Fix operator precedence in SizesCalcParser

Pop all operators with greater/equal precedence rather than just the
top-most.

Bug: 803824
Change-Id: I5f106a0e82ed98ba2510c86ed157bf4b133cb5b8
Reviewed-on: https://chromium-review.googlesource.com/888919
Commit-Queue: Fredrik Söderquist <fs@opera.com>
Reviewed-by: Yoav Weiss <yoav@yoav.ws>
Cr-Commit-Position: refs/heads/master@{#532100}

third_party/WebKit/Source/core/css/parser/SizesCalcParser.cpp

@@ -32,25 +32,31 @@ static bool OperatorPriority(UChar cc, bool& high_priority) {
 
 bool SizesCalcParser::HandleOperator(Vector<CSSParserToken>& stack,
                                      const CSSParserToken& token) {
-  // If the token is an operator, o1, then:
-  // while there is an operator token, o2, at the top of the stack, and
-  // either o1 is left-associative and its precedence is equal to that of o2,
-  // or o1 has precedence less than that of o2,
-  // pop o2 off the stack, onto the output queue;
-  // push o1 onto the stack.
-  bool stack_operator_priority;
+  // If the token is not an operator, then return. Else determine the
+  // precedence of the new operator (op1).
   bool incoming_operator_priority;
-
   if (!OperatorPriority(token.Delimiter(), incoming_operator_priority))
     return false;
-  if (!stack.IsEmpty() && stack.back().GetType() == kDelimiterToken) {
-    if (!OperatorPriority(stack.back().Delimiter(), stack_operator_priority))
+
+  while (!stack.IsEmpty()) {
+    // While there is an operator (op2) at the top of the stack,
+    // determine its precedence, and...
+    const CSSParserToken& top_of_stack = stack.back();
+    if (top_of_stack.GetType() != kDelimiterToken)
+      break;
+    bool stack_operator_priority;
+    if (!OperatorPriority(top_of_stack.Delimiter(), stack_operator_priority))
       return false;
-    if (!incoming_operator_priority || stack_operator_priority) {
-      AppendOperator(stack.back());
-      stack.pop_back();
-    }
+    // ...if op1 is left-associative (all currently supported
+    // operators are) and its precedence is equal to that of op2, or
+    // op1 has precedence less than that of op2, ...
+    if (incoming_operator_priority && !stack_operator_priority)
+      break;
+    // ...pop op2 off the stack and add it to the output queue.
+    AppendOperator(top_of_stack);
+    stack.pop_back();
   }
+  // Push op1 onto the stack.
   stack.push_back(token);
   return true;
 }

third_party/WebKit/Source/core/css/parser/SizesCalcParserTest.cpp

@@ -97,6 +97,14 @@ TEST(SizesCalcParserTest, Basic) {
       {"calc(100px @ 2)", 0, false, false},
       {"calc(1 flim 2)", 0, false, false},
       {"calc(1 flim (2))", 0, false, false},
+      {"calc((100vw - 2 * 40px - 2 * 30px) / 3)", 120, true, false},
+      {"calc((100vw - 40px - 60px - 40px) / 3)", 120, true, false},
+      {"calc((50vw + 40px + 30px + 40px) / 3)", 120, true, false},
+      {"calc((100vw - 2 / 2 * 40px - 2 * 30px) / 4)", 100, true, false},
+      {"calc((100vw - 2 * 2 / 2 * 40px - 2 * 30px) / 3)", 120, true, false},
+      {"calc((100vw - 2 * 2 / 2 * 40px - 2 * 30px) / 3)", 120, true, false},
+      {"calc((100vw - 2 * 2 * 20px - 2 * 30px) / 3)", 120, true, false},
+      {"calc((100vw - 320px / 2 / 2 - 2 * 30px) / 3)", 120, true, false},
       {nullptr, 0, true, false}  // Do not remove the terminator line.
   };