Add FileSystem Rust module.

qml/ClideEditor.qml

@@ -5,10 +5,16 @@ import QtQuick.Layouts
 import clide.module 1.0
 
 SplitView {
+    id: root
     Layout.fillHeight: true
     Layout.fillWidth: true
     orientation: Qt.Vertical
 
+    // The path to the file to show in the text editor.
+    // This is updated by a signal caught within ClideProjectView.
+    // Initialized by the Default trait for the Rust QML singleton FileSystem.
+    required property string filePath;
+
     // Customized handle to drag between the Editor and the Console.
     handle: Rectangle {
         border.color: SplitHandle.pressed ? RustColors.pressed : SplitHandle.hovered ? RustColors.hovered : RustColors.gutter
@@ -102,6 +108,7 @@ SplitView {
                 // selectionColor: RustColors.editor_highlight
                 textFormat: Qt.AutoText
                 wrapMode: TextArea.Wrap
+                text: FileSystem.readFile(root.filePath)
 
                 background: Rectangle {
                     color: RustColors.editor_background

qml/ClideProjectView.qml

@@ -51,5 +51,7 @@ SplitView {
         }
     }
     ClideEditor {
+        // Initialize using the Default trait in Rust QML singleton FileSystem.
+        filePath: FileSystem.filePath
     }
 }

src/filesystem.rs

@@ -0,0 +1,53 @@
+#[cxx_qt::bridge]
+pub mod qobject {
+    unsafe extern "C++" {
+        // Import Qt Types from C++
+        include!("cxx-qt-lib/qstring.h");
+        type QString = cxx_qt_lib::QString;
+        include!("cxx-qt-lib/qmodelindex.h");
+        type QModelIndex = cxx_qt_lib::QModelIndex;
+    }
+
+    unsafe extern "RustQt" {
+        // Export QML Types from Rust
+        #[qobject]
+        #[qml_element]
+        #[qml_singleton]
+        #[qproperty(QString, file_path, cxx_name = "filePath")]
+        type FileSystem = super::FileSystemImpl;
+
+        #[qinvokable]
+        #[cxx_name = "readFile"]
+        fn read_file(self: &FileSystem, path: &QString) -> QString;
+    }
+}
+
+use cxx_qt_lib::{QModelIndex, QString};
+use std::fs;
+pub struct FileSystemImpl {
+    file_path: QString,
+    model_index: QModelIndex,
+}
+
+// Default is explicit to make the editor open this source file initially.
+impl Default for FileSystemImpl {
+    fn default() -> Self {
+        Self {
+            file_path: QString::from(file!()),
+            model_index: Default::default(),
+        }
+    }
+}
+
+impl qobject::FileSystem {
+    fn read_file(&self, path: &QString) -> QString {
+        if path.is_empty() {
+            return QString::default();
+        }
+        // TODO: What if the file is binary or something horrible?
+        QString::from(
+            fs::read_to_string(path.to_string())
+                .expect(format!("Failed to read file {}", path).as_str()),
+        )
+    }
+}