generated from bep/golibtemplate
-
-
Notifications
You must be signed in to change notification settings - Fork 5
Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
Implement passthrough extension Closes #1 Co-authored-by: Jeremy Kun <j2kun@users.noreply.github.com>
- Loading branch information
Showing
4 changed files
with
892 additions
and
5 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -1,6 +1,382 @@ | ||
package passthrough | ||
|
||
// Foo returns a string. | ||
func Foo() string { | ||
return "foo" | ||
import ( | ||
"bytes" | ||
"fmt" | ||
"github.com/yuin/goldmark" | ||
"github.com/yuin/goldmark/ast" | ||
"github.com/yuin/goldmark/parser" | ||
"github.com/yuin/goldmark/renderer" | ||
"github.com/yuin/goldmark/text" | ||
"github.com/yuin/goldmark/util" | ||
"strings" | ||
) | ||
|
||
type Delimiters struct { | ||
Open string | ||
Close string | ||
} | ||
|
||
// Determine if a byte array starts with a given string | ||
func startsWith(b []byte, s string) bool { | ||
if len(b) < len(s) { | ||
return false | ||
} | ||
|
||
return string(b[:len(s)]) == s | ||
} | ||
|
||
type PassthroughInline struct { | ||
ast.BaseInline | ||
|
||
// The segment of text that this inline passthrough represents. | ||
Segment text.Segment | ||
|
||
// The matched delimiters | ||
Delimiters *Delimiters | ||
} | ||
|
||
func NewPassthroughInline(segment text.Segment, delimiters *Delimiters) *PassthroughInline { | ||
return &PassthroughInline{ | ||
Segment: segment, | ||
Delimiters: delimiters, | ||
} | ||
} | ||
|
||
// Text implements Node.Text. | ||
func (n *PassthroughInline) Text(source []byte) []byte { | ||
return n.Segment.Value(source) | ||
} | ||
|
||
// Dump implements Node.Dump. | ||
func (n *PassthroughInline) Dump(source []byte, level int) { | ||
indent := strings.Repeat(" ", level) | ||
fmt.Printf("%sPassthroughInline {\n", indent) | ||
indent2 := strings.Repeat(" ", level+1) | ||
fmt.Printf("%sSegment: \"%s\"\n", indent2, n.Text(source)) | ||
fmt.Printf("%s}\n", indent) | ||
} | ||
|
||
// KindPassthroughInline is a NodeKind of the PassthroughInline node. | ||
var KindPassthroughInline = ast.NewNodeKind("PassthroughInline") | ||
|
||
// Kind implements Node.Kind. | ||
func (n *PassthroughInline) Kind() ast.NodeKind { | ||
return KindPassthroughInline | ||
} | ||
|
||
type inlinePassthroughParser struct { | ||
PassthroughDelimiters []Delimiters | ||
} | ||
|
||
func NewInlinePassthroughParser(ds []Delimiters) parser.InlineParser { | ||
return &inlinePassthroughParser{ | ||
PassthroughDelimiters: ds, | ||
} | ||
} | ||
|
||
// Determine if the input slice starts with a full valid opening delimiter. | ||
// If so, returns the delimiter struct, otherwise returns nil. | ||
func GetFullOpeningDelimiter(delims []Delimiters, line []byte) *Delimiters { | ||
for _, d := range delims { | ||
if startsWith(line, d.Open) { | ||
return &d | ||
} | ||
} | ||
|
||
return nil | ||
} | ||
|
||
// Return an array of bytes containing the first byte of each opening | ||
// delimiter. Used to populate the trigger list for inline and block parsers. | ||
// `Parse` will be executed once for each character that is in this list of | ||
// allowed trigger characters. Our parse function needs to do some additional | ||
// checks because Trigger only works for single-byte delimiters. | ||
func OpenersFirstByte(delims []Delimiters) []byte { | ||
var firstBytes []byte | ||
containsBackslash := false | ||
for _, d := range delims { | ||
if d.Open[0] == '\\' { | ||
containsBackslash = true | ||
} | ||
firstBytes = append(firstBytes, d.Open[0]) | ||
} | ||
|
||
if !containsBackslash { | ||
// always trigger on backslash because it can be used to escape the opening | ||
// delimiter. | ||
firstBytes = append(firstBytes, '\\') | ||
} | ||
return firstBytes | ||
} | ||
|
||
// Determine if the input list of delimiters contains the given delimiter pair | ||
func ContainsDelimiters(delims []Delimiters, toFind *Delimiters) bool { | ||
for _, d := range delims { | ||
if d.Open == toFind.Open && d.Close == toFind.Close { | ||
return true | ||
} | ||
} | ||
|
||
return false | ||
} | ||
|
||
func (s *inlinePassthroughParser) Trigger() []byte { | ||
return OpenersFirstByte(s.PassthroughDelimiters) | ||
} | ||
|
||
func (s *inlinePassthroughParser) Parse(parent ast.Node, block text.Reader, pc parser.Context) ast.Node { | ||
// In order to prevent other parser extensions from operating on the text | ||
// between passthrough delimiters, we must process the entire inline | ||
// passthrough in one execution of Parse. This means we can't use the style | ||
// of multiple triggers with parser.Context state saved between calls. | ||
line, startSegment := block.PeekLine() | ||
|
||
fencePair := GetFullOpeningDelimiter(s.PassthroughDelimiters, line) | ||
// fencePair == nil can happen if only the first byte of an opening delimiter | ||
// matches, but it is not the complete opening delimiter. The trigger causes | ||
// this Parse function to execute, but the trigger interface is limited to | ||
// matching single bytes. | ||
// It can also be because the opening delimiter is escaped with a | ||
// double-backslash. In this case, we advance and return nil. | ||
if fencePair == nil { | ||
if len(line) > 2 && line[0] == '\\' && line[1] == '\\' { | ||
fencePair = GetFullOpeningDelimiter(s.PassthroughDelimiters, line[2:]) | ||
if fencePair != nil { | ||
// Opening delimiter is escaped, return the escaped opener as plain text | ||
// So that the characters are not processed again. | ||
block.Advance(2 + len(fencePair.Open)) | ||
return ast.NewTextSegment(startSegment.WithStop(startSegment.Start + len(fencePair.Open) + 2)) | ||
} | ||
} | ||
return nil | ||
} | ||
|
||
// This roughly follows goldmark/parser/code_span.go | ||
block.Advance(len(fencePair.Open)) | ||
openerSize := len(fencePair.Open) | ||
l, pos := block.Position() | ||
|
||
for { | ||
line, lineSegment := block.PeekLine() | ||
if line == nil { | ||
block.SetPosition(l, pos) | ||
return ast.NewTextSegment(startSegment.WithStop(startSegment.Start + openerSize)) | ||
} | ||
|
||
closingDelimiterPos := bytes.Index(line, []byte(fencePair.Close)) | ||
if closingDelimiterPos == -1 { // no closer on this line | ||
block.AdvanceLine() | ||
continue | ||
} | ||
|
||
// This segment spans from the original starting trigger (including the delimiter) | ||
// up to and including the closing delimiter. | ||
seg := startSegment.WithStop(lineSegment.Start + closingDelimiterPos + len(fencePair.Close)) | ||
if seg.Len() == len(fencePair.Open)+len(fencePair.Close) { | ||
return nil | ||
} | ||
|
||
block.Advance(closingDelimiterPos + len(fencePair.Close)) | ||
return NewPassthroughInline(seg, fencePair) | ||
} | ||
} | ||
|
||
type passthroughInlineRenderer struct { | ||
} | ||
|
||
func (r *passthroughInlineRenderer) renderRawInline(w util.BufWriter, source []byte, n ast.Node, entering bool) (ast.WalkStatus, error) { | ||
if entering { | ||
w.WriteString(string(n.Text(source))) | ||
} | ||
return ast.WalkContinue, nil | ||
} | ||
|
||
// A PassthroughBlock struct represents a fenced block of raw text to pass | ||
// through unchanged. This is not parsed directly, but emitted by an | ||
// ASTTransformer that splits a paragraph at the point of an inline passthrough | ||
// with the matching block delimiters. | ||
type PassthroughBlock struct { | ||
ast.BaseBlock | ||
} | ||
|
||
// Dump implements Node.Dump. | ||
func (n *PassthroughBlock) Dump(source []byte, level int) { | ||
ast.DumpHelper(n, source, level, nil, nil) | ||
} | ||
|
||
// KindPassthroughBlock is a NodeKind of the PassthroughBlock node. | ||
var KindPassthroughBlock = ast.NewNodeKind("PassthroughBlock") | ||
|
||
// Kind implements Node.Kind. | ||
func (n *PassthroughBlock) Kind() ast.NodeKind { | ||
return KindPassthroughBlock | ||
} | ||
|
||
// NewPassthroughBlock return a new PassthroughBlock node. | ||
func NewPassthroughBlock() *PassthroughBlock { | ||
return &PassthroughBlock{ | ||
BaseBlock: ast.BaseBlock{}, | ||
} | ||
} | ||
|
||
type passthroughBlockRenderer struct { | ||
} | ||
|
||
func (r *passthroughBlockRenderer) renderRawBlock(w util.BufWriter, source []byte, n ast.Node, entering bool) (ast.WalkStatus, error) { | ||
if entering { | ||
l := n.Lines().Len() | ||
for i := 0; i < l; i++ { | ||
line := n.Lines().At(i) | ||
w.WriteString(string(line.Value(source))) | ||
} | ||
w.WriteString("\n") | ||
} | ||
return ast.WalkSkipChildren, nil | ||
} | ||
|
||
// To support the use of passthrough block delimiters in inline contexts, I | ||
// wasn't able to get the normal block parser to work. Goldmark seems to only | ||
// trigger the inline parser when the trigger is not the first characters in a | ||
// block. So instead we hook into the transformer interface, and process an | ||
// inline passthrough after it's parsed, looking for nodes whose delimiters | ||
// match the block delimiters, and splitting the paragraph at that point. | ||
type passthroughInlineTransformer struct { | ||
BlockDelimiters []Delimiters | ||
} | ||
|
||
var PassthroughInlineTransformer = &passthroughInlineTransformer{} | ||
|
||
// Note, this transformer destroys the RawText attributes of the paragraph | ||
// nodes that it transforms. However, this does not seem to have an impact on | ||
// rendering. | ||
func (p *passthroughInlineTransformer) Transform( | ||
doc *ast.Document, reader text.Reader, pc parser.Context) { | ||
|
||
ast.Walk(doc, func(n ast.Node, entering bool) (ast.WalkStatus, error) { | ||
// Anchor on paragraphs | ||
if n.Kind() != ast.KindParagraph || !entering { | ||
return ast.WalkContinue, nil | ||
} | ||
|
||
// If no direct children are passthroughs, skip it. | ||
foundInlinePassthrough := false | ||
for c := n.FirstChild(); c != nil; c = c.NextSibling() { | ||
if c.Kind() == KindPassthroughInline { | ||
foundInlinePassthrough = true | ||
break | ||
} | ||
} | ||
if !foundInlinePassthrough { | ||
return ast.WalkContinue, nil | ||
} | ||
|
||
parent := n.Parent() | ||
currentParagraph := ast.NewParagraph() | ||
// AppendChild breaks the link between the node and its siblings, so we | ||
// need to manually track the current and next node. | ||
currentNode := n.FirstChild() | ||
insertionPoint := n | ||
|
||
for currentNode != nil { | ||
nextNode := currentNode.NextSibling() | ||
if currentNode.Kind() != KindPassthroughInline { | ||
currentParagraph.AppendChild(currentParagraph, currentNode) | ||
currentNode = nextNode | ||
} else if currentNode.Kind() == KindPassthroughInline { | ||
inline := currentNode.(*PassthroughInline) | ||
|
||
// Only split into a new block if the delimiters are block delimiters | ||
if !ContainsDelimiters(p.BlockDelimiters, inline.Delimiters) { | ||
currentParagraph.AppendChild(currentParagraph, currentNode) | ||
currentNode = nextNode | ||
continue | ||
} | ||
|
||
newBlock := NewPassthroughBlock() | ||
newBlock.Lines().Append(inline.Segment) | ||
if len(currentParagraph.Text(reader.Source())) > 0 { | ||
parent.InsertAfter(parent, insertionPoint, currentParagraph) | ||
insertionPoint = currentParagraph | ||
} | ||
parent.InsertAfter(parent, insertionPoint, newBlock) | ||
insertionPoint = newBlock | ||
currentParagraph = ast.NewParagraph() | ||
currentNode = nextNode | ||
} | ||
} | ||
|
||
if currentParagraph.ChildCount() > 0 { | ||
parent.InsertAfter(parent, insertionPoint, currentParagraph) | ||
} | ||
|
||
parent.RemoveChild(parent, n) | ||
return ast.WalkContinue, nil | ||
}) | ||
} | ||
|
||
func NewPassthroughInlineTransformer(ds []Delimiters) parser.ASTTransformer { | ||
return &passthroughInlineTransformer{ | ||
BlockDelimiters: ds, | ||
} | ||
} | ||
|
||
// RegisterFuncs implements renderer.NodeRenderer.RegisterFuncs. | ||
func (r *passthroughInlineRenderer) RegisterFuncs(reg renderer.NodeRendererFuncRegisterer) { | ||
reg.Register(KindPassthroughInline, r.renderRawInline) | ||
} | ||
|
||
// RegisterFuncs implements renderer.NodeRenderer.RegisterFuncs. | ||
func (r *passthroughBlockRenderer) RegisterFuncs(reg renderer.NodeRendererFuncRegisterer) { | ||
reg.Register(KindPassthroughBlock, r.renderRawBlock) | ||
} | ||
|
||
func NewPassthroughInlineRenderer() renderer.NodeRenderer { | ||
return &passthroughInlineRenderer{} | ||
} | ||
|
||
func NewPassthroughBlockRenderer() renderer.NodeRenderer { | ||
return &passthroughBlockRenderer{} | ||
} | ||
|
||
// ---- Extension and config ---- | ||
|
||
type passthrough struct { | ||
InlineDelimiters []Delimiters | ||
BlockDelimiters []Delimiters | ||
} | ||
|
||
func NewPassthroughWithDelimiters( | ||
InlineDelimiters []Delimiters, | ||
BlockDelimiters []Delimiters) goldmark.Extender { | ||
// The parser executes in two phases: | ||
// | ||
// Phase 1: parse the input with all delimiters treated as inline, and block delimiters | ||
// taking precedence over inline delimiters. | ||
// | ||
// Phase 2: transform the parsed AST to split paragraphs at the point of | ||
// inline passthroughs with matching block delimiters. | ||
combinedDelimiters := make([]Delimiters, len(InlineDelimiters)+len(BlockDelimiters)) | ||
copy(combinedDelimiters, BlockDelimiters) | ||
copy(combinedDelimiters[len(BlockDelimiters):], InlineDelimiters) | ||
return &passthrough{ | ||
InlineDelimiters: combinedDelimiters, | ||
BlockDelimiters: BlockDelimiters, | ||
} | ||
} | ||
|
||
func (e *passthrough) Extend(m goldmark.Markdown) { | ||
m.Parser().AddOptions( | ||
parser.WithInlineParsers( | ||
util.Prioritized(NewInlinePassthroughParser(e.InlineDelimiters), 201), | ||
), | ||
parser.WithASTTransformers( | ||
util.Prioritized(NewPassthroughInlineTransformer(e.BlockDelimiters), 0), | ||
), | ||
) | ||
|
||
m.Renderer().AddOptions(renderer.WithNodeRenderers( | ||
util.Prioritized(NewPassthroughInlineRenderer(), 101), | ||
util.Prioritized(NewPassthroughBlockRenderer(), 99), | ||
)) | ||
} |
Oops, something went wrong.