- add new ability to transform tags (tag name) prior to sorting, allowing to transform tags into semver format can be achieved

- tags will keep the original name post sorting
  - FIX https://github.com/mikepenz/release-changelog-builder-action/issues/571

src/configuration.ts

@@ -38,7 +38,8 @@ export interface Extractor extends Transformer {
 
 export interface TagResolver {
   method: string // semver, sort
-  filter?: Regex // the regex to filter the tags
+  filter?: Regex // the regex to filter the tags, prior to sorting
+  transformer?: Transformer // transforms the tag name using the regex, run after the filter
 }
 
 export const DefaultConfiguration: Configuration = {
@@ -71,7 +72,8 @@ export const DefaultConfiguration: Configuration = {
   tag_resolver: {
     // defines the logic on how to resolve the previous tag, only relevant if `fromTag` is not specified
     method: 'semver', // defines which method to use, by default it will use `semver` (dropping all non matching tags). Alternative `sort` is also available.
-    filter: undefined // filter out all tags not matching the regex
+    filter: undefined, // filter out all tags not matching the regex
+    transformer: undefined // transforms the tag name using the regex, run after the filter
   },
   base_branches: [] // target branches for the merged PR ignoring PRs with different target branch, by default it will get all PRs
 }

src/tags.ts

@@ -5,6 +5,7 @@ import {Octokit, RestEndpointMethodTypes} from '@octokit/rest'
 import {SemVer} from 'semver'
 import {TagResolver} from './configuration'
 import {createCommandManager} from './gitHelper'
+import {RegexTransformer, validateTransformer} from './transform'
 
 export interface TagResult {
   from: TagInfo | null
@@ -16,6 +17,10 @@ export interface TagInfo {
   commit: string
 }
 
+export interface SortableTagInfo extends TagInfo {
+  tmp: string
+}
+
 export class Tags {
   constructor(private octokit: Octokit) {}
 
@@ -114,8 +119,35 @@ export class Tags {
     maxTagsToFetch: number,
     tagResolver: TagResolver
   ): Promise<TagResult> {
-    const filteredTags = filterTags(await this.getTags(owner, repo, maxTagsToFetch), tagResolver)
-    const tags = sortTags(filteredTags, tagResolver)
+    // filter out tags not matching the specified filter
+    const filteredTags = filterTags(
+      // retrieve the tags from the API
+      await this.getTags(owner, repo, maxTagsToFetch),
+      tagResolver
+    )
+
+    // check if a transformer was defined
+    const tagTransformer = validateTransformer(tagResolver.transformer)
+
+    let transformedTags: TagInfo[]
+    if (tagTransformer != null) {
+      transformedTags = transformTags(filteredTags, tagTransformer)
+    } else {
+      transformedTags = filteredTags
+    }
+
+    let tags = sortTags(transformedTags, tagResolver)
+
+    if (tagTransformer != null) {
+      // restore the original name, after sorting
+      tags = filteredTags.map(function (tag) {
+        if (tag.hasOwnProperty('tmp')) {
+          return {name: (tag as SortableTagInfo).tmp, commit: tag.commit}
+        } else {
+          return tag
+        }
+      })
+    }
 
     let resultToTag: TagInfo | null
     let resultFromTag: TagInfo | null
@@ -209,6 +241,26 @@ export function filterTags(
   }
 }
 
+/**
+ * Helper function to transform the tag name given the transformer
+ */
+function transformTags(
+  tags: TagInfo[],
+  transformer: RegexTransformer
+): TagInfo[] {
+  return tags.map(function (tag) {
+    if (transformer.pattern) {
+      return {
+        tmp: tag.name, // remember the original name
+        name: tag.name.replace(transformer.pattern, transformer.target),
+        commit: tag.commit
+      }
+    } else {
+      return tag
+    }
+  })
+}
+
 /*
   Sorts an array of tags as shown below:
   

src/transform.ts

@@ -293,7 +293,7 @@ function validateTransformers(
     })
 }
 
-function validateTransformer(
+export function validateTransformer(
   transformer?: Transformer
 ): RegexTransformer | null {
   if (transformer === undefined) {
@@ -359,7 +359,7 @@ function extractValues(
   return null
 }
 
-interface RegexTransformer {
+export interface RegexTransformer {
   pattern: RegExp | null
   target: string
   onProperty?: 'title' | 'author' | 'milestone' | 'body' | undefined