support function in custom paint input arguments

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

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/css/parser/CSSPropertyParserHelpers.h"
 
 #include "core/css/CSSCalculationValue.h"
 #include "core/css/CSSColorValue.h"
 #include "core/css/CSSCrossfadeValue.h"
 #include "core/css/CSSGradientValue.h"
@@ skipping 23 matching lines @@
     RefPtr<CSSVariableData> unparsedCSSVariableData =
         CSSVariableData::create(tokenRange, false, false);
     if (unparsedCSSVariableData.get()) {
       variableData->push_back(std::move(unparsedCSSVariableData));
       return true;
     }
   }
   return false;
 }
 
+// Consume input arguments, if encounter function, will return the function
+// block as a Vector of CSSParserToken, otherwise, will just return a Vector of
+// a single CSSParserToken.
+Vector<CSSParserToken> consumeFunctionArgsOrNot(CSSParserTokenRange& args) {
+  Vector<CSSParserToken> argumentTokens;
+  if (args.peek().getBlockType() != CSSParserToken::BlockStart) {

[meade_UTC10, 2017/02/17 06:40:04]

Let's flip the if statement order - It's usually clearer to do

if (condition) {
  // conditionalFoo
} else {
  // notConditonalFoo
}

than

if (!condition) {
  // NotConditionalFoo
} else {
  // conditionalFoo
}

[renjieliu1, 2017/02/19 04:57:58]

Done.

+    argumentTokens.push_back(args.consumeIncludingWhitespace());
+  } else {
+    // Encounter function block.

[meade_UTC10, 2017/02/17 06:40:04]

Incidentally, what does it mean to have got here, but not be encountering a
function block?

[renjieliu1, 2017/02/19 04:57:58]

I think if it is not a function but got here, in the variable resolving phase,
it will fail, but since we don't have knowledge about the argument types here,
we can't check anything here

[meade_UTC10, 2017/02/22 06:56:22]

Could you please add that as a comment? It still seems a bit mysterious if
you're just reading the code :)

+    argumentTokens.push_back(args.peek());

[meade_UTC10, 2017/02/17 06:40:04]

Perhaps, then, a comment to explain this?

if (args.peek().getBlockType() == CSSParserToken::BlockStart) {
  // Function block.
  // Push the function name and initial brace.
  argumentTokens.push_back(args.peek());
  CSSParserTokenRange contents = args.consumeBlock();
  while (!contents.atEnd()) {
     // Push function arguments
     argumentTokens.push_back(contents.consume());
  }
  argumentTokens.push_back(
      CSSParserToken(RightParenthesisToken, CSSParserToken::BlockEnd));
} else {
...
}

[renjieliu1, 2017/02/19 04:57:58]

thank you for the suggestion!

+    CSSParserTokenRange contents = args.consumeBlock();
+    while (!contents.atEnd()) {
+      argumentTokens.push_back(contents.consume());
+    }
+    argumentTokens.push_back(
+        CSSParserToken(RightParenthesisToken, CSSParserToken::BlockEnd));
+  }
+  return argumentTokens;
+}
+
 }  // namespace
 
 void complete4Sides(CSSValue* side[4]) {
   if (side[3])
     return;
   if (!side[2]) {
     if (!side[1])
       side[1] = side[0];
     side[2] = side[0];
   }
@@ skipping 1104 matching lines @@
 
   if (!RuntimeEnabledFeatures::cssPaintAPIArgumentsEnabled()) {
     // Arguments not enabled, but exists. Invalid.
     return nullptr;
   }
 
   // Begin parse paint arguments.
   if (!consumeCommaIncludingWhitespace(args))
     return nullptr;
 
-  // Consume arguments. Currently does not support complicated arguments
-  // like function calls.
+  // Consume arguments.
   // TODO(renjieliu): We may want to optimize the implementation by resolve
   // variables early if paint function is registered.
   Vector<CSSParserToken> argumentTokens;
   Vector<RefPtr<CSSVariableData>> variableData;
   while (!args.atEnd()) {
     if (args.peek().type() != CommaToken) {
-      argumentTokens.push_back(args.consumeIncludingWhitespace());
+      argumentTokens.appendVector(consumeFunctionArgsOrNot(args));
     } else {
       if (!addCSSPaintArgument(argumentTokens, &variableData))
         return nullptr;
       argumentTokens.clear();
       if (!consumeCommaIncludingWhitespace(args))
         return nullptr;
     }
   }
   if (!addCSSPaintArgument(argumentTokens, &variableData))
     return nullptr;
@@ skipping 131 matching lines @@
 
 // https://drafts.csswg.org/css-shapes-1/#typedef-shape-box
 CSSIdentifierValue* consumeShapeBox(CSSParserTokenRange& range) {
   return consumeIdent<CSSValueContentBox, CSSValuePaddingBox, CSSValueBorderBox,
                       CSSValueMarginBox>(range);
 }
 
 }  // namespace CSSPropertyParserHelpers
 
 }  // namespace blink