pl_search_cpp

pl_search_cpp is a C++ library that approximates Prolog predicates using a continuation-passing style. It provides a framework for defining and executing Prolog-like predicates, including support for backtracking, choice points, and unification.

Features

• Prolog-like predicates
• Continuation-passing style execution
• Backtracking and choice points
• Unification of terms
• Support for variables, integers, floats, atoms, and lists

Installation

Prerequisites

• C++11 or later
• CMake 3.10 or later

Building the Library

1. Clone the repository:

git clone https://github.com/yourusername/pl_search_cpp.git
cd pl_search_cpp

2. Create a build directory and navigate to it:

mkdir build
cd build

3: Run CMake to configure the project:

cmake ..

4: Build the project:

make

This will build the pl_search library and place it in the lib directory.

Examples

The examples directory contains the following examples of using the library.

• A solver for the SEND+MORE=MONEY puzzle with lots of comments about the approach and code details (send_more_money.cpp).
• An example of a user defined Term type (prolog_list.hpp).
• An implementation of the Prolog append predicate using the above type (append_pred.hpp).
• A main program ( prolog_list.cpp) that exercises the definitions above.
• A Makefile to build the executables.

Documentation

Documentation can be found here docs/index.html

License

This project is licensed under the MIT License - see the LICENSE file for details.

Version History

• 1.4
  • Change from private to protected in term and pred classes to increase flexibility when subclassing. For example, termcolour can now be used in subclasses of various terms.
• 1.3
  • Add an if-then-else predicate.
• 1.2
  • Several (small) code optimizations - improved send_more_money by about 30%
    • dynamic_cast<PInt*>(t.get()) is faster than dynamic_pointer_cast(t)
    • redo PVar::dereference to avoid shared_ptr copies
    • add Term* Term::deref_term() to avoid copying shared_ptr (for internal use)
    • In Var::bind use raw pointer for pointer test
    • change env_stack and trail_stack to use normal pointers
  • Turned on -O2 optimization in cmake - approximately another 10% improvement
• 1.1
  • Fix problems in unify
  • Remove the test_choice method from Pred
  • merge solve into main in send_more_money.cpp for better testing with valgrind
• 1.0
  • Initial release.