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/*
* Copyright (C) 2015 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef ART_CMDLINE_TOKEN_RANGE_H_
#define ART_CMDLINE_TOKEN_RANGE_H_
#include <assert.h>
#include <algorithm>
#include <memory>
#include <string>
#include <vector>
#include "android-base/strings.h"
namespace art {
// A range of tokens to make token matching algorithms easier.
//
// We try really hard to avoid copying and store only a pointer and iterators to the
// interiors of the vector, so a typical copy constructor never ends up doing a deep copy.
// It is up to the user to play nice and not to mutate the strings in-place.
//
// Tokens are only copied if a mutating operation is performed (and even then only
// if it *actually* mutates the token).
struct TokenRange {
// Short-hand for a vector of strings. A single string and a token is synonymous.
using TokenList = std::vector<std::string>;
// Copying-from-vector constructor.
explicit TokenRange(const TokenList& token_list)
: token_list_(new TokenList(token_list)),
begin_(token_list_->begin()),
end_(token_list_->end())
{}
// Copying-from-iterator constructor
template <typename ForwardIterator>
TokenRange(ForwardIterator it_begin, ForwardIterator it_end)
: token_list_(new TokenList(it_begin, it_end)),
begin_(token_list_->begin()),
end_(token_list_->end())
{}
#if 0
// Copying-from-vector constructor.
TokenRange(const TokenList& token_list ATTRIBUTE_UNUSED,
TokenList::const_iterator it_begin,
TokenList::const_iterator it_end)
: token_list_(new TokenList(it_begin, it_end)),
begin_(token_list_->begin()),
end_(token_list_->end()) {
assert(it_begin >= token_list.begin());
assert(it_end <= token_list.end());
}
#endif
// Copying from char array constructor, convertings into tokens (strings) along the way.
TokenRange(const char* token_list[], size_t length)
: token_list_(new TokenList(&token_list[0], &token_list[length])),
begin_(token_list_->begin()),
end_(token_list_->end())
{}
// Non-copying move-from-vector constructor. Takes over the token vector.
explicit TokenRange(TokenList&& token_list)
: token_list_(new TokenList(std::forward<TokenList>(token_list))),
begin_(token_list_->begin()),
end_(token_list_->end())
{}
// Non-copying constructor. Retain reference to existing list of tokens.
TokenRange(const std::shared_ptr<TokenList>& token_list,
TokenList::const_iterator it_begin,
TokenList::const_iterator it_end)
: token_list_(token_list),
begin_(it_begin),
end_(it_end) {
assert(it_begin >= token_list->begin());
assert(it_end <= token_list->end());
}
// Non-copying copy constructor.
TokenRange(const TokenRange&) = default;
// Non-copying move constructor.
TokenRange(TokenRange&&) = default;
// Non-copying constructor. Retains reference to an existing list of tokens, with offset.
explicit TokenRange(const std::shared_ptr<TokenList>& token_list)
: token_list_(token_list),
begin_(token_list_->begin()),
end_(token_list_->end())
{}
// Iterator type for begin() and end(). Guaranteed to be a RandomAccessIterator.
using iterator = TokenList::const_iterator;
// Iterator type for const begin() and const end(). Guaranteed to be a RandomAccessIterator.
using const_iterator = iterator;
// Create a token range by splitting a string. Each separator gets their own token.
// Since the separator are retained as tokens, it might be useful to call
// RemoveToken afterwards.
static TokenRange Split(const std::string& string, std::initializer_list<char> separators) {
TokenList new_token_list;
std::string tok;
for (auto&& c : string) {
for (char sep : separators) {
if (c == sep) {
// We spotted a separator character.
// Push back everything before the last separator as a new token.
// Push back the separator as a token.
if (!tok.empty()) {
new_token_list.push_back(tok);
tok = "";
}
new_token_list.push_back(std::string() + sep);
} else {
// Build up the token with another character.
tok += c;
}
}
}
if (!tok.empty()) {
new_token_list.push_back(tok);
}
return TokenRange(std::move(new_token_list));
}
// A RandomAccessIterator to the first element in this range.
iterator begin() const {
return begin_;
}
// A RandomAccessIterator to one past the last element in this range.
iterator end() const {
return end_;
}
// The size of the range, i.e. how many tokens are in it.
size_t Size() const {
return std::distance(begin_, end_);
}
// Are there 0 tokens in this range?
bool IsEmpty() const {
return Size() > 0;
}
// Look up a token by it's offset.
const std::string& GetToken(size_t offset) const {
assert(offset < Size());
return *(begin_ + offset);
}
// Does this token range equal the other range?
// Equality is defined as having both the same size, and
// each corresponding token being equal.
bool operator==(const TokenRange& other) const {
if (this == &other) {
return true;
}
if (Size() != other.Size()) {
return false;
}
return std::equal(begin(), end(), other.begin());
}
// Look up the token at the requested index.
const std::string& operator[](int index) const {
assert(index >= 0 && static_cast<size_t>(index) < Size());
return *(begin() + index);
}
// Does this current range start with the other range?
bool StartsWith(const TokenRange& other) const {
if (this == &other) {
return true;
}
if (Size() < other.Size()) {
return false;
}
auto& smaller = Size() < other.Size() ? *this : other;
auto& greater = Size() < other.Size() ? other : *this;
return std::equal(smaller.begin(), smaller.end(), greater.begin());
}
// Remove all characters 'c' from each token, potentially copying the underlying tokens.
TokenRange RemoveCharacter(char c) const {
TokenList new_token_list(begin(), end());
bool changed = false;
for (auto&& token : new_token_list) {
auto it = std::remove_if(token.begin(), token.end(), [&](char ch) {
if (ch == c) {
changed = true;
return true;
}
return false;
});
token.erase(it, token.end());
}
if (!changed) {
return *this;
}
return TokenRange(std::move(new_token_list));
}
// Remove all tokens matching this one, potentially copying the underlying tokens.
TokenRange RemoveToken(const std::string& token) {
return RemoveIf([&](const std::string& tok) { return tok == token; });
}
// Discard all empty tokens, potentially copying the underlying tokens.
TokenRange DiscardEmpty() const {
return RemoveIf([](const std::string& token) { return token.empty(); });
}
// Create a non-copying subset of this range.
// Length is trimmed so that the Slice does not go out of range.
TokenRange Slice(size_t offset, size_t length = std::string::npos) const {
assert(offset < Size());
if (length != std::string::npos && offset + length > Size()) {
length = Size() - offset;
}
iterator it_end;
if (length == std::string::npos) {
it_end = end();
} else {
it_end = begin() + offset + length;
}
return TokenRange(token_list_, begin() + offset, it_end);
}
// Try to match the string with tokens from this range.
// Each token is used to match exactly once (after which the next token is used, and so on).
// The matching happens from left-to-right in a non-greedy fashion.
// If the currently-matched token is the wildcard, then the new outputted token will
// contain as much as possible until the next token is matched.
//
// For example, if this == ["a:", "_", "b:] and "_" is the match string, then
// MatchSubstrings on "a:foob:" will yield: ["a:", "foo", "b:"]
//
// Since the string matching can fail (e.g. ["foo"] against "bar"), then this
// function can fail, in which cause it will return null.
std::unique_ptr<TokenRange> MatchSubstrings(const std::string& string,
const std::string& wildcard) const {
TokenList new_token_list;
size_t wildcard_idx = std::string::npos;
size_t string_idx = 0;
// Function to push all the characters matched as a wildcard so far
// as a brand new token. It resets the wildcard matching.
// Empty wildcards are possible and ok, but only if wildcard matching was on.
auto maybe_push_wildcard_token = [&]() {
if (wildcard_idx != std::string::npos) {
size_t wildcard_length = string_idx - wildcard_idx;
std::string wildcard_substr = string.substr(wildcard_idx, wildcard_length);
new_token_list.push_back(std::move(wildcard_substr));
wildcard_idx = std::string::npos;
}
};
for (iterator it = begin(); it != end(); ++it) {
const std::string& tok = *it;
if (tok == wildcard) {
maybe_push_wildcard_token();
wildcard_idx = string_idx;
continue;
}
size_t next_token_idx = string.find(tok);
if (next_token_idx == std::string::npos) {
// Could not find token at all
return nullptr;
} else if (next_token_idx != string_idx && wildcard_idx == std::string::npos) {
// Found the token at a non-starting location, and we weren't
// trying to parse the wildcard.
return nullptr;
}
new_token_list.push_back(string.substr(next_token_idx, tok.size()));
maybe_push_wildcard_token();
string_idx += tok.size();
}
size_t remaining = string.size() - string_idx;
if (remaining > 0) {
if (wildcard_idx == std::string::npos) {
// Some characters were still remaining in the string,
// but it wasn't trying to match a wildcard.
return nullptr;
}
}
// If some characters are remaining, the rest must be a wildcard.
string_idx += remaining;
maybe_push_wildcard_token();
return std::make_unique<TokenRange>(std::move(new_token_list));
}
// Do a quick match token-by-token, and see if they match.
// Any tokens with a wildcard in them are only matched up until the wildcard.
// If this is true, then the wildcard matching later on can still fail, so this is not
// a guarantee that the argument is correct, it's more of a strong hint that the
// user-provided input *probably* was trying to match this argument.
//
// Returns how many tokens were either matched (or ignored because there was a
// wildcard present). 0 means no match. If the size() tokens are returned.
size_t MaybeMatches(const TokenRange& token_list, const std::string& wildcard) const {
auto token_it = token_list.begin();
auto token_end = token_list.end();
auto name_it = begin();
auto name_end = end();
size_t matched_tokens = 0;
while (token_it != token_end && name_it != name_end) {
// Skip token matching when the corresponding name has a wildcard in it.
const std::string& name = *name_it;
size_t wildcard_idx = name.find(wildcard);
if (wildcard_idx == std::string::npos) { // No wildcard present
// Did the definition token match the user token?
if (name != *token_it) {
return matched_tokens;
}
} else {
std::string name_prefix = name.substr(0, wildcard_idx);
// Did the user token start with the up-to-the-wildcard prefix?
if (!StartsWith(*token_it, name_prefix)) {
return matched_tokens;
}
}
++token_it;
++name_it;
++matched_tokens;
}
// If we got this far, it's either a full match or the token list was too short.
return matched_tokens;
}
// Flatten the token range by joining every adjacent token with the separator character.
// e.g. ["hello", "world"].join('$') == "hello$world"
std::string Join(char separator) const {
TokenList tmp(begin(), end());
return android::base::Join(tmp, separator);
// TODO: Join should probably take an offset or iterators
}
private:
static bool StartsWith(const std::string& larger, const std::string& smaller) {
if (larger.size() >= smaller.size()) {
return std::equal(smaller.begin(), smaller.end(), larger.begin());
}
return false;
}
template <typename TPredicate>
TokenRange RemoveIf(const TPredicate& predicate) const {
// If any of the tokens in the token lists are empty, then
// we need to remove them and compress the token list into a smaller one.
bool remove = false;
for (auto it = begin_; it != end_; ++it) {
auto&& token = *it;
if (predicate(token)) {
remove = true;
break;
}
}
// Actually copy the token list and remove the tokens that don't match our predicate.
if (remove) {
auto token_list = std::make_shared<TokenList>(begin(), end());
TokenList::iterator new_end =
std::remove_if(token_list->begin(), token_list->end(), predicate);
token_list->erase(new_end, token_list->end());
assert(token_list_->size() > token_list->size() && "Nothing was actually removed!");
return TokenRange(token_list);
}
return *this;
}
const std::shared_ptr<std::vector<std::string>> token_list_;
const iterator begin_;
const iterator end_;
};
} // namespace art
#endif // ART_CMDLINE_TOKEN_RANGE_H_