upload android base code part3

android/art/cmdline/token_range.h

@@ -0,0 +1,427 @@
+/*
+ * 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 <vector>
+#include <string>
+#include <algorithm>
+#include <memory>
+
+#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(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(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::unique_ptr<TokenRange>(new 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_