commit 6474b0ba3ae624180293f4e38be3723c06dbf0c8
Author: yafox <yafox@box>
Date:   Tue Nov 24 21:28:40 2020 +0000

    initial commit

diff --git a/.gitignore b/.gitignore
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--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+format/
diff --git a/LICENSE b/LICENSE
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index 0000000..bd8c239
--- /dev/null
+++ b/LICENSE
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+The MIT License (MIT)
+
+Copyright 2020 "yafox"
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software is furnished to do so,
+subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
diff --git a/README b/README
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index 0000000..af05285
--- /dev/null
+++ b/README
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+vercmp
+======
+
+51 SLOC, not counting format scripts.
+
+vercmp evaluates a version comparison expression and prints "yes" if the
+expression evaluates to true and "no" otherwise.
+
+vercmp can be extended with additional formats by adding a shell script defining
+a `comparever` function to the `format` subdirectory.  no `format` subdirectory
+is included by default.  to make bootstrapping easier, instructions for pulling
+some are included in the makefile.  if bootstrapping lix os, for example, the
+following will `git clone` lix os' vercmp formats into the format directory:
+
+    make lix-os-formats
+
+or, if wanting a basis for creating one's own formats using the same foundatiion
+as lix os' formats:
+
+    make bare-formats
+
+to install, just `make install`.
+
+usage:
+
+    vercmp <comparison string> [format]
+    vercmp formats
+
+comparison string:
+    "<version 1> <op> <version 2>"
+
+op:
+    == equal
+    >= greater than or equal
+    <= less than or equal
+    >  greater than
+    <  less than
+
+format:
+    the name of the format to use for parsing and comparing the versions.
+	see 'vercmp formats' for a list of formats.
+	(format scripts are kept in $VERCMPROOT/format)
+
+## examples
+
+    $ vercmp "1.2.3 >= 3.2.1"
+    no
+
+    $ vercmp "1.2 == 1.2"                                                                           
+    yes
+
+    $ vercmp "1.2+meta1 == 1.2+meta2"                                                               
+    yes
+
+    $ vercmp "1.2+meta1 > 1.2-rc1+meta2"                                                            
+    yes
+
+    $ vercmp "1.2-rc1 < 1.2-rc2"
+    yes
+
+## caveat
+
+vercmp format scripts assume both versions are in the same format.  if this is
+not the case, undefined behavior may ensue.  even a simple variation like the
+following can have unexpected results:
+
+     $ vercmp "1.2 == 1.2.0"                                                                         
+     no
diff --git a/makefile b/makefile
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index 0000000..06b9e91
--- /dev/null
+++ b/makefile
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+SRCDIR = $(dir $(realpath $(firstword $(MAKEFILE_LIST))))
+PREFIX ?= /usr
+DESTDIR ?= $(PREFIX)/bin
+VERCMPROOT ?= $(PREFIX)/share/vercmp
+GITBASE ?= $(shell realpath $(shell git config --get remote.origin.url) | rev | \
+           cut -d/ -f2- | rev)
+
+lix-os-vercmp:
+	git clone $(GITBASE)/vercmp-lix-os-formats format
+
+bare-vercmp:
+	git clone $(GITBASE)/vercmp-bare-formats format
+
+install: $(SRCDIR)/format
+	ln -sf $(SRCDIR) $(VERCMPROOT)
+	ln -sf $(VERCMPROOT)/vercmp.sh $(DESTDIR)/vercmp
+
+uninstall:
+	rm $(DESTDIR)/vercmp
+	rm $(VERCMPROOT)
diff --git a/sloc.sh b/sloc.sh
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index 0000000..167e877
--- /dev/null
+++ b/sloc.sh
@@ -0,0 +1,12 @@
+#!/bin/sh
+
+# find all *.sh files not under `format`, strip all trailing whitespace, then
+# all leading whitespace, then all lines starting with '#', then all empty
+# lines, and then count the remaining lines.
+
+find . -name "*.sh" ! -path "**/format/**" \
+| xargs sed 's/[[:space:]]*$//g; s/^[[:space:]]*//g; s/^#.*$//g; /^$/d' \
+| wc -l - \
+| cut -d' ' -f1
+
+# note that this script's ELOC is also included in the count.
diff --git a/vercmp.sh b/vercmp.sh
new file mode 100755
index 0000000..f5883f8
--- /dev/null
+++ b/vercmp.sh
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+#!/bin/sh
+
+set -e
+
+# if this is running on an interactive terminal (as opposed to in a script),
+# and if tput is installed and knows some color codes...
+if [ -t 1 ] && [ "$(tput colors 2>/dev/null || echo 0)" -ge 8 ]; then 
+    _clr="$(tput sgr0)"
+    _red="$(tput setaf 1)"
+fi
+err() { echo "$_red[ERR]$_clr $@" >&2; exit 1; }
+
+VERCMPROOT="$(dirname "$(readlink -f "$0")")"
+
+[ "$1" ] || cat <<EOF
+usage:
+    $(basename $0) [-f <format>] <comparison string>
+    $(basename $0) formats
+
+comparison string:
+    "<version 1> <op> <version 2>"
+
+op:
+    == equal
+    != not equal
+    >= greater than or equal
+    <= less than or equal
+    >  greater than
+    <  less than
+
+format:
+    the name of the format to use for parsing and comparing the versions.
+	see '$(basename $0) formats' for a list of formats.
+	(format scripts are kept in $VERCMPROOT/format)
+EOF
+
+[ -d "$VERCMPROOT/format" ] \
+|| err "no format directory! install one. see makefile or README for details."
+
+if [ "$1" = "formats" ]; then
+    ls $VERCMPROOT/format/*.sh | sed -e 's/.*\/\(.*\).sh/\1/'
+    exit 0
+fi
+
+[ "$1" = "-f" ] && { fmt="$2"; shift; shift; } || fmt="default"
+
+# make $fmt available to version format scripts
+export fmt
+
+v1="$(echo "$1" | awk '{ print $1 }')"
+op="$(echo "$1" | awk '{ print $2 }')"
+v2="$(echo "$1" | awk '{ print $3 }')"
+
+[ "$v2" ] || err "could not determine second version to use in comparison!"
+
+[ -e "$VERCMPROOT/format/$fmt.sh" ] || err "unrecognized version format: $fmt"
+
+. "$VERCMPROOT/format/$fmt.sh"
+
+# 'comparever' returns =, <, or >
+relation="$(comparever $v1 $v2)"
+
+no() { echo "no" && exit 0; }
+case $op in
+    '!=') [ "$relation" != "=" ] || no ;;
+    '=='|'='|'>'|'<'|'>='|'<=') [ "${op#*$relation}" != "${op}" ] || no ;;
+       *) err "unrecognized operator: $op" ;;
+esac
+echo "yes"