Added support for multiple data root paths

AdventOfCode.lpr

@@ -54,7 +54,10 @@ var
   n: Integer;
 begin
   WriteLn('### Advent of Code 2023 ###');
-  engine := TSolverEngine.Create('data');
+  engine := TSolverEngine.Create(TStringArray.Create(
+    'data',
+    ConcatPaths(['..', '..', 'data'])
+  ));
 
   solvers := specialize TList<Integer>.Create;
   if HasOption('p', 'puzzle') then

USolver.pas

@@ -63,13 +63,15 @@ type
 
   TSolverEngine = class
   private
-    FRelativeDataPath: string;
+    FRelativeDataPaths: TStringArray;
   public
-    constructor Create(const ARelativeDataPath: string);
+    constructor Create(constref ARelativeDataPaths: TStringArray);
     procedure ProcessData(const ASolver: ISolver);
     procedure Run(const ASolver: ISolver);
     procedure RunAndFree(const ASolver: ISolver);
-    function GetDataFileName(const ASolver: ISolver): string;
+    function HasValidDataPath(const ASolver: ISolver): Boolean;
+    function TryGetFirstValidDataPath(const ASolver: ISolver; out ODataFilePath: string): Boolean;
+    function GetInvalidDataPathMessage(const ASolver: ISolver): string;
   end;
 
 implementation
@@ -94,19 +96,22 @@ end;
 
 { TSolverEngine }
 
-constructor TSolverEngine.Create(const ARelativeDataPath: string);
+constructor TSolverEngine.Create(constref ARelativeDataPaths: TStringArray);
 begin
-  FRelativeDataPath := ARelativeDataPath;
+  if (ARelativeDataPaths = nil) or (Length(ARelativeDataPaths) = 0) then
+    raise EArgumentOutOfRangeException.Create('Must specify at least one data path.');
+  FRelativeDataPaths := ARelativeDataPaths;
 end;
 
 procedure TSolverEngine.ProcessData(const ASolver: ISolver);
 var
   data: TextFile;
-  s: string;
+  dataFilePath, s: string;
 begin
   ASolver.Init;
 
-  AssignFile(data, GetDataFileName(ASolver));
+  TryGetFirstValidDataPath(ASolver, dataFilePath);
+  AssignFile(data, dataFilePath);
   try
     reset(data);
     while (not EOF(data)) do
@@ -122,22 +127,17 @@ begin
 end;
 
 procedure TSolverEngine.Run(const ASolver: ISolver);
-var
-  fileName: string;
 begin
   WriteLn;
   WriteLn('--- ', ASolver.PuzzleName, ' ---');
-  fileName := GetDataFileName(ASolver);
-  if FileExists(fileName) then
+  if HasValidDataPath(ASolver) then
   begin
     ProcessData(ASolver);
     WriteLn('Part 1: ', ASolver.ResultPart1);
     WriteLn('Part 2: ', ASolver.ResultPart2);
   end
-  else begin
-    WriteLn('Cannot find puzzle input file ''', ExpandFileName(fileName), '''.');
-    WriteLn('Please download the file content from https://adventofcode.com/2023/');
-  end;
+  else
+    WriteLn(GetInvalidDataPathMessage(ASolver));
 end;
 
 procedure TSolverEngine.RunAndFree(const ASolver: ISolver);
@@ -146,9 +146,41 @@ begin
   ASolver.Free;
 end;
 
-function TSolverEngine.GetDataFileName(const ASolver: ISolver): string;
+function TSolverEngine.HasValidDataPath(const ASolver: ISolver): Boolean;
+var
+  s: string;
 begin
-  Result := ConcatPaths([FRelativeDataPath, ASolver.DataFileName]);
+  Result := TryGetFirstValidDataPath(ASolver, s);
+end;
+
+function TSolverEngine.TryGetFirstValidDataPath(const ASolver: ISolver; out ODataFilePath: string): Boolean;
+var
+  path: string;
+begin
+  for path in FRelativeDataPaths do
+  begin
+    ODataFilePath := ConcatPaths([path, ASolver.DataFileName]);
+    if FileExists(ODataFilePath) then
+    begin
+      Result := True;
+      Exit;
+    end;
+  end;
+
+  Result := False;
+  ODataFilePath := '';
+end;
+
+function TSolverEngine.GetInvalidDataPathMessage(const ASolver: ISolver): string;
+var
+  i: Integer;
+begin
+  Result := 'Cannot find puzzle input file '''
+    + ExpandFileName(ConcatPaths([FRelativeDataPaths[0], ASolver.DataFileName]));
+  for i := 1 to Length(FRelativeDataPaths) - 1 do
+    Result := Result + ''', or '''
+      + ExpandFileName(ConcatPaths([FRelativeDataPaths[i], ASolver.DataFileName]));
+  Result := Result + '''. Please download the file content from https://adventofcode.com/2023/';
 end;
 
 end.

tests/UBaseTestCases.pas

@@ -43,14 +43,14 @@ type
     FEngine: TSolverEngine;
     procedure Setup; override;
     procedure TearDown; override;
-    function GetDataPath: string; virtual;
+    function GetDataPaths: TStringArray; virtual;
   end;
 
   { TExampleEngineBaseTest }
 
   TExampleEngineBaseTest = class(TEngineBaseTest)
   protected
-    function GetDataPath: string; override;
+    function GetDataPaths: TStringArray; override;
   end;
 
 implementation
@@ -72,15 +72,10 @@ end;
 { TEngineBaseTest }
 
 procedure TEngineBaseTest.Setup;
-var
-  fileName: string;
 begin
   inherited Setup;
-  FEngine := TSolverEngine.Create(GetDataPath);
-  fileName := FEngine.GetDataFileName(FSolver);
-  AssertTrue('Cannot find puzzle input file ''' + ExpandFileName(fileName) + '''. '
-    + 'Please download the file from https://adventofcode.com/2023/',
-    FileExists(fileName));
+  FEngine := TSolverEngine.Create(GetDataPaths);
+  AssertTrue(FEngine.GetInvalidDataPathMessage(FSolver), FEngine.HasValidDataPath(FSolver));
   FEngine.ProcessData(FSolver);
 end;
 
@@ -90,16 +85,22 @@ begin
   inherited TearDown;
 end;
 
-function TEngineBaseTest.GetDataPath: string;
+function TEngineBaseTest.GetDataPaths: TStringArray;
 begin
-  Result := ConcatPaths(['..', '..', 'bin', 'data']);
+  Result := TStringArray.Create(
+    ConcatPaths(['..', '..', 'bin', 'data']),
+    ConcatPaths(['..', '..', '..', 'data'])
+  );
 end;
 
 { TExampleEngineBaseTest }
 
-function TExampleEngineBaseTest.GetDataPath: string;
+function TExampleEngineBaseTest.GetDataPaths: TStringArray;
 begin
-  Result := 'example_data';
+  Result := TStringArray.Create(
+    ConcatPaths(['..', '..', 'bin', 'data', 'example']),
+    ConcatPaths(['..', '..', '..', 'data', 'example'])
+  );
 end;
 
 end.