Initial check in lib

2026-01-03 18:33:48 +01:00
parent b20cd8e688
commit 5666f85e99
89 changed files with 36370 additions and 1 deletions
@@ -0,0 +1,57 @@
+// ================================================================================================
+// BlockContext stores the information needed when creating an alternative (list of elements).
+// Entering a subrule requires that we save this state as each block of alternatives requires
+// state such as "tail of current alternative."
+// ================================================================================================
+unit dpglib.BlockContext;
+
+interface
+uses
+   dpglib.types;
+
+type
+   TBlockContext = class(TObject)
+      private
+         fAltNum     : integer;
+         fBlock      : IAlternativeBlock;
+         fBlockEnd   : IBlockEndElem;
+
+      public
+         procedure   AddAlternativeElem( pElem: IAlternativeElem); virtual;
+
+         function    CurrentAlt  : IAlternative;
+         function    CurrentElem : IAlternativeElem;
+
+      public
+         property    AltNum   : integer            read  fAltNum     write fAltNum;
+         property    Block    : IAlternativeBlock  read  fBlock      write fBlock;
+         property    BlockEnd : IBlockEndElem      read  fBlockEnd   write fBlockEnd;
+   end;
+
+
+implementation
+// ----------------------------------------------------------------------------
+// CurrentAlt
+// ----------------------------------------------------------------------------
+function TBlockContext.CurrentAlt: IAlternative;
+begin
+   fBlock.Alternatives.Items[fAltNum].QueryInterface( IAlternative, result);
+end;
+
+// ----------------------------------------------------------------------------
+// CurrentElem
+// ----------------------------------------------------------------------------
+function TBlockContext.CurrentElem: IAlternativeElem;
+begin
+   result := CurrentAlt.Tail;
+end;
+
+// ----------------------------------------------------------------------------
+// AddAlternativeElem
+// ----------------------------------------------------------------------------
+procedure TBlockContext.AddAlternativeElem(pElem: IAlternativeElem);
+begin
+   CurrentAlt.AddElem( pElem);
+end;
+
+end.