From 3ae1f6c19533f24964166ec373e739c82919ae75 Mon Sep 17 00:00:00 2001
From: Gard Spreemann <gard.spreemann@epfl.ch>
Date: Wed, 24 Oct 2018 13:07:52 +0200
Subject: Proper option parsing.

---
 src/CMakeLists.txt |  2 +-
 src/main.cpp       | 24 ++++++++++----
 src/options.cpp    | 97 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 src/options.hpp    | 17 ++++++++++
 4 files changed, 132 insertions(+), 8 deletions(-)
 create mode 100644 src/options.cpp
 create mode 100644 src/options.hpp

diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index ecff6e3..f6002e7 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -1,2 +1,2 @@
-add_executable(lapdog main.cpp)
+add_executable(lapdog main.cpp options.cpp)
 target_link_libraries(lapdog ${MPI_LIBRARIES} ${PETSC_LIBRARIES} ${SLEPC_LIBRARIES})
diff --git a/src/main.cpp b/src/main.cpp
index 8d09427..d1dc8b1 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -5,13 +5,22 @@
 #include <slepceps.h>
 #include <petscmat.h>
 
+#include "options.hpp"
+
 int main(int argc, char ** argv)
 {
   SlepcInitialize(&argc, &argv, NULL, NULL);
 
-  std::string infile(argv[1]);
-  std::string outfile_vals(argv[2]); 
-  std::string outfile_vecs(argv[3]);
+  Options opts;
+  int optresult = parse_opts(argc, argv, opts);
+  if (optresult)
+  {
+    SlepcFinalize();
+    if (optresult == 2)
+      exit(0);
+    else
+      exit(1);
+  }
   
   PetscMPIInt mpi_rank;
   PetscMPIInt mpi_size;
@@ -19,15 +28,16 @@ int main(int argc, char ** argv)
   MPI_Comm_size(PETSC_COMM_WORLD, &mpi_size);
   
   PetscErrorCode err;
+
   Mat L;
   err = MatCreate(PETSC_COMM_WORLD, &L); CHKERRQ(err);
   err = MatSetFromOptions(L); CHKERRQ(err);
 
   PetscViewer viewer;
-  err = PetscViewerBinaryOpen(PETSC_COMM_WORLD, infile.c_str(), FILE_MODE_READ, &viewer); CHKERRQ(err);
+  err = PetscViewerBinaryOpen(PETSC_COMM_WORLD, opts.infile.c_str(), FILE_MODE_READ, &viewer); CHKERRQ(err);
   err = MatLoad(L, viewer); CHKERRQ(err);
   err = MatAssemblyBegin(L, MAT_FINAL_ASSEMBLY); CHKERRQ(err);
-  err = MatAssemblyEnd(L, MAT_FINAL_ASSEMBLY); CHKERRQ(err);
+  err = MatAssemblyEnd(L, MAT_FINAL_ASSEMBLY); CHKERRQ(err); 
 
   PetscInt m;
   PetscInt n;
@@ -86,8 +96,8 @@ int main(int argc, char ** argv)
   std::ofstream ofs_vecs;
   if (mpi_rank == 0)
   {
-    ofs_vals.open(outfile_vals, std::ios::out);
-    ofs_vecs.open(outfile_vecs, std::ios::out);
+    ofs_vals.open(opts.outfile_vals, std::ios::out);
+    ofs_vecs.open(opts.outfile_vecs, std::ios::out);
   }
     
   for (PetscInt i = 0; i < num_ev; i++)
diff --git a/src/options.cpp b/src/options.cpp
new file mode 100644
index 0000000..a52a0bc
--- /dev/null
+++ b/src/options.cpp
@@ -0,0 +1,97 @@
+#include <string>
+#include <iostream>
+
+#include "options.hpp"
+
+void print_usage(const std::string & invocation)
+{
+  std::cerr << "Usage:" << std::endl;
+  std::cerr << invocation << " " << usage_args << std::endl;
+}
+
+void print_help(const std::string & invocation)
+{
+  print_usage(invocation);
+  std::cerr << "FIXME: Write help." << std::endl;
+}
+
+int parse_opts(int argc, char ** argv, Options & opts)
+{
+  std::string invocation(argv[0]);
+  
+  for (int i = 1; i < argc; ++i)
+  {
+    std::string arg(argv[i]);
+
+    if (arg == std::string("-h") || arg == std::string("--help"))
+    {
+      print_help(invocation);
+      return 2;
+    }
+
+    else if (arg == std::string("-l") || arg == std::string("--laplacian"))
+    {
+      if (i+1 < argc && argv[i+1][0] != '-')
+        opts.infile = std::string(argv[++i]);
+      else
+      {
+        std::cerr << "Missing argument to --laplacian." << std::endl;
+        print_usage(invocation);
+        return 1;
+      }
+    }
+
+    else if (arg == std::string("--vals"))
+    {
+       if (i+1 < argc && argv[i+1][0] != '-')
+        opts.outfile_vals = std::string(argv[++i]);
+      else
+      {
+        std::cerr << "Missing argument to --vals." << std::endl;
+        print_usage(invocation);
+        return 1;
+      }
+    }
+
+    else if (arg == std::string("--vecs"))
+    {
+       if (i+1 < argc && argv[i+1][0] != '-')
+        opts.outfile_vecs = std::string(argv[++i]);
+      else
+      {
+        std::cerr << "Missing argument to --vecs." << std::endl;
+        print_usage(invocation);
+        return 1;
+      }
+    }
+
+    else
+    {
+      std::cout << "The argument \"" << arg << "\" will be dealt with by PETSc/SLEPc if they understand it. Otherwise it will be silently ignored." << std::endl;
+    }
+  }
+
+  // Begin options validation. 
+  if (opts.infile.empty())
+  {
+    std::cerr << "Missing Laplacian file." << std::endl;
+    print_usage(invocation);
+    return 1;
+  }
+   
+  if (opts.outfile_vecs.empty())
+  {
+    std::cerr << "Missing output eigenvectors file." << std::endl;
+    print_usage(invocation);
+    return 1;
+  }
+  if (opts.outfile_vals.empty())
+  {
+    std::cerr << "Missing output eigenvalues file." << std::endl;
+    print_usage(invocation);
+    return 1;
+  }
+  // End validation.
+  
+  return 0;
+}
diff --git a/src/options.hpp b/src/options.hpp
new file mode 100644
index 0000000..05a6ee5
--- /dev/null
+++ b/src/options.hpp
@@ -0,0 +1,17 @@
+#pragma once
+
+#include <string>
+
+typedef struct Options
+{
+  std::string infile;
+  std::string outfile_vals;
+  std::string outfile_vecs;
+} Options;
+
+int parse_opts(int argc, char ** argv, Options & opts);
+
+void print_usage(const std::string & invocation);
+void print_help(const std::string & invocation);
+
+static const std::string usage_args("--laplacian|-l file --vals file --vecs file [-h|--help] [PETSc/SLEPc options]");
-- 
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