mex: unlink

Author: scivision

+stdlib/unlink.m

@@ -0,0 +1,18 @@
+%% UNLINK delete file or empty directory
+% requires: mex
+%
+% Matlab or GNU Octave delete() has trouble with not being able to delete
+% open files on Windows, this function overcomes that.
+% Also, this function returns boolean success status, which factory
+% delete() does not.
+%
+%%% Inputs
+% * path (1,1) string
+%%% Outputs
+% * ok (1,1) logical
+%
+% This function is written in C++ using STL <filesystem>
+
+function unlink(~)
+error("buildtool mex")
+end

buildfile.m

@@ -95,6 +95,7 @@ function publishTask(context)
 
 
 srcs = {
+"src/unlink.cpp", ...
 ["src/is_admin.cpp", "src/admin_fs.cpp"] ...
 "src/is_char_device.cpp", ...
 ["src/parent.cpp", "src/parent_fs.cpp", normal], ...

octave_build.m

@@ -20,6 +20,11 @@ function octave_build(overwrite)
 fullfile(d, "relative_to.cpp"), ...
 };
 
+% need this for loop below
+unlink_bin = fullfile(t, "unlink.oct");
+if ~isfile(unlink_bin)
+  mkoctfile(fullfile(d, "unlink.cpp"), ["-I", inc], "--output", unlink_bin)
+end
 
 %% build C+ Octave
 for s = srcs
@@ -32,6 +37,8 @@ function octave_build(overwrite)
   end
 
   disp(["mkoctfile: ", src, " => ", bin])
-  delete(bin)
+  if isfile(bin)
+    assert(stdlib.unlink(bin))
+  end
   mkoctfile(src, ["-I", inc], "--output", bin)
 end

src/octave/unlink.cpp

@@ -0,0 +1,19 @@
+#include <octave/oct.h>
+
+#include <string>
+#include <filesystem>
+
+
+DEFUN_DLD (unlink, args, nargout,
+           "delete file or empty directory")
+{
+  if (args.length() != 1){
+    octave_stdout << "Oct: One input required\n";
+    return octave_value(false);
+  }
+
+  std::error_code ec;
+  bool y = std::filesystem::remove(args(0).string_value(), ec) && !ec;
+
+  return octave_value(y);
+}

src/unlink.cpp

@@ -0,0 +1,41 @@
+#include "mex.hpp"
+#include "mexAdapter.hpp"
+
+#include <vector>
+#include <memory>
+
+#include <filesystem>
+#include <system_error>
+
+
+class MexFunction : public matlab::mex::Function {
+public:
+  void operator()(matlab::mex::ArgumentList outputs, matlab::mex::ArgumentList inputs) {
+// boilerplate engine & ArrayFactory setup
+    std::shared_ptr<matlab::engine::MATLABEngine> matlabEng = getEngine();
+    matlab::data::ArrayFactory factory;
+// wrangle inputs
+    std::string in;
+
+    if (inputs.size() != 1) {
+      matlabEng->feval(u"error", 0,
+        std::vector<matlab::data::Array>({ factory.createScalar("Mex: One input required") }));
+    }
+    if ((inputs[0].getType() == matlab::data::ArrayType::MATLAB_STRING && inputs[0].getNumberOfElements() == 1)){
+        matlab::data::TypedArray<matlab::data::MATLABString> stringArr = inputs[0];
+        in = stringArr[0];
+    } else if (inputs[0].getType() == matlab::data::ArrayType::CHAR){
+        matlab::data::CharArray charArr = inputs[0];
+        in.assign(charArr.begin(), charArr.end());
+    } else {
+        matlabEng->feval(u"error", 0,
+        std::vector<matlab::data::Array>({ factory.createScalar("Mex: First input must be a scalar string or char vector") }));
+    }
+
+// actual function algorithm / computation
+    std::error_code ec;
+    bool y = std::filesystem::remove(in, ec) && !ec;
+
+    outputs[0] = factory.createScalar<bool>(y);
+  }
+};

test/TestMex.m

@@ -5,7 +5,6 @@
 function test_is_char_device(tc)
 tc.applyFixture(matlab.unittest.fixtures.CurrentFolderFixture(".."))
 % matlab exist() doesn't work for MEX detection with ".." leading path
-
 tc.assumeEqual(exist("+stdlib/is_char_device", "file"), 3)
 
 % /dev/stdin may not be available on CI systems
@@ -21,11 +20,47 @@ function test_is_char_device(tc)
 
 function test_is_admin(tc)
 tc.applyFixture(matlab.unittest.fixtures.CurrentFolderFixture(".."))
-
 tc.assumeEqual(exist("+stdlib/is_admin", "file"), 3)
+
 tc.verifyClass(stdlib.is_admin(), "logical")
 end
 
+
+function test_unlink_file(tc)
+tc.applyFixture(matlab.unittest.fixtures.CurrentFolderFixture(".."))
+tc.assumeEqual(exist("+stdlib/unlink", "file"), 3)
+
+d = tc.createTemporaryFolder();
+
+f = tempname(d);
+
+tc.verifyFalse(stdlib.unlink(f), "should not succeed at unlinking non-existant path")
+
+tc.assumeTrue(stdlib.touch(f))
+tc.verifyTrue(stdlib.unlink(f), "failed to unlink file")
+end
+
+
+function test_unlink_empty_dir(tc)
+tc.applyFixture(matlab.unittest.fixtures.CurrentFolderFixture(".."))
+tc.assumeEqual(exist("+stdlib/unlink", "file"), 3)
+
+d = tc.createTemporaryFolder();
+
+tc.verifyTrue(stdlib.unlink(d), "failed to unlink empty directory")
+end
+
+
+function test_unlink_recursive(tc)
+tc.applyFixture(matlab.unittest.fixtures.CurrentFolderFixture(".."))
+tc.assumeEqual(exist("+stdlib/unlink", "file"), 3)
+
+d = tc.createTemporaryFolder();
+
+tc.assumeTrue(stdlib.touch(fullfile(d, "junk.txt")))
+tc.verifyFalse(stdlib.unlink(d), "should not unlink directory recursively")
+end
+
 end
 
 end