Introduce [[sharePromise]] internal slot (#113)

Author: Marcos Cáceres

index.html

@@ -104,6 +104,25 @@ <h3>
           target</a>. Clients can use the presence or absence of this method to
           determine whether to show UI that triggers its use.
         </div>
+        <section>
+          <h4>
+            Internal Slots
+          </h4>
+          <p>
+            This API adds the following internal slot to the {{Navigator}}
+            interface.
+          </p>
+          <dl>
+            <dt>
+              {{Promise}}? <dfn>[[\sharePromise]]</dfn>
+            </dt>
+            <dd>
+              The {{[[sharePromise]]}} is a promise that represents a user's
+              current intent to share some data with a <a>share target</a>. It
+              is initialized to `null`.
+            </dd>
+          </dl>
+        </section>
         <section>
           <h4>
             <dfn>share()</dfn> method
@@ -113,6 +132,9 @@ <h4>
             |data:ShareData|, run the following steps:
           </p>
           <ol class="algorithm">
+            <li>If {{[[sharePromise]]}} is not `null`, return <a>a promise
+            rejected with</a> {{InvalidStateError}}.
+            </li>
             <li>If none of |data|'s members {{ShareData/title}},
             {{ShareData/text}}, or {{ShareData/url}} are present, return <a>a
             promise rejected with</a> a {{TypeError}}.
@@ -140,32 +162,60 @@ <h4>
             return <a>a promise rejected with</a> with a {{"NotAllowedError"}}
             {{DOMException}}.
             </li>
-            <li>Let |p:Promise| be <a>a new promise</a>.
+            <li>Set {{[[sharePromise]]}} to be <a>a new promise</a>.
             </li>
-            <li>Return |p| and <a>in parallel</a>:
+            <li>Return {{[[sharePromise]]}} and <a>in parallel</a>:
               <ol>
-                <li>If there are no <a>share targets</a> available,
-                <a>reject</a> |p| with an {{"AbortError"}} {{DOMException}},
-                and abort these steps.
+                <li>If there are no <a>share targets</a> available:
+                  <ol>
+                    <li>
+                      <a>Reject</a> {{[[sharePromise]]}} with an
+                      "{{AbortError}}" {{DOMException}}.
+                    </li>
+                    <li>Set {{[[sharePromise]]}} to `null`.
+                    </li>
+                    <li>Abort these steps.
+                    </li>
+                  </ol>
                 </li>
                 <li>Present the user with a choice of one or more <a>share
                 targets</a>, selected at the user agent's discretion. The user
                 MUST be given the option to cancel rather than choosing any of
                 the share targets. Wait for the user's choice.
                 </li>
-                <li>If the user chose to cancel the share operation,
-                <a>reject</a> |p| with an {{"AbortError"}} {{DOMException}},
-                and abort these steps.
+                <li>If the user chose to cancel the share operation:
+                  <ol>
+                    <li>
+                      <a>Reject</a> {{[[sharePromise]]}} with an
+                      "{{AbortError}}" {{DOMException}},
+                    </li>
+                    <li>Set {{[[sharePromise]]}} to `null`.
+                    </li>
+                    <li>Abort these steps.
+                    </li>
+                  </ol>
                 </li>
                 <li>Activate the chosen <a>share target</a>, <a>convert |data|
                 to a format suitable for ingestion into the target</a>, and
-                transmit the converted data to the target. If an error occurs
-                starting the target or transmitting the data, <a>reject</a> |p|
-                with an {{"AbortError"}} {{DOMException}}, and abort these
-                steps.
+                transmit the converted data to the target.
+                </li>
+                <li>If an error occurs starting the target or transmitting the
+                data:
+                  <ol>
+                    <li>
+                      <a>reject</a> {{[[sharePromise]]}} with an
+                      "{{DataError}}" {{DOMException}}, and abort these steps.
+                    </li>
+                    <li>Set {{[[sharePromise]]}} to `null`.
+                    </li>
+                    <li>Abort these steps.
+                    </li>
+                  </ol>
                 </li>
                 <li>Once the data has been successfully transmitted to the
-                target, <a>resolve</a> |p| with <b>undefined</b>.
+                target, <a>resolve</a> {{[[sharePromise]]}} with `undefined`.
+                </li>
+                <li>Set {{[[sharePromise]]}} to `null`.
                 </li>
               </ol>
             </li>