autocxx_parser/
multi_bindings.rs

1// Copyright 2022 Google LLC
2//
3// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
4// https://www.apache.org/licenses/LICENSE-2.0> or the MIT license
5// <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your
6// option. This file may not be copied, modified, or distributed
7// except according to those terms.
8
9use indexmap::IndexMap;
10use proc_macro2::TokenStream;
11use serde::{Deserialize, Serialize};
12
13use crate::IncludeCppConfig;
14
15/// Struct which stores multiple sets of bindings and can be serialized
16/// to disk. This is used when our build system uses `autocxx_gen`; that
17/// can handle multiple `include_cpp!` macros and therefore generate multiple
18/// sets of Rust bindings. We can't simply `include!` those because there's
19/// no (easy) way to pass their details from the codegen phase across to
20/// the Rust macro phase. Instead, we use this data structure to store
21/// several sets of .rs bindings in a single file, and then the macro
22/// extracts the correct set of bindings at expansion time.
23#[derive(Serialize, Deserialize, Default)]
24pub struct MultiBindings(IndexMap<u64, String>);
25
26use thiserror::Error;
27
28#[derive(Error, Debug)]
29pub enum MultiBindingsErr {
30    #[error("unable to find the desired bindings within the archive of Rust bindings produced by the autocxx code generation phase")]
31    MissingBindings,
32    #[error("the stored bindings within the JSON file could not be parsed as valid Rust tokens")]
33    BindingsNotParseable,
34}
35
36impl MultiBindings {
37    /// Insert some generated Rust bindings into this data structure.
38    pub fn insert(&mut self, config: &IncludeCppConfig, bindings: TokenStream) {
39        self.0.insert(config.get_hash(), bindings.to_string());
40    }
41
42    /// Retrieves the bindings corresponding to a given [`IncludeCppConfig`].
43    pub fn get(&self, config: &IncludeCppConfig) -> Result<TokenStream, MultiBindingsErr> {
44        match self.0.get(&(config.get_hash())) {
45            None => Err(MultiBindingsErr::MissingBindings),
46            Some(bindings) => Ok(bindings
47                .parse()
48                .map_err(|_| MultiBindingsErr::BindingsNotParseable)?),
49        }
50    }
51}
52
53#[cfg(test)]
54mod tests {
55    use proc_macro2::Span;
56    use quote::quote;
57    use syn::parse_quote;
58
59    use crate::IncludeCppConfig;
60
61    use super::MultiBindings;
62
63    #[test]
64    fn test_multi_bindings() {
65        let hexathorpe = syn::token::Pound(Span::call_site());
66        let config1: IncludeCppConfig = parse_quote! {
67            #hexathorpe include "a.h"
68            generate!("Foo")
69        };
70        let config2: IncludeCppConfig = parse_quote! {
71            #hexathorpe include "b.h"
72            generate!("Bar")
73        };
74        let config3: IncludeCppConfig = parse_quote! {
75            #hexathorpe include "c.h"
76            generate!("Bar")
77        };
78        let mut multi_bindings = MultiBindings::default();
79        multi_bindings.insert(&config1, quote! { first; });
80        multi_bindings.insert(&config2, quote! { second; });
81        let json = serde_json::to_string(&multi_bindings).unwrap();
82        let multi_bindings2: MultiBindings = serde_json::from_str(&json).unwrap();
83        assert_eq!(
84            multi_bindings2.get(&config2).unwrap().to_string(),
85            "second ;"
86        );
87        assert_eq!(
88            multi_bindings2.get(&config1).unwrap().to_string(),
89            "first ;"
90        );
91        assert!(multi_bindings2.get(&config3).is_err());
92    }
93}
autocxx_parser/multi_bindings.rs

autocxx_parser/
multi_bindings.rs
