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-rw-r--r--absl/strings/BUILD.bazel1
-rw-r--r--absl/strings/CMakeLists.txt1
-rw-r--r--absl/strings/cord.h19
-rw-r--r--absl/strings/cord_test.cc71
-rw-r--r--absl/types/span.h34
5 files changed, 101 insertions, 25 deletions
diff --git a/absl/strings/BUILD.bazel b/absl/strings/BUILD.bazel
index b950ec76..e72db82c 100644
--- a/absl/strings/BUILD.bazel
+++ b/absl/strings/BUILD.bazel
@@ -285,6 +285,7 @@ cc_library(
"//absl/container:inlined_vector",
"//absl/functional:function_ref",
"//absl/meta:type_traits",
+ "//absl/types:optional",
],
)
diff --git a/absl/strings/CMakeLists.txt b/absl/strings/CMakeLists.txt
index cebc5928..0757a9cb 100644
--- a/absl/strings/CMakeLists.txt
+++ b/absl/strings/CMakeLists.txt
@@ -546,6 +546,7 @@ absl_cc_library(
absl::fixed_array
absl::function_ref
absl::inlined_vector
+ absl::optional
absl::raw_logging_internal
absl::type_traits
PUBLIC
diff --git a/absl/strings/cord.h b/absl/strings/cord.h
index 68a7e52f..29ed7f75 100644
--- a/absl/strings/cord.h
+++ b/absl/strings/cord.h
@@ -53,6 +53,7 @@
#include "absl/strings/internal/cord_internal.h"
#include "absl/strings/internal/resize_uninitialized.h"
#include "absl/strings/string_view.h"
+#include "absl/types/optional.h"
namespace absl {
ABSL_NAMESPACE_BEGIN
@@ -512,6 +513,10 @@ class Cord {
// REQUIRES: 0 <= i < size()
char operator[](size_t i) const;
+ // If this cord's representation is a single flat array, return a
+ // string_view referencing that array. Otherwise return nullopt.
+ absl::optional<absl::string_view> TryFlat() const;
+
// Flattens the cord into a single array and returns a view of the data.
//
// If the cord was already flat, the contents are not modified.
@@ -630,7 +635,7 @@ class Cord {
// Helper for MemoryUsage()
static size_t MemoryUsageAux(const absl::cord_internal::CordRep* rep);
- // Helper for GetFlat()
+ // Helper for GetFlat() and TryFlat()
static bool GetFlatAux(absl::cord_internal::CordRep* rep,
absl::string_view* fragment);
@@ -942,6 +947,18 @@ inline size_t Cord::EstimatedMemoryUsage() const {
return result;
}
+inline absl::optional<absl::string_view> Cord::TryFlat() const {
+ absl::cord_internal::CordRep* rep = contents_.tree();
+ if (rep == nullptr) {
+ return absl::string_view(contents_.data(), contents_.size());
+ }
+ absl::string_view fragment;
+ if (GetFlatAux(rep, &fragment)) {
+ return fragment;
+ }
+ return absl::nullopt;
+}
+
inline absl::string_view Cord::Flatten() {
absl::cord_internal::CordRep* rep = contents_.tree();
if (rep == nullptr) {
diff --git a/absl/strings/cord_test.cc b/absl/strings/cord_test.cc
index 68515cbf..a683cc4b 100644
--- a/absl/strings/cord_test.cc
+++ b/absl/strings/cord_test.cc
@@ -70,9 +70,8 @@ static std::string RandomLowercaseString(RandomEngine* rng) {
static std::string RandomLowercaseString(RandomEngine* rng, size_t length) {
std::string result(length, '\0');
std::uniform_int_distribution<int> chars('a', 'z');
- std::generate(result.begin(), result.end(), [&]() {
- return static_cast<char>(chars(*rng));
- });
+ std::generate(result.begin(), result.end(),
+ [&]() { return static_cast<char>(chars(*rng)); });
return result;
}
@@ -424,6 +423,50 @@ TEST(Cord, CopyToString) {
"copying ", "to ", "a ", "string."}));
}
+TEST(TryFlat, Empty) {
+ absl::Cord c;
+ EXPECT_EQ(c.TryFlat(), "");
+}
+
+TEST(TryFlat, Flat) {
+ absl::Cord c("hello");
+ EXPECT_EQ(c.TryFlat(), "hello");
+}
+
+TEST(TryFlat, SubstrInlined) {
+ absl::Cord c("hello");
+ c.RemovePrefix(1);
+ EXPECT_EQ(c.TryFlat(), "ello");
+}
+
+TEST(TryFlat, SubstrFlat) {
+ absl::Cord c("longer than 15 bytes");
+ c.RemovePrefix(1);
+ EXPECT_EQ(c.TryFlat(), "onger than 15 bytes");
+}
+
+TEST(TryFlat, Concat) {
+ absl::Cord c = absl::MakeFragmentedCord({"hel", "lo"});
+ EXPECT_EQ(c.TryFlat(), absl::nullopt);
+}
+
+TEST(TryFlat, External) {
+ absl::Cord c = absl::MakeCordFromExternal("hell", [](absl::string_view) {});
+ EXPECT_EQ(c.TryFlat(), "hell");
+}
+
+TEST(TryFlat, SubstrExternal) {
+ absl::Cord c = absl::MakeCordFromExternal("hell", [](absl::string_view) {});
+ c.RemovePrefix(1);
+ EXPECT_EQ(c.TryFlat(), "ell");
+}
+
+TEST(TryFlat, SubstrConcat) {
+ absl::Cord c = absl::MakeFragmentedCord({"hello", " world"});
+ c.RemovePrefix(1);
+ EXPECT_EQ(c.TryFlat(), absl::nullopt);
+}
+
static bool IsFlat(const absl::Cord& c) {
return c.chunk_begin() == c.chunk_end() || ++c.chunk_begin() == c.chunk_end();
}
@@ -511,24 +554,24 @@ TEST(Cord, MultipleLengths) {
for (size_t i = 0; i < d.size(); i++) {
std::string a = d.data(i);
- { // Construct from Cord
+ { // Construct from Cord
absl::Cord tmp(a);
absl::Cord x(tmp);
EXPECT_EQ(a, std::string(x)) << "'" << a << "'";
}
- { // Construct from absl::string_view
+ { // Construct from absl::string_view
absl::Cord x(a);
EXPECT_EQ(a, std::string(x)) << "'" << a << "'";
}
- { // Append cord to self
+ { // Append cord to self
absl::Cord self(a);
self.Append(self);
EXPECT_EQ(a + a, std::string(self)) << "'" << a << "' + '" << a << "'";
}
- { // Prepend cord to self
+ { // Prepend cord to self
absl::Cord self(a);
self.Prepend(self);
EXPECT_EQ(a + a, std::string(self)) << "'" << a << "' + '" << a << "'";
@@ -538,40 +581,40 @@ TEST(Cord, MultipleLengths) {
for (size_t j = 0; j < d.size(); j++) {
std::string b = d.data(j);
- { // CopyFrom Cord
+ { // CopyFrom Cord
absl::Cord x(a);
absl::Cord y(b);
x = y;
EXPECT_EQ(b, std::string(x)) << "'" << a << "' + '" << b << "'";
}
- { // CopyFrom absl::string_view
+ { // CopyFrom absl::string_view
absl::Cord x(a);
x = b;
EXPECT_EQ(b, std::string(x)) << "'" << a << "' + '" << b << "'";
}
- { // Cord::Append(Cord)
+ { // Cord::Append(Cord)
absl::Cord x(a);
absl::Cord y(b);
x.Append(y);
EXPECT_EQ(a + b, std::string(x)) << "'" << a << "' + '" << b << "'";
}
- { // Cord::Append(absl::string_view)
+ { // Cord::Append(absl::string_view)
absl::Cord x(a);
x.Append(b);
EXPECT_EQ(a + b, std::string(x)) << "'" << a << "' + '" << b << "'";
}
- { // Cord::Prepend(Cord)
+ { // Cord::Prepend(Cord)
absl::Cord x(a);
absl::Cord y(b);
x.Prepend(y);
EXPECT_EQ(b + a, std::string(x)) << "'" << b << "' + '" << a << "'";
}
- { // Cord::Prepend(absl::string_view)
+ { // Cord::Prepend(absl::string_view)
absl::Cord x(a);
x.Prepend(b);
EXPECT_EQ(b + a, std::string(x)) << "'" << b << "' + '" << a << "'";
@@ -1089,7 +1132,7 @@ TEST(ConstructFromExternal, ReferenceQualifierOverloads) {
}
TEST(ExternalMemory, BasicUsage) {
- static const char* strings[] = { "", "hello", "there" };
+ static const char* strings[] = {"", "hello", "there"};
for (const char* str : strings) {
absl::Cord dst("(prefix)");
AddExternalMemory(str, &dst);
diff --git a/absl/types/span.h b/absl/types/span.h
index 25347c63..21cda34b 100644
--- a/absl/types/span.h
+++ b/absl/types/span.h
@@ -292,60 +292,74 @@ class Span {
// Span::front()
//
- // Returns a reference to the first element of this span.
+ // Returns a reference to the first element of this span. The span must not
+ // be empty.
constexpr reference front() const noexcept {
return ABSL_ASSERT(size() > 0), *data();
}
// Span::back()
//
- // Returns a reference to the last element of this span.
+ // Returns a reference to the last element of this span. The span must not
+ // be empty.
constexpr reference back() const noexcept {
return ABSL_ASSERT(size() > 0), *(data() + size() - 1);
}
// Span::begin()
//
- // Returns an iterator to the first element of this span.
+ // Returns an iterator pointing to the first element of this span, or `end()`
+ // if the span is empty.
constexpr iterator begin() const noexcept { return data(); }
// Span::cbegin()
//
- // Returns a const iterator to the first element of this span.
+ // Returns a const iterator pointing to the first element of this span, or
+ // `end()` if the span is empty.
constexpr const_iterator cbegin() const noexcept { return begin(); }
// Span::end()
//
- // Returns an iterator to the last element of this span.
+ // Returns an iterator pointing just beyond the last element at the
+ // end of this span. This iterator acts as a placeholder; attempting to
+ // access it results in undefined behavior.
constexpr iterator end() const noexcept { return data() + size(); }
// Span::cend()
//
- // Returns a const iterator to the last element of this span.
+ // Returns a const iterator pointing just beyond the last element at the
+ // end of this span. This iterator acts as a placeholder; attempting to
+ // access it results in undefined behavior.
constexpr const_iterator cend() const noexcept { return end(); }
// Span::rbegin()
//
- // Returns a reverse iterator starting at the last element of this span.
+ // Returns a reverse iterator pointing to the last element at the end of this
+ // span, or `rend()` if the span is empty.
constexpr reverse_iterator rbegin() const noexcept {
return reverse_iterator(end());
}
// Span::crbegin()
//
- // Returns a reverse const iterator starting at the last element of this span.
+ // Returns a const reverse iterator pointing to the last element at the end of
+ // this span, or `crend()` if the span is empty.
constexpr const_reverse_iterator crbegin() const noexcept { return rbegin(); }
// Span::rend()
//
- // Returns a reverse iterator starting at the first element of this span.
+ // Returns a reverse iterator pointing just before the first element
+ // at the beginning of this span. This pointer acts as a placeholder;
+ // attempting to access its element results in undefined behavior.
constexpr reverse_iterator rend() const noexcept {
return reverse_iterator(begin());
}
// Span::crend()
//
- // Returns a reverse iterator starting at the first element of this span.
+ // Returns a reverse const iterator pointing just before the first element
+ // at the beginning of this span. This pointer acts as a placeholder;
+ // attempting to access its element results in undefined behavior.
constexpr const_reverse_iterator crend() const noexcept { return rend(); }
// Span mutations
generated by cgit v1.2.3 (git 2.39.1) at 2024-07-06 20:31:59 +0000