comparison win64-msvc/include/kj/string-tree.h @ 47:d93140aac40b

Current Capnp libs and headers from git

+// Copyright (c) 2013-2014 Sandstorm Development Group, Inc. and contributors
+// Licensed under the MIT License:
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+#ifndef KJ_STRING_TREE_H_
+#define KJ_STRING_TREE_H_
+
+#if defined(__GNUC__) && !KJ_HEADER_WARNINGS
+#pragma GCC system_header
+#endif
+
+#include "string.h"
+
+namespace kj {
+
+class StringTree {
+  // A long string, represented internally as a tree of strings.  This data structure is like a
+  // String, but optimized for concatenation and iteration at the expense of seek time.  The
+  // structure is intended to be used for building large text blobs from many small pieces, where
+  // repeatedly concatenating smaller strings into larger ones would waste copies.  This structure
+  // is NOT intended for use cases requiring random access or computing substrings.  For those,
+  // you should use a Rope, which is a much more complicated data structure.
+  //
+  // The proper way to construct a StringTree is via kj::strTree(...), which works just like
+  // kj::str(...) but returns a StringTree rather than a String.
+  //
+  // KJ_STRINGIFY() functions that construct large strings from many smaller strings are encouraged
+  // to return StringTree rather than a flat char container.
+
+public:
+  inline StringTree(): size_(0) {}
+  inline StringTree(String&& text): size_(text.size()), text(kj::mv(text)) {}
+
+  StringTree(Array<StringTree>&& pieces, StringPtr delim);
+  // Build a StringTree by concatenating the given pieces, delimited by the given delimiter
+  // (e.g. ", ").
+
+  inline size_t size() const { return size_; }
+
+  template <typename Func>
+  void visit(Func&& func) const;
+
+  String flatten() const;
+  // Return the contents as a string.
+
+  // TODO(someday):  flatten() when *this is an rvalue and when branches.size() == 0 could simply
+  //   return `kj::mv(text)`.  Requires reference qualifiers (Clang 3.3 / GCC 4.8).
+
+  void flattenTo(char* __restrict__ target) const;
+  // Copy the contents to the given character array.  Does not add a NUL terminator.
+
+private:
+  size_t size_;
+  String text;
+
+  struct Branch;
+  Array<Branch> branches;  // In order.
+
+  inline void fill(char* pos, size_t branchIndex);
+  template <typename First, typename... Rest>
+  void fill(char* pos, size_t branchIndex, First&& first, Rest&&... rest);
+  template <typename... Rest>
+  void fill(char* pos, size_t branchIndex, StringTree&& first, Rest&&... rest);
+  template <typename... Rest>
+  void fill(char* pos, size_t branchIndex, Array<char>&& first, Rest&&... rest);
+  template <typename... Rest>
+  void fill(char* pos, size_t branchIndex, String&& first, Rest&&... rest);
+
+  template <typename... Params>
+  static StringTree concat(Params&&... params);
+  static StringTree&& concat(StringTree&& param) { return kj::mv(param); }
+
+  template <typename T>
+  static inline size_t flatSize(const T& t) { return t.size(); }
+  static inline size_t flatSize(String&& s) { return 0; }
+  static inline size_t flatSize(StringTree&& s) { return 0; }
+
+  template <typename T>
+  static inline size_t branchCount(const T& t) { return 0; }
+  static inline size_t branchCount(String&& s) { return 1; }
+  static inline size_t branchCount(StringTree&& s) { return 1; }
+
+  template <typename... Params>
+  friend StringTree strTree(Params&&... params);
+};
+
+inline StringTree&& KJ_STRINGIFY(StringTree&& tree) { return kj::mv(tree); }
+inline const StringTree& KJ_STRINGIFY(const StringTree& tree) { return tree; }
+
+inline StringTree KJ_STRINGIFY(Array<StringTree>&& trees) { return StringTree(kj::mv(trees), ""); }
+
+template <typename... Params>
+StringTree strTree(Params&&... params);
+// Build a StringTree by stringifying the given parameters and concatenating the results.
+// If any of the parameters stringify to StringTree rvalues, they will be incorporated as
+// branches to avoid a copy.
+
+// =======================================================================================
+// Inline implementation details
+
+namespace _ {  // private
+
+template <typename... Rest>
+char* fill(char* __restrict__ target, const StringTree& first, Rest&&... rest) {
+  // Make str() work with stringifiers that return StringTree by patching fill().
+
+  first.flattenTo(target);
+  return fill(target + first.size(), kj::fwd<Rest>(rest)...);
+}
+
+template <typename T> constexpr bool isStringTree() { return false; }
+template <> constexpr bool isStringTree<StringTree>() { return true; }
+
+inline StringTree&& toStringTreeOrCharSequence(StringTree&& tree) { return kj::mv(tree); }
+inline StringTree toStringTreeOrCharSequence(String&& str) { return StringTree(kj::mv(str)); }
+
+template <typename T>
+inline auto toStringTreeOrCharSequence(T&& value)
+    -> decltype(toCharSequence(kj::fwd<T>(value))) {
+  static_assert(!isStringTree<Decay<T>>(),
+      "When passing a StringTree into kj::strTree(), either pass it by rvalue "
+      "(use kj::mv(value)) or explicitly call value.flatten() to make a copy.");
+
+  return toCharSequence(kj::fwd<T>(value));
+}
+
+}  // namespace _ (private)
+
+struct StringTree::Branch {
+  size_t index;
+  // Index in `text` where this branch should be inserted.
+
+  StringTree content;
+};
+
+template <typename Func>
+void StringTree::visit(Func&& func) const {
+  size_t pos = 0;
+  for (auto& branch: branches) {
+    if (branch.index > pos) {
+      func(text.slice(pos, branch.index));
+      pos = branch.index;
+    }
+    branch.content.visit(func);
+  }
+  if (text.size() > pos) {
+    func(text.slice(pos, text.size()));
+  }
+}
+
+inline void StringTree::fill(char* pos, size_t branchIndex) {
+  KJ_IREQUIRE(pos == text.end() && branchIndex == branches.size(),
+              kj::str(text.end() - pos, ' ', branches.size() - branchIndex).cStr());
+}
+
+template <typename First, typename... Rest>
+void StringTree::fill(char* pos, size_t branchIndex, First&& first, Rest&&... rest) {
+  pos = _::fill(pos, kj::fwd<First>(first));
+  fill(pos, branchIndex, kj::fwd<Rest>(rest)...);
+}
+
+template <typename... Rest>
+void StringTree::fill(char* pos, size_t branchIndex, StringTree&& first, Rest&&... rest) {
+  branches[branchIndex].index = pos - text.begin();
+  branches[branchIndex].content = kj::mv(first);
+  fill(pos, branchIndex + 1, kj::fwd<Rest>(rest)...);
+}
+
+template <typename... Rest>
+void StringTree::fill(char* pos, size_t branchIndex, String&& first, Rest&&... rest) {
+  branches[branchIndex].index = pos - text.begin();
+  branches[branchIndex].content = StringTree(kj::mv(first));
+  fill(pos, branchIndex + 1, kj::fwd<Rest>(rest)...);
+}
+
+template <typename... Params>
+StringTree StringTree::concat(Params&&... params) {
+  StringTree result;
+  result.size_ = _::sum({params.size()...});
+  result.text = heapString(
+      _::sum({StringTree::flatSize(kj::fwd<Params>(params))...}));
+  result.branches = heapArray<StringTree::Branch>(
+      _::sum({StringTree::branchCount(kj::fwd<Params>(params))...}));
+  result.fill(result.text.begin(), 0, kj::fwd<Params>(params)...);
+  return result;
+}
+
+template <typename... Params>
+StringTree strTree(Params&&... params) {
+  return StringTree::concat(_::toStringTreeOrCharSequence(kj::fwd<Params>(params))...);
+}
+
+}  // namespace kj
+
+#endif  // KJ_STRING_TREE_H_