--Internal tool to rebuild an abs path to be relative to another abs …

…path.
facebookresearch · May 21, 2024 · 03bc117 · 03bc117
1 parent 2561215
commit 03bc117
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Showing 3 changed files with 75 additions and 2 deletions.
diff --git a/src/esp/io/Io.cpp b/src/esp/io/Io.cpp
@@ -46,6 +46,47 @@ std::string normalizePath(const std::string& srcPath) {
   return normalizePath(filteredPath);
 }  // normalizePath
 
+std::string getPathRelativeToAbsPath(const std::string& toRelPath,
+                                     const std::string& absPath) {
+  std::string result = "";
+  const char* delim = "/";
+
+  std::vector<std::string> absDirs =
+                               Cr::Utility::String::split(absPath, delim[0]),
+                           relDirs =
+                               Cr::Utility::String::split(toRelPath, delim[0]);
+  auto absIter = absDirs.cbegin();
+  auto relIter = relDirs.cbegin();
+
+  // find where both paths diverge - skip shared path components
+  while (*relIter == *absIter && absIter != absDirs.cend() &&
+         relIter != relDirs.cend()) {
+    ++relIter;
+    ++absIter;
+  }
+
+  // Add back-path components for each directory in abspath not found in
+  // toRelPaath
+  while (absIter != absDirs.cend()) {
+    if (*absIter != *absDirs.crbegin()) {
+      Cr::Utility::formatInto(result, result.size(), "..{}", delim);
+    }
+    ++absIter;
+  }
+  std::string scratch = "";
+  // build relative path in scratch
+  while (relIter != relDirs.cend()) {
+    if (*relIter == *relDirs.crbegin()) {
+      Cr::Utility::formatInto(result, result.size(), "{}{}", scratch,
+                              *relDirs.crbegin());
+    } else {
+      Cr::Utility::formatInto(scratch, scratch.size(), "{}{}", *relIter, delim);
+    }
+    ++relIter;
+  }
+  return result;
+}  // getPathRelativeToAbsPath
+
 std::vector<std::string> globDirs(const std::string& pattern) {
   // Check for ellipsis, if so process here.
   glob_t glob_result;

diff --git a/src/esp/io/Io.h b/src/esp/io/Io.h
@@ -30,6 +30,16 @@ std::string changeExtension(const std::string& file, const std::string& ext);
  */
 std::string normalizePath(const std::string& srcPath);
 
+/**
+ * @brief This function will find the relative path of @p toRelPath relative to
+ * @p absPath
+ * @param toRelPath The absolute path to be converted to relative
+ * @param absPath The absolute path the conversion should be relative to
+ * @return the relative path of @p toRelPath relative to @p absPath
+ */
+std::string getPathRelativeToAbsPath(const std::string& toRelPath,
+                                     const std::string& absPath);
+
 /**
  * @brief This function will perform [glob-based pattern matching]
  * (https://en.wikipedia.org/wiki/Glob_(programming)) to find and return all the

diff --git a/src/tests/IOTest.cpp b/src/tests/IOTest.cpp
@@ -28,6 +28,7 @@ const std::string dataDir = Corrade::Utility::Path::join(SCENE_DATASETS, "../");
 struct IOTest : Cr::TestSuite::Tester {
   explicit IOTest();
   void fileReplaceExtTest();
+  void absToRelativePathConverison();
   void testEllipsisFilter();
   void parseURDF();
   void testJson();
@@ -52,8 +53,8 @@ struct IOTest : Cr::TestSuite::Tester {
 };
 
 IOTest::IOTest() {
-  addTests({&IOTest::fileReplaceExtTest, &IOTest::testEllipsisFilter,
-            &IOTest::parseURDF, &IOTest::testJson,
+  addTests({&IOTest::fileReplaceExtTest, &IOTest::absToRelativePathConverison,
+            &IOTest::testEllipsisFilter, &IOTest::parseURDF, &IOTest::testJson,
             &IOTest::testJsonBuiltinTypes, &IOTest::testJsonStlTypes,
             &IOTest::testJsonMagnumTypes, &IOTest::testJsonEspTypes,
             &IOTest::testJsonUserType});
@@ -137,6 +138,27 @@ void IOTest::testEllipsisFilter() {
 
 }  // IOTest::testEllipsisFilter
 
+void IOTest::absToRelativePathConverison() {
+  // Test conversion of an absolute path to a path relative to another path.
+  // Path to be relative to
+  const std::string absPathTarget = "/aa/bb/cc/dd/ee/ff/gg/";
+
+  // Path to convert
+  std::string absPathToConvert = "/aa/bb/cc/dd/xx/yy/zz/";
+  // Result of conversion
+  std::string relPathToBaseTarget =
+      esp::io::getPathRelativeToAbsPath(absPathToConvert, absPathTarget);
+
+  CORRADE_COMPARE(relPathToBaseTarget, "../../../xx/yy/zz/");
+
+  absPathToConvert = "/aa/bb/cc/../dd/xx/yy/zz/";
+  relPathToBaseTarget =
+      esp::io::getPathRelativeToAbsPath(absPathToConvert, absPathTarget);
+
+  CORRADE_COMPARE(relPathToBaseTarget, "../../../../../dd/xx/yy/zz/");
+
+}  // IOTest::absToRelativePathConverison
+
 void IOTest::parseURDF() {
   const std::string iiwaURDF = Cr::Utility::Path::join(
       TEST_ASSETS, "urdf/kuka_iiwa/model_free_base.urdf");