Issue #2506 - Part 3: Implement parsing for CSS media query range context operators

layout/style/CSSStyleSheet.cpp

@@ -283,6 +283,14 @@ nsMediaExpression::Matches(nsPresContext *aPresContext,
       return cmp != 1;
     case nsMediaExpression::eEqual:
       return cmp == 0;
+    case nsMediaExpression::eLessThan:
+      return cmp == -1;
+    case nsMediaExpression::eGreaterThan:
+      return cmp == 1;
+    case nsMediaExpression::eLessThanOrEqual:
+      return cmp != 1;
+    case nsMediaExpression::eGreaterThanOrEqual:
+      return cmp != -1;
   }
   NS_NOTREACHED("unexpected mRange");
   return false;
@@ -482,6 +490,16 @@ nsMediaQuery::AppendToString(nsAString& aString) const
       aString.AppendLiteral("min-");
     } else if (expr.mRange == nsMediaExpression::eMax) {
       aString.AppendLiteral("max-");
+    } else if (expr.mRange == nsMediaExpression::eLessThan) {
+      aString.AppendLiteral("< ");
+    } else if (expr.mRange == nsMediaExpression::eGreaterThan) {
+      aString.AppendLiteral("> ");
+    } else if (expr.mRange == nsMediaExpression::eLessThanOrEqual) {
+      aString.AppendLiteral("<= ");
+    } else if (expr.mRange == nsMediaExpression::eGreaterThanOrEqual) {
+      aString.AppendLiteral(">= ");
+    } else if (expr.mRange == nsMediaExpression::eEqual) {
+      aString.AppendLiteral("= ");
     }
 
     aString.Append(nsDependentAtomString(*feature->mName));

layout/style/nsCSSParser.cpp

@@ -3794,7 +3794,42 @@ CSSParserImpl::ParseMediaQueryExpression(nsMediaQuery* aQuery)
     expr->mRange = nsMediaExpression::eMax;
     featureString.Rebind(featureString, 4);
   } else {
-    expr->mRange = nsMediaExpression::eEqual;
+    // Check for new comparison operators
+    nsCSSScannerPosition pos;
+    mScanner->SavePosition(pos);
+    if (GetToken(true)) {
+      if (mToken.IsSymbol('<')) {
+        if (GetToken(true) && mToken.IsSymbol('=')) {
+          expr->mRange = nsMediaExpression::eLessThanOrEqual;
+        } else {
+          UngetToken();
+          expr->mRange = nsMediaExpression::eLessThan;
+        }
+      } else if (mToken.IsSymbol('>')) {
+        if (GetToken(true) && mToken.IsSymbol('=')) {
+          expr->mRange = nsMediaExpression::eGreaterThanOrEqual;
+        } else {
+          UngetToken();
+          expr->mRange = nsMediaExpression::eGreaterThan;
+        }
+      } else if (mToken.IsSymbol('=')) {
+        expr->mRange = nsMediaExpression::eEqual;
+      } else {
+        // If it's not a comparison operator, put the token back and
+        // assume it's a boolean feature or an equality comparison.
+        UngetToken();
+        expr->mRange = nsMediaExpression::eEqual;
+      }
+    } else {
+      // If EOF, assume it's a boolean feature or an equality comparison.
+      expr->mRange = nsMediaExpression::eEqual;
+    }
+    // If we parsed a comparison operator, we need to restore the scanner
+    // position to before the operator was consumed, so that the subsequent
+    // parsing of the feature value can consume it.
+    if (expr->mRange != nsMediaExpression::eEqual) {
+      mScanner->RestoreSavedPosition(pos);
+    }
   }
 
   nsCOMPtr<nsIAtom> mediaFeatureAtom = NS_Atomize(featureString);

layout/style/nsCSSScanner.cpp

@@ -331,6 +331,21 @@ nsCSSToken::AppendToString(nsString& aBuffer) const
     case eCSSToken_Containsmatch:
       aBuffer.AppendLiteral("*=");
       break;
+    case eCSSToken_LessThan:
+      aBuffer.Append(char16_t('<'));
+      break;
+    case eCSSToken_GreaterThan:
+      aBuffer.Append(char16_t('>'));
+      break;
+    case eCSSToken_LessThanOrEqual:
+      aBuffer.AppendLiteral("<=");
+      break;
+    case eCSSToken_GreaterThanOrEqual:
+      aBuffer.AppendLiteral(">=");
+      break;
+    case eCSSToken_Equals:
+      aBuffer.Append(char16_t('='));
+      break;
 
     default:
       NS_ERROR("invalid token type");
@@ -1346,6 +1361,32 @@ nsCSSScanner::Next(nsCSSToken& aToken, nsCSSScannerExclude aSkip)
     return ScanString(aToken);
   }
 
+  // Media Query Range Context operators: < > <= >= =
+  switch (ch) {
+    case '=':
+      aToken.mType = eCSSToken_Equals;
+      Advance();
+      return true;
+    case '<':
+      if (Peek(1) == '=') {
+        aToken.mType = eCSSToken_LessThanOrEqual;
+        Advance(2);
+      } else {
+        aToken.mType = eCSSToken_LessThan;
+        Advance();
+      }
+      return true;
+    case '>':
+      if (Peek(1) == '=') {
+        aToken.mType = eCSSToken_GreaterThanOrEqual;
+        Advance(2);
+      } else {
+        aToken.mType = eCSSToken_GreaterThan;
+        Advance();
+      }
+      return true;
+  }
+
   // Match operators: ~= |= ^= $= *=
   nsCSSTokenType opType = MatchOperatorType(ch);
   if (opType != eCSSToken_Symbol && Peek(1) == '=') {

layout/style/nsCSSScanner.h

@@ -78,6 +78,13 @@ enum nsCSSTokenType {
   eCSSToken_Endsmatch,      // $=
   eCSSToken_Containsmatch,  // *=
 
+  // Media Query Range Context operators.
+  eCSSToken_LessThan,       // <
+  eCSSToken_GreaterThan,    // >
+  eCSSToken_LessThanOrEqual,// <=
+  eCSSToken_GreaterThanOrEqual, // >=
+  eCSSToken_Equals,         // =
+
   // Unicode-range token: currently used only in @font-face.
   // The lexical rule for this token includes several forms that are
   // semantically invalid.  Therefore, mIdent always holds the
@@ -130,6 +137,10 @@ enum nsCSSTokenSerializationType {
   eCSSTokenSerialization_Symbol_Bar,          // '|'
   eCSSTokenSerialization_Symbol_Slash,        // '/'
   eCSSTokenSerialization_Symbol_Asterisk,     // '*'
+  eCSSTokenSerialization_Symbol_LessThan,     // '<'
+  eCSSTokenSerialization_Symbol_GreaterThan,  // '>'
+  eCSSTokenSerialization_Symbol_LessThanOrEqual, // '<='
+  eCSSTokenSerialization_Symbol_GreaterThanOrEqual, // '>='
   eCSSTokenSerialization_Other                // anything else
 };
 

layout/style/nsIMediaList.h

@@ -33,7 +33,15 @@ class DocumentRule;
 } // namespace mozilla
 
 struct nsMediaExpression {
-  enum Range { eMin, eMax, eEqual };
+  enum Range {
+    eMin,
+    eMax,
+    eEqual,
+    eLessThan,
+    eGreaterThan,
+    eLessThanOrEqual,
+    eGreaterThanOrEqual
+  };
 
   const nsMediaFeature *mFeature;
   Range mRange;