link.go

Documentation: golang.org/x/tools/present

     1  // Copyright 2012 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package present
     6  
     7  import (
     8  	"fmt"
     9  	"log"
    10  	"net/url"
    11  	"strings"
    12  )
    13  
    14  func init() {
    15  	Register("link", parseLink)
    16  }
    17  
    18  type Link struct {
    19  	Cmd   string // original command from present source
    20  	URL   *url.URL
    21  	Label string
    22  }
    23  
    24  func (l Link) PresentCmd() string   { return l.Cmd }
    25  func (l Link) TemplateName() string { return "link" }
    26  
    27  func parseLink(ctx *Context, fileName string, lineno int, text string) (Elem, error) {
    28  	args := strings.Fields(text)
    29  	if len(args) < 2 {
    30  		return nil, fmt.Errorf("link element must have at least 2 arguments")
    31  	}
    32  	url, err := url.Parse(args[1])
    33  	if err != nil {
    34  		return nil, err
    35  	}
    36  	label := ""
    37  	if len(args) > 2 {
    38  		label = strings.Join(args[2:], " ")
    39  	} else {
    40  		scheme := url.Scheme + "://"
    41  		if url.Scheme == "mailto" {
    42  			scheme = "mailto:"
    43  		}
    44  		label = strings.Replace(url.String(), scheme, "", 1)
    45  	}
    46  	return Link{text, url, label}, nil
    47  }
    48  
    49  func renderLink(href, text string) string {
    50  	text = font(text)
    51  	if text == "" {
    52  		text = href
    53  	}
    54  	// Open links in new window only when their url is absolute.
    55  	target := "_blank"
    56  	if u, err := url.Parse(href); err != nil {
    57  		log.Println("renderLink parsing url:", err)
    58  	} else if !u.IsAbs() || u.Scheme == "javascript" {
    59  		target = "_self"
    60  	}
    61  
    62  	return fmt.Sprintf(`<a href="%s" target="%s">%s</a>`, href, target, text)
    63  }
    64  
    65  // parseInlineLink parses an inline link at the start of s, and returns
    66  // a rendered HTML link and the total length of the raw inline link.
    67  // If no inline link is present, it returns all zeroes.
    68  func parseInlineLink(s string) (link string, length int) {
    69  	if !strings.HasPrefix(s, "[[") {
    70  		return
    71  	}
    72  	end := strings.Index(s, "]]")
    73  	if end == -1 {
    74  		return
    75  	}
    76  	urlEnd := strings.Index(s, "]")
    77  	rawURL := s[2:urlEnd]
    78  	const badURLChars = `<>"{}|\^[] ` + "`" // per RFC2396 section 2.4.3
    79  	if strings.ContainsAny(rawURL, badURLChars) {
    80  		return
    81  	}
    82  	if urlEnd == end {
    83  		simpleURL := ""
    84  		url, err := url.Parse(rawURL)
    85  		if err == nil {
    86  			// If the URL is http://foo.com, drop the http://
    87  			// In other words, render [[http://golang.org]] as:
    88  			//   <a href="http://golang.org">golang.org</a>
    89  			if strings.HasPrefix(rawURL, url.Scheme+"://") {
    90  				simpleURL = strings.TrimPrefix(rawURL, url.Scheme+"://")
    91  			} else if strings.HasPrefix(rawURL, url.Scheme+":") {
    92  				simpleURL = strings.TrimPrefix(rawURL, url.Scheme+":")
    93  			}
    94  		}
    95  		return renderLink(rawURL, simpleURL), end + 2
    96  	}
    97  	if s[urlEnd:urlEnd+2] != "][" {
    98  		return
    99  	}
   100  	text := s[urlEnd+2 : end]
   101  	return renderLink(rawURL, text), end + 2
   102  }
   103
View as plain text