Add constructor utilities for generated Option<> types

[ldk-c-bindings] / c-bindings-gen / src / blocks.rs

diff --git a/c-bindings-gen/src/blocks.rs b/c-bindings-gen/src/blocks.rs
index dd57a82b5f2d557a188c8a15068d112a5f809afa..4f957ce882ceb990c9e37411d1243ab522410f28 100644 (file)
--- a/c-bindings-gen/src/blocks.rs
+++ b/c-bindings-gen/src/blocks.rs
@@ -1,3 +1,11 @@
+// This file is Copyright its original authors, visible in version control
+// history.
+//
+// This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE>
+// or the MIT license <LICENSE-MIT>, at your option.
+// You may not use this file except in accordance with one or both of these
+// licenses.
+
 //! Printing logic for basic blocks of Rust-mapped code - parts of functions and declarations but
 //! not the full mapping logic.
 
@@ -287,6 +295,44 @@ pub fn write_tuple_block<W: std::io::Write>(w: &mut W, mangled_container: &str,
        writeln!(w, "pub extern \"C\" fn {}_free(_res: {}) {{ }}", mangled_container, mangled_container).unwrap();
 }
 
+/// Writes out a C-callable concrete Option<A> struct and utility methods
+pub fn write_option_block<W: std::io::Write>(w: &mut W, mangled_container: &str, inner_type: &str, clonable: bool) {
+       writeln!(w, "#[repr(C)]").unwrap();
+       if clonable {
+               writeln!(w, "#[derive(Clone)]").unwrap();
+       }
+       writeln!(w, "pub enum {} {{", mangled_container).unwrap();
+       writeln!(w, "\tSome({}),", inner_type).unwrap();
+       writeln!(w, "\tNone").unwrap();
+       writeln!(w, "}}").unwrap();
+
+       writeln!(w, "impl {} {{", mangled_container).unwrap();
+       writeln!(w, "\t#[allow(unused)] pub(crate) fn is_some(&self) -> bool {{").unwrap();
+       writeln!(w, "\t\tif let Self::Some(_) = self {{ true }} else {{ false }}").unwrap();
+       writeln!(w, "\t}}").unwrap();
+       writeln!(w, "\t#[allow(unused)] pub(crate) fn take(mut self) -> {} {{", inner_type).unwrap();
+       writeln!(w, "\t\tif let Self::Some(v) = self {{ v }} else {{ unreachable!() }}").unwrap();
+       writeln!(w, "\t}}").unwrap();
+       writeln!(w, "}}").unwrap();
+
+       writeln!(w, "#[no_mangle]").unwrap();
+       writeln!(w, "pub extern \"C\" fn {}_some(o: {}) -> {} {{", mangled_container, inner_type, mangled_container).unwrap();
+       writeln!(w, "\t{}::Some(o)", mangled_container).unwrap();
+       writeln!(w, "}}").unwrap();
+
+       writeln!(w, "#[no_mangle]").unwrap();
+       writeln!(w, "pub extern \"C\" fn {}_none() -> {} {{", mangled_container, mangled_container).unwrap();
+       writeln!(w, "\t{}::None", mangled_container).unwrap();
+       writeln!(w, "}}").unwrap();
+
+       writeln!(w, "#[no_mangle]").unwrap();
+       writeln!(w, "pub extern \"C\" fn {}_free(_res: {}) {{ }}", mangled_container, mangled_container).unwrap();
+       if clonable {
+               writeln!(w, "#[no_mangle]").unwrap();
+               writeln!(w, "pub extern \"C\" fn {}_clone(orig: &{}) -> {} {{ orig.clone() }}", mangled_container, mangled_container, mangled_container).unwrap();
+       }
+}
+
 /// Prints the docs from a given attribute list unless its tagged no export
 pub fn writeln_docs<W: std::io::Write>(w: &mut W, attrs: &[syn::Attribute], prefix: &str) {
        for attr in attrs.iter() {