markdown.go

Documentation: k8s.io/kubectl/pkg/util/templates

     1  /*
     2  Copyright 2016 The Kubernetes Authors.
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8      http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  
    17  package templates
    18  
    19  import (
    20  	"fmt"
    21  	"io"
    22  	"strings"
    23  
    24  	"github.com/russross/blackfriday/v2"
    25  )
    26  
    27  const linebreak = "\n"
    28  
    29  // ASCIIRenderer implements blackfriday.Renderer
    30  var _ blackfriday.Renderer = &ASCIIRenderer{}
    31  
    32  // ASCIIRenderer is a blackfriday.Renderer intended for rendering markdown
    33  // documents as plain text, well suited for human reading on terminals.
    34  type ASCIIRenderer struct {
    35  	Indentation string
    36  
    37  	listItemCount uint
    38  	listLevel     uint
    39  }
    40  
    41  // render markdown to text
    42  func (r *ASCIIRenderer) RenderNode(w io.Writer, node *blackfriday.Node, entering bool) blackfriday.WalkStatus {
    43  	switch node.Type {
    44  	case blackfriday.Text:
    45  		raw := string(node.Literal)
    46  		lines := strings.Split(raw, linebreak)
    47  		for _, line := range lines {
    48  			trimmed := strings.Trim(line, " \n\t")
    49  			if len(trimmed) > 0 && trimmed[0] != '_' {
    50  				w.Write([]byte(" "))
    51  			}
    52  			w.Write([]byte(trimmed))
    53  		}
    54  	case blackfriday.HorizontalRule, blackfriday.Hardbreak:
    55  		w.Write([]byte(linebreak + "----------" + linebreak))
    56  	case blackfriday.Code, blackfriday.CodeBlock:
    57  		w.Write([]byte(linebreak))
    58  		lines := []string{}
    59  		for _, line := range strings.Split(string(node.Literal), linebreak) {
    60  			trimmed := strings.Trim(line, " \t")
    61  			// Adding 4 times of indentation will let blackfriday to accept
    62  			// this literal as Code or CodeBlock again in next invocation
    63  			indented := strings.Repeat(r.Indentation, 4) + trimmed
    64  			lines = append(lines, indented)
    65  		}
    66  		w.Write([]byte(strings.Join(lines, linebreak)))
    67  	case blackfriday.Image:
    68  		w.Write(node.LinkData.Destination)
    69  	case blackfriday.Link:
    70  		w.Write([]byte(" "))
    71  		w.Write(node.LinkData.Destination)
    72  	case blackfriday.Paragraph:
    73  		if r.listLevel == 0 {
    74  			w.Write([]byte(linebreak))
    75  		}
    76  	case blackfriday.List:
    77  		if entering {
    78  			w.Write([]byte(linebreak))
    79  			r.listLevel++
    80  		} else {
    81  			r.listLevel--
    82  			r.listItemCount = 0
    83  		}
    84  	case blackfriday.Item:
    85  		if entering {
    86  			r.listItemCount++
    87  			for i := 0; uint(i) < r.listLevel; i++ {
    88  				w.Write([]byte(r.Indentation))
    89  			}
    90  			if node.ListFlags&blackfriday.ListTypeOrdered != 0 {
    91  				w.Write([]byte(fmt.Sprintf("%d. ", r.listItemCount)))
    92  			} else {
    93  				w.Write([]byte("* "))
    94  			}
    95  		} else {
    96  			w.Write([]byte(linebreak))
    97  		}
    98  	default:
    99  		normalText(w, node.Literal)
   100  	}
   101  	return blackfriday.GoToNext
   102  }
   103  
   104  func normalText(w io.Writer, text []byte) {
   105  	w.Write([]byte(strings.Trim(string(text), " \n\t")))
   106  }
   107  
   108  // RenderHeader writes document preamble and TOC if requested.
   109  func (r *ASCIIRenderer) RenderHeader(w io.Writer, ast *blackfriday.Node) {
   110  
   111  }
   112  
   113  // RenderFooter writes document footer.
   114  func (r *ASCIIRenderer) RenderFooter(w io.Writer, ast *blackfriday.Node) {
   115  	io.WriteString(w, "\n")
   116  }
   117
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