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feat: finish string strip (maybe)

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- add Trie Tree for string strip op.
- finish string strip but it may still buggy (though i have tested it)
This commit is contained in:
yyc12345
2025-09-28 16:13:06 +08:00
parent 190beeed58
commit cc1ce5bb04
3 changed files with 164 additions and 55 deletions
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153
src/yycc/string/op.cpp
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@ -1,4 +1,7 @@
#include "op.hpp"
#include <map>
#include <memory>
#include <iterator>
#include <type_traits>
#include <algorithm>
#include <stdexcept>
@ -172,7 +175,7 @@ namespace yycc::string::op {
class CodePointIterator {
public:
using iterator_category = std::forward_iterator_tag;
using iterator_category = std::input_iterator_tag;
using value_type = std::u8string_view;
using difference_type = std::ptrdiff_t;
using pointer = const std::u8string_view*;
@ -274,39 +277,149 @@ namespace yycc::string::op {
}
};
#pragma endregion
#pragma region Trie Tree Node
struct TrieTreeNode {
TrieTreeNode() : is_end(false), children() {}
bool is_end; ///< Whether this node is a viable end.
std::map<char8_t, std::unique_ptr<TrieTreeNode>> children; ///< The children node.
};
#pragma endregion
#pragma region Trie Tree
class TrieTree {
private:
std::unique_ptr<TrieTreeNode> root;
public:
TrieTree() : root(std::make_unique<TrieTreeNode>()) {
// Do not accept root element always (no empty string).
root->is_end = false;
}
/**
* @brief Insert new words in trie tree.
* @details
* The reason why use iterator, rather than string view, is that in strip function, we may need insert a string backwardly,
* so using string view reverse iterator and iterator argument can easily achieve this goal without any more burden.
* @tparam InputIt The iterator following input iterator name convention.
* @param[in] first The head of iterator.
* @param[in] last The tail of iterator.
*/
template<std::input_iterator InputIt>
requires std::is_same_v<std::iter_value_t<InputIt>, char8_t>
void insert(InputIt first, InputIt last) {
// prevent empty string
if (first == last) return;
// insert item
TrieTreeNode* node = root.get();
for (auto it = first; it != last; ++it) {
char8_t c = *it;
if (node->children.find(c) == node->children.end()) {
node->children[c] = std::make_unique<TrieTreeNode>();
}
node = node->children[c].get();
}
node->is_end = true;
}
/**
* @brief Check whether given words has prefix stored in this trie tree.
* @details Same reason for using iterator as function argument.
* @tparam InputIt The iterator following input iterator name convention.
* @param[in] first The head of iterator.
* @param[in] last The tail of iterator.
* @return \c std::nullopt if there is no match, otherwise the length of matched prefix.
*/
template<std::input_iterator InputIt>
requires std::is_same_v<std::iter_value_t<InputIt>, char8_t>
std::optional<size_t> search(InputIt first, InputIt last) {
TrieTreeNode* node = root.get();
size_t cnt = 0;
for (auto it = first; it != last; ++it) {
char8_t c = *it;
auto finder = node->children.find(c);
if (finder == node->children.end()) {
// There is no more matching, break the while.
break;
} else {
// There are more matching item, find next one.
node = finder->second.get();
++cnt;
}
}
// YYC MARK:
// There is a fatal bug for Trie Tree, but it doesn't matter with our usage scenario.
//
// Assume there is two string "ab" and "abcd". If user give "abc",
// we should match it with "ab" prefix, but this function will return there is no match.
// However, this is impossible for UTF8 sequence.
// There is no possibility that two UTF8 sequence, indicating two different Unicode code point respectively,
// has the same prefix and different length. Because their first byte must be different,
// the first byte indicate the length of sequence.
//
// This result also can be proven for suffix,
// because first byte must not be equal to any other continuation bytes.
// It is impossible that they have same "ab".
//
// So it is safe for our usage scenario although this bug is presented.
// check whether current is valid end.
// if it is, return the count of prefix, otherwise return nothing.
if (node->is_end) {
return cnt;
} else {
return std::nullopt;
}
}
};
#pragma endregion
template<bool bDoLeft, bool bDoRight>
void internal_strip(std::u8string& strl, const std::u8string_view& words) {
std::u8string_view internal_strip(const std::u8string_view& strl, const std::u8string_view& words) {
std::optional<TrieTree> prefix, suffix;
if constexpr (bDoLeft) prefix = TrieTree();
if constexpr (bDoRight) suffix = TrieTree();
CodePoint code_point(words);
for (const auto& seq : code_point) {
if (prefix.has_value()) prefix.value().insert(seq.begin(), seq.end());
if (suffix.has_value()) suffix.value().insert(seq.rbegin(), seq.rend());
}
std::u8string_view striped = strl;
if constexpr (bDoLeft) {
while (auto cnt = prefix.value().search(striped.begin(), striped.end())) {
striped = striped.substr(cnt.value());
}
}
if constexpr (bDoRight) {
while (auto cnt = suffix.value().search(striped.rbegin(), striped.rend())) {
striped = striped.substr(0, striped.size() - cnt.value());
}
}
void strip(std::u8string& strl, const std::u8string_view& words) {}
std::u8string to_strip(const std::u8string_view& strl, const std::u8string_view& words) {
std::u8string rv(strl);
strip(rv, words);
return rv;
return striped;
}
void lstrip(std::u8string& strl, const std::u8string_view& words) {}
std::u8string to_lstrip(const std::u8string_view& strl, const std::u8string_view& words) {
std::u8string rv(strl);
lstrip(rv, words);
return rv;
std::u8string_view strip(const std::u8string_view& strl, const std::u8string_view& words) {
return internal_strip<true, true>(strl, words);
}
void rstrip(std::u8string& strl, const std::u8string_view& words) {}
std::u8string_view lstrip(const std::u8string_view& strl, const std::u8string_view& words) {
return internal_strip<true, false>(strl, words);
}
std::u8string to_rstrip(const std::u8string_view& strl, const std::u8string_view& words) {
std::u8string rv(strl);
rstrip(rv, words);
return rv;
std::u8string_view rstrip(const std::u8string_view& strl, const std::u8string_view& words) {
return internal_strip<false, true>(strl, words);
}
#pragma endregion

35
src/yycc/string/op.hpp
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@ -145,46 +145,25 @@ namespace yycc::string::op {
* @brief Remove leading and trailing whitespace from the string.
* @param[in,out] strl The string to be stripped.
* @param[in] words The characters to be stripped.
* @return The string view with leading and trailing whitespace removed.
*/
void strip(std::u8string& strl, const std::u8string_view& words);
/**
* @brief Return a copy of the string with leading and trailing whitespace removed.
* @param[in] strl The string to be stripped.
* @param[in] words The characters to be stripped.
* @return The copy of the string with leading and trailing whitespace removed.
*/
std::u8string to_strip(const std::u8string_view& strl, const std::u8string_view& words);
std::u8string_view strip(const std::u8string_view& strl, const std::u8string_view& words);
/**
* @brief Remove leading whitespace from the string.
* @param[in,out] strl The string to be stripped.
* @param[in] words The characters to be stripped.
* @return The string view with leading whitespace removed.
*/
void lstrip(std::u8string& strl, const std::u8string_view& words);
/**
* @brief Return a copy of the string with leading whitespace removed.
* @param[in] strl The string to be stripped.
* @param[in] words The characters to be stripped.
* @return The copy of the string with leading whitespace removed.
*/
std::u8string to_lstrip(const std::u8string_view& strl, const std::u8string_view& words);
std::u8string_view lstrip(const std::u8string_view& strl, const std::u8string_view& words);
/**
* @brief Remove trailing whitespace from the string.
* @param[in,out] strl The string to be stripped.
* @param[in] words The characters to be stripped.
* @return The string view with trailing whitespace removed.
*/
void rstrip(std::u8string& strl, const std::u8string_view& words);
/**
* @brief Return a copy of the string with trailing whitespace removed.
* @param[in] strl The string to be stripped.
* @param[in] words The characters to be stripped.
* @return The copy of the string with trailing whitespace removed.
*/
std::u8string to_rstrip(const std::u8string_view& strl, const std::u8string_view& words);
std::u8string_view rstrip(const std::u8string_view& strl, const std::u8string_view& words);
#pragma endregion
@ -195,7 +174,7 @@ namespace yycc::string::op {
*/
class LazySplitIterator {
public:
using iterator_category = std::forward_iterator_tag;
using iterator_category = std::input_iterator_tag;
using value_type = std::u8string_view;
using difference_type = std::ptrdiff_t;
using pointer = const std::u8string_view*;

29
testbench/yycc/string/op.cpp
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@ -74,22 +74,39 @@ namespace yycctest::string::op {
TEST(StringOp, Strip) {
// Normal strip
{
auto rv = OP::to_strip(u8" \taaa\n", u8" \t\r\n");
auto rv = OP::strip(u8" \taaa\n", u8" \t\r\n");
EXPECT_EQ(rv, u8"aaa");
}
{
auto rv = OP::lstrip(u8" \taaa\n", u8" \t\r\n");
EXPECT_EQ(rv, u8"aaa\n");
}
{
auto rv = OP::rstrip(u8" \taaa\n", u8" \t\r\n");
EXPECT_EQ(rv, u8" \taaa");
}
// Special strip
{
auto rv = OP::to_strip(u8"<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>aaa<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>", u8"<EFBFBD><EFBFBD><EFBFBD><EFBFBD>");
auto rv = OP::strip(u8"啊啊啊aaaあああ", u8"啊あ");
EXPECT_EQ(rv, u8"aaa");
}
{
auto rv = OP::to_strip(u8"<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>aaa<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>", u8"<EFBFBD><EFBFBD>");
EXPECT_EQ(rv, u8"aaa<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>");
auto rv = OP::strip(u8"啊啊啊aaaあああ", u8"啊");
EXPECT_EQ(rv, u8"aaaあああ");
}
{
auto rv = OP::to_strip(u8"<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>aaa<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>", u8"<EFBFBD><EFBFBD>");
EXPECT_EQ(rv, u8"<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>aaa");
auto rv = OP::strip(u8"啊啊啊aaaあああ", u8"あ");
EXPECT_EQ(rv, u8"啊啊啊aaa");
}
// Possible buggy strip.
// We use 2 UTF8 code points introduced following:
// U+00AA (UTF-8: C2 AA)
// U+1002A (UTF-8 : F0 90 80 AA)
{
auto rv = OP::rstrip(u8"aaa\u00AA", u8"\u00AA\U0001002A");
EXPECT_EQ(rv, u8"aaa");
}
}