hmn/src/parsing/bbcode.go

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package parsing
import (
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"regexp"
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"github.com/frustra/bbcode"
"github.com/yuin/goldmark"
gast "github.com/yuin/goldmark/ast"
"github.com/yuin/goldmark/parser"
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"github.com/yuin/goldmark/renderer"
"github.com/yuin/goldmark/renderer/html"
"github.com/yuin/goldmark/text"
"github.com/yuin/goldmark/util"
)
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var BBCodePriority = 1 // TODO: This is maybe too high a priority?
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var reTag = regexp.MustCompile(`(?P<open>\[\s*(?P<opentagname>[a-zA-Z]+))|(?P<close>\[\s*\/\s*(?P<closetagname>[a-zA-Z]+)\s*\])`)
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var bbcodeCompiler = bbcode.NewCompiler(false, false)
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// ----------------------
// Parser and delimiters
// ----------------------
type bbcodeParser struct{}
func NewBBCodeParser() parser.InlineParser {
return bbcodeParser{}
}
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func (s bbcodeParser) Trigger() []byte {
return []byte{'['}
}
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func (s bbcodeParser) Parse(parent gast.Node, block text.Reader, pc parser.Context) gast.Node {
_, pos := block.Position()
restOfSource := block.Source()[pos.Start:]
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matches := reTag.FindAllSubmatchIndex(restOfSource, -1)
if matches == nil {
// No tags anywhere
return nil
}
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otIndex := reTag.SubexpIndex("opentagname")
ctIndex := reTag.SubexpIndex("closetagname")
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tagName := extractStringBySubmatchIndices(restOfSource, matches[0], otIndex)
if tagName == "" {
// Not an opening tag
return nil
}
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depth := 0
endIndex := -1
for _, m := range matches {
if openName := extractStringBySubmatchIndices(restOfSource, m, otIndex); openName != "" {
if openName == tagName {
depth++
}
} else if closeName := extractStringBySubmatchIndices(restOfSource, m, ctIndex); closeName != "" {
if closeName == tagName {
depth--
if depth == 0 {
// We have balanced out!
endIndex = m[1] // the end index of this closing tag (exclusive)
}
}
}
}
if endIndex < 0 {
// Unbalanced, too many opening tags
return nil
}
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unparsedBBCode := restOfSource[:endIndex]
block.Advance(len(unparsedBBCode))
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return NewBBCode(bbcodeCompiler.Compile(string(unparsedBBCode)))
}
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func extractStringBySubmatchIndices(src []byte, m []int, subexpIndex int) string {
srcIndices := m[2*subexpIndex : 2*subexpIndex+1+1]
if srcIndices[0] < 0 {
return ""
}
return string(src[srcIndices[0]:srcIndices[1]])
}
// ----------------------
// AST node
// ----------------------
type BBCodeNode struct {
gast.BaseInline
HTML string
}
var _ gast.Node = &BBCodeNode{}
func (n *BBCodeNode) Dump(source []byte, level int) {
gast.DumpHelper(n, source, level, nil, nil)
}
var KindBBCode = gast.NewNodeKind("BBCode")
func (n *BBCodeNode) Kind() gast.NodeKind {
return KindBBCode
}
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func NewBBCode(html string) gast.Node {
return &BBCodeNode{
HTML: html,
}
}
// ----------------------
// Renderer
// ----------------------
type BBCodeHTMLRenderer struct {
html.Config
}
func NewBBCodeHTMLRenderer(opts ...html.Option) renderer.NodeRenderer {
r := &BBCodeHTMLRenderer{
Config: html.NewConfig(),
}
for _, opt := range opts {
opt.SetHTMLOption(&r.Config)
}
return r
}
func (r *BBCodeHTMLRenderer) RegisterFuncs(reg renderer.NodeRendererFuncRegisterer) {
reg.Register(KindBBCode, r.renderBBCode)
}
func (r *BBCodeHTMLRenderer) renderBBCode(w util.BufWriter, source []byte, n gast.Node, entering bool) (gast.WalkStatus, error) {
if entering {
w.WriteString(n.(*BBCodeNode).HTML)
}
return gast.WalkContinue, nil
}
// ----------------------
// Extension
// ----------------------
type BBCodeExtension struct{}
func (e BBCodeExtension) Extend(m goldmark.Markdown) {
m.Parser().AddOptions(parser.WithInlineParsers(
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util.Prioritized(NewBBCodeParser(), BBCodePriority),
))
m.Renderer().AddOptions(renderer.WithNodeRenderers(
util.Prioritized(NewBBCodeHTMLRenderer(), BBCodePriority),
))
}