[chore/bugfix] Switch markdown from blackfriday to goldmark (#1267)

Co-authored-by: Autumn! <autumnull@posteo.net>

vendor/github.com/yuin/goldmark/renderer/renderer.go

@@ -0,0 +1,174 @@
+// Package renderer renders the given AST to certain formats.
+package renderer
+
+import (
+	"bufio"
+	"io"
+	"sync"
+
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/util"
+)
+
+// A Config struct is a data structure that holds configuration of the Renderer.
+type Config struct {
+	Options       map[OptionName]interface{}
+	NodeRenderers util.PrioritizedSlice
+}
+
+// NewConfig returns a new Config
+func NewConfig() *Config {
+	return &Config{
+		Options:       map[OptionName]interface{}{},
+		NodeRenderers: util.PrioritizedSlice{},
+	}
+}
+
+// An OptionName is a name of the option.
+type OptionName string
+
+// An Option interface is a functional option type for the Renderer.
+type Option interface {
+	SetConfig(*Config)
+}
+
+type withNodeRenderers struct {
+	value []util.PrioritizedValue
+}
+
+func (o *withNodeRenderers) SetConfig(c *Config) {
+	c.NodeRenderers = append(c.NodeRenderers, o.value...)
+}
+
+// WithNodeRenderers is a functional option that allow you to add
+// NodeRenderers to the renderer.
+func WithNodeRenderers(ps ...util.PrioritizedValue) Option {
+	return &withNodeRenderers{ps}
+}
+
+type withOption struct {
+	name  OptionName
+	value interface{}
+}
+
+func (o *withOption) SetConfig(c *Config) {
+	c.Options[o.name] = o.value
+}
+
+// WithOption is a functional option that allow you to set
+// an arbitrary option to the parser.
+func WithOption(name OptionName, value interface{}) Option {
+	return &withOption{name, value}
+}
+
+// A SetOptioner interface sets given option to the object.
+type SetOptioner interface {
+	// SetOption sets given option to the object.
+	// Unacceptable options may be passed.
+	// Thus implementations must ignore unacceptable options.
+	SetOption(name OptionName, value interface{})
+}
+
+// NodeRendererFunc is a function that renders a given node.
+type NodeRendererFunc func(writer util.BufWriter, source []byte, n ast.Node, entering bool) (ast.WalkStatus, error)
+
+// A NodeRenderer interface offers NodeRendererFuncs.
+type NodeRenderer interface {
+	// RendererFuncs registers NodeRendererFuncs to given NodeRendererFuncRegisterer.
+	RegisterFuncs(NodeRendererFuncRegisterer)
+}
+
+// A NodeRendererFuncRegisterer registers
+type NodeRendererFuncRegisterer interface {
+	// Register registers given NodeRendererFunc to this object.
+	Register(ast.NodeKind, NodeRendererFunc)
+}
+
+// A Renderer interface renders given AST node to given
+// writer with given Renderer.
+type Renderer interface {
+	Render(w io.Writer, source []byte, n ast.Node) error
+
+	// AddOptions adds given option to this renderer.
+	AddOptions(...Option)
+}
+
+type renderer struct {
+	config               *Config
+	options              map[OptionName]interface{}
+	nodeRendererFuncsTmp map[ast.NodeKind]NodeRendererFunc
+	maxKind              int
+	nodeRendererFuncs    []NodeRendererFunc
+	initSync             sync.Once
+}
+
+// NewRenderer returns a new Renderer with given options.
+func NewRenderer(options ...Option) Renderer {
+	config := NewConfig()
+	for _, opt := range options {
+		opt.SetConfig(config)
+	}
+
+	r := &renderer{
+		options:              map[OptionName]interface{}{},
+		config:               config,
+		nodeRendererFuncsTmp: map[ast.NodeKind]NodeRendererFunc{},
+	}
+
+	return r
+}
+
+func (r *renderer) AddOptions(opts ...Option) {
+	for _, opt := range opts {
+		opt.SetConfig(r.config)
+	}
+}
+
+func (r *renderer) Register(kind ast.NodeKind, v NodeRendererFunc) {
+	r.nodeRendererFuncsTmp[kind] = v
+	if int(kind) > r.maxKind {
+		r.maxKind = int(kind)
+	}
+}
+
+// Render renders the given AST node to the given writer with the given Renderer.
+func (r *renderer) Render(w io.Writer, source []byte, n ast.Node) error {
+	r.initSync.Do(func() {
+		r.options = r.config.Options
+		r.config.NodeRenderers.Sort()
+		l := len(r.config.NodeRenderers)
+		for i := l - 1; i >= 0; i-- {
+			v := r.config.NodeRenderers[i]
+			nr, _ := v.Value.(NodeRenderer)
+			if se, ok := v.Value.(SetOptioner); ok {
+				for oname, ovalue := range r.options {
+					se.SetOption(oname, ovalue)
+				}
+			}
+			nr.RegisterFuncs(r)
+		}
+		r.nodeRendererFuncs = make([]NodeRendererFunc, r.maxKind+1)
+		for kind, nr := range r.nodeRendererFuncsTmp {
+			r.nodeRendererFuncs[kind] = nr
+		}
+		r.config = nil
+		r.nodeRendererFuncsTmp = nil
+	})
+	writer, ok := w.(util.BufWriter)
+	if !ok {
+		writer = bufio.NewWriter(w)
+	}
+	err := ast.Walk(n, func(n ast.Node, entering bool) (ast.WalkStatus, error) {
+		s := ast.WalkStatus(ast.WalkContinue)
+		var err error
+		f := r.nodeRendererFuncs[n.Kind()]
+		if f != nil {
+			s, err = f(writer, source, n, entering)
+		}
+		return s, err
+	})
+	if err != nil {
+		return err
+	}
+	return writer.Flush()
+}