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//===--- Trie.h - Trie with terms as keys ---------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2021 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
#ifndef SWIFT_RQM_TRIE_H
#define SWIFT_RQM_TRIE_H
#include "llvm/ADT/MapVector.h"
#include "Histogram.h"
namespace swift {
namespace rewriting {
enum class MatchKind {
Shortest,
Longest
};
template<typename ValueType, MatchKind Kind>
class Trie {
public:
struct Node;
struct Entry {
std::optional<ValueType> Value;
Node *Children = nullptr;
};
struct Node {
llvm::SmallMapVector<Symbol, Entry, 1> Entries;
};
private:
/// We never delete nodes, except for when the entire trie is torn down.
std::vector<Node *> Nodes;
/// The root is stored directly.
Node Root;
public:
void updateHistograms(Histogram &stats, Histogram &rootStats) const {
for (const auto &node : Nodes)
stats.add(node->Entries.size());
rootStats.add(Root.Entries.size());
}
/// Delete all entries from the trie.
void clear() {
Root.Entries.clear();
for (auto iter = Nodes.rbegin(); iter != Nodes.rend(); ++iter) {
auto *node = *iter;
delete node;
}
Nodes.clear();
}
~Trie() {
clear();
}
/// Insert an entry with the key given by the range [begin, end).
/// Returns the old value if the trie already had an entry for this key;
/// this is actually an invariant violation, but we can produce a better
/// assertion further up the stack.
template <typename Iter>
std::optional<ValueType> insert(Iter begin, Iter end, ValueType value) {
assert(begin != end);
auto *node = &Root;
while (true) {
auto &entry = node->Entries[*begin];
++begin;
if (begin == end) {
auto oldValue = entry.Value;
entry.Value = value;
return oldValue;
}
if (entry.Children == nullptr) {
entry.Children = new Node();
Nodes.push_back(entry.Children);
}
node = entry.Children;
}
}
/// Find the shortest or longest prefix of the range given by [begin,end),
/// depending on whether the Kind template parameter was bound to
/// MatchKind::Shortest or MatchKind::Longest.
template <typename Iter>
std::optional<ValueType> find(Iter begin, Iter end) const {
assert(begin != end);
auto *node = &Root;
std::optional<ValueType> bestMatch = std::nullopt;
while (true) {
auto found = node->Entries.find(*begin);
++begin;
if (found == node->Entries.end())
return bestMatch;
const auto &entry = found->second;
if (entry.Value) {
if (Kind == MatchKind::Shortest)
return entry.Value;
bestMatch = entry.Value;
}
if (begin == end)
return bestMatch;
if (entry.Children == nullptr)
return bestMatch;
node = entry.Children;
}
}
/// Find all keys that begin with the given symbol. Fn must take a single
/// argument of type ValueType.
template<typename Fn>
void findAll(Symbol symbol, Fn fn) const {
auto found = Root.Entries.find(symbol);
if (found == Root.Entries.end())
return;
const auto &entry = found->second;
if (entry.Value)
fn(*entry.Value);
if (entry.Children == nullptr)
return;
visitChildren(entry.Children, fn);
}
/// Find all keys that either match a prefix of [begin,end), or where
/// [begin,end) matches a prefix of the key. Fn must take a single
/// argument of type ValueType.
template<typename Iter, typename Fn>
void findAll(Iter begin, Iter end, Fn fn) const {
assert(begin != end);
auto *node = &Root;
while (true) {
auto found = node->Entries.find(*begin);
++begin;
if (found == node->Entries.end())
return;
const auto &entry = found->second;
if (entry.Value)
fn(*entry.Value);
if (entry.Children == nullptr)
return;
node = entry.Children;
if (begin == end) {
visitChildren(node, fn);
return;
}
}
}
private:
/// Depth-first traversal of all children of the given node, including
/// the node itself. Fn must take a single argument of type ValueType.
template<typename Fn>
void visitChildren(const Node *node, Fn fn) const {
for (const auto &pair : node->Entries) {
const auto &entry = pair.second;
if (entry.Value)
fn(*entry.Value);
if (entry.Children)
visitChildren(entry.Children, fn);
}
}
};
} // end namespace rewriting
} // end namespace swift
#endif
|
