Механизм прост, после сбора всех директив с ноды, angular сортирует их через функцию
/**
* Looks for directives on the given node and adds them to the directive collection which is
* sorted.
*
* @param node Node to search.
* @param directives An array to which the directives are added to. This array is sorted before
* the function returns.
* @param attrs The shared attrs object which is used to populate the normalized attributes.
* @param {number=} maxPriority Max directive priority.
*/
function collectDirectives(node, directives, attrs, maxPriority, ignoreDirective) {
...
directives.sort(byPriority);
return directives;
}
/**
* Sorting function for bound directives.
*/
function byPriority(a, b) {
var diff = b.priority - a.priority;
if (diff !== 0) return diff;
if (a.name !== b.name) return (a.name < b.name) ? -1 : 1;
return a.index - b.index;
}
A флаг terminal заставляет оборвать цикл применения директив, тем самым выкидывает все директивы с меньшим приоритетом
/**
* Once the directives have been collected, their compile functions are executed. This method
* is responsible for inlining directive templates as well as terminating the application
* of the directives if the terminal directive has been reached.
*
* @param {Array} directives Array of collected directives to execute their compile function.
* this needs to be pre-sorted by priority order.
* @param {Node} compileNode The raw DOM node to apply the compile functions to
* @param {Object} templateAttrs The shared attribute function
* @param {function(angular.Scope[, cloneAttachFn]} transcludeFn A linking function, where the
* scope argument is auto-generated to the new
* child of the transcluded parent scope.
* @param {JQLite} jqCollection If we are working on the root of the compile tree then this
* argument has the root jqLite array so that we can replace nodes
* on it.
* @param {Object=} originalReplaceDirective An optional directive that will be ignored when
* compiling the transclusion.
* @param {Array.<Function>} preLinkFns
* @param {Array.<Function>} postLinkFns
* @param {Object} previousCompileContext Context used for previous compilation of the current
* node
* @returns linkFn
*/
function applyDirectivesToNode(directives, compileNode, templateAttrs, transcludeFn, jqCollection, originalReplaceDirective, preLinkFns, postLinkFns, previousCompileContext) {
...
var terminalPriority = -Number.MAX_VALUE,
...
// executes all directives on the current element
for(var i = 0, ii = directives.length; i < ii; i++) {
...
if (terminalPriority > directive.priority) {
break; // prevent further processing of directives
}
...
if (directive.terminal) {
nodeLinkFn.terminal = true;
terminalPriority = Math.max(terminalPriority, directive.priority);
}
}
...
}
