Extract text backend into separate module

src/textual/_text_backend.py

@@ -0,0 +1,95 @@
+from __future__ import annotations
+
+from dataclasses import dataclass
+
+
+@dataclass
+class TextEditorBackend:
+    content: str = ""
+    cursor_index: int = 0
+
+    def set_content(self, text: str):
+        self.content = text
+
+    def delete_back(self) -> bool:
+        """Delete the character behind the cursor
+
+        Returns: True if the text content was modified. False otherwise.
+        """
+        if self.cursor_index == 0:
+            return False
+
+        new_text = (
+            self.content[: self.cursor_index - 1] + self.content[self.cursor_index :]
+        )
+        self.content = new_text
+        self.cursor_index = max(0, self.cursor_index - 1)
+        return True
+
+    def delete_forward(self) -> bool:
+        """Delete the character in front of the cursor
+
+        Returns: True if the text content was modified. False otherwise.
+        """
+        if self.cursor_index == len(self.content):
+            return False
+
+        new_text = (
+            self.content[: self.cursor_index] + self.content[self.cursor_index + 1 :]
+        )
+        self.content = new_text
+        return True
+
+    def cursor_left(self) -> bool:
+        """Move the cursor 1 character left in the text"""
+        previous_index = self.cursor_index
+        new_index = max(0, previous_index - 1)
+        self.cursor_index = new_index
+        return previous_index != new_index
+
+    def cursor_right(self) -> bool:
+        """Move the cursor 1 character right in the text"""
+        previous_index = self.cursor_index
+        new_index = min(len(self.content), previous_index + 1)
+        self.cursor_index = new_index
+        return previous_index != new_index
+
+    def query_cursor_left(self) -> bool:
+        """Check if the cursor can move 1 character left in the text"""
+        previous_index = self.cursor_index
+        new_index = max(0, previous_index - 1)
+        return previous_index != new_index
+
+    def query_cursor_right(self) -> bool:
+        """Check if the cursor can move right"""
+        previous_index = self.cursor_index
+        new_index = min(len(self.content), previous_index + 1)
+        return previous_index != new_index
+
+    def cursor_text_start(self) -> bool:
+        if self.cursor_index == 0:
+            return False
+
+        self.cursor_index = 0
+        return True
+
+    def cursor_text_end(self) -> bool:
+        text_length = len(self.content)
+        if self.cursor_index == text_length:
+            return False
+
+        self.cursor_index = text_length
+        return True
+
+    def insert_at_cursor(self, text: str) -> bool:
+        new_text = (
+            self.content[: self.cursor_index] + text + self.content[self.cursor_index :]
+        )
+        self.content = new_text
+        self.cursor_index = min(len(self.content), self.cursor_index + 1)
+        return True
+
+    def get_range(self, start: int, end: int) -> str:
+        """Return the text between 2 indices. Useful for previews/views into
+        a subset of the content e.g. scrollable single-line input fields"""
+        return self.content[start:end]

src/textual/widgets/text_input.py

@@ -1,13 +1,12 @@
 from __future__ import annotations
 
-from dataclasses import dataclass
-
 from rich.console import RenderableType
 from rich.padding import Padding
 from rich.style import Style
 from rich.text import Text
 
 from textual import events
+from textual._text_backend import TextEditorBackend
 from textual._types import MessageTarget
 from textual.app import ComposeResult
 from textual.geometry import Size
@@ -16,98 +15,6 @@ from textual.message import Message
 from textual.widget import Widget
 
 
-@dataclass
-class TextEditorBackend:
-    content: str = ""
-    cursor_index: int = 0
-
-    def set_content(self, text: str):
-        self.content = text
-
-    def delete_back(self) -> bool:
-        """Delete the character behind the cursor
-
-        Returns: True if the text content was modified. False otherwise.
-        """
-        if self.cursor_index == 0:
-            return False
-
-        new_text = (
-            self.content[: self.cursor_index - 1] + self.content[self.cursor_index :]
-        )
-        self.content = new_text
-        self.cursor_index = max(0, self.cursor_index - 1)
-        return True
-
-    def delete_forward(self) -> bool:
-        """Delete the character in front of the cursor
-
-        Returns: True if the text content was modified. False otherwise.
-        """
-        if self.cursor_index == len(self.content):
-            return False
-
-        new_text = (
-            self.content[: self.cursor_index] + self.content[self.cursor_index + 1 :]
-        )
-        self.content = new_text
-        return True
-
-    def cursor_left(self) -> bool:
-        """Move the cursor 1 character left in the text"""
-        previous_index = self.cursor_index
-        new_index = max(0, previous_index - 1)
-        self.cursor_index = new_index
-        return previous_index != new_index
-
-    def cursor_right(self) -> bool:
-        """Move the cursor 1 character right in the text"""
-        previous_index = self.cursor_index
-        new_index = min(len(self.content), previous_index + 1)
-        self.cursor_index = new_index
-        return previous_index != new_index
-
-    def query_cursor_left(self) -> bool:
-        """Check if the cursor can move 1 character left in the text"""
-        previous_index = self.cursor_index
-        new_index = max(0, previous_index - 1)
-        return previous_index != new_index
-
-    def query_cursor_right(self) -> bool:
-        """Check if the cursor can move right"""
-        previous_index = self.cursor_index
-        new_index = min(len(self.content), previous_index + 1)
-        return previous_index != new_index
-
-    def cursor_text_start(self) -> bool:
-        if self.cursor_index == 0:
-            return False
-
-        self.cursor_index = 0
-        return True
-
-    def cursor_text_end(self) -> bool:
-        text_length = len(self.content)
-        if self.cursor_index == text_length:
-            return False
-
-        self.cursor_index = text_length
-        return True
-
-    def insert_at_cursor(self, text: str) -> bool:
-        new_text = (
-            self.content[: self.cursor_index] + text + self.content[self.cursor_index :]
-        )
-        self.content = new_text
-        self.cursor_index = min(len(self.content), self.cursor_index + 1)
-        return True
-
-    def get_range(self, start: int, end: int) -> str:
-        """Return the text between 2 indices. Useful for previews/views into
-        a subset of the content e.g. scrollable single-line input fields"""
-        return self.content[start:end]
-
-
 class TextWidgetBase(Widget):
     STOP_PROPAGATE = set()
 
@@ -184,7 +91,7 @@ class TextInput(TextWidgetBase, can_focus=True):
     }
 
     TextInput:hover {
-        background: $primary-darken-1;
+        background: $primary-darken-2;
     }
 
     TextInput:focus {