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| -rw-r--r-- | src/select.rs | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/src/select.rs b/src/select.rs index f64944b..a3c83b1 100644 --- a/src/select.rs +++ b/src/select.rs @@ -193,10 +193,20 @@ fn cfg_block(async_branch: &TokenStream2, sync_branch: &TokenStream2) -> TokenSt }} } +/// Checks if the given string has the '!' (not) prefix. +/// This is used to denote negated feature names in select! arms. fn has_not_prefix(s: &str) -> bool { s.starts_with('!') } +/// Checks if the given token stream contains a `.await` expression. +/// +/// This function traverses the token stream looking for the pattern `. await`, +/// which indicates an `.await` call in Rust syntax. It is used to determine +/// whether an implicit select arm contains async code, which influences how +/// the generated code handles the `cfg` blocks. +/// +/// Returns `true` if `.await` is found, `false` otherwise. fn token_stream_has_await(ts: &TokenStream2) -> bool { let mut tokens = ts.clone().into_iter(); while let Some(token) = tokens.next() { @@ -213,6 +223,21 @@ fn token_stream_has_await(ts: &TokenStream2) -> bool { false } +/// Strips a trailing `.await` from a token stream. +/// +/// This function is used when both arms of a `select!` macro contain `.await` expressions. +/// In that case, one arm's `.await` must be removed so that the generated `#[cfg]` blocks +/// produce valid code for both async and sync contexts. +/// +/// # Examples +/// +/// ```ignore +/// let ts: TokenStream2 = quote! { foo.bar().await }; +/// let stripped = strip_await_from_tokens(&ts); +/// assert_eq!(stripped.to_string(), "foo . bar ()"); +/// ``` +/// +/// If the token stream does not end with `.await`, the original stream is returned unchanged. fn strip_await_from_tokens(ts: &TokenStream2) -> TokenStream2 { let tokens: Vec<_> = ts.clone().into_iter().collect(); let len = tokens.len(); |