CSS Custom Properties (Variables)

Source/core/css/parser/CSSVariableParser.cpp

+// Copyright 2015 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 "config.h"
+#include "core/css/parser/CSSVariableParser.h"
+
+#include "core/css/parser/CSSParserTokenRange.h"
+#include "core/css/parser/CSSParserValues.h"
+
+namespace blink {
+
+static bool isValidVariableName(const CSSParserToken& token)
+{
+    CSSParserString value = token.value();
+    return value.length() >= 2 && value[0] == '-' && value[0] == value[1];
+}
+
+static bool isValidVariableReference(CSSParserTokenRange& range)
+{
+    bool foundVariableIdentToken = false;
+    bool foundComma = false;
+    bool contentAfterComma = false;
+    unsigned bracketCount = 0;
+    while (!range.atEnd()) {
+        const CSSParserToken& token = range.consume();
+        switch (token.type()) {
+        case WhitespaceToken:
+            if (foundComma)
+                contentAfterComma = true;
+            break;
+        case IdentToken:
+            if (foundComma) {
+                contentAfterComma = true;
+            } else if (!foundVariableIdentToken) {
+                if (!isValidVariableName(token))
+                    return false;
+                foundVariableIdentToken = true;
+            } else {
+                return false;
+            }
+            break;
+        case FunctionToken:
+        case LeftParenthesisToken:
+            if (!foundComma)
+                return false;
+            bracketCount++;
+            break;
+        case RightParenthesisToken:
+            if (!foundVariableIdentToken)
+                return false;
+            if (!bracketCount)
+                return foundVariableIdentToken && (!foundComma || contentAfterComma);
+            bracketCount--;
+            break;
+        case CommaToken:
+            if (!foundVariableIdentToken)
+                return false;
+            foundComma = true;
+            break;
+        case CommentToken:
+        case EOFToken:
+            ASSERT_NOT_REACHED();
+        case SemicolonToken:
+            return false;
+        case CDOToken:
+        case CDCToken:
+        case AtKeywordToken:
+        case IncludeMatchToken:
+        case DashMatchToken:
+        case PrefixMatchToken:
+        case SuffixMatchToken:
+        case SubstringMatchToken:
+        case ColumnToken:
+        case BadStringToken:
+        case BadUrlToken:
+        case ColonToken:
+            // TODO(leviw): Need to match CDO/CDC tokens
+            if (!foundComma)
+                return false;
+            break;
+        default:
+            if (!foundComma)
+                return false;
+            break;
+        }
+    }
+    return false;
+}
+
+static CSSVariableParser::DefinitionType classifyVariableRange(const CSSParserTokenRange& originalRange, bool& important)
+{
+    CSSParserTokenRange range = originalRange;
+    CSSVariableParser::DefinitionType type = CSSVariableParser::Variable;
+    bool lastTokenWasExclamation = false;
+
+    // TODO(leviw): this needs to be a stack.
+    bool foundImportant = false;
+
+    int bracketCount = 0;
+

[Timothy Loh, 2015/07/23 08:11:47]

Probably something like:

range.consumeWhitespace();
if (range.peek().type() == IdentToken) {
  const CSSParserToken& ident = range.consumeIncludingWhitespace();
  if (range.atEnd()) {
    if (ident.valueEqualsIgnoringCase("initial"))
      return ..;
    ..
  }
}

while (!range.atEnd()) {
  if (range.peek().type() == FunctionToken &&
range.peek().valueEqualsIgnoringCase("var")) {
    CSSParserTokenRange referenceRange = range.consumeBlock();
    if (referenceRange.end() == range.peek())
      return Invalid; // Unclosed brackets
    if (isValidVariableReference(referenceRange)) {
       ...
    }
    continue;
  }
  // rest of code
}

+    while (!range.atEnd()) {
+        const CSSParserToken& token = range.consume();
+        switch (token.type()) {
+        case FunctionToken:
+            if (token.valueEqualsIgnoringCase("var")) {
+                if (!isValidVariableReference(range))
+                    return CSSVariableParser::Invalid; // Bail if any references are invalid
+                type = CSSVariableParser::VariableWithReferences;
+            } else {
+                bracketCount++;
+            }
+            lastTokenWasExclamation = false;
+            break;
+        case CommentToken:
+        case EOFToken:
+            ASSERT_NOT_REACHED();
+        case IdentToken:
+            // TODO(leviw): This isn't correct.
+            if (token.valueEqualsIgnoringCase("inherit")) {
+                type = CSSVariableParser::Inherit;
+            } else if (token.valueEqualsIgnoringCase("initial")) {
+                type = CSSVariableParser::Initial;
+            } else if (token.valueEqualsIgnoringCase("unset")) {
+                type = CSSVariableParser::Unset;
+            } else if (lastTokenWasExclamation && token.valueEqualsIgnoringCase("important")) {

[Timothy Loh, 2015/07/23 08:11:47]

Why does this need to handle !important when consumeDeclaration already does so?

+                if (foundImportant)
+                    return CSSVariableParser::Invalid;
+                foundImportant = true;
+                important = true;
+            }
+            lastTokenWasExclamation = false;
+            break;
+        case DelimiterToken:
+            lastTokenWasExclamation = token.delimiter() == '!';
+            break;
+        case RightParenthesisToken:
+            if (!bracketCount)
+                return CSSVariableParser::Invalid;
+            bracketCount--;
+            break;
+        case LeftParenthesisToken:
+            bracketCount++;
+            break;
+        case SemicolonToken:
+            return CSSVariableParser::Invalid;
+        case CDOToken:

[Timothy Loh, 2015/07/23 08:11:47]

The spec doesn't say these are invalid

+        case CDCToken:
+        case AtKeywordToken:
+        case IncludeMatchToken:
+        case DashMatchToken:
+        case PrefixMatchToken:
+        case SuffixMatchToken:
+        case SubstringMatchToken:
+        case ColumnToken:
+        case BadStringToken:
+        case BadUrlToken:
+        case ColonToken:
+            return CSSVariableParser::Invalid;
+        case WhitespaceToken:
+            break;
+        default:
+            lastTokenWasExclamation = false;
+            break;
+        }
+    }
+    if (bracketCount)
+        return CSSVariableParser::Invalid;
+    return type;
+}
+
+bool CSSVariableParser::containsValidVariableReferences(const CSSParserTokenRange& originalRange)
+{
+    bool important;
+    return VariableWithReferences == classifyVariableRange(originalRange, important);
+}
+
+CSSVariableParser::DefinitionType CSSVariableParser::parseVariableDefinition(const CSSParserTokenRange& originalRange, bool& important)
+{
+    important = false;
+    if (originalRange.atEnd())
+        return CSSVariableParser::Invalid;
+    return classifyVariableRange(originalRange, important);
+}
+
+} // namespace blink