hugolib: Add .Position to shortcode

To allow for better error logging in shortcodes. Note that this may be expensive to calculate, so this is primarily for error situations.

See #5371

4 files changed, 109 insertions, 7 deletions

diff --git a/hugolib/page_content.go b/hugolib/page_content.go
index 5a8258279..b3e8668ef 100644
--- a/hugolib/page_content.go
+++ b/hugolib/page_content.go
@@ -17,6 +17,8 @@ import (
 	"bytes"
 	"io"
 
+	"github.com/gohugoio/hugo/source"
+
 	errors "github.com/pkg/errors"
 
 	bp "github.com/gohugoio/hugo/bufferpool"
@@ -68,7 +70,7 @@ func (p *Page) mapContent() error {
 	iter := p.source.parsed.Iterator()
 
 	fail := func(err error, i pageparser.Item) error {
-		return parseError(err, iter.Input(), i.Pos)
+		return p.parseError(err, iter.Input(), i.Pos)
 	}
 
 	// the parser is guaranteed to return items in proper order or fail, so …
@@ -194,15 +196,30 @@ func (p *Page) parse(reader io.Reader) error {
 	return nil
 }
 
-func parseError(err error, input []byte, pos int) error {
+func (p *Page) parseError(err error, input []byte, offset int) error {
 	if herrors.UnwrapFileError(err) != nil {
 		// Use the most specific location.
 		return err
 	}
+	pos := p.posFromInput(input, offset)
+	return herrors.NewFileError("md", -1, pos.LineNumber, pos.ColumnNumber, err)
+
+}
+
+func (p *Page) posFromInput(input []byte, offset int) source.Position {
 	lf := []byte("\n")
-	input = input[:pos]
+	input = input[:offset]
 	lineNumber := bytes.Count(input, lf) + 1
 	endOfLastLine := bytes.LastIndex(input, lf)
-	return herrors.NewFileError("md", -1, lineNumber, pos-endOfLastLine, err)
 
+	return source.Position{
+		Filename:     p.pathOrTitle(),
+		LineNumber:   lineNumber,
+		ColumnNumber: offset - endOfLastLine,
+		Offset:       offset,
+	}
+}
+
+func (p *Page) posFromPage(offset int) source.Position {
+	return p.posFromInput(p.source.parsed.Input(), offset)
 }
diff --git a/hugolib/shortcode.go b/hugolib/shortcode.go
index 024a919ed..41d8d76c4 100644
--- a/hugolib/shortcode.go
+++ b/hugolib/shortcode.go
@@ -19,6 +19,8 @@ import (
 	"fmt"
 	"html/template"
 
+	"github.com/gohugoio/hugo/source"
+
 	"reflect"
 
 	"regexp"
@@ -53,9 +55,23 @@ type ShortcodeWithPage struct {
 	// this ordinal will represent the position of this shortcode in the page content.
 	Ordinal int
 
+	// pos is the position in bytes in the source file. Used for error logging.
+	posInit   sync.Once
+	posOffset int
+	pos       source.Position
+
 	scratch *maps.Scratch
 }
 
+// Position returns this shortcode's detailed position. Note that this information
+// may be expensive to calculate, so only use this in error situations.
+func (scp *ShortcodeWithPage) Position() source.Position {
+	scp.posInit.Do(func() {
+		scp.pos = scp.Page.posFromPage(scp.posOffset)
+	})
+	return scp.pos
+}
+
 // Site returns information about the current site.
 func (scp *ShortcodeWithPage) Site() *SiteInfo {
 	return scp.Page.Site
@@ -313,7 +329,7 @@ func renderShortcode(
 		return "", nil
 	}
 
-	data := &ShortcodeWithPage{Ordinal: sc.ordinal, Params: sc.params, Page: p, Parent: parent}
+	data := &ShortcodeWithPage{Ordinal: sc.ordinal, posOffset: sc.pos, Params: sc.params, Page: p, Parent: parent}
 	if sc.params != nil {
 		data.IsNamedParams = reflect.TypeOf(sc.params).Kind() == reflect.Map
 	}
@@ -463,7 +479,7 @@ func (s *shortcodeHandler) executeShortcodesForDelta(p *PageWithoutContent) erro
 		if err != nil {
 			sc := s.shortcodes.getShortcode(k.(scKey).ShortcodePlaceholder)
 			if sc != nil {
-				err = p.errWithFileContext(parseError(_errors.Wrapf(err, "failed to render shortcode %q", sc.name), p.source.parsed.Input(), sc.pos))
+				err = p.errWithFileContext(p.parseError(_errors.Wrapf(err, "failed to render shortcode %q", sc.name), p.source.parsed.Input(), sc.pos))
 			}
 
 			p.s.SendError(err)
@@ -505,7 +521,7 @@ func (s *shortcodeHandler) extractShortcode(ordinal int, pt *pageparser.Iterator
 	var nestedOrdinal = 0
 
 	fail := func(err error, i pageparser.Item) error {
-		return parseError(err, pt.Input(), i.Pos)
+		return p.parseError(err, pt.Input(), i.Pos)
 	}
 
 Loop:
diff --git a/hugolib/shortcode_test.go b/hugolib/shortcode_test.go
index 0d397f9ee..2ddecc2ff 100644
--- a/hugolib/shortcode_test.go
+++ b/hugolib/shortcode_test.go
@@ -1026,3 +1026,39 @@ ordinal: 2 scratch ordinal: 3 scratch get ordinal: 2
 ordinal: 4 scratch ordinal: 5 scratch get ordinal: 4`)
 
 }
+
+func TestShortcodePosition(t *testing.T) {
+	t.Parallel()
+	assert := require.New(t)
+
+	builder := newTestSitesBuilder(t).WithSimpleConfigFile()
+
+	builder.WithContent("page.md", `---
+title: "Hugo Rocks!"
+---
+
+# doc
+
+   {{< s1 >}}
+
+`).WithTemplatesAdded("layouts/shortcodes/s1.html", `
+{{ with .Position }}
+File: {{ .Filename }}
+Offset: {{ .Offset }}
+Line: {{ .LineNumber }}
+Column: {{ .ColumnNumber }}
+String: {{ . | safeHTML }}
+{{ end }}
+
+`).CreateSites().Build(BuildCfg{})
+
+	s := builder.H.Sites[0]
+	assert.Equal(1, len(s.RegularPages))
+
+	builder.AssertFileContent("public/page/index.html",
+		"File: content/page.md",
+		"Line: 7", "Column: 4", "Offset: 40",
+		"String: content/page.md:7:4",
+	)
+
+}
diff --git a/source/position.go b/source/position.go
new file mode 100644
index 000000000..8c1ea3d2b
--- /dev/null
+++ b/source/position.go
@@ -0,0 +1,33 @@
+// Copyright 2018 The Hugo Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package source
+
+import "fmt"
+
+// Position holds a source position.
+type Position struct {
+	Filename     string // filename, if any
+	Offset       int    // byte offset, starting at 0
+	LineNumber   int    // line number, starting at 1
+	ColumnNumber int    // column number, starting at 1 (character count per line)
+}
+
+func (pos Position) String() string {
+	filename := pos.Filename
+	if filename == "" {
+		filename = "<stream>"
+	}
+	return fmt.Sprintf("%s:%d:%d", filename, pos.LineNumber, pos.ColumnNumber)
+
+}