Add support for a custom tag prefix

action.yml

@@ -3,10 +3,10 @@ description: GitHub Action for creating GitHub Releases based on changelog
 
 inputs:
   changelog:
-    description: Path to changelog
+    description: Path to changelog (variables `$tag`, `$version`, `$prefix`, and any string)
     required: false
   title:
-    description: Format of title (variables `$tag`, `$version`, and any string)
+    description: Format of title (variables `$tag`, `$version`, `$prefix`, and any string)
     required: false
     default: '$tag'
   draft:
@@ -16,6 +16,26 @@ inputs:
   branch:
     description: Reject releases from commits not contained in branches that match the specified pattern (regular expression)
     required: false
+  prefix:
+    description: >
+      An optional pattern that matches a prefix for the release tag, before the
+      version number.
+
+      If a prefix is provided, an optional '-' character is permitted (but not
+      required) between the prefix and the version number.   For example, the
+      tags 'my-crate-v0.1.2' and 'my-crate0.1.0' both have the prefix 'my-crate'.
+
+      This is interpreted as a bash-style regular expression, so it may be used
+      to match multiple prefix strings. Therefore, literal characters that
+      are part of bash's regular expression syntax, such as `$`, `^`, `[`, `]`,
+      `{`, `}`, `(`, `)`, and `|` must be escaped if they occur in the prefix
+      pattern.
+
+      If a prefix pattern is provided, the portion of the tag that matched the
+      prefix can be interpolated into `title` and `changelog` via the `$prefix`
+      variable.
+    required: false
+    default: ''
 
 runs:
   using: node12

main.sh

@@ -17,6 +17,7 @@ title="${INPUT_TITLE:?}"
 changelog="${INPUT_CHANGELOG:-}"
 draft="${INPUT_DRAFT:-}"
 branch="${INPUT_BRANCH:-}"
+prefix="${INPUT_PREFIX:-}"
 
 if [[ -z "${GITHUB_TOKEN:-}" ]]; then
     error "GITHUB_TOKEN not set"
@@ -29,18 +30,31 @@ if [[ "${GITHUB_REF:?}" != "refs/tags/"* ]]; then
 fi
 tag="${GITHUB_REF#refs/tags/}"
 
-# TODO: Support custom prefix of tags https://github.com/taiki-e/create-gh-release-action/issues/1
-if [[ ! "${tag}" =~ ^v?[0-9]+\.[0-9]+\.[0-9]+(-[a-zA-Z_0-9\.-]+)?(\+[a-zA-Z_0-9\.-]+)?$ ]]; then
+if [[ ! "${tag}" =~ ^${prefix}-?v?[0-9]+\.[0-9]+\.[0-9]+(-[a-zA-Z_0-9\.-]+)?(\+[a-zA-Z_0-9\.-]+)?$ ]]; then
     error "invalid tag format: '${tag}'"
     exit 1
 fi
-if [[ "${tag}" =~ ^v?[0-9\.]+-[a-zA-Z_0-9\.-]+(\+[a-zA-Z_0-9\.-]+)?$ ]]; then
+if [[ "${tag}" =~ ^${prefix}-?v?[0-9\.]+-[a-zA-Z_0-9\.-]+(\+[a-zA-Z_0-9\.-]+)?$ ]]; then
     prerelease="--prerelease"
 fi
-version="${tag#v}"
+
+version="${tag}"
+# extract the portion of the tag matching the prefix pattern
+if [[ ! "${prefix}" = "" ]]; then
+    prefix=$(grep <<<"${tag}" -Eo "^${prefix}")
+    version="${tag#${prefix}}"
+    version="${version#-}"
+fi
+version="${version#v}"
+
+# interpolate $tag, $version, and $prefix into the title string
 title="${title/\$tag/${tag}}"
 title="${title/\$version/${version}}"
-
+title="${title/\$prefix/${prefix}}"
+# interpolate $tag, $version, and $prefix into the changelog path
+changelog="${changelog/\$tag/${tag}}"
+changelog="${changelog/\$version/${version}}"
+changelog="${changelog/\$prefix/${prefix}}"
 case "${draft}" in
     true) draft_option="--draft" ;;
     false) ;;