rusqlite_macros/
lib.rs

1//! Private implementation details of `rusqlite`.
2
3use litrs::StringLit;
4use proc_macro::{Delimiter, Group, Literal, Span, TokenStream, TokenTree};
5
6use fallible_iterator::FallibleIterator;
7use sqlite3_parser::ast::fmt::ToTokens;
8use sqlite3_parser::ast::ParameterInfo;
9use sqlite3_parser::lexer::sql::Parser;
10
11// https://internals.rust-lang.org/t/custom-error-diagnostics-with-procedural-macros-on-almost-stable-rust/8113
12
13#[doc(hidden)]
14#[proc_macro]
15pub fn __bind(input: TokenStream) -> TokenStream {
16    try_bind(input).unwrap_or_else(|msg| parse_ts(&format!("compile_error!({msg:?})")))
17}
18
19type Result<T> = std::result::Result<T, String>;
20
21fn try_bind(input: TokenStream) -> Result<TokenStream> {
22    let (stmt, literal) = {
23        let mut iter = input.into_iter();
24        let stmt = iter.next().unwrap();
25        let literal = iter.next().unwrap();
26        assert!(iter.next().is_none());
27        (stmt, literal)
28    };
29
30    let Some(literal) = into_literal(&literal) else {
31        return Err("expected a plain string literal".to_string());
32    };
33    let call_site = literal.span();
34    let string_lit = match StringLit::try_from(literal) {
35        Ok(string_lit) => string_lit,
36        Err(e) => return Ok(e.to_compile_error()),
37    };
38    let sql = string_lit.value();
39
40    let mut parser = Parser::new(sql.as_bytes());
41    let ast = match parser.next() {
42        Ok(None) => return Err("Invalid input".to_owned()),
43        Err(err) => {
44            return Err(err.to_string());
45        }
46        Ok(Some(ast)) => ast,
47    };
48    let mut info = ParameterInfo::default();
49    if let Err(err) = ast.to_tokens(&mut info) {
50        return Err(err.to_string());
51    }
52    if info.count == 0 {
53        return Ok(TokenStream::new());
54    }
55    if info.count as usize != info.names.len() {
56        return Err("Mixing named and numbered parameters is not supported.".to_string());
57    }
58
59    let mut res = TokenStream::new();
60    for (i, name) in info.names.iter().enumerate() {
61        res.extend(Some(stmt.clone()));
62        res.extend(respan(
63            parse_ts(&format!(
64                ".raw_bind_parameter({}, &{})?;",
65                i + 1,
66                &name[1..]
67            )),
68            call_site,
69        ));
70    }
71
72    Ok(res)
73}
74
75fn into_literal(ts: &TokenTree) -> Option<Literal> {
76    match ts {
77        TokenTree::Literal(l) => Some(l.clone()),
78        TokenTree::Group(g) => match g.delimiter() {
79            Delimiter::None => match g.stream().into_iter().collect::<Vec<_>>().as_slice() {
80                [TokenTree::Literal(l)] => Some(l.clone()),
81                _ => None,
82            },
83            Delimiter::Parenthesis | Delimiter::Brace | Delimiter::Bracket => None,
84        },
85        _ => None,
86    }
87}
88
89fn respan(ts: TokenStream, span: Span) -> TokenStream {
90    let mut res = TokenStream::new();
91    for tt in ts {
92        let tt = match tt {
93            TokenTree::Ident(mut ident) => {
94                ident.set_span(ident.span().resolved_at(span).located_at(span));
95                TokenTree::Ident(ident)
96            }
97            TokenTree::Group(group) => {
98                TokenTree::Group(Group::new(group.delimiter(), respan(group.stream(), span)))
99            }
100            _ => tt,
101        };
102        res.extend(Some(tt))
103    }
104    res
105}
106
107fn parse_ts(s: &str) -> TokenStream {
108    s.parse().unwrap()
109}
rusqlite_macros/lib.rs

rusqlite_macros/
lib.rs
