status-go/vendor/olympos.io/encoding/edn/compact.go

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2022-02-02 22:50:55 +00:00
// Copyright 2015 Jean Niklas L'orange. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package edn
import (
"bytes"
"io"
)
func tokNeedsDelim(t tokenType) bool {
switch t {
case tokenString, tokenListStart, tokenListEnd, tokenVectorStart,
tokenVectorEnd, tokenMapEnd, tokenMapStart, tokenSetStart, tokenDiscard, tokenError:
return false
}
return true
}
func delimits(r rune) bool {
switch r {
case '{', '}', '[', ']', '(', ')', '\\', '"':
return true
}
return isWhitespace(r)
}
// Compact appends to dst a compacted form of the EDN-encoded src. It does not
// remove discard values.
func Compact(dst *bytes.Buffer, src []byte) error {
origLen := dst.Len()
var lex lexer
lex.reset()
buf := bytes.NewBuffer(src)
start, pos := 0, 0
needsDelim := false
prevIgnore := '\uFFFD'
r, size, err := buf.ReadRune()
for ; err == nil; r, size, err = buf.ReadRune() {
ls := lex.state(r)
ppos := pos
pos += size
switch ls {
case lexCont:
if ppos == start && needsDelim && !delimits(r) {
dst.WriteRune(prevIgnore)
}
continue
case lexIgnore:
prevIgnore = r
start = pos
case lexError:
dst.Truncate(origLen)
return lex.err
case lexEnd:
// here we might want to discard #_ and the like. Currently we don't.
dst.Write(src[start:pos])
needsDelim = tokNeedsDelim(lex.token)
lex.reset()
start = pos
case lexEndPrev:
dst.Write(src[start:ppos])
lex.reset()
lss := lex.state(r)
needsDelim = tokNeedsDelim(lex.token)
switch lss {
case lexIgnore:
prevIgnore = r
start = pos
case lexCont:
start = ppos
case lexEnd:
dst.WriteRune(r)
lex.reset()
start = pos
case lexEndPrev:
dst.Truncate(origLen)
return errInternal
case lexError:
dst.Truncate(origLen)
return lex.err
}
}
}
if err != io.EOF {
return err
}
ls := lex.eof()
switch ls {
case lexEnd:
dst.Write(src[start:pos])
case lexError:
dst.Truncate(origLen)
return lex.err
}
return nil
}