Add missing files.

structs.go

@@ -0,0 +1,7 @@
+package main
+
+type enotfounderr struct{ name string }
+
+func (e *enotfounderr) Error() string {
+	return "strict mode on: environment variable not found: $" + e.name
+}

template_functions.go

@@ -0,0 +1,92 @@
+package main
+
+import (
+	"fmt"
+	"html/template"
+	"math/rand"
+	"os"
+	"strings"
+	"time"
+	"unsafe"
+)
+
+var templateFunctions = template.FuncMap{
+	"env": envfunc,
+	"raw": func(s string) string {
+		return s
+	},
+
+	"sprintf": func(s string, args ...interface{}) string {
+		return fmt.Sprintf(s, args...)
+	},
+
+	"envdefault": func(k, defval string) (string, error) {
+		s, err := envfunc(k)
+
+		if err != nil {
+			if _, ok := err.(*enotfounderr); ok {
+				return defval, nil
+			}
+
+			return "", err
+		}
+
+		if s != "" {
+			return s, nil
+		}
+
+		return defval, nil
+	},
+
+	"rndstring": rndgen,
+	"lowercase": strings.ToLower,
+	"uppercase": strings.ToUpper,
+	"title":     strings.Title,
+}
+
+func envfunc(k string) (string, error) {
+	k = strings.ToUpper(k)
+
+	if v, found := os.LookupEnv(k); found {
+		return v, nil
+	}
+
+	if v, found := envvars[k]; found {
+		return v, nil
+	}
+
+	if strict {
+		return "", &enotfounderr{name: k}
+	}
+
+	return "", nil
+}
+
+// from: https://stackoverflow.com/a/31832326
+
+var src = rand.NewSource(time.Now().UnixNano())
+
+const letterBytes = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
+const (
+	letterIdxBits = 6                    // 6 bits to represent a letter index
+	letterIdxMask = 1<<letterIdxBits - 1 // All 1-bits, as many as letterIdxBits
+	letterIdxMax  = 63 / letterIdxBits   // # of letter indices fitting in 63 bits
+)
+
+func rndgen(n int) string {
+	b := make([]byte, n)
+	// A src.Int63() generates 63 random bits, enough for letterIdxMax characters!
+	for i, cache, remain := n-1, src.Int63(), letterIdxMax; i >= 0; {
+		if remain == 0 {
+			cache, remain = src.Int63(), letterIdxMax
+		}
+		if idx := int(cache & letterIdxMask); idx < len(letterBytes) {
+			b[i] = letterBytes[idx]
+			i--
+		}
+		cache >>= letterIdxBits
+		remain--
+	}
+
+	return *(*string)(unsafe.Pointer(&b))
+}