ENH: Added displayDocOptions for default behaviour when no arg specified

applications/utilities/miscellaneous/foamHelp/helpTypes/helpBoundary/helpBoundary.C

@@ -179,6 +179,13 @@ void Foam::helpTypes::helpBoundary::execute
             << "-field option must be specified when using the -fixedValue "
             << "option" << exit(FatalError);
     }
+    else
+    {
+        // TODO: strip scoping info if present?
+        // e.g. conditions with leading "compressible::" will not be found
+        // ".*[fF]vPatchField.*" + className + ".*"
+        displayDocOptions(".*[fF]vPatchField.*", false);
+    }
 }
 
 

applications/utilities/miscellaneous/foamHelp/helpTypes/helpFunctionObject/helpFunctionObject.C

@@ -78,6 +78,10 @@ void Foam::helpTypes::helpFunctionObject::execute
     {
         displayDoc(function, ".*[fF]unctionObject.*", true);
     }
+    else
+    {
+        displayDocOptions(".*[fF]unctionObject.*", true);
+    }
 }
 
 

applications/utilities/miscellaneous/foamHelp/helpTypes/helpType/helpType.C

@@ -37,6 +37,53 @@ namespace Foam
 
 // * * * * * * * * * * * * Protected Member Functions  * * * * * * * * * * * //
 
+void Foam::helpType::displayDocOptions
+(
+    const string& searchStr,
+    const bool exactMatch
+) const
+{
+    const dictionary& docDict = debug::controlDict().subDict("Documentation");
+    List<fileName> docDirs(docDict.lookup("doxyDocDirs"));
+
+    label i = -1;
+    forAll(docDirs, dirI)
+    {
+        if (isDir(docDirs[dirI].expand()))
+        {
+            i = dirI;
+            break;
+        }
+    }
+
+    if (i != -1)
+    {
+        Info<< "Found doxygen help in " << docDirs[i].c_str() << nl << endl;
+
+        string docBrowser = getEnv("FOAM_DOC_BROWSER");
+        if (docBrowser.empty())
+        {
+            docDict.lookup("docBrowser") >> docBrowser;
+        }
+
+        doxygenXmlParser parser
+        (
+            docDirs[i]/"../DTAGS",
+            "tagfile",
+            searchStr,
+            exactMatch
+        );
+
+        Info<< "Valid types include:" << nl << SortableList<word>(parser.toc());
+    }
+    else
+    {
+        Info<< "No Doxygen sources found under search paths: "
+            << docDirs << endl;
+    }
+}
+
+
 void Foam::helpType::displayDoc
 (
     const word& className,

applications/utilities/miscellaneous/foamHelp/helpTypes/helpType/helpType.H

@@ -58,6 +58,13 @@ class helpType
 
 protected:
 
+    //- Display the list of documentation options
+    void displayDocOptions
+    (
+        const string& searchStr,
+        const bool exactMatch
+    ) const;
+
     //- Display the help documentation in a browser
     void displayDoc
     (