testdata_embed.sh

#!/usr/bin/env bash

# Copyright 2023 The flatgeobuf (Go) Authors. All rights reserved.
# Use of this source code is governed by an MIT-style
# license that can be found in the LICENSE file.

set -eo pipefail


if ! command -v bzip2 >/dev/null; then
  >&2 << EOF cat
error: bzip2 not found
  | This script uses bzip2 to compress test data files from
  | https://github.com/flatgeobuf/flatgeobuf prior to embedding
  | them in the Go code.
  |
  | Install bzip2 if you want to proceed.
EOF
  exit 2
fi


function version() {
  local version='$Id$'
  version="${version##\$Id: }"
  version="${version%% \$}"
  echo $version
}


testdata_file="$1"
if ! [ -f "$testdata_file" ]; then
  >&2 printf "unable to import %s: not found or not a file\n" "$testdata_file"
fi


# Derive the name of the string variable to contain the contents of the
# testdata file.
testdata_filename_root="$(basename "$testdata_file")"
declare -a testdata_varname_parts
testdata_filename_root="${testdata_filename_root%%.fgb}"
readarray -td $'\n' testdata_varname_parts <<<"${testdata_filename_root//_/$'\n'}"
testdata_varname=
for (( i=0; i<"${#testdata_varname_parts}"; i++ )); do
  part="${testdata_varname_parts[$i]}"
  testdata_varname+="${part^}"
done
testdata_varname+=FGB


# Create a temporary file to contain the input $GOFILE with generated
# code inserted. Set a trap to make sure the file gets deleted if we
# error out unexpectedly.
tmp_file=""
function cleanup() {
  rm -f "$tmp_file"
}
trap cleanup EXIT
tmp_file=$(mktemp "$GOFILE.XXXXXXXX")


# Print status.
>&2 printf 'embedding %s into %s (%s) at line %d using %s\n' "$testdata_file" "$GOFILE" "var $testdata_varname" "$GOLINE" "$tmp_file"

# PREFIX: Echo every line of the Go file prior to the go:generate
# directive to the temporary file.
>"$tmp_file" head -n "$GOLINE" "$GOFILE"


# INFIX: Insert the generated code.
>>"$tmp_file" <<EOF cat
// DO NOT EDIT. Code generated by testdata_embed.sh version $(version).
//
// This string contains the base64-encoded, bzip2-compressed, contents of the
// file \`$testdata_file\`. For license information, please see
// https://github.com/gogama/flatgeobuf/flatgeobuf/testdata/flatgeobuf/LICENSE.
//
// Last generated by $USER on $(date). The raw source
// SHA-256 is $(sha256sum "$testdata_file" | cut -d' ' -f1).
//
// This silly byte-embedding trick is needed to access the example test code
// when running example code within the docs website,
// https://pkg.go.dev/github.com/gogama/flatgeobuf.
var $testdata_varname = \`
EOF
<"$testdata_file" bzip2 | base64 -w 8192 >>"$tmp_file"
>>"$tmp_file" echo '`'


# Find the end of the string literal within the input file so we can
# skip past it.
offset="$(tail -n +"$GOLINE" "$GOFILE" | grep -n -m1 '\(^\|`\)`$' | cut -d: -f 1)"


# SUFFIX: Echo every line of the Go file after the go:generate directive
# to the temporary file.
>>"$tmp_file" tail -n +$((GOLINE + offset)) "$GOFILE"


# Swap the temporary file in for the original target Go file.
mv "$tmp_file" "$GOFILE"