115 lines
2.5 KiB
Go
115 lines
2.5 KiB
Go
// Copyright 2010 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 json
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import "bytes"
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// Compact appends to dst the JSON-encoded src with
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// insignificant space characters elided.
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func Compact(dst *bytes.Buffer, src []byte) error {
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origLen := dst.Len()
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var scan scanner
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scan.reset()
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start := 0
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for i, c := range src {
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v := scan.step(&scan, int(c))
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if v >= scanSkipSpace {
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if v == scanError {
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break
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}
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if start < i {
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dst.Write(src[start:i])
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}
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start = i + 1
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}
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}
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if scan.eof() == scanError {
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dst.Truncate(origLen)
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return scan.err
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}
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if start < len(src) {
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dst.Write(src[start:])
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}
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return nil
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}
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func newline(dst *bytes.Buffer, prefix, indent string, depth int) {
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dst.WriteByte('\n')
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dst.WriteString(prefix)
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for i := 0; i < depth; i++ {
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dst.WriteString(indent)
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}
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}
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// Indent appends to dst an indented form of the JSON-encoded src.
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// Each element in a JSON object or array begins on a new,
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// indented line beginning with prefix followed by one or more
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// copies of indent according to the indentation nesting.
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// The data appended to dst has no trailing newline, to make it easier
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// to embed inside other formatted JSON data.
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func Indent(dst *bytes.Buffer, src []byte, prefix, indent string) error {
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origLen := dst.Len()
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var scan scanner
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scan.reset()
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needIndent := false
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depth := 0
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for _, c := range src {
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scan.bytes++
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v := scan.step(&scan, int(c))
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if v == scanSkipSpace {
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continue
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}
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if v == scanError {
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break
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}
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if needIndent && v != scanEndObject && v != scanEndArray {
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needIndent = false
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depth++
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newline(dst, prefix, indent, depth)
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}
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// Emit semantically uninteresting bytes
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// (in particular, punctuation in strings) unmodified.
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if v == scanContinue {
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dst.WriteByte(c)
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continue
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}
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// Add spacing around real punctuation.
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switch c {
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case '{', '[':
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// delay indent so that empty object and array are formatted as {} and [].
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needIndent = true
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dst.WriteByte(c)
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case ',':
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dst.WriteByte(c)
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newline(dst, prefix, indent, depth)
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case ':':
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dst.WriteByte(c)
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dst.WriteByte(' ')
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case '}', ']':
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if needIndent {
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// suppress indent in empty object/array
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needIndent = false
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} else {
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depth--
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newline(dst, prefix, indent, depth)
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}
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dst.WriteByte(c)
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default:
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dst.WriteByte(c)
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}
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}
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if scan.eof() == scanError {
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dst.Truncate(origLen)
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return scan.err
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}
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return nil
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}
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