Alt/Bus: fix Lines/Loads/PCElements/PDElements when multiple elements are present

Previous elements in the result were not being preserved.

`Alt_Bus_Get_PDElements` also had an off-by-one error.

Author: PMeira

docs/changelog.md

@@ -19,6 +19,7 @@
 
 ## Version 0.14.2 (to be released)
 
+- Alt/Bus: fix Lines/Loads/PCElements/PDElements when multiple elements are present
 - Alt/CE: Fix `Alt_CE_Get_RegisterValues` in the C header.
 - Alt/PDE: Check for missing solution in a few functions.
 - Commands/`CalcLaplacian`: Give proper error message instead of crashing or giving "access violation" messages.

src/CAPI/CAPI_Alt.pas

@@ -2617,7 +2617,8 @@ procedure _Alt_Bus_Get_XElements(DSS: TDSSContext; var ResultPtr: PPointer; Resu
     maxTerm: Integer = 1;
     Result: PPointerArray0;
 begin
-    Result := DSS_RecreateArray_PPointer(ResultPtr, ResultCount, ResultCount^ + 1);
+    // Initially allocate a buffer for 10 elements.
+    Result := DSS_RecreateArray_PPointer(ResultPtr, ResultCount, 10);
     ResultCount[0] := 0;
     SetLength(nodes, pBus.NumNodesThisBus);
     for i := 1 to pBus.NumNodesThisBus do
@@ -2662,16 +2663,16 @@ procedure _Alt_Bus_Get_XElements(DSS: TDSSContext; var ResultPtr: PPointer; Resu
 
                             if pdes then
                             begin
-                                elemBus := AnsiLowerCase(StripExtension(elem.GetBus(t)));
+                                elemBus := AnsiLowerCase(StripExtension(elem.GetBus(t + 1)));
                                 if (t = 0) then
-                                    elemBus2 := AnsiLowerCase(StripExtension(elem.GetBus(t + 1)))
+                                    elemBus2 := AnsiLowerCase(StripExtension(elem.GetBus(t + 2)))
                                 else
-                                    elemBus2 := AnsiLowerCase(StripExtension(elem.GetBus(t - 1)));
+                                    elemBus2 := AnsiLowerCase(StripExtension(elem.GetBus(t)));
 
                                 if elemBus = elemBus2 then
                                     break;
                             end;
-                            Result := DSS_RecreateArray_PPointer(ResultPtr, ResultCount, ResultCount^ + 1);
+                            Result := DSS_RecreateArray_PPointer(ResultPtr, ResultCount, ResultCount^ + 1, true);
                             Result[ResultCount^ - 1] := elem;
                             break;
                         end;
@@ -2702,7 +2703,7 @@ procedure _Alt_Bus_Get_XElements(DSS: TDSSContext; var ResultPtr: PPointer; Resu
                         break;
                 end;
 
-                Result := DSS_RecreateArray_PPointer(ResultPtr, ResultCount, ResultCount^ + 1);
+                Result := DSS_RecreateArray_PPointer(ResultPtr, ResultCount, ResultCount^ + 1, true);
                 Result[ResultCount^ - 1] := elem;
                 break;
             end;

src/CAPI/CAPI_Utils.pas

@@ -89,13 +89,13 @@ procedure DSS_RecreateArray_PSingle(var res: PSingleArray0; var p: PSingle; cnt:
 procedure DSS_RecreateArray_PDouble(var res: PDoubleArray0; var p: PDouble; cnt: PAPISize; const incount: TAPISize; const nr: TAPISize=0; const nc: TAPISize=0);
 procedure DSS_RecreateArray_PInteger(var res: PIntegerArray0; var p: PInteger; cnt: PAPISize; const incount: TAPISize; const nr: TAPISize=0; const nc: TAPISize=0);
 procedure DSS_RecreateArray_PPAnsiChar(var res: PPAnsiCharArray0; var p: PPAnsiChar; cnt: PAPISize; const incount: TAPISize);
-procedure DSS_RecreateArray_PPointer(var res: PPointerArray0; var p: PPointer; cnt: PAPISize; const incount: TAPISize);
+procedure DSS_RecreateArray_PPointer(var res: PPointerArray0; var p: PPointer; cnt: PAPISize; const incount: TAPISize; preserve: Boolean=false);
 function DSS_RecreateArray_PByte(var p: PByte; cnt: PAPISize; const incount: TAPISize): PByteArray;
 function DSS_RecreateArray_PSingle(var p: PSingle; cnt: PAPISize; const incount: TAPISize; const nr: TAPISize=0; const nc: TAPISize=0): PSingleArray0;
 function DSS_RecreateArray_PDouble(var p: PDouble; cnt: PAPISize; const incount: TAPISize; const nr: TAPISize=0; const nc: TAPISize=0): PDoubleArray0;
 function DSS_RecreateArray_PInteger(var p: PInteger; cnt: PAPISize; const incount: TAPISize; const nr: TAPISize=0; const nc: TAPISize=0): PIntegerArray0;
 function DSS_RecreateArray_PPAnsiChar(var p: PPAnsiChar; cnt: PAPISize; const incount: TAPISize): PPAnsiCharArray0;
-function DSS_RecreateArray_PPointer(var p: PPointer; cnt: PAPISize; const incount: TAPISize): PPointerArray0;
+function DSS_RecreateArray_PPointer(var p: PPointer; cnt: PAPISize; const incount: TAPISize; preserve: Boolean=false): PPointerArray0;
 // MATLAB doesn't handle pointers that well,
 // this just gets a single string from the pointer of strings
 function DSS_Get_PAnsiChar(var p: Pointer; Index: TAPISize): PAnsiChar; CDECL;
@@ -470,7 +470,7 @@ procedure DSS_RecreateArray_PPAnsiChar(var res: PPAnsiCharArray0; var p: PPAnsiC
 end;
 
 //------------------------------------------------------------------------------
-function DSS_RecreateArray_PPointer(var p: PPointer; cnt: PAPISize; const incount: TAPISize): PPointerArray0;
+function DSS_RecreateArray_PPointer(var p: PPointer; cnt: PAPISize; const incount: TAPISize; preserve: Boolean): PPointerArray0;
 begin
     if (cnt[1] < incount) then
     begin
@@ -480,12 +480,13 @@ function DSS_RecreateArray_PPointer(var p: PPointer; cnt: PAPISize; const incoun
     end;
     cnt[0] := incount;
     Result := PPointerArray0(p);
-    FillByte(Result^, incount * sizeof(Pointer), 0); // needs to zero it for compatibility
+    if not preserve then // If we have capacity, decide if we will preserve existing data
+        FillByte(Result^, incount * sizeof(Pointer), 0);
 end;
 
-procedure DSS_RecreateArray_PPointer(var res: PPointerArray0; var p: PPointer; cnt: PAPISize; const incount: TAPISize);
+procedure DSS_RecreateArray_PPointer(var res: PPointerArray0; var p: PPointer; cnt: PAPISize; const incount: TAPISize; preserve: Boolean);
 begin
-    res := DSS_RecreateArray_PPointer(p, cnt, incount);
+    res := DSS_RecreateArray_PPointer(p, cnt, incount, preserve);
 end;
 
 //------------------------------------------------------------------------------