Add ui.MarkdownStream (#1782)

Author: cpsievert

CHANGELOG.md

@@ -9,6 +9,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### New features
 
+* Added a new `ui.MarkdownStream()` component for performantly streaming in chunks of markdown/html strings into the UI. This component is primarily useful for text-based generative AI where responses are received incrementally. (#1782)
+
 * Added a new `.add_sass_layer_file()` method to `ui.Theme` that supports reading a Sass file with layer boundary comments, e.g. `/*-- scss:defaults --*/`. This format [is supported by Quarto](https://quarto.org/docs/output-formats/html-themes-more.html#bootstrap-bootswatch-layering) and makes it easier to store Sass rules and declarations that need to be woven into Shiny's Sass Bootstrap files. (#1790)
 
 * The `ui.Chat()` component's `.on_user_submit()` decorator method now passes the user input to the decorated function. This makes it a bit more obvious how to access the user input inside the decorated function. See the new templates (mentioned below) for examples. (#1801)

docs/_quartodoc-core.yml

@@ -102,6 +102,11 @@ quartodoc:
       contents:
         - ui.Chat
         - ui.chat_ui
+    - title: Streaming markdown
+      desc: Stream markdown content into the UI
+      contents:
+        - ui.MarkdownStream
+        - ui.output_markdown_stream
     - title: Custom UI
       desc: Lower-level UI functions for creating custom HTML/CSS/JS
       contents:
@@ -358,4 +363,3 @@ quartodoc:
           contents:
             - name: experimental.ui.card_image
               dynamic: false
-

docs/_quartodoc-express.yml

@@ -81,6 +81,10 @@ quartodoc:
       desc: Build a chatbot interface
       contents:
         - express.ui.Chat
+    - title: Streaming markdown
+      desc: Stream markdown content into the UI
+      contents:
+        - express.ui.MarkdownStream
     - title: Reactive programming
       desc: Create reactive functions and dependencies.
       contents:

js/build.ts

@@ -74,6 +74,20 @@ const opts: Array<BuildOptions> = [
     plugins: [sassPlugin({ type: "css", sourceMap: false })],
     metafile: true,
   },
+  {
+    entryPoints: {
+      "markdown-stream/markdown-stream": "markdown-stream/markdown-stream.ts",
+    },
+    minify: true,
+    sourcemap: true,
+  },
+  {
+    entryPoints: {
+      "markdown-stream/markdown-stream": "markdown-stream/markdown-stream.scss",
+    },
+    plugins: [sassPlugin({ type: "css", sourceMap: false })],
+    metafile: true,
+  },
   {
     entryPoints: {
       "chat/chat": "chat/chat.ts",

js/chat/_utils.ts

@@ -1,5 +1,3 @@
-@use "highlight_styles" as highlight_styles;
-
 shiny-chat-container {
   --shiny-chat-border: var(--bs-border-width, 1px) solid var(--bs-border-color, #e9ecef);
   --shiny-chat-user-message-bg: RGBA(var(--bs-primary-rgb, 0, 123, 194), 0.06);
@@ -39,7 +37,7 @@ shiny-chat-message {
     }
   }
   /* Vertically center the 2nd column (message content) */
-  .message-content {
+  shiny-markdown-stream {
     align-self: center;
   }
 }
@@ -101,53 +99,3 @@ shiny-chat-input {
 .shiny-busy:has(shiny-chat-input[disabled])::after {
   display: none;
 }
-
-/* Code highlighting (for both light and dark mode) */
-@include highlight_styles.atom_one_light;
-[data-bs-theme="dark"] {
-  @include highlight_styles.atom_one_dark;
-}
-
-/*
-  Styling for the code-copy button (inspired by Quarto's code-copy feature)
-*/
-pre:has(.code-copy-button) {
-  position: relative;
-}
-
-.code-copy-button {
-  position: absolute;
-  top: 0;
-  right: 0;
-  border: 0;
-  margin-top: 5px;
-  margin-right: 5px;
-  background-color: transparent;
-
-  > .bi {
-    display: flex;
-    gap: 0.25em;
-
-    &::after {
-      content: "";
-      display: block;
-      height: 1rem;
-      width: 1rem;
-      mask-image: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" fill="currentColor" viewBox="0 0 16 16"><path d="M4 1.5H3a2 2 0 0 0-2 2V14a2 2 0 0 0 2 2h10a2 2 0 0 0 2-2V3.5a2 2 0 0 0-2-2h-1v1h1a1 1 0 0 1 1 1V14a1 1 0 0 1-1 1H3a1 1 0 0 1-1-1V3.5a1 1 0 0 1 1-1h1v-1z"/><path d="M9.5 1a.5.5 0 0 1 .5.5v1a.5.5 0 0 1-.5.5h-3a.5.5 0 0 1-.5-.5v-1a.5.5 0 0 1 .5-.5h3zm-3-1A1.5 1.5 0 0 0 5 1.5v1A1.5 1.5 0 0 0 6.5 4h3A1.5 1.5 0 0 0 11 2.5v-1A1.5 1.5 0 0 0 9.5 0h-3z"/></svg>');
-      background-color: var(--bs-body-color, #222);
-    }
-  }
-}
-
-.code-copy-button-checked {
-  > .bi::before {
-    content: "Copied!";
-    font-size: 0.75em;
-    vertical-align: 0.25em;
-  }
-
-  > .bi::after {
-    mask-image: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" fill="currentColor" viewBox="0 0 16 16"><path d="M13.854 3.646a.5.5 0 0 1 0 .708l-7 7a.5.5 0 0 1-.708 0l-3.5-3.5a.5.5 0 1 1 .708-.708L6.5 10.293l6.646-6.647a.5.5 0 0 1 .708 0z"/></svg>');
-    background-color: var(--bs-success, #198754);
-  }
-}