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