Add select prompt example

examples/prompts/select.py

@@ -0,0 +1,94 @@
+#!/usr/bin/env python
+"""
+An example of select prompt.
+"""
+
+from prompt_toolkit.application import Application
+from prompt_toolkit.filters import IsDone
+from prompt_toolkit.key_binding import KeyBindings
+from prompt_toolkit.layout.containers import ConditionalContainer, HSplit, Window
+from prompt_toolkit.layout.controls import FormattedTextControl
+from prompt_toolkit.layout.dimension import Dimension
+from prompt_toolkit.layout.layout import Layout
+
+
+class SelectControl(FormattedTextControl):
+    def __init__(self, options):
+        self.options = options
+        self.selected_index = 0
+        super().__init__(key_bindings=self._create_key_bindings())
+
+    @property
+    def selected_option(self):
+        return self.options[self.selected_index]
+
+    def _create_key_bindings(self):
+        kb = KeyBindings()
+        count = len(self.options)
+
+        @kb.add('down', eager=True)
+        def move_cursor_down(event):
+            self.selected_index = (self.selected_index + 1) % count
+
+        @kb.add('up', eager=True)
+        def move_cursor_up(event):
+            self.selected_index = (self.selected_index - 1) % count
+
+        @kb.add('enter', eager=True)
+        def set_selected(event):
+            value = self.selected_option
+            event.app.exit(result=value)
+
+        @kb.add('c-q', eager=True)
+        @kb.add('c-c', eager=True)
+        def _(event):
+            raise KeyboardInterrupt()
+
+        return kb
+
+    def select_option_text(self, mark):
+        text = []
+        for idx, op in enumerate(self.options):
+            if idx == self.selected_index:
+                line = f'{mark} {op}\n'
+            else:
+                line = f'  {op}\n'
+            text.append(('', line))  # style, string
+        return text
+
+
+def select_prompt(message, options, mark='>'):
+    control = SelectControl(options)
+
+    def get_formatted_text():
+        return control.select_option_text(mark)
+
+    layout = Layout(HSplit([
+        Window(
+            height=Dimension.exact(1),
+            content=FormattedTextControl(
+                lambda: message + '\n',
+                show_cursor=False
+            ),
+        ),
+        Window(
+            height=Dimension.exact(len(control.options)),
+            content=FormattedTextControl(get_formatted_text)
+        ),
+        ConditionalContainer(
+            Window(control),
+            filter=~IsDone()
+        )
+    ]))
+
+    app = Application(
+        layout=layout,
+        key_bindings=control.key_bindings,
+        full_screen=False
+    )
+    return app.run()
+
+
+if __name__ == '__main__':
+    result = select_prompt('select a option:', ['foo', 'bar'], mark='>')
+    print(f'You selected {result}')