[base] Add some utilities for working with containers

This CL adds src/base/container-utils.h wich contains a few utilities
to make working with containers easier by providing a few additional
functions (e.g. contains, all_equal, ...) that are not (yet) shipped
with C++ standard containers.

Change-Id: I365b88c4286bf58bcac32c7bb89a5b0a98fc3509
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3865966Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Nico Hartmann <nicohartmann@chromium.org>
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82907}

BUILD.bazel

@@ -593,6 +593,7 @@ filegroup(
         "src/base/bounds.h",
         "src/base/build_config.h",
         "src/base/compiler-specific.h",
+        "src/base/container-utils.h",
         "src/base/cpu.cc",
         "src/base/cpu.h",
         "src/base/debug/stack_trace.cc",

BUILD.gn

@@ -5428,6 +5428,7 @@ v8_component("v8_libbase") {
     "src/base/bounds.h",
     "src/base/build_config.h",
     "src/base/compiler-specific.h",
+    "src/base/container-utils.h",
     "src/base/cpu.cc",
     "src/base/cpu.h",
     "src/base/debug/stack_trace.cc",

src/base/container-utils.h

+// Copyright 2022 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_BASE_CONTAINER_UTILS_H_
+#define V8_BASE_CONTAINER_UTILS_H_
+
+#include <algorithm>
+#include <optional>
+
+namespace v8::base {
+
+// Returns true iff the {element} is found in the {container}.
+template <typename C, typename T>
+bool contains(const C& container, const T& element) {
+  const auto e = end(container);
+  return std::find(begin(container), e, element) != e;
+}
+
+// Returns the first index of {element} in {container}. Returns std::nullopt if
+// {container} does not contain {element}.
+template <typename C, typename T>
+std::optional<size_t> index_of(const C& container, const T& element) {
+  const auto b = begin(container);
+  const auto e = end(container);
+  if (auto it = std::find(b, e, element); it != e) {
+    return {std::distance(b, it)};
+  }
+  return std::nullopt;
+}
+
+// Returns the index of the first element in {container} that satisfies
+// {predicate}. Returns std::nullopt if no element satisfies {predicate}.
+template <typename C, typename P>
+std::optional<size_t> index_of_if(const C& container, const P& predicate) {
+  const auto b = begin(container);
+  const auto e = end(container);
+  if (auto it = std::find_if(b, e, predicate); it != e) {
+    return {std::distance(b, it)};
+  }
+  return std::nullopt;
+}
+
+// Removes {count} elements from {container} starting at {index}. If {count} is
+// larger than the number of elements after {index}, all elements after {index}
+// are removed. Returns the number of removed elements.
+template <typename C>
+inline size_t erase_at(C& container, size_t index, size_t count = 1) {
+  // TODO(C++20): Replace with std::erase.
+  if (size(container) <= index) return 0;
+  auto start = begin(container) + index;
+  count = std::min<size_t>(count, std::distance(start, end(container)));
+  container.erase(start, start + count);
+  return count;
+}
+
+// Removes all elements from {container} that satisfy {predicate}. Returns the
+// number of removed elements.
+// TODO(C++20): Replace with std::erase_if.
+template <typename C, typename P>
+inline size_t erase_if(C& container, const P& predicate) {
+  size_t count = 0;
+  auto e = end(container);
+  for (auto it = begin(container); it != e;) {
+    it = std::find_if(it, e, predicate);
+    if (it == e) break;
+    it = container.erase(it);
+    e = end(container);
+    ++count;
+  }
+  return count;
+}
+
+// Helper for std::count_if.
+template <typename C, typename P>
+inline size_t count_if(const C& container, const P& predicate) {
+  return std::count_if(begin(container), end(container), predicate);
+}
+
+// Returns true iff all elements of {container} compare equal using operator==.
+template <typename C>
+inline bool all_equal(const C& container) {
+  if (size(container) <= 1) return true;
+  auto b = begin(container);
+  const auto& value = *b;
+  return std::all_of(++b, end(container),
+                     [&](const auto& v) { return v == value; });
+}
+
+}  // namespace v8::base
+
+#endif  // V8_BASE_CONTAINER_UTILS_H_