github.com/linchen2chris/hugo@v0.0.0-20230307053224-cec209389705/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/gohugoio/hugo/common/hexec"
    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.ResultRender, error) {
    51  	b, err := c.getRstContent(ctx.Src, c.ctx)
    52  	if err != nil {
    53  		return nil, err
    54  	}
    55  	return converter.Bytes(b), nil
    56  }
    57  
    58  func (c *rstConverter) Supports(feature identity.Identity) bool {
    59  	return false
    60  }
    61  
    62  // getRstContent calls the Python script rst2html as an external helper
    63  // to convert reStructuredText content to HTML.
    64  func (c *rstConverter) getRstContent(src []byte, ctx converter.DocumentContext) ([]byte, error) {
    65  	logger := c.cfg.Logger
    66  	binaryName, binaryPath := getRstBinaryNameAndPath()
    67  
    68  	if binaryName == "" {
    69  		logger.Println("rst2html / rst2html.py not found in $PATH: Please install.\n",
    70  			"                 Leaving reStructuredText content unrendered.")
    71  		return src, nil
    72  	}
    73  
    74  	logger.Infoln("Rendering", ctx.DocumentName, "with", binaryName, "...")
    75  
    76  	var result []byte
    77  	var err error
    78  
    79  	// certain *nix based OSs wrap executables in scripted launchers
    80  	// invoking binaries on these OSs via python interpreter causes SyntaxError
    81  	// invoke directly so that shebangs work as expected
    82  	// handle Windows manually because it doesn't do shebangs
    83  	if runtime.GOOS == "windows" {
    84  		pythonBinary, _ := internal.GetPythonBinaryAndExecPath()
    85  		args := []string{binaryPath, "--leave-comments", "--initial-header-level=2"}
    86  		result, err = internal.ExternallyRenderContent(c.cfg, ctx, src, pythonBinary, args)
    87  	} else {
    88  		args := []string{"--leave-comments", "--initial-header-level=2"}
    89  		result, err = internal.ExternallyRenderContent(c.cfg, ctx, src, binaryName, args)
    90  	}
    91  
    92  	if err != nil {
    93  		return nil, err
    94  	}
    95  
    96  	// TODO(bep) check if rst2html has a body only option.
    97  	bodyStart := bytes.Index(result, []byte("<body>\n"))
    98  	if bodyStart < 0 {
    99  		bodyStart = -7 // compensate for length
   100  	}
   101  
   102  	bodyEnd := bytes.Index(result, []byte("\n</body>"))
   103  	if bodyEnd < 0 || bodyEnd >= len(result) {
   104  		bodyEnd = len(result) - 1
   105  		if bodyEnd < 0 {
   106  			bodyEnd = 0
   107  		}
   108  	}
   109  
   110  	return result[bodyStart+7 : bodyEnd], err
   111  }
   112  
   113  var rst2Binaries = []string{"rst2html", "rst2html.py"}
   114  
   115  func getRstBinaryNameAndPath() (string, string) {
   116  	for _, candidate := range rst2Binaries {
   117  		if pth := hexec.LookPath(candidate); pth != "" {
   118  			return candidate, pth
   119  		}
   120  	}
   121  	return "", ""
   122  }
   123  
   124  // Supports returns whether rst is (or should be) installed on this computer.
   125  func Supports() bool {
   126  	name, _ := getRstBinaryNameAndPath()
   127  	hasBin := name != ""
   128  	if htesting.SupportsAll() {
   129  		if !hasBin {
   130  			panic("rst not installed")
   131  		}
   132  		return true
   133  	}
   134  	return hasBin
   135  }