Added checks that selection is valid, and fix set_selection_range.

components/script/textinput.rs

@@ -215,6 +215,16 @@ impl<T: ClipboardProvider> TextInput<T> {
         })
     }
 
+    // Check that the selection is valid.
+    fn assert_ok_selection(&self) {
+        if let Some(begin) = self.selection_begin {
+            debug_assert!(begin.line < self.lines.len());
+            debug_assert!(begin.index <= self.lines[begin.line].len());
+        }
+        debug_assert!(self.edit_point.line < self.lines.len());
+        debug_assert!(self.edit_point.index <= self.lines[self.edit_point.line].len());
+    }
+
     /// Return the selection range as UTF-8 byte offsets from the start of the content.
     ///
     /// If there is no selection, returns an empty range at the insertion point.
@@ -319,6 +329,7 @@ impl<T: ClipboardProvider> TextInput<T> {
 
             self.lines = new_lines;
         }
+        self.assert_ok_selection();
     }
 
     /// Return the length in UTF-8 bytes of the current line under the editing point.
@@ -360,6 +371,7 @@ impl<T: ClipboardProvider> TextInput<T> {
 
         self.edit_point.line = target_line as usize;
         self.edit_point.index = len_of_first_n_chars(&self.lines[self.edit_point.line], col);
+        self.assert_ok_selection();
     }
 
     /// Adjust the editing point position by a given number of bytes. If the adjustment
@@ -441,6 +453,7 @@ impl<T: ClipboardProvider> TextInput<T> {
                                             self.edit_point.index + adjust as usize);
             }
         }
+        self.assert_ok_selection();
     }
 
     /// Deal with a newline input.
@@ -462,6 +475,7 @@ impl<T: ClipboardProvider> TextInput<T> {
         let last_line = self.lines.len() - 1;
         self.edit_point.line = last_line;
         self.edit_point.index = self.lines[last_line].len();
+        self.assert_ok_selection();
     }
 
     /// Remove the current selection.
@@ -534,6 +548,7 @@ impl<T: ClipboardProvider> TextInput<T> {
             }
             Key::End => {
                 self.edit_point.index = self.current_line_length();
+                self.assert_ok_selection();
                 KeyReaction::RedrawSelection
             }
             Key::PageUp => {
@@ -598,6 +613,7 @@ impl<T: ClipboardProvider> TextInput<T> {
         self.edit_point.line = min(self.edit_point.line, self.lines.len() - 1);
         self.edit_point.index = min(self.edit_point.index, self.current_line_length());
         self.selection_begin = None;
+        self.assert_ok_selection();
     }
 
     /// Get the insertion point as a byte offset from the start of the content.
@@ -646,16 +662,16 @@ impl<T: ClipboardProvider> TextInput<T> {
         let mut end = end as usize;
         let text_end = self.get_content().len();
 
-        if start > text_end {
-            start = text_end;
-        } else if end > text_end {
+        if end > text_end {
             end = text_end;
-        } else if start >= end {
+        }
+        if start > end {
             start = end;
         }
 
         self.selection_begin = Some(self.get_text_point_for_absolute_point(start));
         self.edit_point = self.get_text_point_for_absolute_point(end);
+        self.assert_ok_selection();
     }
 
     pub fn get_selection_start(&self) -> u32 {

tests/wpt/web-platform-tests/html/semantics/forms/textfieldselection/textfieldselection-setSelectionRange.html

@@ -31,6 +31,18 @@
     assert_equals(input.selectionEnd, input.value.length, "Arguments greater than the length of the value of the text field must be treated as pointing at the end of the text field");
   },'input setSelectionRange(0,input.value.length+1)');
 
+  test(function() {
+    input.setSelectionRange(input.value.length+1,input.value.length+1)
+    assert_equals(input.selectionStart, input.value.length, "Arguments (start) greater than the length of the value of the text field must be treated as pointing at the end of the text field");
+    assert_equals(input.selectionEnd, input.value.length, "Arguments (end) greater than the length of the value of the text field must be treated as pointing at the end of the text field");
+  },'input setSelectionRange(input.value.length+1,input.value.length+1)');
+
+  test(function() {
+    input.setSelectionRange(input.value.length+1,1)
+    assert_equals(input.selectionStart, 1, "If end is less than or equal to start then the start of the selection and the end of the selection must both be placed immediately before the character with offset end");
+    assert_equals(input.selectionEnd, 1, "element.selectionEnd should be 1");
+  },'input setSelectionRange(input.value.length+1,input.value.length+1)');
+
   test(function() {
     input.setSelectionRange(2,2)
     assert_equals(input.selectionStart, 2, "If end is less than or equal to start then the start of the selection and the end of the selection must both be placed immediately before the character with offset end");
@@ -73,6 +85,18 @@
     assert_equals(input.selectionDirection, "none", "if the argument is omitted");
   },'input direction of setSelectionRange(0,1)');
 
+  test(function() {
+    input.setSelectionRange(1,-1);
+    assert_equals(input.selectionStart, 1, "element.selectionStart should be 1");
+    assert_equals(input.selectionEnd, input.value.length, "ECMAScript conversion to unsigned long");
+  },'input setSelectionRange(1,-1)');
+
+  test(function() {
+    input.setSelectionRange(-1,1);
+    assert_equals(input.selectionStart, 1, "ECMAScript conversion to unsigned long + if end is less than or equal to start then the start of the selection and the end of the selection must both be placed immediately before the character with offset end");
+    assert_equals(input.selectionEnd, 1, "element.selectionEnd should be 1");
+  },'input setSelectionRange(-1,1)');
+
   test(function() {
     input.setSelectionRange("string",1);
     assert_equals(input.selectionStart, 0, "element.selectionStart should be 0");