Introduce a simple line-by-line iterator type into the Support library.

This is an iterator which you can build around a MemoryBuffer. It will
iterate through the non-empty, non-comment lines of the buffer as
a forward iterator. It should be small and reasonably fast (although it
could be made much faster if anyone cares, I don't really...).

This will be used to more simply support the text-based sample
profile file format, and is largely based on the original patch by
Diego. I've re-worked the style of it and separated it from the work of
producing a MemoryBuffer from a file which both simplifies the interface
and makes it easier to test.

The style of the API follows the C++ standard naming conventions to fit
in better with iterators in general, much like the Path and FileSystem
interfaces follow standard-based naming conventions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@198068 91177308-0d34-0410-b5e6-96231b3b80d8

unittests/Support/LineIteratorTest.cpp

@@ -0,0 +1,115 @@
+//===- LineIterator.cpp - Unit tests --------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/LineIterator.h"
+#include "llvm/ADT/OwningPtr.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include "gtest/gtest.h"
+
+using namespace llvm;
+using namespace llvm::sys;
+
+namespace {
+
+TEST(LineIteratorTest, Basic) {
+  OwningPtr<MemoryBuffer> Buffer(MemoryBuffer::getMemBuffer("line 1\n"
+                                                            "line 2\n"
+                                                            "line 3"));
+
+  line_iterator I = line_iterator(*Buffer), E;
+
+  EXPECT_FALSE(I.is_at_eof());
+  EXPECT_NE(E, I);
+
+  EXPECT_EQ("line 1", *I);
+  EXPECT_EQ(1, I.line_number());
+  ++I;
+  EXPECT_EQ("line 2", *I);
+  EXPECT_EQ(2, I.line_number());
+  ++I;
+  EXPECT_EQ("line 3", *I);
+  EXPECT_EQ(3, I.line_number());
+  ++I;
+
+  EXPECT_TRUE(I.is_at_eof());
+  EXPECT_EQ(E, I);
+}
+
+TEST(LineIteratorTest, CommentSkipping) {
+  OwningPtr<MemoryBuffer> Buffer(MemoryBuffer::getMemBuffer("line 1\n"
+                                                            "line 2\n"
+                                                            "# Comment 1\n"
+                                                            "line 4\n"
+                                                            "# Comment 2"));
+
+  line_iterator I = line_iterator(*Buffer, '#'), E;
+
+  EXPECT_FALSE(I.is_at_eof());
+  EXPECT_NE(E, I);
+
+  EXPECT_EQ("line 1", *I);
+  EXPECT_EQ(1, I.line_number());
+  ++I;
+  EXPECT_EQ("line 2", *I);
+  EXPECT_EQ(2, I.line_number());
+  ++I;
+  EXPECT_EQ("line 4", *I);
+  EXPECT_EQ(4, I.line_number());
+  ++I;
+
+  EXPECT_TRUE(I.is_at_eof());
+  EXPECT_EQ(E, I);
+}
+
+TEST(LineIteratorTest, BlankSkipping) {
+  OwningPtr<MemoryBuffer> Buffer(MemoryBuffer::getMemBuffer("\n\n\n"
+                                                            "line 1\n"
+                                                            "\n\n\n"
+                                                            "line 2\n"
+                                                            "\n\n\n"));
+
+  line_iterator I = line_iterator(*Buffer), E;
+
+  EXPECT_FALSE(I.is_at_eof());
+  EXPECT_NE(E, I);
+
+  EXPECT_EQ("line 1", *I);
+  EXPECT_EQ(4, I.line_number());
+  ++I;
+  EXPECT_EQ("line 2", *I);
+  EXPECT_EQ(8, I.line_number());
+  ++I;
+
+  EXPECT_TRUE(I.is_at_eof());
+  EXPECT_EQ(E, I);
+}
+
+TEST(LineIteratorTest, EmptyBuffers) {
+  OwningPtr<MemoryBuffer> Buffer(MemoryBuffer::getMemBuffer(""));
+  EXPECT_TRUE(line_iterator(*Buffer).is_at_eof());
+  EXPECT_EQ(line_iterator(), line_iterator(*Buffer));
+
+  Buffer.reset(MemoryBuffer::getMemBuffer("\n\n\n"));
+  EXPECT_TRUE(line_iterator(*Buffer).is_at_eof());
+  EXPECT_EQ(line_iterator(), line_iterator(*Buffer));
+
+  Buffer.reset(MemoryBuffer::getMemBuffer("# foo\n"
+                                          "\n"
+                                          "# bar"));
+  EXPECT_TRUE(line_iterator(*Buffer, '#').is_at_eof());
+  EXPECT_EQ(line_iterator(), line_iterator(*Buffer, '#'));
+
+  Buffer.reset(MemoryBuffer::getMemBuffer("\n"
+                                          "# baz\n"
+                                          "\n"));
+  EXPECT_TRUE(line_iterator(*Buffer, '#').is_at_eof());
+  EXPECT_EQ(line_iterator(), line_iterator(*Buffer, '#'));
+}
+
+} // anonymous namespace