Task to generate changelog

tasks/changelog.sh

@@ -0,0 +1,56 @@
+#!/bin/bash
+#
+# Generate a Markdown-formatted changelog from merge commits.
+#
+
+set -o errexit
+
+#
+# Regex to match the standard pull request commit message.  Creates capture
+# groups for pull request number, GitHub username, and commit message body.
+#
+MERGE_RE=Merge\ pull\ request\ #\([0-9]+\)\ from\ \([^/]+\)\/[^\ ]+\ \(.*\)
+
+GITHUB_URL=https://github.com
+PULLS_URL=${GITHUB_URL}/tschaub/gh-pages/pull
+
+display_usage() {
+  cat <<-EOF
+
+  Usage: ${1} <revision range>
+
+  Creates a Markdown-formatted changelog given a revision range.
+
+  E.g.
+      ${1} v3.0.0.. > changelog/v3.1.0.md
+
+  See git-log(1) for details on the revision range syntax.
+
+EOF
+}
+
+#
+# Scan the git log for merge commit messages and output Markdown.  This only
+# follows the first parent of merge commits to avoid merges within a topic
+# branch (instead only showing merges to master).
+#
+main() {
+  git log --first-parent --format='%s %b' ${1} |
+  {
+    while read l; do
+      if [[ ${l} =~ ${MERGE_RE} ]] ; then
+        number="${BASH_REMATCH[1]}"
+        author="${BASH_REMATCH[2]}"
+        summary="${BASH_REMATCH[3]}"
+        echo " * [#${number}](${PULLS_URL}/${number}) - ${summary} ([@${author}](${GITHUB_URL}/${author}))"
+      fi
+    done
+  }
+}
+
+if test ${#} -ne 1; then
+  display_usage ${0}
+  exit 1
+else
+  main ${1}
+fi