Export of internal Abseil changes
-- 87cdfd6aa40941e116cd79ef70f9a7a8271db163 by Abseil Team <absl-team@google.com>: Fix a typo in random.h API documentation. PiperOrigin-RevId: 305176308 -- 8a38e1df49a18a954daca3ce617fd69045ff4c19 by Derek Mauro <dmauro@google.com>: Import GitHub #647: Allow external add_subdirectory for using GoogleTest PiperOrigin-RevId: 305156797 -- b1a2441536d4964fbe4e2329e74c322e6c41a4e6 by Gennadiy Rozental <rogeeff@google.com>: temporary roll back. PiperOrigin-RevId: 305149619 -- c78767577264348d2f881893f9407aadfe73ab75 by CJ Johnson <johnsoncj@google.com>: Rollback update to linux_clang-latest container while investigating a compiler bug. PiperOrigin-RevId: 304897689 -- 3c6fd38f53d2e982569fdba4043f75271c7b5de4 by Derek Mauro <dmauro@google.com>: Update linux_clang-latest container to one based on Ubuntu 18.04, which has libstdc++-8. PiperOrigin-RevId: 304885120 GitOrigin-RevId: 87cdfd6aa40941e116cd79ef70f9a7a8271db163 Change-Id: Iefa6efee93907ec0eecb8add804c5cc2f052b64d
This commit is contained in:
Abseil Team
Gennadiy Rozental
parent
c01b9916e7
commit
73ea9a9572
5 changed files with 173 additions and 351 deletions
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@ -82,7 +82,8 @@ endif()
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find_package(Threads REQUIRED)
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option(ABSL_USE_EXTERNAL_GOOGLETEST
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"If ON, abseil will assume that the targets for googletest are already provided by the including project folder. This makes sense when abseil is used with add_subproject." OFF)
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"If ON, Abseil will assume that the targets for GoogleTest are already provided by the including project. This makes sense when Abseil is used with add_subproject." OFF)
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option(ABSL_USE_GOOGLETEST_HEAD
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"If ON, abseil will download HEAD from googletest at config time." OFF)
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@ -109,7 +109,7 @@ ABSL_NAMESPACE_BEGIN
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// absl::BitGen::max()
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//
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// Returns the largest possible value from this bit generator., and
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// Returns the largest possible value from this bit generator.
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// absl::BitGen::discard(num)
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//
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@ -31,6 +31,7 @@
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#include "absl/base/macros.h"
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#include "absl/base/port.h"
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#include "absl/container/fixed_array.h"
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#include "absl/container/inlined_vector.h"
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#include "absl/strings/escaping.h"
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#include "absl/strings/internal/cord_internal.h"
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#include "absl/strings/internal/resize_uninitialized.h"
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@ -132,14 +133,6 @@ inline const CordRepExternal* CordRep::external() const {
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return static_cast<const CordRepExternal*>(this);
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}
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using CordTreeConstPath = CordTreePath<const CordRep*, MaxCordDepth()>;
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// This type is used to store the list of pending nodes during re-balancing.
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// Its maximum size is 2 * MaxCordDepth() because the tree has a maximum
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// possible depth of MaxCordDepth() and every concat node along a tree path
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// could theoretically be split during rebalancing.
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using RebalancingStack = CordTreePath<CordRep*, 2 * MaxCordDepth()>;
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} // namespace cord_internal
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static const size_t kFlatOverhead = offsetof(CordRep, data);
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@ -188,78 +181,64 @@ static constexpr size_t TagToLength(uint8_t tag) {
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// Enforce that kMaxFlatSize maps to a well-known exact tag value.
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static_assert(TagToAllocatedSize(224) == kMaxFlatSize, "Bad tag logic");
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constexpr size_t Fibonacci(uint8_t n, const size_t a = 0, const size_t b = 1) {
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return n == 0
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? a
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: n == 1 ? b
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: Fibonacci(n - 1, b,
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(a > (size_t(-1) - b)) ? size_t(-1) : a + b);
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constexpr uint64_t Fibonacci(unsigned char n, uint64_t a = 0, uint64_t b = 1) {
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return n == 0 ? a : Fibonacci(n - 1, b, a + b);
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}
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static_assert(Fibonacci(63) == 6557470319842,
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"Fibonacci values computed incorrectly");
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// Minimum length required for a given depth tree -- a tree is considered
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// balanced if
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// length(t) >= kMinLength[depth(t)]
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// The node depth is allowed to become larger to reduce rebalancing
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// for larger strings (see ShouldRebalance).
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constexpr size_t kMinLength[] = {
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Fibonacci(2), Fibonacci(3), Fibonacci(4), Fibonacci(5), Fibonacci(6),
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Fibonacci(7), Fibonacci(8), Fibonacci(9), Fibonacci(10), Fibonacci(11),
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Fibonacci(12), Fibonacci(13), Fibonacci(14), Fibonacci(15), Fibonacci(16),
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Fibonacci(17), Fibonacci(18), Fibonacci(19), Fibonacci(20), Fibonacci(21),
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Fibonacci(22), Fibonacci(23), Fibonacci(24), Fibonacci(25), Fibonacci(26),
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Fibonacci(27), Fibonacci(28), Fibonacci(29), Fibonacci(30), Fibonacci(31),
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Fibonacci(32), Fibonacci(33), Fibonacci(34), Fibonacci(35), Fibonacci(36),
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Fibonacci(37), Fibonacci(38), Fibonacci(39), Fibonacci(40), Fibonacci(41),
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Fibonacci(42), Fibonacci(43), Fibonacci(44), Fibonacci(45), Fibonacci(46),
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Fibonacci(47), Fibonacci(48), Fibonacci(49), Fibonacci(50), Fibonacci(51),
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Fibonacci(52), Fibonacci(53), Fibonacci(54), Fibonacci(55), Fibonacci(56),
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Fibonacci(57), Fibonacci(58), Fibonacci(59), Fibonacci(60), Fibonacci(61),
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Fibonacci(62), Fibonacci(63), Fibonacci(64), Fibonacci(65), Fibonacci(66),
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Fibonacci(67), Fibonacci(68), Fibonacci(69), Fibonacci(70), Fibonacci(71),
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Fibonacci(72), Fibonacci(73), Fibonacci(74), Fibonacci(75), Fibonacci(76),
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Fibonacci(77), Fibonacci(78), Fibonacci(79), Fibonacci(80), Fibonacci(81),
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Fibonacci(82), Fibonacci(83), Fibonacci(84), Fibonacci(85), Fibonacci(86),
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Fibonacci(87), Fibonacci(88), Fibonacci(89), Fibonacci(90), Fibonacci(91),
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Fibonacci(92), Fibonacci(93), Fibonacci(94), Fibonacci(95)};
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// length(t) >= min_length[depth(t)]
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// The root node depth is allowed to become twice as large to reduce rebalancing
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// for larger strings (see IsRootBalanced).
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static constexpr uint64_t min_length[] = {
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Fibonacci(2), Fibonacci(3), Fibonacci(4), Fibonacci(5),
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Fibonacci(6), Fibonacci(7), Fibonacci(8), Fibonacci(9),
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Fibonacci(10), Fibonacci(11), Fibonacci(12), Fibonacci(13),
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Fibonacci(14), Fibonacci(15), Fibonacci(16), Fibonacci(17),
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Fibonacci(18), Fibonacci(19), Fibonacci(20), Fibonacci(21),
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Fibonacci(22), Fibonacci(23), Fibonacci(24), Fibonacci(25),
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Fibonacci(26), Fibonacci(27), Fibonacci(28), Fibonacci(29),
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Fibonacci(30), Fibonacci(31), Fibonacci(32), Fibonacci(33),
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Fibonacci(34), Fibonacci(35), Fibonacci(36), Fibonacci(37),
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Fibonacci(38), Fibonacci(39), Fibonacci(40), Fibonacci(41),
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Fibonacci(42), Fibonacci(43), Fibonacci(44), Fibonacci(45),
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Fibonacci(46), Fibonacci(47),
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0xffffffffffffffffull, // Avoid overflow
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};
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static_assert(sizeof(kMinLength) / sizeof(size_t) >=
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(cord_internal::MaxCordDepth() + 1),
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"Not enough elements in kMinLength array to cover all the "
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"supported Cord depth(s)");
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static const int kMinLengthSize = ABSL_ARRAYSIZE(min_length);
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inline bool ShouldRebalance(const CordRep* node) {
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if (node->tag != CONCAT) return false;
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// The inlined size to use with absl::InlinedVector.
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//
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// Note: The InlinedVectors in this file (and in cord.h) do not need to use
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// the same value for their inlined size. The fact that they do is historical.
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// It may be desirable for each to use a different inlined size optimized for
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// that InlinedVector's usage.
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//
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// TODO(jgm): Benchmark to see if there's a more optimal value than 47 for
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// the inlined vector size (47 exists for backward compatibility).
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static const int kInlinedVectorSize = 47;
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size_t node_depth = node->concat()->depth();
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if (node_depth <= 15) return false;
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// Rebalancing Cords is expensive, so we reduce how often rebalancing occurs
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// by allowing shallow Cords to have twice the depth that the Fibonacci rule
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// would otherwise imply. Deep Cords need to follow the rule more closely,
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// however to ensure algorithm correctness. We implement this with linear
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// interpolation. Cords of depth 16 are treated as though they have a depth
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// of 16 * 1/2, and Cords of depth MaxCordDepth() interpolate to
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// MaxCordDepth() * 1.
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return node->length <
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kMinLength[(node_depth * (cord_internal::MaxCordDepth() - 16)) /
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(2 * cord_internal::MaxCordDepth() - 16 - node_depth)];
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}
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// Unlike root balancing condition this one is part of the re-balancing
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// algorithm and has to be always matching against right depth for
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// algorithm to be correct.
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inline bool IsNodeBalanced(const CordRep* node) {
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if (node->tag != CONCAT) return true;
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size_t node_depth = node->concat()->depth();
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return node->length >= kMinLength[node_depth];
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static inline bool IsRootBalanced(CordRep* node) {
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if (node->tag != CONCAT) {
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return true;
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} else if (node->concat()->depth() <= 15) {
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return true;
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} else if (node->concat()->depth() > kMinLengthSize) {
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return false;
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} else {
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// Allow depth to become twice as large as implied by fibonacci rule to
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// reduce rebalancing for larger strings.
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return (node->length >= min_length[node->concat()->depth() / 2]);
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}
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}
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static CordRep* Rebalance(CordRep* node);
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static void DumpNode(const CordRep* rep, bool include_data, std::ostream* os);
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static bool VerifyNode(const CordRep* root, const CordRep* start_node,
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static void DumpNode(CordRep* rep, bool include_data, std::ostream* os);
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static bool VerifyNode(CordRep* root, CordRep* start_node,
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bool full_validation);
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static inline CordRep* VerifyTree(CordRep* node) {
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@ -306,8 +285,7 @@ __attribute__((preserve_most))
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static void UnrefInternal(CordRep* rep) {
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assert(rep != nullptr);
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cord_internal::RebalancingStack pending;
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absl::InlinedVector<CordRep*, kInlinedVectorSize> pending;
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while (true) {
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if (rep->tag == CONCAT) {
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CordRepConcat* rep_concat = rep->concat();
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@ -389,11 +367,6 @@ static void SetConcatChildren(CordRepConcat* concat, CordRep* left,
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concat->length = left->length + right->length;
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concat->set_depth(1 + std::max(Depth(left), Depth(right)));
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ABSL_INTERNAL_CHECK(concat->depth() <= cord_internal::MaxCordDepth(),
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"Cord depth exceeds max");
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ABSL_INTERNAL_CHECK(concat->length >= left->length, "Cord is too long");
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ABSL_INTERNAL_CHECK(concat->length >= right->length, "Cord is too long");
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}
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// Create a concatenation of the specified nodes.
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@ -419,7 +392,7 @@ static CordRep* RawConcat(CordRep* left, CordRep* right) {
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static CordRep* Concat(CordRep* left, CordRep* right) {
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CordRep* rep = RawConcat(left, right);
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if (rep != nullptr && ShouldRebalance(rep)) {
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if (rep != nullptr && !IsRootBalanced(rep)) {
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rep = Rebalance(rep);
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}
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return VerifyTree(rep);
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@ -714,14 +687,6 @@ void Cord::InlineRep::ClearSlow() {
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memset(data_, 0, sizeof(data_));
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}
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inline Cord::InternalChunkIterator Cord::internal_chunk_begin() const {
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return InternalChunkIterator(this);
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}
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inline Cord::InternalChunkRange Cord::InternalChunks() const {
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return InternalChunkRange(this);
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}
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// --------------------------------------------------------------------
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// Constructors and destructors
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@ -918,7 +883,7 @@ void Cord::Prepend(absl::string_view src) {
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static CordRep* RemovePrefixFrom(CordRep* node, size_t n) {
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if (n >= node->length) return nullptr;
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if (n == 0) return Ref(node);
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cord_internal::CordTreeMutablePath rhs_stack;
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absl::InlinedVector<CordRep*, kInlinedVectorSize> rhs_stack;
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while (node->tag == CONCAT) {
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assert(n <= node->length);
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@ -959,7 +924,7 @@ static CordRep* RemovePrefixFrom(CordRep* node, size_t n) {
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static CordRep* RemoveSuffixFrom(CordRep* node, size_t n) {
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if (n >= node->length) return nullptr;
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if (n == 0) return Ref(node);
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absl::cord_internal::CordTreeMutablePath lhs_stack;
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absl::InlinedVector<CordRep*, kInlinedVectorSize> lhs_stack;
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bool inplace_ok = node->refcount.IsOne();
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while (node->tag == CONCAT) {
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@ -1030,7 +995,6 @@ void Cord::RemoveSuffix(size_t n) {
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// Work item for NewSubRange().
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struct SubRange {
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SubRange() = default;
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SubRange(CordRep* a_node, size_t a_pos, size_t a_n)
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: node(a_node), pos(a_pos), n(a_n) {}
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CordRep* node; // nullptr means concat last 2 results.
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@ -1039,11 +1003,8 @@ struct SubRange {
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};
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static CordRep* NewSubRange(CordRep* node, size_t pos, size_t n) {
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cord_internal::CordTreeMutablePath results;
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// The algorithm below in worst case scenario adds up to 3 nodes to the `todo`
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// list, but we also pop one out on every cycle. If original tree has depth d
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// todo list can grew up to 2*d in size.
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cord_internal::CordTreePath<SubRange, 2 * cord_internal::MaxCordDepth()> todo;
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absl::InlinedVector<CordRep*, kInlinedVectorSize> results;
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absl::InlinedVector<SubRange, kInlinedVectorSize> todo;
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todo.push_back(SubRange(node, pos, n));
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do {
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const SubRange& sr = todo.back();
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@ -1080,7 +1041,7 @@ static CordRep* NewSubRange(CordRep* node, size_t pos, size_t n) {
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}
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} while (!todo.empty());
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assert(results.size() == 1);
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return results.back();
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return results[0];
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}
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Cord Cord::Subcord(size_t pos, size_t new_size) const {
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@ -1096,7 +1057,7 @@ Cord Cord::Subcord(size_t pos, size_t new_size) const {
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} else if (new_size == 0) {
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// We want to return empty subcord, so nothing to do.
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} else if (new_size <= InlineRep::kMaxInline) {
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Cord::InternalChunkIterator it = internal_chunk_begin();
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Cord::ChunkIterator it = chunk_begin();
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it.AdvanceBytes(pos);
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char* dest = sub_cord.contents_.data_;
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size_t remaining_size = new_size;
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@ -1119,12 +1080,11 @@ Cord Cord::Subcord(size_t pos, size_t new_size) const {
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class CordForest {
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public:
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explicit CordForest(size_t length) : root_length_(length), trees_({}) {}
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explicit CordForest(size_t length)
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: root_length_(length), trees_(kMinLengthSize, nullptr) {}
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void Build(CordRep* cord_root) {
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// We are adding up to two nodes to the `pending` list, but we also popping
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// one, so the size of `pending` will never exceed `MaxCordDepth()`.
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cord_internal::CordTreeMutablePath pending(cord_root);
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std::vector<CordRep*> pending = {cord_root};
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while (!pending.empty()) {
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CordRep* node = pending.back();
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@ -1136,20 +1096,21 @@ class CordForest {
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}
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CordRepConcat* concat_node = node->concat();
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if (IsNodeBalanced(concat_node)) {
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AddNode(node);
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continue;
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}
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pending.push_back(concat_node->right);
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pending.push_back(concat_node->left);
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if (concat_node->depth() >= kMinLengthSize ||
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concat_node->length < min_length[concat_node->depth()]) {
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pending.push_back(concat_node->right);
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pending.push_back(concat_node->left);
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if (concat_node->refcount.IsOne()) {
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concat_node->left = concat_freelist_;
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concat_freelist_ = concat_node;
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if (concat_node->refcount.IsOne()) {
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concat_node->left = concat_freelist_;
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concat_freelist_ = concat_node;
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} else {
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Ref(concat_node->right);
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Ref(concat_node->left);
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Unref(concat_node);
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}
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} else {
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Ref(concat_node->right);
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Ref(concat_node->left);
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Unref(concat_node);
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AddNode(node);
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}
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}
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}
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@ -1181,7 +1142,7 @@ class CordForest {
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// Collect together everything with which we will merge with node
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int i = 0;
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for (; node->length >= kMinLength[i + 1]; ++i) {
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for (; node->length > min_length[i + 1]; ++i) {
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auto& tree_at_i = trees_[i];
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if (tree_at_i == nullptr) continue;
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@ -1192,7 +1153,7 @@ class CordForest {
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sum = AppendNode(node, sum);
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// Insert sum into appropriate place in the forest
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for (; sum->length >= kMinLength[i]; ++i) {
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for (; sum->length >= min_length[i]; ++i) {
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auto& tree_at_i = trees_[i];
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if (tree_at_i == nullptr) continue;
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@ -1200,7 +1161,7 @@ class CordForest {
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tree_at_i = nullptr;
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}
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// kMinLength[0] == 1, which means sum->length >= kMinLength[0]
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// min_length[0] == 1, which means sum->length >= min_length[0]
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assert(i > 0);
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trees_[i - 1] = sum;
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}
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@ -1233,7 +1194,9 @@ class CordForest {
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}
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size_t root_length_;
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std::array<cord_internal::CordRep*, cord_internal::MaxCordDepth()> trees_;
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// use an inlined vector instead of a flat array to get bounds checking
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absl::InlinedVector<CordRep*, kInlinedVectorSize> trees_;
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|
||||
// List of concat nodes we can re-use for Cord balancing.
|
||||
CordRepConcat* concat_freelist_ = nullptr;
|
||||
|
|
@ -1334,7 +1297,7 @@ inline absl::string_view Cord::InlineRep::FindFlatStartPiece() const {
|
|||
|
||||
inline int Cord::CompareSlowPath(absl::string_view rhs, size_t compared_size,
|
||||
size_t size_to_compare) const {
|
||||
auto advance = [](Cord::InternalChunkIterator* it, absl::string_view* chunk) {
|
||||
auto advance = [](Cord::ChunkIterator* it, absl::string_view* chunk) {
|
||||
if (!chunk->empty()) return true;
|
||||
++*it;
|
||||
if (it->bytes_remaining_ == 0) return false;
|
||||
|
|
@ -1342,7 +1305,7 @@ inline int Cord::CompareSlowPath(absl::string_view rhs, size_t compared_size,
|
|||
return true;
|
||||
};
|
||||
|
||||
Cord::InternalChunkIterator lhs_it = internal_chunk_begin();
|
||||
Cord::ChunkIterator lhs_it = chunk_begin();
|
||||
|
||||
// compared_size is inside first chunk.
|
||||
absl::string_view lhs_chunk =
|
||||
|
|
@ -1364,7 +1327,7 @@ inline int Cord::CompareSlowPath(absl::string_view rhs, size_t compared_size,
|
|||
|
||||
inline int Cord::CompareSlowPath(const Cord& rhs, size_t compared_size,
|
||||
size_t size_to_compare) const {
|
||||
auto advance = [](Cord::InternalChunkIterator* it, absl::string_view* chunk) {
|
||||
auto advance = [](Cord::ChunkIterator* it, absl::string_view* chunk) {
|
||||
if (!chunk->empty()) return true;
|
||||
++*it;
|
||||
if (it->bytes_remaining_ == 0) return false;
|
||||
|
|
@ -1372,8 +1335,8 @@ inline int Cord::CompareSlowPath(const Cord& rhs, size_t compared_size,
|
|||
return true;
|
||||
};
|
||||
|
||||
Cord::InternalChunkIterator lhs_it = internal_chunk_begin();
|
||||
Cord::InternalChunkIterator rhs_it = rhs.internal_chunk_begin();
|
||||
Cord::ChunkIterator lhs_it = chunk_begin();
|
||||
Cord::ChunkIterator rhs_it = rhs.chunk_begin();
|
||||
|
||||
// compared_size is inside both first chunks.
|
||||
absl::string_view lhs_chunk =
|
||||
|
|
@ -1507,9 +1470,7 @@ void Cord::CopyToArraySlowPath(char* dst) const {
|
|||
}
|
||||
}
|
||||
|
||||
template <typename StorageType>
|
||||
Cord::GenericChunkIterator<StorageType>&
|
||||
Cord::GenericChunkIterator<StorageType>::operator++() {
|
||||
Cord::ChunkIterator& Cord::ChunkIterator::operator++() {
|
||||
ABSL_HARDENING_ASSERT(bytes_remaining_ > 0 &&
|
||||
"Attempted to iterate past `end()`");
|
||||
assert(bytes_remaining_ >= current_chunk_.size());
|
||||
|
|
@ -1549,8 +1510,7 @@ Cord::GenericChunkIterator<StorageType>::operator++() {
|
|||
return *this;
|
||||
}
|
||||
|
||||
template <typename StorageType>
|
||||
Cord Cord::GenericChunkIterator<StorageType>::AdvanceAndReadBytes(size_t n) {
|
||||
Cord Cord::ChunkIterator::AdvanceAndReadBytes(size_t n) {
|
||||
ABSL_HARDENING_ASSERT(bytes_remaining_ >= n &&
|
||||
"Attempted to iterate past `end()`");
|
||||
Cord subcord;
|
||||
|
|
@ -1664,8 +1624,7 @@ Cord Cord::GenericChunkIterator<StorageType>::AdvanceAndReadBytes(size_t n) {
|
|||
return subcord;
|
||||
}
|
||||
|
||||
template <typename StorageType>
|
||||
void Cord::GenericChunkIterator<StorageType>::AdvanceBytesSlowPath(size_t n) {
|
||||
void Cord::ChunkIterator::AdvanceBytesSlowPath(size_t n) {
|
||||
assert(bytes_remaining_ >= n && "Attempted to iterate past `end()`");
|
||||
assert(n >= current_chunk_.size()); // This should only be called when
|
||||
// iterating to a new node.
|
||||
|
|
@ -1851,18 +1810,18 @@ absl::string_view Cord::FlattenSlowPath() {
|
|||
}
|
||||
}
|
||||
|
||||
static void DumpNode(const CordRep* rep, bool include_data, std::ostream* os) {
|
||||
static void DumpNode(CordRep* rep, bool include_data, std::ostream* os) {
|
||||
const int kIndentStep = 1;
|
||||
int indent = 0;
|
||||
cord_internal::CordTreeConstPath stack;
|
||||
cord_internal::CordTreePath<int, cord_internal::MaxCordDepth()> indents;
|
||||
absl::InlinedVector<CordRep*, kInlinedVectorSize> stack;
|
||||
absl::InlinedVector<int, kInlinedVectorSize> indents;
|
||||
for (;;) {
|
||||
*os << std::setw(3) << rep->refcount.Get();
|
||||
*os << " " << std::setw(7) << rep->length;
|
||||
*os << " [";
|
||||
if (include_data) *os << static_cast<const void*>(rep);
|
||||
if (include_data) *os << static_cast<void*>(rep);
|
||||
*os << "]";
|
||||
*os << " " << (IsNodeBalanced(rep) ? 'b' : 'u');
|
||||
*os << " " << (IsRootBalanced(rep) ? 'b' : 'u');
|
||||
*os << " " << std::setw(indent) << "";
|
||||
if (rep->tag == CONCAT) {
|
||||
*os << "CONCAT depth=" << Depth(rep) << "\n";
|
||||
|
|
@ -1883,7 +1842,7 @@ static void DumpNode(const CordRep* rep, bool include_data, std::ostream* os) {
|
|||
} else {
|
||||
*os << "FLAT cap=" << TagToLength(rep->tag) << " [";
|
||||
if (include_data)
|
||||
*os << absl::CEscape(absl::string_view(rep->data, rep->length));
|
||||
*os << absl::CEscape(std::string(rep->data, rep->length));
|
||||
*os << "]\n";
|
||||
}
|
||||
if (stack.empty()) break;
|
||||
|
|
@ -1896,19 +1855,19 @@ static void DumpNode(const CordRep* rep, bool include_data, std::ostream* os) {
|
|||
ABSL_INTERNAL_CHECK(indents.empty(), "");
|
||||
}
|
||||
|
||||
static std::string ReportError(const CordRep* root, const CordRep* node) {
|
||||
static std::string ReportError(CordRep* root, CordRep* node) {
|
||||
std::ostringstream buf;
|
||||
buf << "Error at node " << node << " in:";
|
||||
DumpNode(root, true, &buf);
|
||||
return buf.str();
|
||||
}
|
||||
|
||||
static bool VerifyNode(const CordRep* root, const CordRep* start_node,
|
||||
static bool VerifyNode(CordRep* root, CordRep* start_node,
|
||||
bool full_validation) {
|
||||
cord_internal::CordTreeConstPath worklist;
|
||||
absl::InlinedVector<CordRep*, 2> worklist;
|
||||
worklist.push_back(start_node);
|
||||
do {
|
||||
const CordRep* node = worklist.back();
|
||||
CordRep* node = worklist.back();
|
||||
worklist.pop_back();
|
||||
|
||||
ABSL_INTERNAL_CHECK(node != nullptr, ReportError(root, node));
|
||||
|
|
@ -1958,7 +1917,7 @@ static bool VerifyNode(const CordRep* root, const CordRep* start_node,
|
|||
// Iterate over the tree. cur_node is never a leaf node and leaf nodes will
|
||||
// never be appended to tree_stack. This reduces overhead from manipulating
|
||||
// tree_stack.
|
||||
cord_internal::CordTreeConstPath tree_stack;
|
||||
absl::InlinedVector<const CordRep*, kInlinedVectorSize> tree_stack;
|
||||
const CordRep* cur_node = rep;
|
||||
while (true) {
|
||||
const CordRep* next_node = nullptr;
|
||||
|
|
@ -2005,9 +1964,6 @@ std::ostream& operator<<(std::ostream& out, const Cord& cord) {
|
|||
return out;
|
||||
}
|
||||
|
||||
template class Cord::GenericChunkIterator<cord_internal::CordTreeMutablePath>;
|
||||
template class Cord::GenericChunkIterator<cord_internal::CordTreeDynamicPath>;
|
||||
|
||||
namespace strings_internal {
|
||||
size_t CordTestAccess::FlatOverhead() { return kFlatOverhead; }
|
||||
size_t CordTestAccess::MaxFlatLength() { return kMaxFlatLength; }
|
||||
|
|
|
|||
|
|
@ -123,132 +123,12 @@ H HashFragmentedCord(H, const Cord&);
|
|||
// Additionally, the API provides iterator utilities to iterate through Cord
|
||||
// data via chunks or character bytes.
|
||||
//
|
||||
|
||||
namespace cord_internal {
|
||||
|
||||
// It's expensive to keep a Cord's tree perfectly balanced, so instead we keep
|
||||
// trees approximately balanced. A tree node N of depth D(N) that contains a
|
||||
// string of L(N) characters is considered balanced if L >= Fibonacci(D + 2).
|
||||
// The "+ 2" is used to ensure that every balanced leaf node contains at least
|
||||
// one character. Here we presume that
|
||||
// Fibonacci(0) = 0
|
||||
// Fibonacci(1) = 1
|
||||
// Fibonacci(2) = 1
|
||||
// Fibonacci(3) = 2
|
||||
// ...
|
||||
// The algorithm is based on paper by Hans Boehm et al:
|
||||
// https://www.cs.rit.edu/usr/local/pub/jeh/courses/QUARTERS/FP/Labs/CedarRope/rope-paper.pdf
|
||||
// In this paper authors shows that rebalancing based on cord forest of already
|
||||
// balanced subtrees can be proven to never produce tree of depth larger than
|
||||
// largest Fibonacci number representable in the same integral type as cord size
|
||||
// For 64 bit integers this is the 93rd Fibonacci number. For 32 bit integrals
|
||||
// this is 47th Fibonacci number.
|
||||
constexpr size_t MaxCordDepth() { return sizeof(size_t) == 8 ? 93 : 47; }
|
||||
|
||||
// This class models fixed max size stack of CordRep pointers.
|
||||
// The elements are being pushed back and popped from the back.
|
||||
template <typename CordRepPtr, size_t N>
|
||||
class CordTreePath {
|
||||
public:
|
||||
CordTreePath() {}
|
||||
explicit CordTreePath(CordRepPtr root) { push_back(root); }
|
||||
|
||||
bool empty() const { return size_ == 0; }
|
||||
size_t size() const { return size_; }
|
||||
void clear() { size_ = 0; }
|
||||
|
||||
CordRepPtr back() { return data_[size_ - 1]; }
|
||||
|
||||
void pop_back() {
|
||||
--size_;
|
||||
assert(size_ < N);
|
||||
}
|
||||
void push_back(CordRepPtr elem) { data_[size_++] = elem; }
|
||||
|
||||
private:
|
||||
CordRepPtr data_[N];
|
||||
size_t size_ = 0;
|
||||
};
|
||||
|
||||
// Fixed length container for mutable "path" in cord tree, which can hold any
|
||||
// possible valid path in cord tree.
|
||||
using CordTreeMutablePath = CordTreePath<CordRep*, MaxCordDepth()>;
|
||||
// Variable length container for mutable "path" in cord tree. It starts with
|
||||
// capacity for 15 elements and grow if necessary.
|
||||
using CordTreeDynamicPath =
|
||||
absl::InlinedVector<absl::cord_internal::CordRep*, 15>;
|
||||
} // namespace cord_internal
|
||||
|
||||
// A Cord is a sequence of characters.
|
||||
class Cord {
|
||||
private:
|
||||
template <typename T>
|
||||
using EnableIfString =
|
||||
absl::enable_if_t<std::is_same<T, std::string>::value, int>;
|
||||
|
||||
//----------------------------------------------------------------------------
|
||||
// Cord::GenericChunkIterator
|
||||
//----------------------------------------------------------------------------
|
||||
//
|
||||
// A `Cord::GenericChunkIterator` provides an interface for the standard
|
||||
// `Cord::ChunkIterator` as well as some private implementations.
|
||||
template <typename StorageType>
|
||||
class GenericChunkIterator {
|
||||
public:
|
||||
using iterator_category = std::input_iterator_tag;
|
||||
using value_type = absl::string_view;
|
||||
using difference_type = ptrdiff_t;
|
||||
using pointer = const value_type*;
|
||||
using reference = value_type;
|
||||
|
||||
GenericChunkIterator() = default;
|
||||
|
||||
GenericChunkIterator& operator++();
|
||||
GenericChunkIterator operator++(int);
|
||||
bool operator==(const GenericChunkIterator& other) const;
|
||||
bool operator!=(const GenericChunkIterator& other) const;
|
||||
reference operator*() const;
|
||||
pointer operator->() const;
|
||||
|
||||
friend class Cord;
|
||||
friend class CharIterator;
|
||||
|
||||
private:
|
||||
// Constructs a `begin()` iterator from `cord`.
|
||||
explicit GenericChunkIterator(const Cord* cord);
|
||||
|
||||
// Removes `n` bytes from `current_chunk_`. Expects `n` to be smaller than
|
||||
// `current_chunk_.size()`.
|
||||
void RemoveChunkPrefix(size_t n);
|
||||
Cord AdvanceAndReadBytes(size_t n);
|
||||
void AdvanceBytes(size_t n);
|
||||
// Iterates `n` bytes, where `n` is expected to be greater than or equal to
|
||||
// `current_chunk_.size()`.
|
||||
void AdvanceBytesSlowPath(size_t n);
|
||||
|
||||
// A view into bytes of the current `CordRep`. It may only be a view to a
|
||||
// suffix of bytes if this is being used by `CharIterator`.
|
||||
absl::string_view current_chunk_;
|
||||
// The current leaf, or `nullptr` if the iterator points to short data.
|
||||
// If the current chunk is a substring node, current_leaf_ points to the
|
||||
// underlying flat or external node.
|
||||
cord_internal::CordRep* current_leaf_ = nullptr;
|
||||
// The number of bytes left in the `Cord` over which we are iterating.
|
||||
size_t bytes_remaining_ = 0;
|
||||
StorageType stack_of_right_children_;
|
||||
};
|
||||
template <typename IteratorType>
|
||||
class GenericChunkRange {
|
||||
public:
|
||||
explicit GenericChunkRange(const Cord* cord) : cord_(cord) {}
|
||||
|
||||
IteratorType begin() const { return IteratorType(cord_); }
|
||||
IteratorType end() const { return IteratorType(); }
|
||||
|
||||
private:
|
||||
const Cord* cord_;
|
||||
};
|
||||
|
||||
public:
|
||||
// Cord::Cord() Constructors
|
||||
|
||||
|
|
@ -464,8 +344,51 @@ class Cord {
|
|||
// * The iterator keeps state that can grow for Cords that contain many
|
||||
// nodes and are imbalanced due to sharing. Prefer to pass this type by
|
||||
// const reference instead of by value.
|
||||
using ChunkIterator =
|
||||
GenericChunkIterator<cord_internal::CordTreeDynamicPath>;
|
||||
class ChunkIterator {
|
||||
public:
|
||||
using iterator_category = std::input_iterator_tag;
|
||||
using value_type = absl::string_view;
|
||||
using difference_type = ptrdiff_t;
|
||||
using pointer = const value_type*;
|
||||
using reference = value_type;
|
||||
|
||||
ChunkIterator() = default;
|
||||
|
||||
ChunkIterator& operator++();
|
||||
ChunkIterator operator++(int);
|
||||
bool operator==(const ChunkIterator& other) const;
|
||||
bool operator!=(const ChunkIterator& other) const;
|
||||
reference operator*() const;
|
||||
pointer operator->() const;
|
||||
|
||||
friend class Cord;
|
||||
friend class CharIterator;
|
||||
|
||||
private:
|
||||
// Constructs a `begin()` iterator from `cord`.
|
||||
explicit ChunkIterator(const Cord* cord);
|
||||
|
||||
// Removes `n` bytes from `current_chunk_`. Expects `n` to be smaller than
|
||||
// `current_chunk_.size()`.
|
||||
void RemoveChunkPrefix(size_t n);
|
||||
Cord AdvanceAndReadBytes(size_t n);
|
||||
void AdvanceBytes(size_t n);
|
||||
// Iterates `n` bytes, where `n` is expected to be greater than or equal to
|
||||
// `current_chunk_.size()`.
|
||||
void AdvanceBytesSlowPath(size_t n);
|
||||
|
||||
// A view into bytes of the current `CordRep`. It may only be a view to a
|
||||
// suffix of bytes if this is being used by `CharIterator`.
|
||||
absl::string_view current_chunk_;
|
||||
// The current leaf, or `nullptr` if the iterator points to short data.
|
||||
// If the current chunk is a substring node, current_leaf_ points to the
|
||||
// underlying flat or external node.
|
||||
absl::cord_internal::CordRep* current_leaf_ = nullptr;
|
||||
// The number of bytes left in the `Cord` over which we are iterating.
|
||||
size_t bytes_remaining_ = 0;
|
||||
absl::InlinedVector<absl::cord_internal::CordRep*, 4>
|
||||
stack_of_right_children_;
|
||||
};
|
||||
|
||||
// Cord::ChunkIterator::chunk_begin()
|
||||
//
|
||||
|
|
@ -504,7 +427,16 @@ class Cord {
|
|||
//
|
||||
// Implementation note: `ChunkRange` is simply a convenience wrapper over
|
||||
// `Cord::chunk_begin()` and `Cord::chunk_end()`.
|
||||
using ChunkRange = GenericChunkRange<ChunkIterator>;
|
||||
class ChunkRange {
|
||||
public:
|
||||
explicit ChunkRange(const Cord* cord) : cord_(cord) {}
|
||||
|
||||
ChunkIterator begin() const;
|
||||
ChunkIterator end() const;
|
||||
|
||||
private:
|
||||
const Cord* cord_;
|
||||
};
|
||||
|
||||
// Cord::Chunks()
|
||||
//
|
||||
|
|
@ -800,14 +732,6 @@ class Cord {
|
|||
static bool GetFlatAux(absl::cord_internal::CordRep* rep,
|
||||
absl::string_view* fragment);
|
||||
|
||||
// Iterators for use inside Cord implementation
|
||||
using InternalChunkIterator =
|
||||
GenericChunkIterator<cord_internal::CordTreeMutablePath>;
|
||||
using InternalChunkRange = GenericChunkRange<InternalChunkIterator>;
|
||||
|
||||
InternalChunkIterator internal_chunk_begin() const;
|
||||
InternalChunkRange InternalChunks() const;
|
||||
|
||||
// Helper for ForEachChunk()
|
||||
static void ForEachChunkAux(
|
||||
absl::cord_internal::CordRep* rep,
|
||||
|
|
@ -842,11 +766,6 @@ class Cord {
|
|||
void AppendImpl(C&& src);
|
||||
};
|
||||
|
||||
extern template class Cord::GenericChunkIterator<
|
||||
cord_internal::CordTreeMutablePath>;
|
||||
extern template class Cord::GenericChunkIterator<
|
||||
cord_internal::CordTreeDynamicPath>;
|
||||
|
||||
ABSL_NAMESPACE_END
|
||||
} // namespace absl
|
||||
|
||||
|
|
@ -1186,9 +1105,7 @@ inline bool Cord::StartsWith(absl::string_view rhs) const {
|
|||
return EqualsImpl(rhs, rhs_size);
|
||||
}
|
||||
|
||||
template <typename StorageType>
|
||||
inline Cord::GenericChunkIterator<StorageType>::GenericChunkIterator(
|
||||
const Cord* cord)
|
||||
inline Cord::ChunkIterator::ChunkIterator(const Cord* cord)
|
||||
: bytes_remaining_(cord->size()) {
|
||||
if (cord->empty()) return;
|
||||
if (cord->contents_.is_tree()) {
|
||||
|
|
@ -1199,50 +1116,37 @@ inline Cord::GenericChunkIterator<StorageType>::GenericChunkIterator(
|
|||
}
|
||||
}
|
||||
|
||||
template <typename StorageType>
|
||||
inline Cord::GenericChunkIterator<StorageType>
|
||||
Cord::GenericChunkIterator<StorageType>::operator++(int) {
|
||||
GenericChunkIterator tmp(*this);
|
||||
inline Cord::ChunkIterator Cord::ChunkIterator::operator++(int) {
|
||||
ChunkIterator tmp(*this);
|
||||
operator++();
|
||||
return tmp;
|
||||
}
|
||||
|
||||
template <typename StorageType>
|
||||
inline bool Cord::GenericChunkIterator<StorageType>::operator==(
|
||||
const GenericChunkIterator<StorageType>& other) const {
|
||||
inline bool Cord::ChunkIterator::operator==(const ChunkIterator& other) const {
|
||||
return bytes_remaining_ == other.bytes_remaining_;
|
||||
}
|
||||
|
||||
template <typename StorageType>
|
||||
inline bool Cord::GenericChunkIterator<StorageType>::operator!=(
|
||||
const GenericChunkIterator<StorageType>& other) const {
|
||||
inline bool Cord::ChunkIterator::operator!=(const ChunkIterator& other) const {
|
||||
return !(*this == other);
|
||||
}
|
||||
|
||||
template <typename StorageType>
|
||||
inline typename Cord::GenericChunkIterator<StorageType>::reference
|
||||
Cord::GenericChunkIterator<StorageType>::operator*() const {
|
||||
inline Cord::ChunkIterator::reference Cord::ChunkIterator::operator*() const {
|
||||
ABSL_HARDENING_ASSERT(bytes_remaining_ != 0);
|
||||
return current_chunk_;
|
||||
}
|
||||
|
||||
template <typename StorageType>
|
||||
inline typename Cord::GenericChunkIterator<StorageType>::pointer
|
||||
Cord::GenericChunkIterator<StorageType>::operator->() const {
|
||||
inline Cord::ChunkIterator::pointer Cord::ChunkIterator::operator->() const {
|
||||
ABSL_HARDENING_ASSERT(bytes_remaining_ != 0);
|
||||
return ¤t_chunk_;
|
||||
}
|
||||
|
||||
template <typename StorageType>
|
||||
inline void Cord::GenericChunkIterator<StorageType>::RemoveChunkPrefix(
|
||||
size_t n) {
|
||||
inline void Cord::ChunkIterator::RemoveChunkPrefix(size_t n) {
|
||||
assert(n < current_chunk_.size());
|
||||
current_chunk_.remove_prefix(n);
|
||||
bytes_remaining_ -= n;
|
||||
}
|
||||
|
||||
template <typename StorageType>
|
||||
inline void Cord::GenericChunkIterator<StorageType>::AdvanceBytes(size_t n) {
|
||||
inline void Cord::ChunkIterator::AdvanceBytes(size_t n) {
|
||||
if (ABSL_PREDICT_TRUE(n < current_chunk_.size())) {
|
||||
RemoveChunkPrefix(n);
|
||||
} else if (n != 0) {
|
||||
|
|
@ -1256,6 +1160,14 @@ inline Cord::ChunkIterator Cord::chunk_begin() const {
|
|||
|
||||
inline Cord::ChunkIterator Cord::chunk_end() const { return ChunkIterator(); }
|
||||
|
||||
inline Cord::ChunkIterator Cord::ChunkRange::begin() const {
|
||||
return cord_->chunk_begin();
|
||||
}
|
||||
|
||||
inline Cord::ChunkIterator Cord::ChunkRange::end() const {
|
||||
return cord_->chunk_end();
|
||||
}
|
||||
|
||||
inline Cord::ChunkRange Cord::Chunks() const { return ChunkRange(this); }
|
||||
|
||||
inline Cord::CharIterator& Cord::CharIterator::operator++() {
|
||||
|
|
|
|||
|
|
@ -1403,53 +1403,6 @@ TEST(CordChunkIterator, Operations) {
|
|||
VerifyChunkIterator(subcords, 128);
|
||||
}
|
||||
|
||||
TEST(CordChunkIterator, MaxLengthFullTree) {
|
||||
// Start with a 1-byte cord, and then double its length in a loop. We should
|
||||
// be able to do this until the point where we would overflow size_t.
|
||||
|
||||
absl::Cord cord;
|
||||
size_t size = 1;
|
||||
AddExternalMemory("x", &cord);
|
||||
EXPECT_EQ(cord.size(), size);
|
||||
|
||||
const int kCordLengthDoublingLimit = std::numeric_limits<size_t>::digits - 1;
|
||||
for (int i = 0; i < kCordLengthDoublingLimit; ++i) {
|
||||
cord.Prepend(absl::Cord(cord));
|
||||
size <<= 1;
|
||||
|
||||
EXPECT_EQ(cord.size(), size);
|
||||
|
||||
auto chunk_it = cord.chunk_begin();
|
||||
EXPECT_EQ(*chunk_it, "x");
|
||||
}
|
||||
|
||||
EXPECT_DEATH_IF_SUPPORTED(
|
||||
(cord.Prepend(absl::Cord(cord)), *cord.chunk_begin()),
|
||||
"Cord is too long");
|
||||
}
|
||||
|
||||
TEST(CordChunkIterator, MaxDepth) {
|
||||
// By reusing nodes, it's possible in pathological cases to build a Cord that
|
||||
// exceeds both the maximum permissible length and depth. In this case, the
|
||||
// violation of the maximum depth is reported.
|
||||
absl::Cord left_child;
|
||||
AddExternalMemory("x", &left_child);
|
||||
absl::Cord root = left_child;
|
||||
|
||||
for (int i = 0; i < absl::cord_internal::MaxCordDepth() - 2; ++i) {
|
||||
size_t new_size = left_child.size() + root.size();
|
||||
root.Prepend(left_child);
|
||||
EXPECT_EQ(root.size(), new_size);
|
||||
|
||||
auto chunk_it = root.chunk_begin();
|
||||
EXPECT_EQ(*chunk_it, "x");
|
||||
|
||||
std::swap(left_child, root);
|
||||
}
|
||||
|
||||
EXPECT_DEATH_IF_SUPPORTED(root.Prepend(left_child), "Cord is too long");
|
||||
}
|
||||
|
||||
TEST(CordCharIterator, Traits) {
|
||||
static_assert(std::is_copy_constructible<absl::Cord::CharIterator>::value,
|
||||
"");
|
||||
|
|
|
|||
Loading…
Add table
Add a link
Reference in a new issue