Merge branch '6.4' into 7.0

* 6.4:
  [ExpressionLanguage] Add operators precedence documentation

Author: javiereguiluz

reference/formats/expression_language.rst

@@ -397,6 +397,41 @@ Other Operators
 * ``?.`` (:ref:`null-safe operator <component-expression-null-safe-operator>`)
 * ``??`` (:ref:`null-coalescing operator <component-expression-null-coalescing-operator>`)
 
+Operators Precedence
+~~~~~~~~~~~~~~~~~~~~
+
+Operator precedence determines the order in which operations are processed in an
+expression. For example, the result of the expression ``1 + 2 * 4`` is ``9``
+and not ``12`` because the multiplication operator (``*``) takes precedence over
+the addition operator (``+``).
+
+To avoid ambiguities (or to alter the default order of operations) add
+parentheses in your expressions (e.g. ``(1 + 2) * 4`` or ``1 + (2 * 4)``.
+
+The following table summarizes the operators and their associativity from the
+**highest to the lowest precedence**:
+
+=======================================================  =============
+Operators                                                associativity
+=======================================================  =============
+``-``, ``+`` (unary operators that add the number sign)  none
+``**``                                                   right
+``*``, ``/``, ``%``                                      left
+``not``, ``!``                                           none
+``~``                                                    left
+``+``, ``-``                                             left
+``..``                                                   left
+``==``, ``===``, ``!=``, ``!==``,                        left
+``<``, ``>``, ``>=``, ``<=``,
+``not in``, ``in``, ``contains``,
+``starts with``, ``ends with``, ``matches``
+``&``                                                    left
+``^``                                                    left
+``|``                                                    left
+``and``, ``&&``                                          left
+``or``, ``||``                                           left
+=======================================================  =============
+
 Built-in Objects and Variables
 ------------------------------