CHANGELOG generator

changelog

#!/usr/bin/env ruby
#
# CHANGELOG generator
#
# Usage:
#
#    $ changelog [SINCE UNTIL]
#
# This script collects git commits from a given range (SINCE and UNTIL
# are optional refs, SINCE defaults to the last tag, UNTIL to HEAD).
#
# It looks for markers which indictate that a commit should show up in
# the changelog. In this case it searches for tags inside brackets,
# e.g. [addition, change] which correspond to the according sections.
#
# Your milage may vary, but it should be easy to adapt.
#
# Example Output:
#
# Additions
# * Create changelog generator script (2h3gnm4r5t)
# * Write some documentation (89uyt3fze5) 
#
# Changes
# * Yay, never again have to do this by hand (r64rtaq2ke)
# 

require 'date'

# config
markers = {
  addition: "Additions",
  change: "Changes",
  bugfix: "Bugfixes" }

pattern = "\\[.*(#{markers.keys.join('|')}).*\\]"

# take commit range from arguments, default to latest git tag and HEAD
_since = ARGV[0] || `git describe --tags --always`.strip
_until = ARGV[1] || 'HEAD'
range = "#{_since}..#{_until}"

# extract commits
log = `git log #{range} --grep="#{pattern}" -i -E --no-decorate`.strip
commits = log.split(/^commit /)[1..-1] || []

# collect output
marks = {}
commits.each do |commit|
  lines = commit.lines

  info = {
    sha: lines[0].strip,
    email: lines[1][/<(.*)>/, 1],
    author: lines[1][/Author:\s+(.*) </, 1],
    message: lines[4].strip,
    extended: lines[6..-1].join(' ').strip,
    date: DateTime.parse(lines[2][/Date:\s+(.*)/, 1])
  }

  commit_marks = commit.match(pattern)[0].gsub(/\[|\]/, '').split(/,\s*/)
  commit_marks.each do |mark|
    mark = mark.to_sym
    marks[mark] ||= []
    marks[mark] << info
  end
end

# generate output
markers.each do |marker, title|
  commits = marks[marker]
  next unless commits

  puts "#{title}\n\n"
  commits.each { |commit| puts "* #{commit[:message]} (#{commit[:sha][0..9]})"}

  puts ''
end