feat: basic command mode, add text box primitives

1 files changed, 134 insertions, 0 deletions

diff --git a/src/command.rs b/src/command.rs
new file mode 100644
index 0000000..3beb700
--- /dev/null
+++ b/src/command.rs
@@ -0,0 +1,134 @@
+#[derive(Debug)]
+pub struct CommandBox {
+    pub enabled: bool,
+    pub history: Vec<String>,
+    pub text: String,
+    pub cursor: usize,
+}
+
+// cursor value of 0 is behind all text
+// cursor value of n is after n characters (insert after index n - 1)
+// cursor value of text.len() is after all text
+
+impl CommandBox {
+    pub fn new() -> Self {
+        CommandBox {
+            enabled: false,
+            history: vec![],
+            text: String::new(),
+            cursor: 0,
+        }
+    }
+
+    pub fn forward(&mut self) {
+        if self.cursor < self.text.len() {
+            self.cursor += 1;
+        }
+    }
+
+    pub fn backward(&mut self) {
+        self.cursor = self.cursor.saturating_sub(1);
+    }
+
+    pub fn backspace(&mut self) {
+        if self.cursor != 0 {
+            self.text.remove(self.cursor - 1);
+            self.backward();
+        }
+    }
+
+    pub fn delete(&mut self) {
+        if self.cursor < self.text.len() {
+            self.text.remove(self.cursor);
+        }
+    }
+
+    pub fn push_str(&mut self, v: &str) {
+        self.text.push_str(v);
+        self.cursor += v.len();
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.text.is_empty()
+    }
+
+    pub fn clear(&mut self) {
+        self.text.clear();
+        self.cursor = 0;
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn setup_with(text: &str) -> CommandBox {
+        let mut cmd = CommandBox::new();
+        cmd.push_str(text);
+        cmd
+    }
+
+    #[test]
+    fn entering_text() {
+        let cmd = setup_with("save as file.png");
+        assert_eq!(&cmd.text, "save as file.png");
+        assert_eq!(cmd.cursor, 16)
+    }
+
+    #[test]
+    fn backspacing_from_end() {
+        let mut cmd = setup_with("save");
+        cmd.backspace();
+        assert_eq!(&cmd.text, "sav");
+        assert_eq!(cmd.cursor, 3);
+    }
+
+    #[test]
+    fn backspacing_from_middle() {
+        let mut cmd = setup_with("save");
+        cmd.backward();
+        cmd.backspace();
+        assert_eq!(&cmd.text, "sae");
+        assert_eq!(cmd.cursor, 2);
+    }
+
+    #[test]
+    fn delete() {
+        let mut cmd = setup_with("save");
+        cmd.backward();
+        cmd.delete();
+        assert_eq!(&cmd.text, "sav");
+        assert_eq!(cmd.cursor, 3);
+    }
+
+    #[test]
+    fn delete_end() {
+        let mut cmd = setup_with("save");
+        cmd.delete();
+        assert_eq!(&cmd.text, "save");
+    }
+
+    #[test]
+    fn delete_all() {
+        let mut cmd = setup_with("save");
+        for _ in 0..4 {
+            cmd.backward();
+        }
+        for _ in 0..4 {
+            cmd.delete();
+        }
+        assert_eq!(&cmd.text, "");
+        assert_eq!(cmd.cursor, 0);
+    }
+
+    #[test]
+    fn seeking() {
+        let mut cmd = setup_with("save");
+        for _ in 0..4 {
+            cmd.backward();
+        }
+        assert_eq!(cmd.cursor, 0);
+        cmd.forward();
+        assert_eq!(cmd.cursor, 1);
+    }
+}