cmGeneratorFileSet: Support different mappings

The full path of a file in a file set can be broken into groups like
`<base>/[<sub>/]<name>`, where `<base>` is the base directory and
`<name>` is the file name without any directory components. Existing
users evaluate file set files as a mapping from `<rel>` to the full
path. However, CPS export needs files grouped by base directory, and
cares about the composition of `<rel>` and `<name>`. To facilitate
obtaining this information in a more useful form, refactor how we
extract file set files to allow the user to pass a lambda 'handler' for
each file, which has the base directory, full path, and path relative to
the base directory available. (We already obtained `<rel>` from the
latter, so while this technically means the existing use needs to do
additional work, in practice it just means the call to get `<rel>` moves
to the lambda.)

Because there are many existing users that would need to duplicate the
lambda, the old methods are retained as-is, although this does result in
minor code duplication between `GetFiles` (which calls the overload of
`EvaluateFileEntry` which fills the old file map) and `EvaluateFiles`
(which is essentially `GetFiles`, but accepts a user-provided 'handler'
lambda rather than directly producing a file map).

Source/cmGeneratorFileSet.cxx

@@ -498,8 +498,7 @@ std::vector<std::string> cmGeneratorFileSet::EvaluateDirectoryEntries(
 }
 
 void cmGeneratorFileSet::EvaluateFileEntry(
-  std::vector<std::string> const& dirs,
-  std::map<std::string, std::vector<std::string>>& filesPerDir,
+  std::vector<std::string> const& dirs, EvaluateFileEntryFunction handler,
   std::unique_ptr<cmCompiledGeneratorExpression> const& cge,
   cm::GenEx::Context const& context, cmGeneratorTarget const* target,
   cmGeneratorExpressionDAGChecker* dagChecker) const
@@ -510,18 +509,17 @@ void cmGeneratorFileSet::EvaluateFileEntry(
       file = cmStrCat(context.LG->GetCurrentSourceDirectory(), '/', file);
     }
     auto collapsedFile = cmSystemTools::CollapseFullPath(file);
-    bool found = false;
-    std::string relDir;
+    std::string baseDir;
+    std::string relPath;
     for (auto const& dir : dirs) {
       auto collapsedDir = cmSystemTools::CollapseFullPath(dir);
       if (cmSystemTools::IsSubDirectory(collapsedFile, collapsedDir)) {
-        found = true;
-        relDir = cmSystemTools::GetParentDirectory(
-          cmSystemTools::RelativePath(collapsedDir, collapsedFile));
+        baseDir = collapsedDir;
+        relPath = cmSystemTools::RelativePath(collapsedDir, collapsedFile);
         break;
       }
     }
-    if (!found) {
+    if (baseDir.empty()) {
       std::ostringstream e;
       e << "File:\n  " << file
         << "\nmust be in one of the file set's base directories:";
@@ -533,10 +531,24 @@ void cmGeneratorFileSet::EvaluateFileEntry(
       return;
     }
 
-    filesPerDir[relDir].push_back(file);
+    handler(std::move(baseDir), std::move(relPath), std::move(file));
   }
 }
 
+void cmGeneratorFileSet::EvaluateFileEntry(
+  std::vector<std::string> const& dirs, FileMap& filesPerDir,
+  std::unique_ptr<cmCompiledGeneratorExpression> const& cge,
+  cm::GenEx::Context const& context, cmGeneratorTarget const* target,
+  cmGeneratorExpressionDAGChecker* dagChecker) const
+{
+  auto handler = [&filesPerDir](std::string&& /*baseDir*/,
+                                std::string&& relPath, std::string&& file) {
+    std::string relDir = cmSystemTools::GetParentDirectory(relPath);
+    filesPerDir[std::move(relDir)].emplace_back(std::move(file));
+  };
+  this->EvaluateFileEntry(dirs, handler, cge, context, target, dagChecker);
+}
+
 namespace {
 bool EntryIsContextSensitive(
   std::unique_ptr<cmCompiledGeneratorExpression> const& cge)
@@ -577,10 +589,9 @@ std::pair<std::vector<std::string>, bool> cmGeneratorFileSet::GetDirectories(
   return std::make_pair(std::move(directories), contextSensitive);
 }
 
-std::pair<std::map<std::string, std::vector<std::string>>, bool>
-cmGeneratorFileSet::GetFiles(cm::GenEx::Context const& context,
-                             cmGeneratorTarget const* target,
-                             cmGeneratorExpressionDAGChecker* dagChecker) const
+std::pair<cmGeneratorFileSet::FileMap, bool> cmGeneratorFileSet::GetFiles(
+  cm::GenEx::Context const& context, cmGeneratorTarget const* target,
+  cmGeneratorExpressionDAGChecker* dagChecker) const
 {
   auto directories = this->GetDirectories(context, target, dagChecker);
 
@@ -596,3 +607,20 @@ cmGeneratorFileSet::GetFiles(cm::GenEx::Context const& context,
 
   return std::make_pair(std::move(files), contextSensitive);
 }
+
+bool cmGeneratorFileSet::EvaluateFiles(
+  cm::GenEx::Context const& context, cmGeneratorTarget const* target,
+  EvaluateFileEntryFunction callback,
+  cmGeneratorExpressionDAGChecker* dagChecker) const
+{
+  auto directories = this->GetDirectories(context, target, dagChecker);
+
+  auto const& fileEntries = this->CompileFileEntries();
+  for (auto const& entry : fileEntries) {
+    this->EvaluateFileEntry(directories.first, callback, entry, context,
+                            target, dagChecker);
+  }
+  return directories.second ||
+    std::any_of(fileEntries.begin(), fileEntries.end(),
+                EntryIsContextSensitive);
+}

Source/cmGeneratorFileSet.h

@@ -4,6 +4,7 @@
 
 #include "cmConfigure.h" // IWYU pragma: keep
 
+#include <functional>
 #include <map>
 #include <memory>
 #include <string>
@@ -79,6 +80,8 @@ public:
     cm::GenEx::Context const& context, cmGeneratorTarget const* target,
     cmGeneratorExpressionDAGChecker* dagChecker = nullptr) const;
 
+  using FileMap = std::map<std::string, std::vector<std::string>>;
+
   // returned value:
   // first: list of directories
   // second: is context sensitive
@@ -88,7 +91,7 @@ public:
   // returned value:
   // first: list of files per directory
   // second: is context sensitive
-  std::pair<std::map<std::string, std::vector<std::string>>, bool> GetFiles(
+  std::pair<FileMap, bool> GetFiles(
     cm::GenEx::Context const& context, cmGeneratorTarget const* target,
     cmGeneratorExpressionDAGChecker* dagChecker = nullptr) const;
 
@@ -103,9 +106,23 @@ public:
     cm::GenEx::Context const& context, cmGeneratorTarget const* target,
     cmGeneratorExpressionDAGChecker* dagChecker = nullptr) const;
 
+  using EvaluateFileEntryFunction =
+    std::function<void(std::string&&, std::string&&, std::string&&)>;
+
+  // returned value: is context sensitive
+  bool EvaluateFiles(
+    cm::GenEx::Context const& context, cmGeneratorTarget const* target,
+    EvaluateFileEntryFunction callback,
+    cmGeneratorExpressionDAGChecker* dagChecker = nullptr) const;
+
   void EvaluateFileEntry(
-    std::vector<std::string> const& dirs,
-    std::map<std::string, std::vector<std::string>>& filesPerDir,
+    std::vector<std::string> const& dirs, EvaluateFileEntryFunction handler,
+    std::unique_ptr<cmCompiledGeneratorExpression> const& cge,
+    cm::GenEx::Context const& context, cmGeneratorTarget const* target,
+    cmGeneratorExpressionDAGChecker* dagChecker = nullptr) const;
+
+  void EvaluateFileEntry(
+    std::vector<std::string> const& dirs, FileMap& filesPerDir,
     std::unique_ptr<cmCompiledGeneratorExpression> const& cge,
     cm::GenEx::Context const& context, cmGeneratorTarget const* target,
     cmGeneratorExpressionDAGChecker* dagChecker = nullptr) const;