Add support for multi-select choice prompts

This change adds support for the variant of $host.UI.PromptForChoice which
is enabled by the IHostUISupportsMultipleChoiceSelection.

examples/PromptExamples.ps1

@@ -0,0 +1,10 @@
+
+# Multi-choice prompt
+$choices = @(
+    New-Object "System.Management.Automation.Host.ChoiceDescription" "&Apple", "Apple"
+    New-Object "System.Management.Automation.Host.ChoiceDescription" "&Banana", "Banana"
+    New-Object "System.Management.Automation.Host.ChoiceDescription" "&Orange", "Orange"
+)
+
+$defaults = [int[]]@(0, 2)
+$host.UI.PromptForChoice("Choose a fruit", "You may choose more than one", $choices, $defaults)

src/features/Console.ts

@@ -4,6 +4,7 @@
 
 import vscode = require('vscode');
 import { IFeature } from '../feature';
+import { showCheckboxQuickPick, CheckboxQuickPickItem } from '../checkboxQuickPick'
 import { LanguageClient, RequestType, NotificationType } from 'vscode-languageclient';
 
 export namespace EvaluateRequest {
@@ -46,14 +47,15 @@ interface ShowInputPromptRequestArgs {
 }
 
 interface ShowChoicePromptRequestArgs {
+    isMultiChoice: boolean;
     caption: string;
     message: string;
     choices: ChoiceDetails[];
-    defaultChoice: number;
+    defaultChoices: number[];
 }
 
 interface ShowChoicePromptResponseBody {
-    chosenItem: string;
+    responseText: string;
     promptCancelled: boolean;
 }
 
@@ -66,36 +68,62 @@ function showChoicePrompt(
     promptDetails: ShowChoicePromptRequestArgs,
     client: LanguageClient) : Thenable<ShowChoicePromptResponseBody> {
 
-    var quickPickItems =
-        promptDetails.choices.map<vscode.QuickPickItem>(choice => {
-            return {
-                label: choice.label,
-                description: choice.helpMessage
-            }
-        });
+    var resultThenable: Thenable<ShowChoicePromptResponseBody> = undefined;
+
+    if (!promptDetails.isMultiChoice) {
+        var quickPickItems =
+            promptDetails.choices.map<vscode.QuickPickItem>(choice => {
+                return {
+                    label: choice.label,
+                    description: choice.helpMessage
+                }
+            });
+
+        if (promptDetails.defaultChoices &&
+            promptDetails.defaultChoices.length > 0) {
 
-    // Shift the default item to the front of the
-    // array so that the user can select it easily
-    if (promptDetails.defaultChoice > -1 &&
-        promptDetails.defaultChoice < promptDetails.choices.length) {
+            // Shift the default items to the front of the
+            // array so that the user can select it easily
+            var defaultChoice = promptDetails.defaultChoices[0];
+            if (defaultChoice > -1 &&
+                defaultChoice < promptDetails.choices.length) {
 
-        var defaultChoiceItem = quickPickItems[promptDetails.defaultChoice];
-        quickPickItems.splice(promptDetails.defaultChoice, 1);
+                var defaultChoiceItem = quickPickItems[defaultChoice];
+                quickPickItems.splice(defaultChoice, 1);
 
-        // Add the default choice to the head of the array
-        quickPickItems = [defaultChoiceItem].concat(quickPickItems);
+                // Add the default choice to the head of the array
+                quickPickItems = [defaultChoiceItem].concat(quickPickItems);
+            }
+        }
+
+        resultThenable =
+            vscode.window
+                .showQuickPick(
+                    quickPickItems,
+                    { placeHolder: promptDetails.caption + " - " + promptDetails.message })
+                .then(onItemSelected);
     }
+    else {
+        var checkboxQuickPickItems =
+            promptDetails.choices.map<CheckboxQuickPickItem>(choice => {
+                return {
+                    label: choice.label,
+                    description: choice.helpMessage,
+                    isSelected: false
+                }
+            });
 
-    // For some bizarre reason, the quick pick dialog does not
-    // work if I return the Thenable immediately at this point.
-    // It only works if I save the thenable to a variable and
-    // return the variable instead...
-    var resultThenable =
-        vscode.window
-            .showQuickPick(
-                quickPickItems,
-                { placeHolder: promptDetails.caption + " - " + promptDetails.message })
-            .then(onItemSelected);
+        // Select the defaults
+        promptDetails.defaultChoices.forEach(choiceIndex => {
+            checkboxQuickPickItems[choiceIndex].isSelected = true
+        });
+
+        resultThenable =
+            showCheckboxQuickPick(
+                    checkboxQuickPickItems,
+                    { confirmPlaceHolder: `${promptDetails.caption} - ${promptDetails.message}`})
+                .then(onItemsSelected);
+    }
 
     return resultThenable;
 }
@@ -112,18 +140,34 @@ function showInputPrompt(
     return resultThenable;
 }
 
+function onItemsSelected(chosenItems: CheckboxQuickPickItem[]): ShowChoicePromptResponseBody {
+    if (chosenItems !== undefined) {
+        return {
+            promptCancelled: false,
+            responseText: chosenItems.filter(item => item.isSelected).map(item => item.label).join(", ")
+        };
+    }
+    else {
+        // User cancelled the prompt, send the cancellation
+        return {
+            promptCancelled: true,
+            responseText: undefined
+        };
+    }
+}
+
 function onItemSelected(chosenItem: vscode.QuickPickItem): ShowChoicePromptResponseBody {
     if (chosenItem !== undefined) {
         return {
             promptCancelled: false,
-            chosenItem: chosenItem.label
+            responseText: chosenItem.label
         };
     }
     else {
         // User cancelled the prompt, send the cancellation
         return {
             promptCancelled: true,
-            chosenItem: undefined
+            responseText: undefined
         };
     }
 }