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-rw-r--r--rust/macros/helpers.rs155
1 files changed, 155 insertions, 0 deletions
diff --git a/rust/macros/helpers.rs b/rust/macros/helpers.rs
new file mode 100644
index 0000000000..afb0f2e3a3
--- /dev/null
+++ b/rust/macros/helpers.rs
@@ -0,0 +1,155 @@
+// SPDX-License-Identifier: GPL-2.0
+
+use proc_macro::{token_stream, Group, Punct, Spacing, TokenStream, TokenTree};
+
+pub(crate) fn try_ident(it: &mut token_stream::IntoIter) -> Option<String> {
+ if let Some(TokenTree::Ident(ident)) = it.next() {
+ Some(ident.to_string())
+ } else {
+ None
+ }
+}
+
+pub(crate) fn try_literal(it: &mut token_stream::IntoIter) -> Option<String> {
+ if let Some(TokenTree::Literal(literal)) = it.next() {
+ Some(literal.to_string())
+ } else {
+ None
+ }
+}
+
+pub(crate) fn try_string(it: &mut token_stream::IntoIter) -> Option<String> {
+ try_literal(it).and_then(|string| {
+ if string.starts_with('\"') && string.ends_with('\"') {
+ let content = &string[1..string.len() - 1];
+ if content.contains('\\') {
+ panic!("Escape sequences in string literals not yet handled");
+ }
+ Some(content.to_string())
+ } else if string.starts_with("r\"") {
+ panic!("Raw string literals are not yet handled");
+ } else {
+ None
+ }
+ })
+}
+
+pub(crate) fn expect_ident(it: &mut token_stream::IntoIter) -> String {
+ try_ident(it).expect("Expected Ident")
+}
+
+pub(crate) fn expect_punct(it: &mut token_stream::IntoIter) -> char {
+ if let TokenTree::Punct(punct) = it.next().expect("Reached end of token stream for Punct") {
+ punct.as_char()
+ } else {
+ panic!("Expected Punct");
+ }
+}
+
+pub(crate) fn expect_string(it: &mut token_stream::IntoIter) -> String {
+ try_string(it).expect("Expected string")
+}
+
+pub(crate) fn expect_string_ascii(it: &mut token_stream::IntoIter) -> String {
+ let string = try_string(it).expect("Expected string");
+ assert!(string.is_ascii(), "Expected ASCII string");
+ string
+}
+
+pub(crate) fn expect_group(it: &mut token_stream::IntoIter) -> Group {
+ if let TokenTree::Group(group) = it.next().expect("Reached end of token stream for Group") {
+ group
+ } else {
+ panic!("Expected Group");
+ }
+}
+
+pub(crate) fn expect_end(it: &mut token_stream::IntoIter) {
+ if it.next().is_some() {
+ panic!("Expected end");
+ }
+}
+
+pub(crate) struct Generics {
+ pub(crate) impl_generics: Vec<TokenTree>,
+ pub(crate) ty_generics: Vec<TokenTree>,
+}
+
+/// Parses the given `TokenStream` into `Generics` and the rest.
+///
+/// The generics are not present in the rest, but a where clause might remain.
+pub(crate) fn parse_generics(input: TokenStream) -> (Generics, Vec<TokenTree>) {
+ // `impl_generics`, the declared generics with their bounds.
+ let mut impl_generics = vec![];
+ // Only the names of the generics, without any bounds.
+ let mut ty_generics = vec![];
+ // Tokens not related to the generics e.g. the `where` token and definition.
+ let mut rest = vec![];
+ // The current level of `<`.
+ let mut nesting = 0;
+ let mut toks = input.into_iter();
+ // If we are at the beginning of a generic parameter.
+ let mut at_start = true;
+ for tt in &mut toks {
+ match tt.clone() {
+ TokenTree::Punct(p) if p.as_char() == '<' => {
+ if nesting >= 1 {
+ // This is inside of the generics and part of some bound.
+ impl_generics.push(tt);
+ }
+ nesting += 1;
+ }
+ TokenTree::Punct(p) if p.as_char() == '>' => {
+ // This is a parsing error, so we just end it here.
+ if nesting == 0 {
+ break;
+ } else {
+ nesting -= 1;
+ if nesting >= 1 {
+ // We are still inside of the generics and part of some bound.
+ impl_generics.push(tt);
+ }
+ if nesting == 0 {
+ break;
+ }
+ }
+ }
+ tt => {
+ if nesting == 1 {
+ // Here depending on the token, it might be a generic variable name.
+ match &tt {
+ // Ignore const.
+ TokenTree::Ident(i) if i.to_string() == "const" => {}
+ TokenTree::Ident(_) if at_start => {
+ ty_generics.push(tt.clone());
+ // We also already push the `,` token, this makes it easier to append
+ // generics.
+ ty_generics.push(TokenTree::Punct(Punct::new(',', Spacing::Alone)));
+ at_start = false;
+ }
+ TokenTree::Punct(p) if p.as_char() == ',' => at_start = true,
+ // Lifetimes begin with `'`.
+ TokenTree::Punct(p) if p.as_char() == '\'' && at_start => {
+ ty_generics.push(tt.clone());
+ }
+ _ => {}
+ }
+ }
+ if nesting >= 1 {
+ impl_generics.push(tt);
+ } else if nesting == 0 {
+ // If we haven't entered the generics yet, we still want to keep these tokens.
+ rest.push(tt);
+ }
+ }
+ }
+ }
+ rest.extend(toks);
+ (
+ Generics {
+ impl_generics,
+ ty_generics,
+ },
+ rest,
+ )
+}