Add string_piece_util

Following functions are implemented for further performance
optimization.

* JoinStringPiece
* SplitStringPiece
* EqualsCaseInsensitiveASCII
* ToLowerASCII

To improve performance of CLParser, I will introduce above functions
into include_normalize-win32.cc.

4 files changed, 251 insertions, 0 deletions

diff --git a/src/string_piece.h b/src/string_piece.h
index b1bf105..353b24e 100644
--- a/src/string_piece.h
+++ b/src/string_piece.h
@@ -25,6 +25,8 @@ using namespace std;
 /// externally.  It is useful for reducing the number of std::strings
 /// we need to allocate.
 struct StringPiece {
+  typedef const char* const_iterator;
+
   StringPiece() : str_(NULL), len_(0) {}
 
   /// The constructors intentionally allow for implicit conversions.
@@ -46,6 +48,14 @@ struct StringPiece {
     return len_ ? string(str_, len_) : string();
   }
 
+  const_iterator begin() const {
+    return str_;
+  }
+
+  const_iterator end() const {
+    return str_ + len_;
+  }
+
   const char* str_;
   size_t len_;
 };
diff --git a/src/string_piece_util.cc b/src/string_piece_util.cc
new file mode 100644
index 0000000..8e1ecfd
--- /dev/null
+++ b/src/string_piece_util.cc
@@ -0,0 +1,78 @@
+// Copyright 2017 Google Inc. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "string_piece_util.h"
+
+#include <algorithm>
+#include <string>
+#include <vector>
+using namespace std;
+
+vector<StringPiece> SplitStringPiece(StringPiece input, char sep) {
+  vector<StringPiece> elems;
+  elems.reserve(count(input.begin(), input.end(), sep) + 1);
+
+  StringPiece::const_iterator pos = input.begin();
+
+  for (;;) {
+    const char* next_pos = find(pos, input.end(), sep);
+    if (next_pos == input.end()) {
+      elems.push_back(StringPiece(pos, input.end() - pos));
+      break;
+    }
+    elems.push_back(StringPiece(pos, next_pos - pos));
+    pos = next_pos + 1;
+  }
+
+  return elems;
+}
+
+string JoinStringPiece(const vector<StringPiece>& list, char sep) {
+  if (list.size() == 0){
+    return "";
+  }
+
+  string ret;
+
+  {
+    size_t cap = list.size() - 1;
+    for (size_t i = 0; i < list.size(); ++i) {
+      cap += list[i].len_;
+    }
+    ret.reserve(cap);
+  }
+
+  for (size_t i = 0; i < list.size(); ++i) {
+    if (i != 0) {
+      ret += sep;
+    }
+    ret.append(list[i].str_, list[i].len_);
+  }
+
+  return ret;
+}
+
+bool EqualsCaseInsensitiveASCII(StringPiece a, StringPiece b) {
+  if (a.len_ != b.len_) {
+    return false;
+  }
+
+  for (size_t i = 0; i < a.len_; ++i) {
+    if (ToLowerASCII(a.str_[i]) != ToLowerASCII(b.str_[i])) {
+      return false;
+    }
+  }
+
+  return true;
+}
diff --git a/src/string_piece_util.h b/src/string_piece_util.h
new file mode 100644
index 0000000..2e40b9f
--- /dev/null
+++ b/src/string_piece_util.h
@@ -0,0 +1,34 @@
+// Copyright 2017 Google Inc. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef NINJA_STRINGPIECE_UTIL_H_
+#define NINJA_STRINGPIECE_UTIL_H_
+
+#include <string>
+#include <vector>
+
+#include "string_piece.h"
+using namespace std;
+
+vector<StringPiece> SplitStringPiece(StringPiece input, char sep);
+
+string JoinStringPiece(const vector<StringPiece>& list, char sep);
+
+inline char ToLowerASCII(char c) {
+  return (c >= 'A' && c <= 'Z') ? (c + ('a' - 'A')) : c;
+}
+
+bool EqualsCaseInsensitiveASCII(StringPiece a, StringPiece b);
+
+#endif  // NINJA_STRINGPIECE_UTIL_H_
diff --git a/src/string_piece_util_test.cc b/src/string_piece_util_test.cc
new file mode 100644
index 0000000..648c647
--- /dev/null
+++ b/src/string_piece_util_test.cc
@@ -0,0 +1,129 @@
+// Copyright 2017 Google Inc. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "string_piece_util.h"
+
+#include "test.h"
+
+TEST(StringPieceUtilTest, SplitStringPiece) {
+  {
+    string input("a:b:c");
+    vector<StringPiece> list = SplitStringPiece(input, ':');
+
+    EXPECT_EQ(list.size(), 3);
+
+    EXPECT_EQ(list[0], "a");
+    EXPECT_EQ(list[1], "b");
+    EXPECT_EQ(list[2], "c");
+  }
+
+  {
+    string empty("");
+    vector<StringPiece> list = SplitStringPiece(empty, ':');
+
+    EXPECT_EQ(list.size(), 1);
+
+    EXPECT_EQ(list[0], "");
+  }
+
+  {
+    string one("a");
+    vector<StringPiece> list = SplitStringPiece(one, ':');
+
+    EXPECT_EQ(list.size(), 1);
+
+    EXPECT_EQ(list[0], "a");
+  }
+
+  {
+    string sep_only(":");
+    vector<StringPiece> list = SplitStringPiece(sep_only, ':');
+
+    EXPECT_EQ(list.size(), 2);
+
+    EXPECT_EQ(list[0], "");
+    EXPECT_EQ(list[1], "");
+  }
+
+  {
+    string sep(":a:b:c:");
+    vector<StringPiece> list = SplitStringPiece(sep, ':');
+
+    EXPECT_EQ(list.size(), 5);
+
+    EXPECT_EQ(list[0], "");
+    EXPECT_EQ(list[1], "a");
+    EXPECT_EQ(list[2], "b");
+    EXPECT_EQ(list[3], "c");
+    EXPECT_EQ(list[4], "");
+  }
+}
+
+TEST(StringPieceUtilTest, JoinStringPiece) {
+  {
+    string input("a:b:c");
+    vector<StringPiece> list = SplitStringPiece(input, ':');
+
+    EXPECT_EQ("a:b:c", JoinStringPiece(list, ':'));
+    EXPECT_EQ("a/b/c", JoinStringPiece(list, '/'));
+  }
+
+  {
+    string empty("");
+    vector<StringPiece> list = SplitStringPiece(empty, ':');
+
+    EXPECT_EQ("", JoinStringPiece(list, ':'));
+  }
+
+  {
+    vector<StringPiece> empty_list;
+
+    EXPECT_EQ("", JoinStringPiece(empty_list, ':'));
+  }
+
+  {
+    string one("a");
+    vector<StringPiece> single_list = SplitStringPiece(one, ':');
+
+    EXPECT_EQ("a", JoinStringPiece(single_list, ':'));
+  }
+
+  {
+    string sep(":a:b:c:");
+    vector<StringPiece> list = SplitStringPiece(sep, ':');
+
+    EXPECT_EQ(":a:b:c:", JoinStringPiece(list, ':'));
+  }
+}
+
+TEST(StringPieceUtilTest, ToLowerASCII) {
+  EXPECT_EQ('a', ToLowerASCII('A'));
+  EXPECT_EQ('z', ToLowerASCII('Z'));
+  EXPECT_EQ('a', ToLowerASCII('a'));
+  EXPECT_EQ('z', ToLowerASCII('z'));
+  EXPECT_EQ('/', ToLowerASCII('/'));
+  EXPECT_EQ('1', ToLowerASCII('1'));
+}
+
+TEST(StringPieceUtilTest, EqualsCaseInsensitiveASCII) {
+  EXPECT_TRUE(EqualsCaseInsensitiveASCII("abc", "abc"));
+  EXPECT_TRUE(EqualsCaseInsensitiveASCII("abc", "ABC"));
+  EXPECT_TRUE(EqualsCaseInsensitiveASCII("abc", "aBc"));
+  EXPECT_TRUE(EqualsCaseInsensitiveASCII("AbC", "aBc"));
+  EXPECT_TRUE(EqualsCaseInsensitiveASCII("", ""));
+
+  EXPECT_FALSE(EqualsCaseInsensitiveASCII("a", "ac"));
+  EXPECT_FALSE(EqualsCaseInsensitiveASCII("/", "\\"));
+  EXPECT_FALSE(EqualsCaseInsensitiveASCII("1", "10"));
+}