Add BufferSearch (from arch-repo-manager) to use it in syncthingtray as well

CMakeLists.txt

@@ -21,6 +21,7 @@ set(HEADER_FILES
     io/binaryreader.h
     io/binarywriter.h
     io/bitreader.h
+    io/buffersearch.h
     io/copy.h
     io/inifile.h
     io/path.h
@@ -49,6 +50,7 @@ set(SRC_FILES
     io/binaryreader.cpp
     io/binarywriter.cpp
     io/bitreader.cpp
+    io/buffersearch.cpp
     io/inifile.cpp
     io/path.cpp
     io/nativefilestream.cpp
@@ -112,8 +114,8 @@ set(META_APP_AUTHOR "Martchus")
 set(META_APP_URL "https://github.com/${META_APP_AUTHOR}/${META_PROJECT_NAME}")
 set(META_APP_DESCRIPTION "Useful C++ classes and routines such as argument parser, IO and conversion utilities")
 set(META_VERSION_MAJOR 5)
-set(META_VERSION_MINOR 10)
-set(META_VERSION_PATCH 6)
+set(META_VERSION_MINOR 11)
+set(META_VERSION_PATCH 0)
 
 # find required 3rd party libraries
 include(3rdParty)

io/buffersearch.cpp

@@ -0,0 +1,80 @@
+#include "./buffersearch.h"
+
+using namespace std;
+
+namespace CppUtilities {
+
+/*!
+ * \class BufferSearch
+ * \brief The BufferSearch struct invokes a callback if an initially given search term occurs in consecutively provided buffers.
+ * \remarks
+ * - The class works without making internal copies of the specified buffers, except for the search result.
+ * - The callback is invoked after the search term has been found and one of the specified termination characters occurred. The
+ *   search result is passed to the callback.
+ * - The "search result" is the data after the last character of the search term and before any of the specified termination
+ *   characters.
+ * - If no termination characters are specified, the callback is invoked directly after the search term occurred (with an empty
+ *   search result).
+ * - If the specified give-up term has occurred, operator() will exit early and the specified callback will not be invoked
+ *   anymore.
+ * - If the callback has been invoked, operator() will exit early and the callback will not be invoked anymore (even if the
+ *   search term occurs again). Call reset() after consuming the result within the callback to continue the search.
+ */
+
+/*!
+ * \brief Processes the specified \a buffer. Invokes the callback according to the remarks mentioned in the class documentation.
+ */
+void BufferSearch::operator()(const char *buffer, std::size_t bufferSize)
+{
+    if (m_hasResult || (!m_giveUpTerm.empty() && m_giveUpTermIterator == m_giveUpTerm.end())) {
+        return;
+    }
+    for (auto i = buffer, end = buffer + bufferSize; i != end; ++i) {
+        const auto currentChar = *i;
+        if (m_searchTermIterator == m_searchTerm.end()) {
+            if (m_terminationChars.empty()) {
+                m_hasResult = true;
+            } else {
+                for (const auto &terminationChar : m_terminationChars) {
+                    if (currentChar == terminationChar) {
+                        m_hasResult = true;
+                        break;
+                    }
+                }
+            }
+            if (m_hasResult) {
+                m_callback(*this, std::move(m_result));
+                return;
+            }
+            m_result += currentChar;
+            continue;
+        }
+        if (currentChar == *m_searchTermIterator) {
+            ++m_searchTermIterator;
+        } else {
+            m_searchTermIterator = m_searchTerm.begin();
+        }
+        if (m_giveUpTerm.empty()) {
+            continue;
+        }
+        if (currentChar == *m_giveUpTermIterator) {
+            ++m_giveUpTermIterator;
+        } else {
+            m_giveUpTermIterator = m_giveUpTerm.begin();
+        }
+    }
+}
+
+/*!
+ * \brief Resets the search to its initial state (assuming no characters of the search term or give-up term have been found yet).
+ */
+void BufferSearch::reset()
+{
+    m_searchTermIterator = m_searchTerm.begin();
+    m_giveUpTermIterator = m_giveUpTerm.begin();
+    m_terminationTermIterator = m_terminationTerm.begin();
+    m_hasResult = false;
+    m_result.clear();
+}
+
+} // namespace CppUtilities

io/buffersearch.h

@@ -0,0 +1,59 @@
+#ifndef IOUTILITIES_BUFFER_SEARCH_H
+#define IOUTILITIES_BUFFER_SEARCH_H
+
+#include "../global.h"
+
+#include <functional>
+#include <string>
+#include <string_view>
+
+namespace CppUtilities {
+
+class CPP_UTILITIES_EXPORT BufferSearch {
+public:
+    using CallbackType = std::function<void(BufferSearch &, std::string &&)>;
+    BufferSearch(std::string_view searchTerm, std::string_view terminationChars, std::string_view giveUpTerm, CallbackType &&callback);
+    void operator()(std::string_view buffer);
+    void operator()(const char *buffer, std::size_t bufferSize);
+    void reset();
+
+private:
+    const std::string_view m_searchTerm;
+    const std::string_view m_terminationChars;
+    const std::string_view m_terminationTerm;
+    const std::string_view m_giveUpTerm;
+    const CallbackType m_callback;
+    std::string_view::const_iterator m_searchTermIterator;
+    std::string_view::const_iterator m_giveUpTermIterator;
+    std::string_view::const_iterator m_terminationTermIterator;
+    std::string m_result;
+    bool m_hasResult;
+};
+
+/*!
+ * \brief Constructs a new BufferSearch. Might be overloaded in the future.
+ */
+inline BufferSearch::BufferSearch(
+    std::string_view searchTerm, std::string_view terminationChars, std::string_view giveUpTerm, CallbackType &&callback)
+    : m_searchTerm(searchTerm)
+    , m_terminationChars(terminationChars)
+    , m_giveUpTerm(giveUpTerm)
+    , m_callback(std::move(callback))
+    , m_searchTermIterator(m_searchTerm.begin())
+    , m_giveUpTermIterator(m_giveUpTerm.begin())
+    , m_terminationTermIterator(m_terminationTerm.begin())
+    , m_hasResult(false)
+{
+}
+
+/*!
+ * \brief Processes the specified \a buffer. Invokes the callback according to the remarks mentioned in the class documentation.
+ */
+inline void BufferSearch::operator()(std::string_view buffer)
+{
+    (*this)(buffer.data(), buffer.size());
+}
+
+} // namespace CppUtilities
+
+#endif // IOUTILITIES_BUFFER_SEARCH_H

tests/iotests.cpp

@@ -7,6 +7,7 @@
 #include "../io/binaryreader.h"
 #include "../io/binarywriter.h"
 #include "../io/bitreader.h"
+#include "../io/buffersearch.h"
 #include "../io/copy.h"
 #include "../io/inifile.h"
 #include "../io/misc.h"
@@ -43,6 +44,7 @@ class IoTests : public TestFixture {
     CPPUNIT_TEST(testBinaryReader);
     CPPUNIT_TEST(testBinaryWriter);
     CPPUNIT_TEST(testBitReader);
+    CPPUNIT_TEST(testBufferSearch);
     CPPUNIT_TEST(testPathUtilities);
     CPPUNIT_TEST(testIniFile);
     CPPUNIT_TEST(testAdvancedIniFile);
@@ -62,6 +64,7 @@ public:
     void testBinaryReader();
     void testBinaryWriter();
     void testBitReader();
+    void testBufferSearch();
     void testPathUtilities();
     void testIniFile();
     void testAdvancedIniFile();
@@ -233,7 +236,7 @@ void IoTests::testBinaryWriter()
 }
 
 /*!
- * \brief Tests the BitReader.
+ * \brief Tests the BitReader class.
  */
 void IoTests::testBitReader()
 {
@@ -259,6 +262,40 @@ void IoTests::testBitReader()
     CPPUNIT_ASSERT_EQUAL(static_cast<std::size_t>(8 * sizeof(testData)), reader.bitsAvailable());
 }
 
+/*!
+ * \brief Tests the BufferSearch class.
+ */
+void IoTests::testBufferSearch()
+{
+    // setup search to test
+    auto expectedResult = std::string();
+    auto hasResult = false;
+    auto bs = BufferSearch("Updated version: ", "\e\n", "Starting build", [&](BufferSearch &, std::string &&result) {
+        CPPUNIT_ASSERT_EQUAL(expectedResult, result);
+        CPPUNIT_ASSERT_MESSAGE("callback only invoked once", !hasResult);
+        hasResult = true;
+    });
+
+    // feed data into the search
+    char buffer[30];
+    bs(buffer, 0);
+    CPPUNIT_ASSERT(!hasResult);
+    std::strcpy(buffer, "Starting Updated");
+    bs(std::string_view(buffer, 16));
+    CPPUNIT_ASSERT(!hasResult);
+    std::strcpy(buffer, " version: some ");
+    bs(buffer, 15);
+    CPPUNIT_ASSERT(!hasResult);
+    expectedResult = "some version number";
+    std::strcpy(buffer, "version number\emore chars");
+    bs(buffer, 25);
+    CPPUNIT_ASSERT(hasResult);
+    hasResult = false;
+    std::strcpy(buffer, "... Starting build ...");
+    bs(buffer, 22);
+    CPPUNIT_ASSERT(!hasResult);
+}
+
 /*!
  * \brief Tests fileName() and removeInvalidChars().
  */