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/CSSCustomVariableValue.h"
+#include "core/css/parser/CSSParserTokenRange.h"
+#include "core/css/parser/CSSParserValues.h"
+
+namespace blink {
+
+static bool isValidVariableName(const CSSParserToken& token)
+{

[Timothy Loh, 2015/08/25 09:21:10]

Probably a good idea to check the token type is an ident token here

+    CSSParserString value = token.value();
+    return value.length() >= 2 && value[0] == '-' && value[0] == value[1];

[Timothy Loh, 2015/08/25 09:21:11]

err.. value[1] == '-'?

+}
+
+static bool isValidVariableReference(CSSParserTokenRange& range)

[Timothy Loh, 2015/08/25 09:21:10]

Use consumeBlock in the calling function and make this just take the contents of
the var() functions, so you don't have to check for right parenthesis.

+{
+    bool foundVariableIdentToken = false;
+    bool foundComma = false;
+    bool contentAfterComma = false;
+
+    // TODO(leviw): Use CSSParserToken::BlockType signals instead of checking for these directly.
+    int parenthesisCount = 0;
+    int braceCount = 0;
+    int bracketCount = 0;
+    while (!range.atEnd()) {
+        const CSSParserToken& token = range.consume();
+
+        if (!foundVariableIdentToken) {

[Timothy Loh, 2015/08/25 09:21:10]

This would be easier without the state machine loop, e.g.

range.consumeWhitespace()
if (!isValidVariableName(range.consumeIncludingWhitespace()))
    return false;
if (range.atEnd())
    return true;

if (range.consumeIncludingWhitespace().type() != CommaToken)
    return false;
if (range.atEnd())
    return false;
// check for declaration value

+            if (token.type() == IdentToken) {
+                if (!isValidVariableName(token))
+                    return false;
+                foundVariableIdentToken = true;
+            } else if (token.type() != WhitespaceToken) {
+                return false;
+            }
+            continue;
+        }
+
+        if (!foundComma) {
+            if (token.type() == CommaToken)
+                foundComma = true;
+            else if (token.type() == RightParenthesisToken)
+                return true;
+            else if (token.type() != WhitespaceToken)
+                return false;
+            continue;
+        }
+
+        if (!contentAfterComma) {
+            if (token.type() == RightParenthesisToken)
+                return false;
+            contentAfterComma = true;
+        }
+
+        switch (token.type()) {
+        case DelimiterToken:
+            if (token.delimiter() == '!' && !parenthesisCount && !bracketCount && !braceCount)
+                return false;
+            break;
+        case FunctionToken:
+        case LeftParenthesisToken:
+            parenthesisCount++;
+            break;
+        case RightParenthesisToken:
+            if (!parenthesisCount)
+                return true;
+            parenthesisCount--;
+            break;
+        case RightBraceToken:
+            if (!braceCount)
+                return false;
+            braceCount--;
+            break;
+        case LeftBraceToken:
+            braceCount++;
+            break;
+        case RightBracketToken:
+            if (!bracketCount)
+                return false;
+            bracketCount--;
+            break;
+        case LeftBracketToken:
+            bracketCount++;
+            break;
+        case BadStringToken:
+        case BadUrlToken:
+            return false;
+        case CommentToken:
+        case EOFToken:
+            ASSERT_NOT_REACHED();
+        case SemicolonToken:
+            if (!parenthesisCount && !bracketCount && !braceCount)
+                return false;
+            break;
+        default:
+            break;
+        }
+    }
+    return foundVariableIdentToken && (!foundComma || contentAfterComma);
+}
+
+static CSSValueID classifyVariableRange(CSSParserTokenRange& originalRange, bool& hasReferences)

[Timothy Loh, 2015/08/25 09:21:11]

CSSParserTokenRange& originalRange -> CSSParserTokenRange range?

+{
+    hasReferences = false;
+    CSSParserTokenRange range = originalRange;
+
+    int parenthesisCount = 0;
+    int braceCount = 0;
+    int bracketCount = 0;
+
+    range.consumeWhitespace();
+    if (range.peek().type() == IdentToken) {
+        const CSSParserToken& ident = range.consumeIncludingWhitespace();
+        if (range.atEnd()) {
+            if (ident.valueEqualsIgnoringCase("inherit"))
+                return CSSValueInherit;
+            if (ident.valueEqualsIgnoringCase("initial"))
+                return CSSValueInitial;
+            if (ident.valueEqualsIgnoringCase("unset"))
+                return CSSValueUnset;
+        }
+    }
+
+    // TODO(leviw): Use consumeBlock to keep track of nesting instead of doing it directly here.
+    while (!range.atEnd()) {
+        const CSSParserToken& token = range.consume();
+        switch (token.type()) {
+        case FunctionToken:
+            if (token.valueEqualsIgnoringCase("var")) {
+                if (!isValidVariableReference(range))
+                    return CSSValueInvalid; // Bail if any references are invalid
+                hasReferences = true;
+            } else {
+                parenthesisCount++;
+            }
+            break;
+        case CommentToken:
+        case EOFToken:
+            ASSERT_NOT_REACHED();
+        case DelimiterToken: {
+            if (token.delimiter() == '!' && !parenthesisCount && !bracketCount && !braceCount)
+                return CSSValueInvalid;
+            break;
+        }
+        case RightParenthesisToken:
+            if (!parenthesisCount)
+                return CSSValueInvalid;
+            parenthesisCount--;
+            break;
+        case LeftParenthesisToken:
+            parenthesisCount++;
+            break;
+        case RightBraceToken:
+            if (!braceCount)
+                return CSSValueInvalid;
+            braceCount--;
+            break;
+        case LeftBraceToken:
+            braceCount++;
+            break;
+        case RightBracketToken:
+            if (!bracketCount)
+                return CSSValueInvalid;
+            bracketCount--;
+            break;
+        case LeftBracketToken:
+            bracketCount++;
+            break;
+        case BadStringToken:
+        case BadUrlToken:
+            return CSSValueInvalid;
+        case WhitespaceToken:
+            break;
+        case SemicolonToken:
+            if (!parenthesisCount && !bracketCount && !braceCount)
+                return CSSValueInvalid;
+        default:
+            break;
+        }
+    }
+    if (parenthesisCount)
+        return CSSValueInvalid;
+    return CSSValueInternalVariableValue;
+}
+
+bool CSSVariableParser::containsValidVariableReferences(const CSSParserTokenRange& originalRange)

[Timothy Loh, 2015/08/25 09:21:10]

CSSParserTokenRange& originalRange -> CSSParserTokenRange range?

+{
+    CSSParserTokenRange range = originalRange;
+    bool hasReferences;
+    CSSValueID type = classifyVariableRange(range, hasReferences);
+    return type == CSSValueInternalVariableValue && hasReferences;
+}
+
+PassRefPtrWillBeRawPtr<CSSCustomVariableValue> CSSVariableParser::parseDeclarationValue(const AtomicString& variableName, CSSParserTokenRange& originalRange)

[Timothy Loh, 2015/08/25 09:21:11]

CSSParserTokenRange& originalRange -> CSSParserTokenRange range?

+{
+    if (originalRange.atEnd())
+        return nullptr;
+
+    bool hasReferences;
+    CSSValueID type = classifyVariableRange(originalRange, hasReferences);
+
+    if (type == CSSValueInvalid)
+        return nullptr;
+    if (type == CSSValueInternalVariableValue)
+        return CSSCustomVariableValue::create(variableName, CSSVariableData::create(originalRange, hasReferences));
+    return CSSCustomVariableValue::create(variableName, type);
+}
+
+} // namespace blink