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112 lines
3.5 KiB
Go
112 lines
3.5 KiB
Go
package markdown
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import (
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"bytes"
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"io"
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"github.com/gomarkdown/markdown/ast"
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"github.com/gomarkdown/markdown/html"
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"github.com/gomarkdown/markdown/parser"
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)
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// Renderer is an interface for implementing custom renderers.
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type Renderer interface {
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// RenderNode renders markdown node to w.
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// It's called once for a leaf node.
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// It's called twice for non-leaf nodes:
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// * first with entering=true
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// * then with entering=false
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//
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// Return value is a way to tell the calling walker to adjust its walk
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// pattern: e.g. it can terminate the traversal by returning Terminate. Or it
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// can ask the walker to skip a subtree of this node by returning SkipChildren.
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// The typical behavior is to return GoToNext, which asks for the usual
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// traversal to the next node.
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RenderNode(w io.Writer, node ast.Node, entering bool) ast.WalkStatus
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// RenderHeader is a method that allows the renderer to produce some
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// content preceding the main body of the output document. The header is
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// understood in the broad sense here. For example, the default HTML
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// renderer will write not only the HTML document preamble, but also the
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// table of contents if it was requested.
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//
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// The method will be passed an entire document tree, in case a particular
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// implementation needs to inspect it to produce output.
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//
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// The output should be written to the supplied writer w. If your
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// implementation has no header to write, supply an empty implementation.
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RenderHeader(w io.Writer, ast ast.Node)
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// RenderFooter is a symmetric counterpart of RenderHeader.
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RenderFooter(w io.Writer, ast ast.Node)
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}
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// Parse parsers a markdown document using provided parser. If parser is nil,
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// we use parser configured with parser.CommonExtensions.
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//
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// It returns AST (abstract syntax tree) that can be converted to another
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// format using Render function.
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func Parse(markdown []byte, p *parser.Parser) ast.Node {
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if p == nil {
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p = parser.New()
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}
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return p.Parse(markdown)
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}
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// Render uses renderer to convert parsed markdown document into a different format.
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//
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// To convert to HTML, pass html.Renderer
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func Render(doc ast.Node, renderer Renderer) []byte {
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var buf bytes.Buffer
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renderer.RenderHeader(&buf, doc)
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ast.WalkFunc(doc, func(node ast.Node, entering bool) ast.WalkStatus {
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return renderer.RenderNode(&buf, node, entering)
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})
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renderer.RenderFooter(&buf, doc)
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return buf.Bytes()
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}
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// ToHTML converts markdownDoc to HTML.
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//
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// You can optionally pass a parser and renderer. This allows to customize
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// a parser, use a customized html render or use completely custom renderer.
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//
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// If you pass nil for both, we use parser configured with parser.CommonExtensions
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// and html.Renderer configured with html.CommonFlags.
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func ToHTML(markdown []byte, p *parser.Parser, renderer Renderer) []byte {
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doc := Parse(markdown, p)
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if renderer == nil {
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opts := html.RendererOptions{
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Flags: html.CommonFlags,
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}
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renderer = html.NewRenderer(opts)
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}
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return Render(doc, renderer)
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}
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// NormalizeNewlines converts Windows and Mac newlines to Unix newlines
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// The parser only supports Unix newlines. If your mardown content
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// might contain Windows or Mac newlines, use this function to convert to Unix newlines
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func NormalizeNewlines(d []byte) []byte {
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wi := 0
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n := len(d)
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for i := 0; i < n; i++ {
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c := d[i]
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// 13 is CR
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if c != 13 {
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d[wi] = c
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wi++
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continue
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}
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// replace CR (mac / win) with LF (unix)
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d[wi] = 10
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wi++
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if i < n-1 && d[i+1] == 10 {
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// this was CRLF, so skip the LF
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i++
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}
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}
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return d[:wi]
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}
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