cargo.eclass: Support separating crate names/versions via `@`

Support specifying crate names and versions separated by `@` character
rather than `-`.  Since `@` are not valid in crate names, this
makes splitting the tokens trivial and free of regular expressions.
Effectively, the `@` variant is roughly 180% faster:

```
 * CRATES with '@' separator
real  952 it/s
user  952 it/s
 * CRATES with '-' separator
real  339 it/s
user  339 it/s
```

Signed-off-by: Michał Górny <mgorny@gentoo.org>

2 files changed, 75 insertions, 60 deletions

diff --git a/eclass/cargo.eclass b/eclass/cargo.eclass
index d97bb0df9348..8618c90bd986 100644
--- a/eclass/cargo.eclass
+++ b/eclass/cargo.eclass
@@ -59,12 +59,16 @@ ECARGO_VENDOR="${ECARGO_HOME}/gentoo"
 # Bash string containing all crates that are to be downloaded.
 # It is used by cargo_crate_uris.
 #
+# Ideally, crate names and versions should be separated by a `@`
+# character.  A legacy syntax using hyphen is also supported but it is
+# much slower.
+#
 # Example:
 # @CODE
 # CRATES="
-# metal-1.2.3
-# bar-4.5.6
-# iron_oxide-0.0.1
+# metal@1.2.3
+# bar@4.5.6
+# iron_oxide@0.0.1
 # "
 # inherit cargo
 # ...
@@ -182,10 +186,16 @@ _cargo_set_crate_uris() {
 	CARGO_CRATE_URIS=
 	for crate in ${crates}; do
 		local name version url
-		[[ $crate =~ $regex ]] || die "Could not parse name and version from crate: $crate"
-		name="${BASH_REMATCH[1]}"
-		version="${BASH_REMATCH[2]}"
-		url="https://crates.io/api/v1/crates/${name}/${version}/download -> ${crate}.crate"
+		if [[ ${crate} == *@* ]]; then
+			name=${crate%@*}
+			version=${crate##*@}
+		else
+			[[ ${crate} =~ ${regex} ]] ||
+				die "Could not parse name and version from crate: ${crate}"
+			name="${BASH_REMATCH[1]}"
+			version="${BASH_REMATCH[2]}"
+		fi
+		url="https://crates.io/api/v1/crates/${name}/${version}/download -> ${name}-${version}.crate"
 		CARGO_CRATE_URIS+="${url} "
 	done
 
diff --git a/eclass/tests/cargo-bench.sh b/eclass/tests/cargo-bench.sh
index 11b740f8dfcd..d30b04569905 100755
--- a/eclass/tests/cargo-bench.sh
+++ b/eclass/tests/cargo-bench.sh
@@ -47,63 +47,68 @@ timeit() {
 
 # taken from cryptograpy-41.0.1
 CRATES="
-	Inflector-0.11.4
-	aliasable-0.1.3
-	asn1-0.15.2
-	asn1_derive-0.15.2
-	autocfg-1.1.0
-	base64-0.13.1
-	bitflags-1.3.2
-	cc-1.0.79
-	cfg-if-1.0.0
-	foreign-types-0.3.2
-	foreign-types-shared-0.1.1
-	indoc-1.0.9
-	libc-0.2.144
-	lock_api-0.4.9
-	memoffset-0.8.0
-	once_cell-1.17.2
-	openssl-0.10.54
-	openssl-macros-0.1.1
-	openssl-sys-0.9.88
-	ouroboros-0.15.6
-	ouroboros_macro-0.15.6
-	parking_lot-0.12.1
-	parking_lot_core-0.9.7
-	pem-1.1.1
-	pkg-config-0.3.27
-	proc-macro-error-1.0.4
-	proc-macro-error-attr-1.0.4
-	proc-macro2-1.0.59
-	pyo3-0.18.3
-	pyo3-build-config-0.18.3
-	pyo3-ffi-0.18.3
-	pyo3-macros-0.18.3
-	pyo3-macros-backend-0.18.3
-	quote-1.0.28
-	redox_syscall-0.2.16
-	scopeguard-1.1.0
-	smallvec-1.10.0
-	syn-1.0.109
-	syn-2.0.18
-	target-lexicon-0.12.7
-	unicode-ident-1.0.9
-	unindent-0.1.11
-	vcpkg-0.2.15
-	version_check-0.9.4
-	windows-sys-0.45.0
-	windows-targets-0.42.2
-	windows_aarch64_gnullvm-0.42.2
-	windows_aarch64_msvc-0.42.2
-	windows_i686_gnu-0.42.2
-	windows_i686_msvc-0.42.2
-	windows_x86_64_gnu-0.42.2
-	windows_x86_64_gnullvm-0.42.2
-	windows_x86_64_msvc-0.42.2
+	Inflector@0.11.4
+	aliasable@0.1.3
+	asn1@0.15.2
+	asn1_derive@0.15.2
+	autocfg@1.1.0
+	base64@0.13.1
+	bitflags@1.3.2
+	cc@1.0.79
+	cfg-if@1.0.0
+	foreign-types@0.3.2
+	foreign-types-shared@0.1.1
+	indoc@1.0.9
+	libc@0.2.144
+	lock_api@0.4.9
+	memoffset@0.8.0
+	once_cell@1.17.2
+	openssl@0.10.54
+	openssl-macros@0.1.1
+	openssl-sys@0.9.88
+	ouroboros@0.15.6
+	ouroboros_macro@0.15.6
+	parking_lot@0.12.1
+	parking_lot_core@0.9.7
+	pem@1.1.1
+	pkg-config@0.3.27
+	proc-macro-error@1.0.4
+	proc-macro-error-attr@1.0.4
+	proc-macro2@1.0.59
+	pyo3@0.18.3
+	pyo3-build-config@0.18.3
+	pyo3-ffi@0.18.3
+	pyo3-macros@0.18.3
+	pyo3-macros-backend@0.18.3
+	quote@1.0.28
+	redox_syscall@0.2.16
+	scopeguard@1.1.0
+	smallvec@1.10.0
+	syn@1.0.109
+	syn@2.0.18
+	target-lexicon@0.12.7
+	unicode-ident@1.0.9
+	unindent@0.1.11
+	vcpkg@0.2.15
+	version_check@0.9.4
+	windows-sys@0.45.0
+	windows-targets@0.42.2
+	windows_aarch64_gnullvm@0.42.2
+	windows_aarch64_msvc@0.42.2
+	windows_i686_gnu@0.42.2
+	windows_i686_msvc@0.42.2
+	windows_x86_64_gnu@0.42.2
+	windows_x86_64_gnullvm@0.42.2
+	windows_x86_64_msvc@0.42.2
 "
 
 inherit cargo
 
+einfo "CRATES with '@' separator"
+timeit
+
+einfo "CRATES with '-' separator"
+CRATES=${CRATES//@/-}
 timeit
 
 texit