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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package main
import (
"bytes"
"ebnf"
"flag"
"fmt"
"go/scanner"
"go/token"
"io/ioutil"
"os"
"path/filepath"
)
var fset = token.NewFileSet()
var start = flag.String("start", "Start", "name of start production")
func usage() {
fmt.Fprintf(os.Stderr, "usage: ebnflint [flags] [filename]\n")
flag.PrintDefaults()
os.Exit(1)
}
// Markers around EBNF sections in .html files
var (
open = []byte(`<pre class="ebnf">`)
close = []byte(`</pre>`)
)
func report(err os.Error) {
scanner.PrintError(os.Stderr, err)
os.Exit(1)
}
func extractEBNF(src []byte) []byte {
var buf bytes.Buffer
for {
// i = beginning of EBNF text
i := bytes.Index(src, open)
if i < 0 {
break // no EBNF found - we are done
}
i += len(open)
// write as many newlines as found in the excluded text
// to maintain correct line numbers in error messages
for _, ch := range src[0:i] {
if ch == '\n' {
buf.WriteByte('\n')
}
}
// j = end of EBNF text (or end of source)
j := bytes.Index(src[i:], close) // close marker
if j < 0 {
j = len(src) - i
}
j += i
// copy EBNF text
buf.Write(src[i:j])
// advance
src = src[j:]
}
return buf.Bytes()
}
func main() {
flag.Parse()
var (
filename string
src []byte
err os.Error
)
switch flag.NArg() {
case 0:
filename = "<stdin>"
src, err = ioutil.ReadAll(os.Stdin)
case 1:
filename = flag.Arg(0)
src, err = ioutil.ReadFile(filename)
default:
usage()
}
if err != nil {
report(err)
}
if filepath.Ext(filename) == ".html" || bytes.Index(src, open) >= 0 {
src = extractEBNF(src)
}
grammar, err := ebnf.Parse(fset, filename, src)
if err != nil {
report(err)
}
if err = ebnf.Verify(fset, grammar, *start); err != nil {
report(err)
}
}
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