implement ECH

src/terminal/Terminal.zig

@@ -131,7 +131,7 @@ pub fn appendChar(self: *Terminal, alloc: Allocator, c: u8) !void {
     //log.debug("char: {}", .{c});
     const actions = self.parser.next(c);
     for (actions) |action_opt| {
-        if (action_opt) |action| log.info("action: {}", .{action});
+        //if (action_opt) |action| log.info("action: {}", .{action});
         switch (action_opt orelse continue) {
             .print => |p| try self.print(alloc, p),
             .execute => |code| try self.execute(alloc, code),
@@ -226,6 +226,16 @@ fn csiDispatch(
             },
         }),
 
+        // Erase Characters (ECH)
+        'X' => try self.eraseChars(switch (action.params.len) {
+            0 => 1,
+            1 => action.params[0],
+            else => {
+                log.warn("invalid erase characters command: {}", .{action});
+                return;
+            },
+        }),
+
         // HPA - Cursor Horizontal Position Absolute
         '`' => if (action.params.len == 0) {
             try self.setCursorPosition(self.cursor.y + 1, 1);
@@ -460,6 +470,25 @@ pub fn deleteChars(self: *Terminal, count: usize) !void {
     }
 }
 
+// TODO: test, docs
+pub fn eraseChars(self: *Terminal, count: usize) !void {
+    var line = &self.screen.items[self.cursor.y];
+
+    // Our last index is at most the end of the number of chars we have
+    // in the current line.
+    const end = @minimum(line.items.len, self.cursor.x + count);
+
+    // Do nothing if we have no values.
+    if (self.cursor.x >= line.items.len) return;
+
+    // Shift
+    var i: usize = self.cursor.x;
+    while (i < end) : (i += 1) {
+        line.items[i].char = 0;
+        // TODO: retain graphical attributes
+    }
+}
+
 /// Move the cursor right amount columns. If amount is greater than the
 /// maximum move distance then it is internally adjusted to the maximum.
 /// This sequence will not scroll the screen or scroll region. If amount is