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main.go
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package main
import (
"bytes"
"flag"
"fmt"
"io"
"io/ioutil"
"net/http"
"os"
"runtime/debug"
"strings"
"github.com/falun/genny/parse"
)
/*
source | genny gen [-in=""] [-out=""] [-pkg=""] "KeyType=string,int ValueType=string,int"
*/
const (
_ = iota
exitcodeInvalidArgs
exitcodeInvalidTypeSet
exitcodeStdinFailed
exitcodeGenFailed
exitcodeGetFailed
exitcodeSourceFileInvalid
exitcodeDestFileFailed
exitcodeInternalError
)
func main() {
var (
mainErr error
exitCode int
)
defer func() {
if r := recover(); r != nil {
fmt.Fprintf(os.Stderr, "panic: %v: %s\n", r, debug.Stack())
exitCode = exitcodeInternalError
}
if mainErr != nil {
fmt.Fprintf(os.Stderr, "error: %v\n", mainErr)
}
os.Exit(exitCode)
}()
var (
in = flag.String("in", "", "file to parse instead of stdin")
out = flag.String("out", "", "file to save output to instead of stdout")
pkgName = flag.String("pkg", "", "package name for generated files")
genTag = flag.String("tag", "", "build tag that is stripped from output")
prefix = "https://github.com/metabition/gennylib/raw/master/"
)
flag.Parse()
args := flag.Args()
if len(args) < 2 {
usage()
os.Exit(exitcodeInvalidArgs)
}
if strings.ToLower(args[0]) != "gen" && strings.ToLower(args[0]) != "get" {
usage()
os.Exit(exitcodeInvalidArgs)
}
// parse the typesets
var setsArg = args[1]
if strings.ToLower(args[0]) == "get" {
setsArg = args[2]
}
typeSets, err := parse.TypeSet(setsArg)
if err != nil {
exitCode, mainErr = exitcodeInvalidTypeSet, err
return
}
var outWriter io.Writer
if len(*out) > 0 {
outFile, err := os.Create(*out)
if err != nil {
exitCode, mainErr = exitcodeDestFileFailed, err
return
}
defer func(outPath string) {
outFile.Close()
if mainErr != nil {
os.RemoveAll(outPath)
}
}(*out)
outWriter = outFile
} else {
outWriter = os.Stdout
}
if strings.ToLower(args[0]) == "get" {
if len(args) != 3 {
fmt.Println("not enough arguments to get")
usage()
os.Exit(exitcodeInvalidArgs)
}
r, err := http.Get(prefix + args[1])
if err != nil {
exitCode, mainErr = exitcodeGetFailed, err
return
}
b, err := ioutil.ReadAll(r.Body)
if err != nil {
exitCode, mainErr = exitcodeGetFailed, err
return
}
r.Body.Close()
br := bytes.NewReader(b)
err = gen(*in, *pkgName, br, typeSets, outWriter, *genTag)
} else if len(*in) > 0 {
var file *os.File
file, err = os.Open(*in)
if err != nil {
exitCode = exitcodeSourceFileInvalid
return
}
defer file.Close()
err = gen(*in, *pkgName, file, typeSets, outWriter, *genTag)
} else {
var source []byte
source, err = ioutil.ReadAll(os.Stdin)
if err != nil {
exitCode = exitcodeStdinFailed
return
}
reader := bytes.NewReader(source)
err = gen("stdin", *pkgName, reader, typeSets, outWriter, *genTag)
}
// do the work
if err != nil {
exitCode, mainErr = exitcodeGenFailed, err
}
}
func usage() {
fmt.Fprintln(os.Stderr, `usage: genny [{flags}] gen "{types}"
gen - generates type specific code from generic code.
get <package/file> - fetch a generic template from the online library and gen it.
{types} - (optional) Command line flags (see below)
{types} - (required) Specific types for each generic type in the source
{types} format: {generic}={specific}[,another][ {generic2}={specific2}]
Examples:
Generic=Specific
Generic1=Specific1 Generic2=Specific2
Generic1=Specific1,Specific2 Generic2=Specific3,Specific4
Flags:`)
flag.PrintDefaults()
}
// gen performs the generic generation.
func gen(filename, pkgName string, in io.ReadSeeker, typesets []map[string]string, out io.Writer, tag string) error {
var output []byte
var err error
output, err = parse.Generics(filename, pkgName, in, typesets, tag)
if err != nil {
return err
}
out.Write(output)
return nil
}