modules/follow-relationship.js

   1 require("element.js");
   2
   3 const RELATIONSHIP_NEXT = 0;
   4 const RELATIONSHIP_PREVIOUS = 1;
   5
   6 var browser_relationship_rel_name = ["next", "previous"];
   7 var browser_relationship_rel_regexp = ["next", "prev|previous"];
   8 var browser_relationship_rev_regexp = ["prev|previous", "next"];
   9
  10 define_variable("browser_relationship_patterns", {}, "Patterns used by `browser-follow-next' and `browser-follow-previous'.");
  11
  12 browser_relationship_patterns[RELATIONSHIP_NEXT] =
  13     [new RegExp("\\bnext","i"),
  14      new RegExp("^>$","i"),
  15      new RegExp("^(>>|»)$","i"),
  16      new RegExp("^(>|»)","i"),
  17      new RegExp("(>|»)$","i")];
  18
  19 browser_relationship_patterns[RELATIONSHIP_PREVIOUS] =
  20     [new RegExp("\\bprev|previous\\b","i"),
  21      new RegExp("^<$","i"),
  22      new RegExp("^(<<|«)$","i"),
  23      new RegExp("^(<|«)","i"),
  24      new RegExp("(<|«)$","i")];
  25
  26 function document_get_element_by_relationship(doc, relationship) {
  27     var patterns = browser_relationship_patterns[relationship];
  28     var rel_name = new RegExp(browser_relationship_rel_regexp[relationship], "i");
  29     var rev_name = new RegExp(browser_relationship_rev_regexp[relationship], "i");
  30
  31     var elems = doc.getElementsByTagName("link");
  32     // links have higher priority than normal <a> hrefs
  33     for (var i = 0; i < elems.length; i++)
  34     {
  35         if (rel_name.test(elems[i].rel) || rev_name.test(elems[i].rev))
  36             return elems[i];
  37     }
  38
  39     // no links? ok, look for hrefs
  40     elems = doc.getElementsByTagName("a");
  41     for (var i = 0; i < elems.length; i++)
  42     {
  43         if (rel_name.test(elems[i].rel) || rev_name.test(elems[i].rev))
  44             return elems[i];
  45     }
  46
  47     for (var j = 0; j < patterns.length; ++j)
  48     {
  49         var pattern = patterns[j];
  50         for (var i = 0; i < elems.length; i++) // Loop through list of A elements again
  51         {
  52             if (pattern.test(elems[i].textContent))
  53                 return elems[i];
  54
  55             // images with alt text being href
  56             var children = elems[i].childNodes;
  57             for (var k = 0; k < children.length; k++)
  58             {
  59                 if (pattern.test(children[k].alt))
  60                     return elems[i];
  61             }
  62         }
  63     }
  64     return null;
  65 }
  66
  67 function browser_follow_relationship(buffer, relationship, target) {
  68     check_buffer(buffer, content_buffer);
  69     function helper(win) {
  70         var elem = document_get_element_by_relationship(win.document, relationship);
  71         if (elem)
  72             return elem;
  73         for (var i = 0; i < win.frames.length; ++i) {
  74             elem = document_get_element_by_relationship(win.frames[i].document, relationship);
  75             if (elem)
  76                 return elem;
  77         }
  78         return null;
  79     }
  80
  81     var elem = helper(buffer.top_frame);
  82     if (!elem)
  83         throw interactive_error("No \"" + browser_relationship_rel_name[relationship]
  84                                 + "\" link found");
  85     browser_element_follow(buffer, target, elem);
  86 }
  87
  88 default_browse_targets["follow-relationship"] = "follow";
  89
  90 interactive("browser-follow-next", function (I) {
  91     browser_follow_relationship(I.buffer, RELATIONSHIP_NEXT, I.browse_target("follow-relationship"))
  92 });
  93
  94 interactive("browser-follow-previous", function (I) {
  95     browser_follow_relationship(I.buffer, RELATIONSHIP_PREVIOUS, I.browse_target("follow-relationship"))
  96 });