extra_indent, this_type, t.ident).unwrap();
 305                                                         writeln!(w, "\t{}// We want to free rust_obj when ret gets drop()'d, not rust_obj, so wipe rust_obj's pointer and set ret's free() fn", extra_indent).unwrap();
 306                                                         writeln!(w, "\t{}rust_obj.inner = std::ptr::null_mut();", extra_indent).unwrap();
 307                                                         writeln!(w, "\t{}ret.free = Some({}_free_void);", extra_indent, this_type).unwrap();
 308                                                         writeln!(w, "\t{}ret", extra_indent).unwrap();
 309                                                         return;
 310                                                 }
 311                                         }
 312                                 }
 313                                 write!(w, "{} {{ inner: Box::into_raw(Box::new(ret)), is_owned: true }}", this_type).unwrap();
 314                         } else if to_c {
 315                                 let new_var = types.write_from_c_conversion_new_var(w, &syn::Ident::new("ret", Span::call_site()), rtype, generics);
 316                                 if new_var {
 317                                         write!(w, "\n\t{}", extra_indent).unwrap();
 318                                 }
 319                                 types.write_from_c_conversion_prefix(w, &*rtype, generics);
 320                                 write!(w, "ret").unwrap();
 321                                 types.write_from_c_conversion_suffix(w, &*rtype, generics);
 322                         } else {
 323                                 let ret_returned = if let syn::Type::Reference(_) = &**rtype { true } else { false };
 324                                 let new_var = types.write_to_c_conversion_new_var(w, &syn::Ident::new("ret", Span::call_site()), &rtype, generics, true);
 325                                 if new_var {
 326                                         write!(w, "\n\t{}", extra_indent).unwrap();
 327                                 }
 328                                 types.write_to_c_conversion_inline_prefix(w, &rtype, generics, true);
 329                                 write!(w, "{}ret", if ret_returned && !new_var { "*" } else { "" }).unwrap();
 330                                 types.write_to_c_conversion_inline_suffix(w, &rtype, generics, true);
 331                         }
 332                 }
 333                 _ => {},
 334         }
 335 }
 336
 337 /// Prints concrete generic parameters for a struct/trait/function, including the less-than and
 338 /// greater-than symbols, if any generic parameters are defined.
 339 pub fn maybe_write_generics<W: std::io::Write>(w: &mut W, generics: &syn::Generics, types: &TypeResolver, concrete_lifetimes: bool) {
 340         let mut gen_types = GenericTypes::new();
 341         assert!(gen_types.learn_generics(generics, types));
 342         if !generics.params.is_empty() {
 343                 write!(w, "<").unwrap();
 344                 for (idx, generic) in generics.params.iter().enumerate() {
 345                         match generic {
 346                                 syn::GenericParam::Type(type_param) => {
 347                                         let mut printed_param = false;
 348                                         for bound in type_param.bounds.iter() {
 349                                                 if let syn::TypeParamBound::Trait(trait_bound) = bound {
 350                                                         assert_simple_bound(&trait_bound);
 351                                                         write!(w, "{}{}", if idx != 0 { ", " } else { "" }, gen_types.maybe_resolve_ident(&type_param.ident).unwrap()).unwrap();
 352                                                         if printed_param {
 353                                                                 unimplemented!("Can't print generic params that have multiple non-lifetime bounds");
 354                                                         }
 355                                                         printed_param = true;
 356                                                 }
 357                                         }
 358                                 },
 359                                 syn::GenericParam::Lifetime(lt) => {
 360                                         if concrete_lifetimes {
 361                                                 write!(w, "'static").unwrap();
 362                                         } else {
 363                                                 write!(w, "{}'{}", if idx != 0 { ", " } else { "" }, lt.lifetime.ident).unwrap();
 364                                         }
 365                                 },
 366                                 _ => unimplemented!(),
 367                         }
 368                 }
 369                 write!(w, ">").unwrap();
 370         }
 371 }
 372
 373