x

Author: howcom

css3-values/Overview.html

@@ -863,10 +863,22 @@ <h4 id=the-calc-min-and-max-functions><span class=secno>6.3.3. </span>The
 min     : "min(" S* sum [ "," S* sum ]* )"" S*;
 max     : "max(" S* sum [ "," S* sum ]* ")" S*;
 sum     : product [ [ "+" | "-" ] S* product ]*;
+product : unit [[ "*" S* unit ] | [ "/" S* NUMBER ]] *;
+unit    : ["+"|"-"]? [ NUMBER S* | DIMENSION S* | PERCENTAGE S* |
+          min | max | "(" S* sum ")" S* ];
+</pre>
+  <!--
+<pre>
+S       : calc | min | max;
+calc    : "calc(" S* sum ")" S*;
+min     : "min(" S* sum [ "," S* sum ]* )"" S*;
+max     : "max(" S* sum [ "," S* sum ]* ")" S*;
+sum     : product [ [ "+" | "-" ] S* product ]*;
 product : unit [ [ "*" | "/" | "mod" ] S* unit ]*;
 unit    : ["+"|"-"]? [ NUMBER S* | DIMENSION S* | PERCENTAGE S* |
           min | max | "(" S* sum ")" S* ];
 </pre>
+-->
 
   <p>The semantic constraints are as follows: The context of the expression
    imposes a target type, which is one of length, frequency, angle, time, or
@@ -886,73 +898,9 @@ <h4 id=the-calc-min-and-max-functions><span class=secno>6.3.3. </span>The
     check: at least one side is "number" return: the type of the other side
 
    <li>At "/":<br>
-    check: either right side is "number," or both have the same type<br>
-    return: if the former, type of left side; otherwise "number"
-
-   <li>At "mod": <br>
-    check: both sides have the same type<br>
-    return: "number"
+    check: right side is "number"<br>
+    return: the type of the left side
   </ol>
-  <!--
-<p>A value is ignored if a division by zero or other mathematical
- errors occur in the calculation.
-
-<div class="example">
-<p>In this example, the second declaration will be ignored due to a
-division by zero.
-<pre>
-p { 
- margin: 1em;
- margin: calc(1em-2px) calc(1em/0) 
-}
-</pre>
-</div>
-
-<p class=issue>Issue: At a later date new operators such as min/max, conditionals, new constants, division by length units etc. may be added.
-
-
-<p>The expression language is defined by &lsquo;<code class=property>length-expression</code>&rsquo; below:
-
-<pre>
-  &lt;length> := calc( &lt;length-expression> ) | &lt;atomic-length>
-
-  &lt;length-expression> := S* &lt;length-additive-expression> S*
-
-  &lt;length-additive-expression> :=
-     &lt;length-multiplicative-expression> |
-     &lt;length-additive-expression> S+ '+' S+ &lt;length-multiplicative-expression> |
-     &lt;length-additive-expression> S+ '-' S+ &lt;length-multiplicative-expression>
-
-  &lt;length-multiplicative-expression>
-     &lt;length-term> |
-     &lt;length-multiplicative-expression> S* '*' S* &lt;number-term> |
-     &lt;number-multiplicative-expression> S* '*' S* &lt;length-term> |
-     &lt;length-multiplicative-expression> S* '/' S* &lt;number-term> |
-     &lt;length-multiplicative-expression> S+ 'mod' S+ &lt;number-term>
-
-  &lt;length-term> := '(' &lt;length-expression> ')' | &lt;atomic-length>
-
-  &lt;number-additive-expression> :=
-     &lt;number-multiplicative-expression> |
-     &lt;number-additive-expression> S+ '+' S+ &lt;number-multiplicative-expression> |
-     &lt;number-additive-expression> S+ '-' S+ &lt;number-multiplicative-expression>
-
-  &lt;number-multiplicative-expression> :=
-     &lt;number-term> |
-     &lt;length-multiplicative-expression> S* '/' S* &lt;length-term> |
-     &lt;length-multiplicative-expression> S+ 'mod' S+ &lt;length-term>
-
-  &lt;number-term> := '(' *S &lt;number-additive-expression> *S ')' | &lt;number>
-
-  &lt;atomic-length> := &lt;number>&lt;length-unit>
-</pre>
-
-<div class="note">Note that &lsquo;<code class=property>mod</code>&rsquo; is used instead of &lsquo;<code class=css>%</code>&rsquo; for modulus since it is very easy to
-get confused about whether &lsquo;<code class=css>%</code>&rsquo; is acting as a unit or an operator. At
-least with &lsquo;<code class=property>mod</code>&rsquo; it always causes a parse error &mdash; invalid unit &mdash; in the
-otherwise ambiguous cases.
-</div>
--->
 
   <h3 id=ltstringgt><span class=secno>6.4. </span>&lt;string&gt;</h3>