Prepare for Goldmark

This commmit prepares for the addition of Goldmark as the new Markdown renderer in Hugo.

This introduces a new `markup` package with some common interfaces and each implementation in its own package.

See #5963

2 files changed, 160 insertions, 0 deletions

diff --git a/markup/internal/blackfriday.go b/markup/internal/blackfriday.go
new file mode 100644
index 000000000..373df0c50
--- /dev/null
+++ b/markup/internal/blackfriday.go
@@ -0,0 +1,108 @@
+// Copyright 2019 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 helpers implements general utility functions that work with
+// and on content.  The helper functions defined here lay down the
+// foundation of how Hugo works with files and filepaths, and perform
+// string operations on content.
+
+package internal
+
+import (
+	"github.com/gohugoio/hugo/common/maps"
+	"github.com/gohugoio/hugo/markup/converter"
+	"github.com/mitchellh/mapstructure"
+	"github.com/pkg/errors"
+)
+
+// BlackFriday holds configuration values for BlackFriday rendering.
+// It is kept here because it's used in several packages.
+type BlackFriday struct {
+	Smartypants           bool
+	SmartypantsQuotesNBSP bool
+	AngledQuotes          bool
+	Fractions             bool
+	HrefTargetBlank       bool
+	NofollowLinks         bool
+	NoreferrerLinks       bool
+	SmartDashes           bool
+	LatexDashes           bool
+	TaskLists             bool
+	PlainIDAnchors        bool
+	Extensions            []string
+	ExtensionsMask        []string
+	SkipHTML              bool
+
+	FootnoteAnchorPrefix       string
+	FootnoteReturnLinkContents string
+}
+
+func UpdateBlackFriday(old *BlackFriday, m map[string]interface{}) (*BlackFriday, error) {
+	// Create a copy so we can modify it.
+	bf := *old
+	if err := mapstructure.Decode(m, &bf); err != nil {
+		return nil, errors.WithMessage(err, "failed to decode rendering config")
+	}
+	return &bf, nil
+}
+
+// NewBlackfriday creates a new Blackfriday filled with site config or some sane defaults.
+func NewBlackfriday(cfg converter.ProviderConfig) (*BlackFriday, error) {
+	var siteConfig map[string]interface{}
+	if cfg.Cfg != nil {
+		siteConfig = cfg.Cfg.GetStringMap("blackfriday")
+	}
+
+	defaultParam := map[string]interface{}{
+		"smartypants":           true,
+		"angledQuotes":          false,
+		"smartypantsQuotesNBSP": false,
+		"fractions":             true,
+		"hrefTargetBlank":       false,
+		"nofollowLinks":         false,
+		"noreferrerLinks":       false,
+		"smartDashes":           true,
+		"latexDashes":           true,
+		"plainIDAnchors":        true,
+		"taskLists":             true,
+		"skipHTML":              false,
+	}
+
+	maps.ToLower(defaultParam)
+
+	config := make(map[string]interface{})
+
+	for k, v := range defaultParam {
+		config[k] = v
+	}
+
+	for k, v := range siteConfig {
+		config[k] = v
+	}
+
+	combinedConfig := &BlackFriday{}
+	if err := mapstructure.Decode(config, combinedConfig); err != nil {
+		return nil, errors.Errorf("failed to decode Blackfriday config: %s", err)
+	}
+
+	// TODO(bep) update/consolidate docs
+	if combinedConfig.FootnoteAnchorPrefix == "" {
+		combinedConfig.FootnoteAnchorPrefix = cfg.Cfg.GetString("footnoteAnchorPrefix")
+	}
+
+	if combinedConfig.FootnoteReturnLinkContents == "" {
+		combinedConfig.FootnoteReturnLinkContents = cfg.Cfg.GetString("footnoteReturnLinkContents")
+	}
+
+	return combinedConfig, nil
+}
diff --git a/markup/internal/external.go b/markup/internal/external.go
new file mode 100644
index 000000000..2105e7cff
--- /dev/null
+++ b/markup/internal/external.go
@@ -0,0 +1,52 @@
+package internal
+
+import (
+	"bytes"
+	"os/exec"
+	"strings"
+
+	"github.com/gohugoio/hugo/markup/converter"
+)
+
+func ExternallyRenderContent(
+	cfg converter.ProviderConfig,
+	ctx converter.DocumentContext,
+	content []byte, path string, args []string) []byte {
+
+	logger := cfg.Logger
+	cmd := exec.Command(path, args...)
+	cmd.Stdin = bytes.NewReader(content)
+	var out, cmderr bytes.Buffer
+	cmd.Stdout = &out
+	cmd.Stderr = &cmderr
+	err := cmd.Run()
+	// Most external helpers exit w/ non-zero exit code only if severe, i.e.
+	// halting errors occurred. -> log stderr output regardless of state of err
+	for _, item := range strings.Split(cmderr.String(), "\n") {
+		item := strings.TrimSpace(item)
+		if item != "" {
+			logger.ERROR.Printf("%s: %s", ctx.DocumentName, item)
+		}
+	}
+	if err != nil {
+		logger.ERROR.Printf("%s rendering %s: %v", path, ctx.DocumentName, err)
+	}
+
+	return normalizeExternalHelperLineFeeds(out.Bytes())
+}
+
+// Strips carriage returns from third-party / external processes (useful for Windows)
+func normalizeExternalHelperLineFeeds(content []byte) []byte {
+	return bytes.Replace(content, []byte("\r"), []byte(""), -1)
+}
+
+func GetPythonExecPath() string {
+	path, err := exec.LookPath("python")
+	if err != nil {
+		path, err = exec.LookPath("python.exe")
+		if err != nil {
+			return ""
+		}
+	}
+	return path
+}