Add NL Writer #30

Templates, inline C++

CMakeLists.txt

@@ -454,16 +454,24 @@ check_cxx_source_compiles("
   int main() {}" MP_VARIADIC_TEMPLATES)
 
 # Option BUILD_EXAMPLES
-option(BUILD_EXAMPLES "Build nl-example" ON)
+option(BUILD_EXAMPLES "Build examples: nl reader, nl writer" ON)
 
+# Build NLReader example
 if (MP_VARIADIC_TEMPLATES AND BUILD_EXAMPLES)
   message(STATUS
-    "Building nl-example. Set -DBUILD_EXAMPLES=off to switch off.")
-  add_executable(nl-example src/nl-example.cc)
-  add_to_folder(${MP_FOLDER_PREFIX}util nl-example)
-  target_link_libraries(nl-example mp)
+    "Building nl-reader-example. Set -DBUILD_EXAMPLES=off to switch off.")
+  add_executable(nl-reader-example examples/nl-reader-example.cc)
+  add_to_folder(${MP_FOLDER_PREFIX}util nl-reader-example)
+  target_link_libraries(nl-reader-example mp)
 endif ()
 
+# Build NLWriter2 example
+if (BUILD_EXAMPLES)
+  message(STATUS
+    "Building NLWriter2 example. Set -DBUILD_EXAMPLES=off to switch off.")
+  add_subdirectory(nl-writer2)
+endif()
+
 option(BUILD_DOC "Build documentation" ON)
 if(BUILD_DOC)
   add_subdirectory(doc)

doc/source/components.rst

@@ -12,13 +12,12 @@ on :ref:`driver-setups`.
 
 .. _NL-SOL-files:
 
-NL and SOL files
-----------------
+Reading NL and writing SOL files
+-----------------------------------
 
 Any AMPL solver driver currenlty needs to input
 an NL file and report results in a SOL file.
-AMPL might add in-memory model communication for efficiency,
-which would be provided via the
+The details are taken care of in the
 :ref:`recommended driver setup <driver-recommended-setup>`.
 However, a :ref:`minimal driver setup <driver-minimal-setup>` might address the
 corresponding APIs directly, as described below.
@@ -131,6 +130,25 @@ A standalone .sol file writer could be implemented by parameterizing the
 templates by minimal implementations of the `mp::BasicSolver` and
 `mp::ProblemBuilder` interfaces.
 
+
+.. _write-nl-read-sol:
+
+Writing NL and reading SOL files
+------------------------------------
+
+For modeling systems and applications using AMPL solvers,
+MP provides a library to write NL and read SOL files.
+The library is zero-overhead: it does not store the model,
+nor does it require any intermediate objects to represent
+model information.
+
+The API is provided by classes `mp::NLSOL`, `mp::NLWriter2`,
+`mp::NLHandler2`, `mp::SOLReader2`, `mp::SOLHandler2`.
+See
+`example </~https://github.com/ampl/mp/blob/develop/nl-writer2/examples/nlsol_ex.cc>`_
+solving a small non-linear model.
+
+
 .. _recommended-driver-logic:
 
 Recommended driver logic

doc/source/index.rst

@@ -7,6 +7,9 @@ new AMPL solver drivers. It provides type-safe and flexible interfaces
 suitable for linear and mixed-integer, non-linear, and
 Constraint Programming solvers. 
 
+Moreover, MP library provides
+a :ref:`lightweight NL writer <write-nl-read-sol>`.
+
 MP replaces the previous
 `AMPL Solver Library`__ for solvers not requiring automatic differentiation.
 It is implemented in C++, parts of the API are exported in C.
@@ -46,7 +49,8 @@ The documentation is divided in two sections:
   * :ref:`library-intro` shows instructions for downloading, installing and building the library
   * :ref:`howto` illustrates how to get familiar with the framework and how to quickly obtain the
     boilerplate code necessary to develop a new solver driver
-  * :ref:`components` shows the main components of the framework
+  * :ref:`components` shows the main components of the framework,
+    including NL reader and writer API
   * :ref:`howto-test` illustrates how to execute tests during development
   * :ref:`cppreference` contains the reference to all the classes in the framework 
 

nl-writer2/CMakeLists.txt

@@ -0,0 +1,32 @@
+cmake_minimum_required(VERSION 3.10)
+
+project(NLWriter2)
+
+
+set(CMAKE_CXX_STANDARD 11)
+set(CMAKE_CXX_STANDARD_REQUIRED True)
+
+
+set(NLW2_DIR ${CMAKE_CURRENT_SOURCE_DIR})
+set(NLW2_LIB_FILES
+        ${NLW2_DIR}/src/nl-writer2.cc
+        ${NLW2_DIR}/src/nl-utils2.cc
+        ${NLW2_DIR}/src/dtoa.c)
+
+# Create library
+set(NLW2_LIB_NAME "nlw2")
+add_library(${NLW2_LIB_NAME} STATIC ${NLW2_LIB_FILES})
+target_include_directories(
+    ${NLW2_LIB_NAME} PUBLIC ${NLW2_DIR}/include)
+
+if (MSVC)               ## Set the same as for your parent project
+##  target_compile_options(
+##      ${NLW2_LIB_NAME} PRIVATE ${AMPL_MSVC_COMPILE_OPTIONS})
+endif()
+
+# NLW2 example
+add_executable(nl-writer-example
+            ${NLW2_DIR}/examples/nlsol_ex.cc)
+target_include_directories(nl-writer-example PUBLIC
+            ${NLW2_DIR}/include)
+target_link_libraries(nl-writer-example ${NLW2_LIB_NAME})

nl-writer2/README.md

@@ -0,0 +1,3 @@
+A lightweight AMPL NL file writer and SOL file reader.
+
+See mp.ampl.com.

nl-writer2/examples/nlsol_ex.cc

@@ -0,0 +1,55 @@
+/**
+ * Example using NLWriter2 and SOLReader2
+ * to write NL file, execute solver, and read SOL file.
+ *
+ */
+
+#include <cstdlib>
+
+#include "nlsol_ex_mdl.h"
+#include "nlsol_ex_nl.h"
+#include "nlsol_ex_sol.h"
+
+#include "mp/nlsol.h"
+#include "mp/nl-writer2.h"
+#include "mp/nl-writer2.hpp"
+#include "mp/sol-reader2.h"
+#include "mp/sol-reader2.hpp"
+
+/// Invoke:
+///   <this_exe> ipopt ["outlev=1 timelim=500" [text [filestub]]]
+int main(int argc, const char* const* argv) {
+  if (argc<2) {
+    printf("%s\n",
+           "AMPL NL writer example.\n"
+           "Usage:\n"
+           "  <this_exe> <solver> [\"<solver_options>\" [binary/text [<stub>]]],\n\n"
+           "where <solver> is ipopt, gurobi, minos, ...;\n"
+           "binary/text is the NL format (default: binary.)\n"
+           "Examples:\n"
+           "  <this_exe> ipopt \"\" text /tmp/stub\n"
+           "  <this_exe> gurobi \"nonconvex=2 funcpieces=-2 funcpieceratio=1e-4\"");
+    exit(0);
+  }
+  std::string solver = (argc>1) ? argv[1] : "minos";
+  std::string sopts = (argc>2) ? argv[2] : "";
+  bool binary = (argc<=3) || std::strcmp("text", argv[3]);
+  std::string stub = (argc>4) ? argv[4] : "stub";
+
+  ExampleModel emdl;
+  ExampleNLFeeder2 nlf(emdl, binary);
+  ExampleSOLHandler2 esolh(emdl);
+  mp::NLUtils utils;
+
+  mp::NLSOL<ExampleNLFeeder2, ExampleSOLHandler2>
+    nlsol(nlf, esolh, utils);
+  nlsol.SetSolver(solver);
+  nlsol.SetSolverOptions(sopts);
+  if (!nlsol.Solve(stub)) {
+    printf("%s\n", nlsol.GetErrorMessage());
+    exit(EXIT_FAILURE);
+  }
+  esolh.PrintSolution(stub);
+
+  return 0;
+}