[Sync] Generalize StringOrdinal to handle ordinal_in_parent field

sync/internal_api/public/base/ordinal_unittest.cc

+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/basictypes.h"
+#include "sync/internal_api/public/base/ordinal.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+#include <algorithm>
+#include <string>
+#include <vector>
+
+namespace syncer {
+
+namespace {
+
+struct TestOrdinalTraits {
+  static const uint8 kZeroDigit = '0';
+  static const uint8 kMaxDigit = '3';
+  static const size_t kMinLength = 1;
+};
+
+struct LongOrdinalTraits {
+  static const uint8 kZeroDigit = '0';
+  static const uint8 kMaxDigit = '9';
+  static const size_t kMinLength = 5;
+};
+
+struct LargeOrdinalTraits {
+  static const uint8 kZeroDigit = 0;
+  static const uint8 kMaxDigit = kuint8max;
+  static const size_t kMinLength = 1;
+};
+
+typedef Ordinal<TestOrdinalTraits> TestOrdinal;
+typedef Ordinal<LongOrdinalTraits> LongOrdinal;
+typedef Ordinal<LargeOrdinalTraits> LargeOrdinal;
+
+COMPILE_ASSERT(TestOrdinal::kZeroDigit == '0',
+               TestOrdinalHasCorrectZeroDigit);
+COMPILE_ASSERT(TestOrdinal::kOneDigit == '1',
+               TestOrdinalHasCorrectOneDigit);
+COMPILE_ASSERT(TestOrdinal::kMidDigit == '2',
+               TestOrdinalHasCorrectMidDigit);
+COMPILE_ASSERT(TestOrdinal::kMaxDigit == '3',
+               TestOrdinalHasCorrectMaxDigit);
+COMPILE_ASSERT(TestOrdinal::kMidDigitValue == 2,
+               TestOrdinalHasCorrectMidDigitValue);
+COMPILE_ASSERT(TestOrdinal::kMaxDigitValue == 3,
+               TestOrdinalHasCorrectMaxDigitValue);
+COMPILE_ASSERT(TestOrdinal::kRadix == 4,
+               TestOrdinalHasCorrectRadix);
+
+COMPILE_ASSERT(LongOrdinal::kZeroDigit == '0',
+               LongOrdinalkZeroDigit_incorrect);
+COMPILE_ASSERT(LongOrdinal::kOneDigit == '1',
+               LongOrdinalkOneDigit_incorrect);
+COMPILE_ASSERT(LongOrdinal::kMidDigit == '5',
+               LongOrdinalkMidDigit_incorrect);
+COMPILE_ASSERT(LongOrdinal::kMaxDigit == '9',
+               LongOrdinalkMaxDigit_incorrect);
+COMPILE_ASSERT(LongOrdinal::kMidDigitValue == 5,
+               LongOrdinalkMidDigitValue_incorrect);
+COMPILE_ASSERT(LongOrdinal::kMaxDigitValue == 9,
+               LongOrdinalkMaxDigitValue_incorrect);
+COMPILE_ASSERT(LongOrdinal::kRadix == 10,
+               LongOrdinalkRadix_incorrect);
+
+COMPILE_ASSERT(static_cast<char>(LargeOrdinal::kZeroDigit) == '\x00',
+               LargeOrdinalkZeroDigit_incorrect);
+COMPILE_ASSERT(static_cast<char>(LargeOrdinal::kOneDigit) == '\x01',
+               LargeOrdinalkOneDigit_incorrect);
+COMPILE_ASSERT(static_cast<char>(LargeOrdinal::kMidDigit) == '\x80',
+               LargeOrdinalkMidDigit_incorrect);
+COMPILE_ASSERT(static_cast<char>(LargeOrdinal::kMaxDigit) == '\xff',
+               LargeOrdinalkMaxDigit_incorrect);
+COMPILE_ASSERT(LargeOrdinal::kMidDigitValue == 128,
+               LargeOrdinalkMidDigitValue_incorrect);
+COMPILE_ASSERT(LargeOrdinal::kMaxDigitValue == 255,
+               LargeOrdinalkMaxDigitValue_incorrect);
+COMPILE_ASSERT(LargeOrdinal::kRadix == 256,
+               LargeOrdinalkRadix_incorrect);
+
+// Create Ordinals that satisfy all but one criterion for validity.
+// IsValid() should return false for all of them.
+TEST(Ordinal, Invalid) {
+  // Length criterion.
+  EXPECT_FALSE(TestOrdinal("").IsValid());
+  EXPECT_FALSE(LongOrdinal("0001").IsValid());
+
+  const char kBeforeZero[] = { '0' - 1, '\0' };
+  const char kAfterNine[] = { '9' + 1, '\0' };
+
+  // Character criterion.
+  EXPECT_FALSE(TestOrdinal(kBeforeZero).IsValid());
+  EXPECT_FALSE(TestOrdinal("4").IsValid());
+  EXPECT_FALSE(LongOrdinal(std::string("0000") + kBeforeZero).IsValid());
+  EXPECT_FALSE(LongOrdinal(std::string("0000") + kAfterNine).IsValid());
+
+  // Zero criterion.
+  EXPECT_FALSE(TestOrdinal("0").IsValid());
+  EXPECT_FALSE(TestOrdinal("00000").IsValid());
+
+  // Trailing zero criterion.
+  EXPECT_FALSE(TestOrdinal("10").IsValid());
+  EXPECT_FALSE(TestOrdinal("111110").IsValid());
+}
+
+// Create Ordinals that satisfy all criteria for validity.
+// IsValid() should return true for all of them.
+TEST(Ordinal, Valid) {
+  // Length criterion.
+  EXPECT_TRUE(TestOrdinal("1").IsValid());
+  EXPECT_TRUE(LongOrdinal("10000").IsValid());
+}
+
+// Create Ordinals from CreateInitialOrdinal.  They should be valid
+// and close to the middle of the range.
+TEST(Ordinal, CreateInitialOrdinal) {
+  const TestOrdinal& ordinal1 = TestOrdinal::CreateInitialOrdinal();
+  const LongOrdinal& ordinal2 = LongOrdinal::CreateInitialOrdinal();
+  ASSERT_TRUE(ordinal1.IsValid());
+  ASSERT_TRUE(ordinal2.IsValid());
+  EXPECT_TRUE(ordinal1.Equals(TestOrdinal("2")));
+  EXPECT_TRUE(ordinal2.Equals(LongOrdinal("50000")));
+}
+
+// Create an invalid and a valid Ordinal.  EqualsOrBothInvalid should
+// return true if called reflexively and false otherwise.
+TEST(Ordinal, EqualsOrBothInvalid) {
+  const TestOrdinal& valid_ordinal = TestOrdinal::CreateInitialOrdinal();
+  const TestOrdinal invalid_ordinal;
+
+  EXPECT_TRUE(valid_ordinal.EqualsOrBothInvalid(valid_ordinal));
+  EXPECT_TRUE(invalid_ordinal.EqualsOrBothInvalid(invalid_ordinal));
+  EXPECT_FALSE(invalid_ordinal.EqualsOrBothInvalid(valid_ordinal));
+  EXPECT_FALSE(valid_ordinal.EqualsOrBothInvalid(invalid_ordinal));
+}
+
+// Create three Ordinals in order.  LessThan should return values
+// consistent with that order.
+TEST(Ordinal, LessThan) {
+  const TestOrdinal small_ordinal("1");
+  const TestOrdinal middle_ordinal("2");
+  const TestOrdinal big_ordinal("3");
+
+  EXPECT_FALSE(small_ordinal.LessThan(small_ordinal));
+  EXPECT_TRUE(small_ordinal.LessThan(middle_ordinal));
+  EXPECT_TRUE(small_ordinal.LessThan(big_ordinal));
+
+  EXPECT_FALSE(middle_ordinal.LessThan(small_ordinal));
+  EXPECT_FALSE(middle_ordinal.LessThan(middle_ordinal));
+  EXPECT_TRUE(middle_ordinal.LessThan(big_ordinal));
+
+  EXPECT_FALSE(big_ordinal.LessThan(small_ordinal));
+  EXPECT_FALSE(big_ordinal.LessThan(middle_ordinal));
+  EXPECT_FALSE(big_ordinal.LessThan(big_ordinal));
+}
+
+// Create two single-digit ordinals with byte values 0 and 255.  The
+// former should compare as less than the latter, even though the
+// native char type may be signed.
+TEST(Ordinal, LessThanLarge) {
+  const LargeOrdinal small_ordinal("\x01");
+  const LargeOrdinal big_ordinal("\xff");
+
+  EXPECT_TRUE(small_ordinal.LessThan(big_ordinal));
+}
+
+// Create three Ordinals in order.  GreaterThan should return values
+// consistent with that order.
+TEST(Ordinal, GreaterThan) {
+  const LongOrdinal small_ordinal("10000");
+  const LongOrdinal middle_ordinal("55555");
+  const LongOrdinal big_ordinal("99999");
+
+  EXPECT_FALSE(small_ordinal.GreaterThan(small_ordinal));
+  EXPECT_FALSE(small_ordinal.GreaterThan(middle_ordinal));
+  EXPECT_FALSE(small_ordinal.GreaterThan(big_ordinal));
+
+  EXPECT_TRUE(middle_ordinal.GreaterThan(small_ordinal));
+  EXPECT_FALSE(middle_ordinal.GreaterThan(middle_ordinal));
+  EXPECT_FALSE(middle_ordinal.GreaterThan(big_ordinal));
+
+  EXPECT_TRUE(big_ordinal.GreaterThan(small_ordinal));
+  EXPECT_TRUE(big_ordinal.GreaterThan(middle_ordinal));
+  EXPECT_FALSE(big_ordinal.GreaterThan(big_ordinal));
+}
+
+// Create two valid Ordinals.  Equals should return true only when
+// called reflexively.
+TEST(Ordinal, Equals) {
+  const TestOrdinal ordinal1("1");
+  const TestOrdinal ordinal2("2");
+
+  EXPECT_TRUE(ordinal1.Equals(ordinal1));
+  EXPECT_FALSE(ordinal1.Equals(ordinal2));
+
+  EXPECT_FALSE(ordinal2.Equals(ordinal1));
+  EXPECT_TRUE(ordinal2.Equals(ordinal2));
+}
+
+// Create some valid ordinals from some byte strings.
+// ToInternalValue() should return the original byte string.
+TEST(OrdinalTest, ToInternalValue) {
+  EXPECT_EQ("2", TestOrdinal("2").ToInternalValue());
+  EXPECT_EQ("12345", LongOrdinal("12345").ToInternalValue());
+  EXPECT_EQ("\1\2\3\4\5", LargeOrdinal("\1\2\3\4\5").ToInternalValue());
+}
+
+// Create some invalid/valid ordinals.  ToDebugString() should always
+// return a printable string.
+TEST(OrdinalTest, ToDebugString) {
+  EXPECT_EQ("INVALID[]", TestOrdinal().ToDebugString());

[rlarocque, 2012/09/06 23:19:21]

IMO, this is a bit too strict.  There are other ways that one could choose to
represent an Ordinal as a string.  The only real requirement is that
ToDebugString() doesn't crash and that it produces a printable string as output.

From a more practical perspective, though, I doubt this will cause trouble for
anyone.  It's not like we'll be changing serialization formats very often.  It's
fine with me if you decide to leave it as is.

[akalin, 2012/09/06 23:44:32]

Done.

+  EXPECT_EQ("INVALID[invalid string]",
+            TestOrdinal("invalid string").ToDebugString());
+  EXPECT_EQ("2", TestOrdinal("2").ToDebugString());
+  EXPECT_EQ("12345", LongOrdinal("12345").ToDebugString());
+  EXPECT_EQ("\\u0001\\u0002\\u0003\\u0004\\u0005",
+            LargeOrdinal("\1\2\3\4\5").ToDebugString());
+}
+
+// Create three Ordinals in order.  LessThanFn should return values
+// consistent with that order.
+TEST(Ordinal, LessThanFn) {
+  const TestOrdinal small_ordinal("1");
+  const TestOrdinal middle_ordinal("2");
+  const TestOrdinal big_ordinal("3");
+
+  const TestOrdinal::LessThanFn less_than;
+
+  EXPECT_FALSE(less_than(small_ordinal, small_ordinal));
+  EXPECT_TRUE(less_than(small_ordinal, middle_ordinal));
+  EXPECT_TRUE(less_than(small_ordinal, big_ordinal));
+
+  EXPECT_FALSE(less_than(middle_ordinal, small_ordinal));
+  EXPECT_FALSE(less_than(middle_ordinal, middle_ordinal));
+  EXPECT_TRUE(less_than(middle_ordinal, big_ordinal));
+
+  EXPECT_FALSE(less_than(big_ordinal, small_ordinal));
+  EXPECT_FALSE(less_than(big_ordinal, middle_ordinal));
+  EXPECT_FALSE(less_than(big_ordinal, big_ordinal));
+}
+
+template <typename Traits>
+std::string GetBetween(const std::string& ordinal_string1,
+                       const std::string& ordinal_string2) {
+  const Ordinal<Traits> ordinal1(ordinal_string1);
+  const Ordinal<Traits> ordinal2(ordinal_string2);
+  const Ordinal<Traits> between1 = ordinal1.CreateBetween(ordinal2);
+  const Ordinal<Traits> between2 = ordinal2.CreateBetween(ordinal1);
+  EXPECT_TRUE(between1.Equals(between2));
+  return between1.ToInternalValue();
+}
+
+// Create some Ordinals from single-digit strings.  Given two strings
+// from this set, CreateBetween should return an Ordinal roughly between
+// them that are also single-digit when possible.
+TEST(Ordinal, CreateBetweenSingleDigit) {
+  EXPECT_EQ("2", GetBetween<TestOrdinal>("1", "3"));
+  EXPECT_EQ("12", GetBetween<TestOrdinal>("1", "2"));
+  EXPECT_EQ("22", GetBetween<TestOrdinal>("2", "3"));
+}
+
+// Create some Ordinals from strings of various lengths.  Given two
+// strings from this set, CreateBetween should return an Ordinal roughly
+// between them that have as few digits as possible.
+TEST(Ordinal, CreateBetweenDifferentLengths) {
+  EXPECT_EQ("102", GetBetween<TestOrdinal>("1", "11"));
+  EXPECT_EQ("2", GetBetween<TestOrdinal>("1", "31"));
+  EXPECT_EQ("132", GetBetween<TestOrdinal>("13", "2"));
+  EXPECT_EQ("2", GetBetween<TestOrdinal>("10001", "3"));
+  EXPECT_EQ("20000", GetBetween<LongOrdinal>("10001", "30000"));
+  EXPECT_EQ("2", GetBetween<TestOrdinal>("10002", "3"));
+  EXPECT_EQ("20001", GetBetween<LongOrdinal>("10002", "30000"));
+  EXPECT_EQ("2", GetBetween<TestOrdinal>("1", "30002"));
+  EXPECT_EQ("20001", GetBetween<LongOrdinal>("10000", "30002"));
+}
+
+// Create some Ordinals specifically designed to trigger overflow
+// cases.  Given two strings from this set, CreateBetween should
+// return an Ordinal roughly between them that have as few digits as
+// possible.
+TEST(Ordinal, CreateBetweenOverflow) {
+  EXPECT_EQ("03", GetBetween<TestOrdinal>("01", "11"));
+  EXPECT_EQ("13", GetBetween<TestOrdinal>("11", "21"));
+  EXPECT_EQ("113", GetBetween<TestOrdinal>("111", "121"));
+  EXPECT_EQ("2", GetBetween<TestOrdinal>("001", "333"));
+  EXPECT_EQ("31", GetBetween<TestOrdinal>("222", "333"));
+  EXPECT_EQ("3", GetBetween<TestOrdinal>("201", "333"));
+  EXPECT_EQ("2", GetBetween<TestOrdinal>("003", "333"));
+  EXPECT_EQ("2", GetBetween<TestOrdinal>("2223", "1113"));
+}
+
+// Create some Ordinals specifically designed to trigger digit
+// overflow cases.  Given two strings from this set, CreateBetween
+// should return an Ordinal roughly between them that have as few digits
+// as possible.
+TEST(Ordinal, CreateBetweenOverflowLarge) {
+  EXPECT_EQ("\x80", GetBetween<LargeOrdinal>("\x01\xff", "\xff\xff"));
+  EXPECT_EQ("\xff\xfe\x80", GetBetween<LargeOrdinal>("\xff\xfe", "\xff\xff"));
+}
+
+// Create some Ordinals.  CreateBefore should return an Ordinal
+// roughly halfway towards 0.
+TEST(Ordinal, CreateBefore) {
+  EXPECT_EQ("02", TestOrdinal("1").CreateBefore().ToInternalValue());
+  EXPECT_EQ("03", TestOrdinal("11").CreateBefore().ToInternalValue());
+  EXPECT_EQ("03", TestOrdinal("12").CreateBefore().ToInternalValue());
+  EXPECT_EQ("1", TestOrdinal("13").CreateBefore().ToInternalValue());
+}
+
+// Create some Ordinals.  CreateAfter should return an Ordinal
+// roughly halfway towards 0.
+TEST(Ordinal, CreateAfter) {
+  EXPECT_EQ("31", TestOrdinal("3").CreateAfter().ToInternalValue());
+  EXPECT_EQ("322", TestOrdinal("32").CreateAfter().ToInternalValue());
+  EXPECT_EQ("33322", TestOrdinal("3332").CreateAfter().ToInternalValue());
+  EXPECT_EQ("3", TestOrdinal("22").CreateAfter().ToInternalValue());
+  EXPECT_EQ("3", TestOrdinal("23").CreateAfter().ToInternalValue());
+}
+
+// Create two valid Ordinals.  EqualsFn should return true only when
+// called reflexively.
+TEST(Ordinal, EqualsFn) {
+  const TestOrdinal ordinal1("1");
+  const TestOrdinal ordinal2("2");
+
+  const TestOrdinal::EqualsFn equals;
+
+  EXPECT_TRUE(equals(ordinal1, ordinal1));
+  EXPECT_FALSE(equals(ordinal1, ordinal2));
+
+  EXPECT_FALSE(equals(ordinal2, ordinal1));
+  EXPECT_TRUE(equals(ordinal2,ordinal2));
+}
+
+// Create some Ordinals and shuffle them.  Sorting them using
+// LessThanFn should produce the correct order.
+TEST(Ordinal, Sort) {
+  const LongOrdinal ordinal1("12345");
+  const LongOrdinal ordinal2("54321");
+  const LongOrdinal ordinal3("87654");
+  const LongOrdinal ordinal4("98765");
+
+  std::vector<LongOrdinal> sorted_ordinals;
+  sorted_ordinals.push_back(ordinal1);
+  sorted_ordinals.push_back(ordinal2);
+  sorted_ordinals.push_back(ordinal3);
+  sorted_ordinals.push_back(ordinal4);
+
+  std::vector<LongOrdinal> ordinals = sorted_ordinals;
+  std::random_shuffle(ordinals.begin(), ordinals.end());
+  std::sort(ordinals.begin(), ordinals.end(), LongOrdinal::LessThanFn());
+  EXPECT_TRUE(std::equal(ordinals.begin(), ordinals.end(),
+                         sorted_ordinals.begin(), LongOrdinal::EqualsFn()));
+}
+
+}  // namespace
+
+}  // namespace syncer