Is. htacg#748 - Implement snap packaging

Snaps are universal Linux packages that can be installed and run on
multiple GNU+Linux distributions with ease.  This patch implements the
necessary files to build tidy as a snap.

Refer-to: Snapcraft - Snaps are universal Linux packages
<https://snapcraft.io>
Conforming-to: tidy-html5/CONTRIBUTING.md at next · htacg/tidy-html5
<https://github.com/htacg/tidy-html5/blob/next/README/CONTRIBUTING.md>
Conforming-to: tidy-html5/CODESTYLE.md at next · htacg/tidy-html5
<https://github.com/htacg/tidy-html5/blob/next/README/CODESTYLE.md>
Signed-off-by: 林博仁(Buo-ren, Lin) <Buo.Ren.Lin@gmail.com>

.gitignore

@@ -16,3 +16,11 @@ temp*
 .DS_Store
 .idea
 *.old
+
+# Snap packaging specific rules
+/parts/
+/stage/
+/prime/
+
+/*.snap
+/*_source.tar.bz2

snap/.editorconfig

@@ -0,0 +1,9 @@
+root = true
+
+[*.yaml]
+indent_style = space
+indent_size = 4
+end_of_line = lf
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true

snap/.gitignore

@@ -0,0 +1,6 @@
+# Version Tracking Ignore Rules for Git VCS
+# https://git-scm.com/docs/gitignore
+/.snapcraft/
+
+__pycache__
+*.pyc

snap/README.md

@@ -0,0 +1,33 @@
+# Snap Packaging for Tidy
+![Placeholder Icon for Tidy](gui/icon.png "Placeholder Icon for Tidy")
+
+**This is the snap for Tidy**, *"HTML parser and pretty printer.  The grand daddy of HTML tools."*. It works on Ubuntu, Fedora, Debian, and other major Linux distributions.
+
+[![Build Status Badge of the `tidy` Snap](https://build.snapcraft.io/badge/htacg/tidy-html5.svg "Build Status of the `tidy` snap")](https://build.snapcraft.io/user/htacg/tidy-html5)
+
+![Screenshot of the Snapped Application](screenshots/tidy-help-heading.png "Screenshot of the Snapped Application")
+
+Published for <img src="http://anything.codes/slack-emoji-for-techies/emoji/tux.png" align="top" width="24" /> with 💝 by Snapcrafters
+
+## Installation
+([Don't have snapd installed?](https://snapcraft.io/docs/core/install))
+
+### In Terminal
+    # Install Snap #
+    sudo snap install tidy-brlin
+
+    # Connect the Snap to Optional Interfaces #
+    ## `removable-media`: For accessing files under /media and /run/media ##
+    sudo snap connect tidy-brlin:removable-media
+
+### The Graphical Way
+Browse <https://snapcraft.io/tidy> and follow the instructions.
+
+## Support
+* Report issues regarding using this snap to the issue tracker:  
+  <https://github.com/htacg/tidy-html5/issues>  
+
+  be sure to mention you are using the snap package.
+
+* You may also post on the Snapcraft Forum, under the `snap` topic category:  
+  <https://forum.snapcraft.io/c/snap>

snap/gui/README.md

@@ -0,0 +1,5 @@
+# /snap/gui
+
+Copy the snapped application's icon here and specify it in snapcraft.yaml file using the `icon` keyword.  This folder is not necessary if the icon is already existed in the source tree.
+
+NOTE: The Snap Store requires SVG scalable image or PNG image with at least 256x256px in size.

snap/screenshots/README.markdown

@@ -0,0 +1,3 @@
+# /snap/screenshots
+
+The screenshots of the snapped application.  This is not currently synced to the product page on the Snap Store and should be uploaded by yourself.

snap/snapcraft.yaml

@@ -0,0 +1,65 @@
+%YAML 1.2
+---
+# Snapcraft Recipe for Tidy
+# ------------------------------
+# This file is in the YAML data serialization format:
+# http://yaml.org
+# For the spec. of writing this file refer the following documentation:
+# * The snapcraft syntax
+#   https://docs.snapcraft.io/build-snaps/syntax
+# * Snap Docs
+#   https://snapdocs.labix.org
+# * Latest doc topics in the Snapcraft Forum
+#   https://forum.snapcraft.io/c/doc
+# For support refer to the snapcraft section in the Snapcraft Forum:
+# https://forum.snapcraft.io/c/snapcraft
+
+name: tidy
+summary: HTML parser and pretty printer.  The grand daddy of HTML tools
+description: |
+    Tidy is a console application for Mac OS X, Linux, Windows, UNIX,
+    and more. It corrects and cleans up HTML and XML documents by fixing
+    markup errors and upgrading legacy code to modern standards.
+
+version: determined-by-version-script
+version-script: snap/utilities/set-snap-version.bash
+
+confinement: strict
+grade: stable
+
+apps:
+    tidy:
+        command: tidy
+        plugs:
+        - home
+        - removable-media
+
+parts:
+    tidy:
+        source: .
+        source-type: local
+
+        # For stable release build
+        #source-tag: '5.6.0'
+
+        plugin: cmake
+        configflags:
+        - -DCMAKE_BUILD_TYPE=Release
+
+        build-packages:
+        - build-essential
+        - xsltproc
+
+        filesets:
+            executables:
+            - bin/*
+            library-headers:
+            - include/*
+            library-shared:
+            - lib/*.so*
+            library-static:
+            - lib/*.a
+            pkgconfig:
+            - lib/pkgconfig/*
+            manpages:
+            - share/man/*

snap/utilities/README.md

@@ -0,0 +1,3 @@
+# /snap/utilities
+
+Here are some utilities programs to help with snap packaging.

snap/utilities/set-snap-version.bash

@@ -0,0 +1,44 @@
+#!/usr/bin/env bash
+# Set snap version according to various factors
+# 林博仁(Buo-ren, Lin) © 2018
+
+set \
+    -o errexit \
+    -o errtrace \
+    -o nounset \
+    -o pipefail
+
+init(){
+    set \
+        -o errexit \
+        -o nounset
+
+    local \
+        upstream_version \
+        upstream_git_revision
+
+    upstream_version="$(
+        head \
+            --lines=1 \
+            parts/tidy/src/version.txt
+    )"
+
+    upstream_git_revision="$(
+        git \
+            -C parts/tidy/src \
+            describe \
+            --always \
+            --dirty \
+            --match nothing \
+        | sed s/^v//
+    )"
+
+    printf \
+        -- \
+        '%s' \
+        "${upstream_version}-g${upstream_git_revision}"
+
+    exit 0
+}
+
+init "${@}"