Add utilities for lower- and sentence-casing camelCase strings.

Swift SVN r15815

Author: DougGregor

include/swift/Basic/StringExtras.h

@@ -177,11 +177,24 @@ namespace swift {
     /// Retrieve the camelCase words in the given string.
     inline Words getWords(StringRef string) { return Words(string); }
 
-    /// Find the last preposition in the given camelCase string.
+    /// Lowercase the first word within the given camelCase string.
     ///
-    /// \returns a pair containing the starting index of the last
-    /// preposition as well as the kind of preposition found.
-    std::pair<unsigned, PrepositionKind> findLastPreposition(StringRef string);
+    /// \param string The string to lowercase.
+    /// \param scratch Scratch buffer used to form the resulting string.
+    ///
+    /// \returns the string with the first word lowercased. When the
+    /// first word is an acronym, the string will be returned
+    /// unchanged.
+    StringRef toLowercaseWord(StringRef string, SmallVectorImpl<char> &scratch);
+
+    /// Sentence-case the given camelCase string by turning the first
+    /// letter into an uppercase letter.
+    ///
+    /// \param string The string to sentence-case.
+    /// \param scratch Scratch buffer used to form the resulting string.
+    ///
+    /// \returns the string in sentence case.
+    StringRef toSentencecase(StringRef string, SmallVectorImpl<char> &scratch);
   } // end namespace camel_case
 }
 

lib/Basic/StringExtras.cpp

@@ -16,6 +16,7 @@
 //===----------------------------------------------------------------------===//
 #include "swift/Basic/StringExtras.h"
 #include "clang/Basic/CharInfo.h"
+#include "llvm/ADT/SmallVector.h"
 using namespace swift;
 using namespace camel_case;
 
@@ -86,7 +87,6 @@ void WordIterator::computePrevPosition() const {
   PrevPositionValid = true;
 }
 
-
 StringRef camel_case::getFirstWord(StringRef string) {
   if (string.empty())
     return "";
@@ -101,3 +101,38 @@ StringRef camel_case::getLastWord(StringRef string) {
   return *--WordIterator(string, string.size());
 }
 
+StringRef camel_case::toLowercaseWord(StringRef string, 
+                                      SmallVectorImpl<char> &scratch) {
+  if (string.empty())
+    return string;
+
+  // Already lowercase.
+  if (!clang::isUppercase(string[0]))
+    return string;
+
+  // Acronym doesn't get lowercased.
+  if (string.size() > 1 && clang::isUppercase(string[1]))
+    return string;
+
+  // Lowercase the first letter, append the rest.
+  scratch.clear();
+  scratch.push_back(clang::toLowercase(string[0]));
+  scratch.append(string.begin() + 1, string.end());
+  return StringRef(scratch.data(), scratch.size());
+}
+
+StringRef camel_case::toSentencecase(StringRef string, 
+                                     SmallVectorImpl<char> &scratch) {
+  if (string.empty())
+    return string;
+
+  // Can't be uppercased.
+  if (!clang::isLowercase(string[0]))
+    return string;
+
+  // Uppercase the first letter, append the rest.
+  scratch.clear();
+  scratch.push_back(clang::toUppercase(string[0]));
+  scratch.append(string.begin() + 1, string.end());
+  return StringRef(scratch.data(), scratch.size());  
+}

unittests/Basic/StringExtrasTest.cpp

@@ -54,3 +54,22 @@ TEST(CamelCaseWordsTest, Iteration) {
   ++iter;
   EXPECT_EQ(iter, words.end());
 }
+
+TEST(ToLowercaseTest, Words) {
+  llvm::SmallString<64> scratch;
+
+  EXPECT_EQ(camel_case::toLowercaseWord("By", scratch), "by");
+  EXPECT_EQ(camel_case::toLowercaseWord("and", scratch), "and");
+  EXPECT_EQ(camel_case::toLowercaseWord("A", scratch), "a");
+  EXPECT_EQ(camel_case::toLowercaseWord("URL", scratch), "URL");
+  EXPECT_EQ(camel_case::toLowercaseWord("", scratch), "");
+}
+
+TEST(ToSentencecaseTest, Words) {
+  llvm::SmallString<64> scratch;
+
+  EXPECT_EQ(camel_case::toSentencecase("by", scratch), "By");
+  EXPECT_EQ(camel_case::toSentencecase("a", scratch), "A");
+  EXPECT_EQ(camel_case::toSentencecase("URL", scratch), "URL");
+  EXPECT_EQ(camel_case::toSentencecase("", scratch), "");
+}