Bug 492931 - Part 0: Add nsContentUtils::EqualsLiteralIgnoreASCIICase. r=sicking

content/base/public/nsContentUtils.h

@@ -1598,7 +1598,43 @@ public:
    * case for ASCII characters a-z.
    */
   static bool EqualsIgnoreASCIICase(const nsAString& aStr1,
-                                      const nsAString& aStr2);
+                                    const nsAString& aStr2);
+
+  /**
+   * Case insensitive comparison between a string and an ASCII literal.
+   * This must ONLY be applied to an actual literal string. Do not attempt
+   * to use it with a regular char* pointer, or with a char array variable.
+   * The template trick to acquire the array length at compile time without
+   * using a macro is due to Corey Kosak, which much thanks.
+   */
+  static bool EqualsLiteralIgnoreASCIICase(const nsAString& aStr1,
+                                           const char* aStr2,
+                                           const PRUint32 len);
+#ifdef NS_DISABLE_LITERAL_TEMPLATE
+  static inline bool
+  EqualsLiteralIgnoreASCIICase(const nsAString& aStr1,
+                               const char* aStr2)
+  {
+    PRUint32 len = strlen(aStr2);
+    return EqualsLiteralIgnoreASCIICase(aStr1, aStr2, len);
+  }
+#else
+  template<int N>
+  static inline bool
+  EqualsLiteralIgnoreASCIICase(const nsAString& aStr1,
+                               const char (&aStr2)[N])
+  {
+    return EqualsLiteralIgnoreASCIICase(aStr1, aStr2, N-1);
+  }
+  template<int N>
+  static inline bool
+  EqualsLiteralIgnoreASCIICase(const nsAString& aStr1,
+                               char (&aStr2)[N])
+  {
+    const char* s = aStr2;
+    return EqualsLiteralIgnoreASCIICase(aStr1, s, N-1);
+  }
+#endif
 
   /**
    * Convert ASCII A-Z to a-z.

content/base/src/nsContentUtils.cpp

@@ -5322,6 +5322,7 @@ nsContentUtils::ASCIIToUpper(const nsAString& aSource, nsAString& aDest)
   }
 }
 
+/* static */
 bool
 nsContentUtils::EqualsIgnoreASCIICase(const nsAString& aStr1,
                                       const nsAString& aStr2)
@@ -5344,7 +5345,45 @@ nsContentUtils::EqualsIgnoreASCIICase(const nsAString& aStr1,
       return false;
     }
 
-    // We know they only differ in the 0x0020 bit.
+    // We know they can only differ in the 0x0020 bit.
+    // Likely the two chars are the same, so check that first
+    if (c1 != c2) {
+      // They do differ, but since it's only in the 0x0020 bit, check if it's
+      // the same ascii char, but just differing in case
+      PRUnichar c1Upper = c1 & 0xffdf;
+      if (!('A' <= c1Upper && c1Upper <= 'Z')) {
+        return false;
+      }
+    }
+  }
+
+  return true;
+}
+
+/* static */
+bool
+nsContentUtils::EqualsLiteralIgnoreASCIICase(const nsAString& aStr1,
+                                             const char* aStr2,
+                                             const PRUint32 len)
+{
+  if (aStr1.Length() != len) {
+    return false;
+  }
+  
+  const PRUnichar* str1 = aStr1.BeginReading();
+  const char*      str2 = str2;
+  const PRUnichar* end = str1 + len;
+  
+  while (str1 < end) {
+    PRUnichar c1 = *str1++;
+    PRUnichar c2 = *str2++;
+
+    // First check if any bits other than the 0x0020 differs
+    if ((c1 ^ c2) & 0xffdf) {
+      return false;
+    }
+    
+    // We know they can only differ in the 0x0020 bit.
     // Likely the two chars are the same, so check that first
     if (c1 != c2) {
       // They do differ, but since it's only in the 0x0020 bit, check if it's