70 lines
1.9 KiB
Go
70 lines
1.9 KiB
Go
/*
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* Amsterdam Web Communities System
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* Copyright (c) 2025 Erbosoft Metaverse Design Solutions, All Rights Reserved
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at https://mozilla.org/MPL/2.0/.
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*/
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// The htmlcheck package contains the HTML Checker.
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package htmlcheck
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import "strings"
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// outputFilter is the interface for an HTML checker output filter.
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type outputFilter interface {
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tryOutputCharacter(strings.Builder, byte) bool
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matchCharacter(byte) bool
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lengthNoMatch(string) int
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}
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// outputFilterRegistry contains a listing of all defined output filters.
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var outputFilterRegistry = make(map[string]outputFilter)
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// init registers all known filters.
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func init() {
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f := htmlEncodingFilter{}
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outputFilterRegistry["html"] = &f
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}
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// htmlEncodingFilter is a filter that escapes certain characters in HTML.
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type htmlEncodingFilter struct{}
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// htmlEscapedChars is a list of HTML characters that are escaped.
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const htmlEscapedChars = "<>&"
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// tryOutputCharacter outputs a character that needs to be escaped.
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func (f *htmlEncodingFilter) tryOutputCharacter(buf strings.Builder, ch byte) bool {
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switch ch {
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case '<':
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buf.WriteString("<")
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case '>':
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buf.WriteString(">")
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case '&':
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buf.WriteString("&")
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default:
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return false
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}
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return true
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}
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// matchCharacter returns true if this character needs to be escaped.
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func (f *htmlEncodingFilter) matchCharacter(ch byte) bool {
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return strings.IndexByte(htmlEscapedChars, ch) >= 0
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}
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// lengthNoMatch returns the maximum length of unmatched characters at the start of the string.
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func (f *htmlEncodingFilter) lengthNoMatch(s string) int {
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rc := len(s)
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for _, c := range []byte(htmlEscapedChars) {
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tmp := strings.IndexByte(s, c)
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if tmp >= 0 && tmp < rc {
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rc = tmp
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if rc == 0 {
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return 0
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}
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}
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}
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return rc
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}
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