lsp-lltl-lib

Low-level Template Library (LLTL) for basic data collections used in LSP Project

This library does not aim to repeat STL. It aims to replace some important parts of STL with generalized templates (generics). Since STL template instantiation may blow up the code with many additional functions, this library tries to economy code space used by collections by generalizing data pointers.

The Paradigm

Let's look at the paradigm by taking std::vector as example.

For STL std::vector<char> and vector<int> are different types, so they will have different instances, so the code:

std::vector<char> a;
std::vector<int> b;

a.push_back('a'); // Instance 1
b.push_back(42); // Instance 2

will instantiate two push_back functions. Moreover, the code will get blown up if these functions will get inlined.

The basic idea is, to generalize std::vector with two instances: a raw container of data structures lsp::lltl::raw_darray and a raw container of pointers lsp::lltl::raw_parray. These data structures are classic 'C' data structures inside and use malloc/free memory allocation instead of new[]/delete[]. That makes the final code exception-safe.

Both raw containers define their template adaptors - lsp::lltl::darray<T> and lsp::lltl::parray<T> which declare inline methods that finally call methods of lsp::lltl::raw_darray and lsp::lltl::raw_parray respectively.

Finally, the code above can be replaced with the following code snippet:

using namespace lsp;

lltl::darray<char> a;
lltl::darray<int> b;

a.push('a'); // Using one of the available instances of lsp::lltl::raw_darray::add()
b.push(42);  // Using the same instance of lsp::lltl::raw_darray::add()

IMPORTANT! Data structures do store plain data and do not call any constructors/destructors to initialize/free data. This responsibility is delegated to the caller code (if not said otherwise).

Also, for automatic managment of objects and lookup, additional interfaces like lsp::lltl::hash_spec, lsp::lltl::compare_spec and lsp::lltl::allocator_spec should be defined.

Library Contents

Available collections:

• lltl::darray - dynamic array of plain data structures of the same type.
• lltl::parray - dynamic array of pointers to any data structure of the same base type.
• lltl::phashset - hash set of pointers, each pointer is managed by the caller.
• lltl::pphash - pointer to pointer hash map, where keys are managed automatically and values are managed by caller.
• lltl::ptrset - set for organize quick storage of raw pointers.
• lltl::bitset - set of bits stored in the optimal for the CPU form for quick data processing and memory economy.

Collection access:

• lltl::iterator - iterator class for sequential data access.

Available inter-process and inter-thread primitive communications:

• lltl::state - object for safe state transfer between Real-time and non-realtime thread.

Data manipulation interfaces:

• lltl::hash_iface - inferface for defining hash function for the object.
• lltl::compare_iface - interface for defining comparison routine for the object.
• lltl::allocator_iface - interface for defining allocation (creating cloned copy) and deallocation of the object.
• lltl::initializer_iface - interface for defining initialization, copying and finalization of in-place stored objects.

Available hashing functions:

• lltl::default_hash_func - default hashing function used for any object if hashing specification for the object is not defined.
• lltl::ptr_hash_func - hashing function for pointers (considering that it uniquely identifies the object the pointer points to).
• lltl::char_hash_func - hashing function for C strings present as char * or const char * types.

Available comparison functions:

• lltl::char_cmp_func - comparison function for C strings present as char * or const char * types.
• lltl::ptr_cmp_func - comparisoin function for pointers (considering that it uniquely identifies the object the pointer points to).

Available allocation functions:

• lltl::char_copy_func - function for copying C strings

Required specifications:

• lltl::hash_spec - specification for computing hash value of the object, required by:
  • lltl::pphash for key object,
  • lltl::phashset for value object
• lltl::compare_spec - specification for comparing two objects, required by:
  • lltl::pphash for key object,
  • lltl::phashset for value object
• lltl::allocator_spec - specification for allocation (creating copy) and deallocation of the object, required by:
  • lltl::pphash for key object

Requirements

The following packages need to be installed for building:

• gcc >= 4.9
• make >= 4.0

Building

To build the library, perform the following commands:

make config # Configure the build
make fetch # Fetch dependencies from Git repository
make
sudo make install

To get more build options, run:

make help

To uninstall library, simply issue:

make uninstall

To clean all binary files, run:

make clean

To clean the whole project tree including configuration files, run:

make prune

Usage

An example of transaction-safe widget creation:

#include <stdlib.h>
#include <lsp-plug.in/lltl/parray.h>


class Widget; // Some widget class

Widget *create(const char *type); // Some abstract factory

using namespace lsp;

bool add_widget(lltl::parray<Widget> &v, const char *type)
{
    Widget *w = create(type);
    if (!w)
        return false;
    if (v.add(w))
        return true;
    
    delete w;
    return false;
}

// Create form and replace all widgets in the passed list with
// new ones
bool create_form(lltl::parray<Widget> &list)
{
    lltl::parray<Widget> v;

    // Create widgets
    bool res = add_widget(v, "label");
    res &= add_widget(v, "edit");
    res &= add_widget(v, "label");
    res &= add_widget(v, "edit");

    // Commit the transaction
    if (res)
        list.swap(v);
    
    // Perform garbage collection
    for(size_t i=0, n=v.size(); i<n; ++i)
    	delete v[i];
    
    return res;
}

SAST Tools

• PVS-Studio - static analyzer for C, C++, C#, and Java code.