cmd/hopp-generate: Add code generator command

cmd/hopp-generate/main.go

@@ -0,0 +1,58 @@
+package main
+
+import "os"
+import "fmt"
+import "strings"
+import "path/filepath"
+import "git.tebibyte.media/sashakoshka/hopp/generate"
+
+func main() {
+	name := os.Args[0]
+	if len(os.Args) != 3 {
+		fmt.Fprintf(os.Stderr, "Usage: %s SOURCE DESTINATION\n", name)
+		os.Exit(2)
+	}
+	source      := os.Args[1]
+	destination := os.Args[2]
+
+	input, err := os.Open(source)
+	handleErr(1, err)
+	defer input.Close()
+	protocol, err := generate.ParseReader(input)
+	handleErr(1, err)
+
+	absDestination, err := filepath.Abs(destination)
+	handleErr(1, err)
+	packageName := cleanPackageName(strings.ReplaceAll(
+		strings.ToLower(filepath.Base(absDestination)),
+		" ", "_"))
+	destination = filepath.Join(os.Args[2], "generated.go")
+
+	output, err := os.Create(destination)
+	handleErr(1, err)
+	err = protocol.Generate(output, packageName)
+	handleErr(1, err)
+	fmt.Fprintf(os.Stderr, "%s: OK\n", name)
+}
+
+func handleErr(code int, err error) {
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "%s: %v\n", os.Args[0], err)
+		os.Exit(code)
+	}
+}
+
+func cleanPackageName(str string) string {
+	buffer := []byte(str)
+	j := 0
+	for _, b := range buffer {
+		if ('a' <= b && b <= 'z') ||
+			('A' <= b && b <= 'Z') ||
+			('0' <= b && b <= '9') ||
+			b == '_' || b == ' ' {
+			buffer[j] = b
+			j++
+		}
+	}
+	return string(buffer[:j])
+}