Add new Compilers.UAutoDetect unit to project

Implements a static class that can detect and register Delphi compilers
present on the user's system that are not yet registered with CodeSnip.

Author: delphidabbler

Src/CodeSnip.dpr

@@ -370,7 +370,8 @@ uses
   UXMLDocConsts in 'UXMLDocConsts.pas',
   UXMLDocHelper in 'UXMLDocHelper.pas',
   UXMLDocumentEx in 'UXMLDocumentEx.pas',
-  FmDeleteUserDBDlg in 'FmDeleteUserDBDlg.pas' {DeleteUserDBDlg};
+  FmDeleteUserDBDlg in 'FmDeleteUserDBDlg.pas' {DeleteUserDBDlg},
+  Compilers.UAutoDetect in 'Compilers.UAutoDetect.pas';
 
 // Include resources
 {$Resource ExternalObj.tlb}       // Type library file

Src/CodeSnip.dproj

@@ -575,6 +575,7 @@
 			<DCCReference Include="FmDeleteUserDBDlg.pas">
 				<Form>DeleteUserDBDlg</Form>
 			</DCCReference>
+			<DCCReference Include="Compilers.UAutoDetect.pas"/>
 			<None Include="CodeSnip.todo"/>
 			<BuildConfiguration Include="Base">
 				<Key>Base</Key>

Src/Compilers.UAutoDetect.pas

@@ -0,0 +1,115 @@
+{
+ * This Source Code Form is subject to the terms of the Mozilla Public License,
+ * v. 2.0. If a copy of the MPL was not distributed with this file, You can
+ * obtain one at https://mozilla.org/MPL/2.0/
+ *
+ * Copyright (C) 2022, Peter Johnson (gravatar.com/delphidabbler).
+ *
+ * Implements a static class that can detect and register Delphi compilers
+ * present on the user's system that are not yet registered with CodeSnip.
+}
+
+
+unit Compilers.UAutoDetect;
+
+interface
+
+uses
+  Compilers.UGlobals,
+  Compilers.UCompilers,
+  UBaseObjects;
+
+type
+  TCompilerAutoDetect = class(TNoConstructObject)
+  public
+    type
+      TCallback = reference to procedure (Compiler: ICompiler);
+  strict private
+    class procedure DoCallback(const Callback: TCallback;
+      Compiler: ICompiler);
+  public
+    class procedure RegisterCompilers(Compilers: ICompilers;
+      const Callback: TCallback = nil); overload;
+    class procedure RegisterSpecificCompilers(AllCompilers: ICompilers;
+      const RegList: TCompilerList; const Callback: TCallback = nil);
+    class procedure ListRegisterableCompilers(Compilers: ICompilers;
+      const Registerable: TCompilerList);
+  end;
+
+implementation
+
+uses
+  SysUtils;
+
+{ TCompilerAutoDetect }
+
+class procedure TCompilerAutoDetect.DoCallback(
+  const Callback: TCallback; Compiler: ICompiler);
+begin
+  if Assigned(Callback) then
+    Callback(Compiler);
+end;
+
+class procedure TCompilerAutoDetect.ListRegisterableCompilers(
+  Compilers: ICompilers; const Registerable: TCompilerList);
+var
+  Compiler: ICompiler;
+begin
+  Registerable.Clear;
+  for Compiler in Compilers do
+  begin
+    if not Supports(Compiler, ICompilerAutoDetect) then
+      Continue; // compiler can't be auto-detected/registered
+    if not (Compiler as ICompilerAutoDetect).IsInstalled then
+      Continue; // compiler is not installed on the user's system
+    if Compiler.IsAvailable then
+      Continue; // compiler installed & already registered for use by CodeSnip
+    if not (Compiler as ICompilerAutoDetect).GetCanAutoInstall then
+      Continue; // user has excluded this compiler from being auto-registered
+    // We get here then we have an installed, un-registered, auto-detectable
+    // compiler with permission to register
+    Registerable.Add(Compiler);
+  end;
+end;
+
+class procedure TCompilerAutoDetect.RegisterSpecificCompilers(
+  AllCompilers: ICompilers; const RegList: TCompilerList;
+  const Callback: TCallback);
+var
+  Compiler: ICompiler;
+begin
+  for Compiler in AllCompilers do
+  begin
+    if RegList.IndexOf(Compiler) >= 0 then
+    begin
+      Assert(Supports(Compiler, ICompilerAutoDetect), ClassName +
+        '.RegisterCompilers: Compiler does not support ICompilerAutoDetect');
+      if (Compiler as ICompilerAutoDetect).DetectExeFile then
+        DoCallback(Callback, Compiler);
+    end;
+  end;
+end;
+
+class procedure TCompilerAutoDetect.RegisterCompilers(Compilers: ICompilers;
+  const Callback: TCallback);
+var
+  Registerable: TCompilerList;
+  Compiler: ICompiler;
+begin
+  Registerable := TCompilerList.Create;
+  try
+    ListRegisterableCompilers(Compilers, Registerable);
+    for Compiler in Registerable do
+    begin
+      Assert(Supports(Compiler, ICompilerAutoDetect), ClassName +
+        '.RegisterCompilers: Compiler does not support ICompilerAutoDetect');
+      if (Compiler as ICompilerAutoDetect).DetectExeFile then
+        DoCallback(Callback, Compiler);
+    end;
+  finally
+    Registerable.Free;
+  end;
+end;
+
+end.
+