Add some utilities for working with camelCase names.

Swift SVN r15802

include/swift/Basic/StringExtras.h

@@ -0,0 +1,188 @@
+//===--- StringExtras.h - String Utilities ----------------------*- C++ -*-===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2015 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See http://swift.org/LICENSE.txt for license information
+// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+//
+// This file provides utilities for working with English words and
+// camelCase names.
+//
+//===----------------------------------------------------------------------===//
+#ifndef SWIFT_BASIC_STRINGEXTRAS_HPP
+#define SWIFT_BASIC_STRINGEXTRAS_HPP
+
+#include "swift/Basic/LLVM.h"
+#include "llvm/ADT/StringRef.h"
+#include <iterator>
+
+namespace swift {
+  /// Describes the kind of preposition a word is.
+  enum PrepositionKind {
+    PK_None = 0,
+    PK_Directional,
+    PK_Nondirectional
+  };
+
+  /// Determine what kind of preposition the given word is, if any,
+  /// ignoring case.
+  PrepositionKind getPrepositionKind(StringRef word);
+
+  namespace camel_case {
+    class WordIterator;
+
+    /// A bidirectional iterator that walks through the words in a camelCase
+    /// string.
+    ///
+    /// Note that this iterator is not technically conforming bidirectional 
+    /// iterator, because it's reference type is not a true reference. But it 
+    /// quacks like a duck.
+    class WordIterator {
+      StringRef String;
+      unsigned Position;
+      mutable unsigned NextPosition : 31;
+      mutable unsigned NextPositionValid : 1;
+      mutable unsigned PrevPosition : 31;
+      mutable unsigned PrevPositionValid : 1;
+
+      void computeNextPosition() const;
+      void computePrevPosition() const;
+
+      /// Proxy used for the arrow operator of the word iterator.
+      class ArrowProxy {
+        StringRef String;
+
+      public:
+        explicit ArrowProxy(StringRef string) : String(string) { }
+
+        const StringRef *operator->() const {
+          return &String;
+        }
+      };
+
+    public:
+      typedef StringRef value_type;
+      typedef StringRef reference;
+      typedef ArrowProxy pointer;
+      typedef int difference_type;
+      typedef std::bidirectional_iterator_tag iterator_category;
+
+      WordIterator(StringRef string, unsigned position)
+        : String(string), Position(position) 
+      {
+        NextPositionValid = false;
+        PrevPositionValid = false;
+      }
+
+      StringRef operator*() const {
+        if (!NextPositionValid)
+          computeNextPosition();
+
+        return String.slice(Position, NextPosition);
+      }
+
+      ArrowProxy operator->() const {
+        return ArrowProxy(**this);
+      }
+
+      WordIterator &operator++() {
+        if (!NextPositionValid)
+          computeNextPosition();
+
+        // Save the previous position.
+        PrevPosition = Position;
+        PrevPositionValid = true;
+
+        // Move to the next position.
+        Position = NextPosition;
+        
+        // We don't know what lies ahead.
+        NextPositionValid = false;
+        return *this;
+      }
+
+      WordIterator operator++(int) {
+        WordIterator tmp(*this);
+        ++(*this);
+        return tmp;
+      }
+
+      WordIterator &operator--() {
+        if (!PrevPositionValid)
+          computePrevPosition();
+
+        // Save the next position.
+        NextPosition = Position;
+        NextPositionValid = true;
+
+        // Move to the previous position.
+        Position = PrevPosition;
+
+        // We don't know what lies behind.
+        PrevPositionValid = false;
+
+        return *this;
+      }
+
+      WordIterator operator--(int) {
+        WordIterator tmp(*this);
+        --(*this);
+        return tmp;
+      }
+
+      friend bool operator==(const WordIterator &x, const WordIterator &y) {
+        assert(x.String.data() == y.String.data() && 
+               x.String.size() == y.String.size() &&
+               "comparing word iterators from different strings");
+        return x.Position == y.Position;
+      }
+
+      friend bool operator!=(const WordIterator &x, const WordIterator &y) {
+        return !(x == y);
+      }
+    };
+
+    /// Find the first camelCase word in the given string.
+    StringRef getFirstWord(StringRef string);
+
+    /// Find the last camelCase word in the given string.
+    StringRef getLastWord(StringRef string);
+
+    /// A wrapper that treats a string as a container of camelCase words.
+    class Words {
+      StringRef String;
+
+    public:
+      typedef WordIterator iterator;
+      typedef WordIterator const_iterator;
+      typedef std::reverse_iterator<WordIterator> reverse_iterator;
+      typedef std::reverse_iterator<WordIterator> const_reverse_iterator;
+      
+      explicit Words(StringRef string) : String(string) { }
+
+      bool empty() const { return String.empty(); }
+
+      iterator begin() const { return WordIterator(String, 0); }
+      iterator end() const { return WordIterator(String, String.size()); }
+
+      reverse_iterator rbegin() const { return reverse_iterator(end()); }
+      reverse_iterator rend() const { return reverse_iterator(begin()); }
+    };
+
+    /// 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.
+    ///
+    /// \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);
+  } // end namespace camel_case
+}
+
+#endif // LLVM_SWIFT_BASIC_STRINGEXTRAS_HPP

lib/Basic/CMakeLists.txt

@@ -9,6 +9,7 @@ add_swift_library(swiftBasic
   Punycode.cpp
   QuotedString.cpp
   SourceLoc.cpp
+  StringExtras.cpp
   TaskQueue.cpp
   ThreadSafeRefCounted.cpp
   Version.cpp

lib/Basic/StringExtras.cpp

@@ -0,0 +1,103 @@
+//===--- StringExtras.cpp - String Utilities ------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2015 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See http://swift.org/LICENSE.txt for license information
+// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements utilities for working with words and camelCase
+// names.
+//
+//===----------------------------------------------------------------------===//
+#include "swift/Basic/StringExtras.h"
+#include "clang/Basic/CharInfo.h"
+using namespace swift;
+using namespace camel_case;
+
+PrepositionKind swift::getPrepositionKind(StringRef word) {
+#define DIRECTIONAL_PREPOSITION(Word)           \
+  if (word.equals_lower(#Word))                 \
+    return PK_Directional;
+#define PREPOSITION(Word)                       \
+  if (word.equals_lower(#Word))                 \
+    return PK_Nondirectional;
+#include "Prepositions.def"
+
+  return PK_None;
+}
+
+void WordIterator::computeNextPosition() const {
+  assert(Position < String.size() && "Already at end of string");
+
+  // Skip over any uppercase letters at the beginning of the word.
+  unsigned i = Position, n = String.size();
+  while (i < n && clang::isUppercase(String[i]))
+    ++i;
+
+  // If there was more than one uppercase letter, this is an
+  // acronym.
+  if (i - Position > 1) {
+    // If we hit the end of the string, that's it. Otherwise, this
+    // word ends at the last uppercase letter, so that the next word
+    // starts with the last uppercase letter.
+    NextPosition = i == n? i : i-1;
+    NextPositionValid = true;
+    return;
+  }
+
+  // Skip non-uppercase letters.
+  while (i < n && !clang::isUppercase(String[i]))
+    ++i;
+
+  NextPosition = i;
+  NextPositionValid = true;
+}
+
+void WordIterator::computePrevPosition() const {
+  assert(Position > 0 && "Already at beginning of string");
+
+  // While we see non-uppercase letters, keep moving back.
+  unsigned i = Position;
+  while (i > 0 && !clang::isUppercase(String[i-1]))
+    --i;
+
+  // If we found any lowercase letters, this was a normal camel case
+  // word (not an acronym).
+  if (i < Position) {
+    // If we hit the beginning of the string, that's it. Otherwise,
+    // this word starts at the uppercase letter that terminated the
+    // search above.
+    PrevPosition = i == 0 ? 0 : i-1;
+    PrevPositionValid = true;
+    return;
+  }
+
+  // There were no lowercase letters, so this is an acronym. Keep
+  // skipping uppercase letters.
+  while (i > 0 && clang::isUppercase(String[i-1]))
+    --i;
+
+  PrevPosition = i;
+  PrevPositionValid = true;
+}
+
+
+StringRef camel_case::getFirstWord(StringRef string) {
+  if (string.empty())
+    return "";
+
+  return *WordIterator(string, 0);
+}
+
+StringRef camel_case::getLastWord(StringRef string) {
+  if (string.empty())
+    return "";
+
+  return *--WordIterator(string, string.size());
+}
+

lib/ClangImporter/ClangImporter.cpp

@@ -24,6 +24,7 @@
 #include "swift/AST/NameLookup.h"
 #include "swift/AST/Types.h"
 #include "swift/Basic/Range.h"
+#include "swift/Basic/StringExtras.h"
 #include "swift/ClangImporter/ClangImporterOptions.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/Basic/CharInfo.h"
@@ -598,19 +599,6 @@ splitSelectorPieceAt(StringRef selector, unsigned index,
   return { selector.substr(0, index), StringRef(buffer.data(), buffer.size()) };
 }
 
-/// Determine whether the given word (which should have its first
-/// letter already capitalized) is a preposition.
-///
-/// The stored boolean indicates whether the preposition has
-/// direction.
-static Optional<bool> isPreposition(StringRef word) {
-  return llvm::StringSwitch<Optional<bool>>(word)
-#define DIRECTIONAL_PREPOSITION(Word) .Case(#Word, true)
-#define PREPOSITION(Word) .Case(#Word, false)
-#include "Prepositions.def"
-    .Default(Nothing);
-}
-
 std::pair<StringRef, StringRef> 
 ClangImporter::Implementation::splitFirstSelectorPiece(
                                  StringRef selector,
@@ -648,7 +636,7 @@ ClangImporter::Implementation::splitFirstSelectorPiece(
       break;
 
     // If this word is a preposition, split here.
-    if (auto isPrep = isPreposition(
+    if (auto prepKind = getPrepositionKind(
                           selector.substr(wordStart, wordEnd - wordStart))) {
       unsigned splitLocation;
       switch (SplitPrepositions) {
@@ -664,7 +652,7 @@ ClangImporter::Implementation::splitFirstSelectorPiece(
         break;
 
       case SelectorSplitKind::DirectionalPreposition:
-        splitLocation = *isPrep ? wordStart : wordEnd;
+        splitLocation = prepKind == PK_Directional ? wordStart : wordEnd;
         break;
       }
 

unittests/Basic/CMakeLists.txt

@@ -1,9 +1,11 @@
 add_swift_unittest(SwiftBasicTests
   SourceManager.cpp
   TreeScopedHashTableTests.cpp
+  StringExtrasTest.cpp
   SuccessorMapTest.cpp
   )
 
 target_link_libraries(SwiftBasicTests
   swiftBasic
+  clangBasic
   )

unittests/Basic/StringExtrasTest.cpp

@@ -0,0 +1,56 @@
+#include "swift/Basic/StringExtras.h"
+#include "gtest/gtest.h"
+#include <algorithm>
+
+using namespace swift;
+
+TEST(CamelCaseWordsTest, Iteration) {
+  auto words = camel_case::getWords("URLByPrependingHTTPToURL");
+
+  // Forward iteration count.
+  EXPECT_EQ(6, std::distance(words.begin(), words.end()));
+
+  // Reverse iteration count.
+  EXPECT_EQ(6, std::distance(words.rbegin(), words.rend()));
+
+  // Iteration contents.
+  auto iter = words.begin();
+  EXPECT_EQ(*iter, "URL");
+  
+  // Stepping forward.
+  ++iter;
+  EXPECT_EQ(*iter, "By");  
+
+  // Immediately stepping back (fast path).
+  --iter;
+  EXPECT_EQ(*iter, "URL");  
+
+  // Immediately stepping forward (fast path).
+  ++iter;
+  EXPECT_EQ(*iter, "By");
+
+  // Stepping forward.
+  ++iter;
+  EXPECT_EQ(*iter, "Prepending");  
+
+  // Stepping back twice (slow path).
+  --iter;
+  --iter;
+  EXPECT_EQ(*iter, "URL");
+
+  // Stepping forward to visit the remaining elements.
+  ++iter;
+  EXPECT_EQ(*iter, "By");
+  ++iter;
+  EXPECT_EQ(*iter, "Prepending");
+  ++iter;
+  EXPECT_EQ(*iter, "HTTP");
+  ++iter;
+  EXPECT_EQ(*iter, "To");
+  ++iter;
+  EXPECT_EQ(*iter, "URL");
+
+  // We're done.
+  ++iter;
+  EXPECT_EQ(iter, words.end());
+}