switch from reflection to code generation

This allows me to make the API much simpler. More simplification
forthcoming in the following commit; I just want to make a cut since
`make test` is happy right now.

1 files changed, 63 insertions, 0 deletions

diff --git a/util/render_template.go b/util/render_template.go
new file mode 100755
index 0000000..1db8840
--- /dev/null
+++ b/util/render_template.go
@@ -0,0 +1,63 @@
+///usr/bin/env go run "$0" "$@"; exit $!
+
+/******************************************************************************
+*
+*  Copyright 2018 Stefan Majewsky <majewsky@gmx.net>
+*
+*  Licensed under the Apache License, Version 2.0 (the "License");
+*  you may not use this file except in compliance with the License.
+*  You may obtain a copy of the License at
+*
+*      http://www.apache.org/licenses/LICENSE-2.0
+*
+*  Unless required by applicable law or agreed to in writing, software
+*  distributed under the License is distributed on an "AS IS" BASIS,
+*  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+*  See the License for the specific language governing permissions and
+*  limitations under the License.
+*
+******************************************************************************/
+
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"html/template"
+	"io/ioutil"
+	"os"
+	"strings"
+)
+
+func main() {
+	input, err := ioutil.ReadAll(os.Stdin)
+	failIfError(err)
+
+	sections := strings.SplitN(string(input), "\n---\n", 2)
+	if len(sections) != 2 {
+		fail("missing separator between data and template")
+	}
+	dataStr, templateStr := sections[0], sections[1]
+
+	data := make(map[string]interface{})
+	failIfError(json.Unmarshal([]byte(dataStr), &data))
+
+	tmpl, err := template.New("tmpl").Parse(templateStr)
+	failIfError(err)
+
+	failIfError(tmpl.Execute(os.Stdout, data))
+}
+
+func failIfError(err error) {
+	if err != nil {
+		fail(err.Error())
+	}
+}
+
+func fail(msg string, args ...interface{}) {
+	if len(args) > 0 {
+		msg = fmt.Sprintf(msg, args...)
+	}
+	fmt.Fprintln(os.Stderr, msg)
+	os.Exit(1)
+}