github.com/graemephi/kahugo@v0.62.3-0.20211121071557-d78c0423784d/markup/rst/convert.go (about)

     1  // Copyright 2019 The Hugo Authors. All rights reserved.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  // http://www.apache.org/licenses/LICENSE-2.0
     7  //
     8  // Unless required by applicable law or agreed to in writing, software
     9  // distributed under the License is distributed on an "AS IS" BASIS,
    10  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    11  // See the License for the specific language governing permissions and
    12  // limitations under the License.
    13  
    14  // Package rst converts content to HTML using the RST external helper.
    15  package rst
    16  
    17  import (
    18  	"bytes"
    19  	"runtime"
    20  
    21  	"github.com/cli/safeexec"
    22  	"github.com/gohugoio/hugo/htesting"
    23  
    24  	"github.com/gohugoio/hugo/identity"
    25  	"github.com/gohugoio/hugo/markup/internal"
    26  
    27  	"github.com/gohugoio/hugo/markup/converter"
    28  )
    29  
    30  // Provider is the package entry point.
    31  var Provider converter.ProviderProvider = provider{}
    32  
    33  type provider struct {
    34  }
    35  
    36  func (p provider) New(cfg converter.ProviderConfig) (converter.Provider, error) {
    37  	return converter.NewProvider("rst", func(ctx converter.DocumentContext) (converter.Converter, error) {
    38  		return &rstConverter{
    39  			ctx: ctx,
    40  			cfg: cfg,
    41  		}, nil
    42  	}), nil
    43  }
    44  
    45  type rstConverter struct {
    46  	ctx converter.DocumentContext
    47  	cfg converter.ProviderConfig
    48  }
    49  
    50  func (c *rstConverter) Convert(ctx converter.RenderContext) (converter.Result, error) {
    51  	return converter.Bytes(c.getRstContent(ctx.Src, c.ctx)), nil
    52  }
    53  
    54  func (c *rstConverter) Supports(feature identity.Identity) bool {
    55  	return false
    56  }
    57  
    58  // getRstContent calls the Python script rst2html as an external helper
    59  // to convert reStructuredText content to HTML.
    60  func (c *rstConverter) getRstContent(src []byte, ctx converter.DocumentContext) []byte {
    61  	logger := c.cfg.Logger
    62  	path := getRstExecPath()
    63  
    64  	if path == "" {
    65  		logger.Println("rst2html / rst2html.py not found in $PATH: Please install.\n",
    66  			"                 Leaving reStructuredText content unrendered.")
    67  		return src
    68  	}
    69  
    70  	logger.Infoln("Rendering", ctx.DocumentName, "with", path, "...")
    71  
    72  	var result []byte
    73  	// certain *nix based OSs wrap executables in scripted launchers
    74  	// invoking binaries on these OSs via python interpreter causes SyntaxError
    75  	// invoke directly so that shebangs work as expected
    76  	// handle Windows manually because it doesn't do shebangs
    77  	if runtime.GOOS == "windows" {
    78  		python := internal.GetPythonExecPath()
    79  		args := []string{path, "--leave-comments", "--initial-header-level=2"}
    80  		result = internal.ExternallyRenderContent(c.cfg, ctx, src, python, args)
    81  	} else {
    82  		args := []string{"--leave-comments", "--initial-header-level=2"}
    83  		result = internal.ExternallyRenderContent(c.cfg, ctx, src, path, args)
    84  	}
    85  	// TODO(bep) check if rst2html has a body only option.
    86  	bodyStart := bytes.Index(result, []byte("<body>\n"))
    87  	if bodyStart < 0 {
    88  		bodyStart = -7 // compensate for length
    89  	}
    90  
    91  	bodyEnd := bytes.Index(result, []byte("\n</body>"))
    92  	if bodyEnd < 0 || bodyEnd >= len(result) {
    93  		bodyEnd = len(result) - 1
    94  		if bodyEnd < 0 {
    95  			bodyEnd = 0
    96  		}
    97  	}
    98  
    99  	return result[bodyStart+7 : bodyEnd]
   100  }
   101  
   102  func getRstExecPath() string {
   103  	path, err := safeexec.LookPath("rst2html")
   104  	if err != nil {
   105  		path, err = safeexec.LookPath("rst2html.py")
   106  		if err != nil {
   107  			return ""
   108  		}
   109  	}
   110  	return path
   111  }
   112  
   113  // Supports returns whether rst is installed on this computer.
   114  func Supports() bool {
   115  	if htesting.SupportsAll() {
   116  		return true
   117  	}
   118  	return getRstExecPath() != ""
   119  }