feat: parse {var} in markdown documentation
1 file changed, 172 insertions(+), 0 deletions(-)
changed files
A internal/nixdocs/variable/var.go
@@ -0,0 +1,172 @@ +//nolint:wrapcheck +package variable + +import ( + "bytes" + + "github.com/yuin/goldmark" + "github.com/yuin/goldmark/ast" + "github.com/yuin/goldmark/parser" + "github.com/yuin/goldmark/renderer" + "github.com/yuin/goldmark/renderer/html" + "github.com/yuin/goldmark/text" + "github.com/yuin/goldmark/util" +) + +// Node represents a variable reference node in markdown AST. +type Node struct { + ast.BaseInline + VarName []byte +} + +// Inline implements ast.Inline interface. +func (n *Node) Inline() bool { + return true +} + +// Kind implements ast.Node.Kind interface. +func (n *Node) Kind() ast.NodeKind { + return KindVar +} + +// Dump implements ast.Node.Dump interface. +func (n *Node) Dump(source []byte, level int) { + ast.DumpHelper(n, source, level, map[string]string{ + "VarName": string(n.VarName), + }, nil) +} + +// KindVar is a NodeKind for variable nodes. +var KindVar = ast.NewNodeKind("Var") + +// Parser is a Goldmark inline parser for parsing variable nodes. +// +// Variable references have the format {var}`pkgs.virtualbox` which will be rendered as +// a var HTML element with the variable name. +type Parser struct{} + +var _ parser.InlineParser = (*Parser)(nil) + +// Trigger reports characters that trigger this parser. +func (*Parser) Trigger() []byte { + return []byte{'{'} +} + +// Parse parses a variable node. +func (p *Parser) Parse(_ ast.Node, block text.Reader, _ parser.Context) ast.Node { + line, segment := block.PeekLine() + + // Check if we have enough characters for {var}` + if len(line) < 6 || line[0] != '{' { + return nil + } + + // Check for {var}` prefix + if !bytes.HasPrefix(line, []byte("{var}`")) { + return nil + } + + // Skip the {var}` prefix + line = line[6:] + start := segment.Start + 6 + + // Find the closing backtick + endPos := bytes.IndexByte(line, '`') + if endPos < 0 { + return nil + } + + // Extract the variable name + varName := line[:endPos] + if len(varName) == 0 { + return nil + } + + // Create the node + n := &Node{ + VarName: varName, + } + + // Set the text segment to include the entire {var}`name` text + textSegment := text.NewSegment(segment.Start, start+endPos+1) + n.AppendChild(n, ast.NewTextSegment(textSegment)) + + // Advance the reader past this node + block.Advance(6 + endPos + 1) // {var}` + name + ` + + return n +} + +// HTMLRenderer is a renderer for variable nodes. +type HTMLRenderer struct { + html.Config +} + +// NewHTMLRenderer returns a new HTMLRenderer. +func NewHTMLRenderer(opts ...html.Option) renderer.NodeRenderer { + r := &HTMLRenderer{ + Config: html.NewConfig(), + } + for _, opt := range opts { + opt.SetHTMLOption(&r.Config) + } + + return r +} + +// RegisterFuncs implements renderer.NodeRenderer.RegisterFuncs. +func (r *HTMLRenderer) RegisterFuncs(reg renderer.NodeRendererFuncRegisterer) { + reg.Register(KindVar, r.renderVar) +} + +func (r *HTMLRenderer) renderVar( + w util.BufWriter, + source []byte, //nolint:revive + node ast.Node, + entering bool, +) (ast.WalkStatus, error) { + if !entering { + return ast.WalkContinue, nil + } + + n := node.(*Node) + + if _, err := w.WriteString("<var>"); err != nil { + return ast.WalkStop, err + } + + if _, err := w.Write(n.VarName); err != nil { + return ast.WalkStop, err + } + + if _, err := w.WriteString("</var>"); err != nil { + return ast.WalkStop, err + } + + return ast.WalkSkipChildren, nil +} + +// Extension is a goldmark extension for variable references. +type Extension struct{} + +// Extend implements goldmark.Extender.Extend. +func (e *Extension) Extend(m goldmark.Markdown) { + // Register the parser + m.Parser().AddOptions( + parser.WithInlineParsers( + util.Prioritized(new(Parser), 100), + ), + ) + + // Register the renderer + m.Renderer().AddOptions( + renderer.WithNodeRenderers( + util.Prioritized(NewHTMLRenderer(), 500), + ), + ) +} + +// New returns a new variable extension. +func New() goldmark.Extender { + return &Extension{} +}