Merge pull request #531 from QB64-Phoenix-Edition/on-error-streamlining

Add _NEWHANDLER option for ON ERROR GOTO...

Author: RhoSigma-QB64

source/qb64pe.bas

@@ -9099,22 +9099,32 @@ DO
         END IF
     END IF
 
-    IF n = 4 THEN
+    IF n = 4 OR n = 5 THEN
         IF getelements(a$, 1, 3) = "ON" + sp + "ERROR" + sp + "GOTO" THEN
             l$ = SCase$("On" + sp + "Error" + sp + "GoTo")
             lbl$ = getelement$(ca$, 4)
-            IF lbl$ = "0" THEN
+            hhc$ = UCASE$(lbl$) '(H)andler(H)istory(C)ommand
+            IF n = 5 THEN
+                IF hhc$ = "_LASTHANDLER" OR (hhc$ = "LASTHANDLER" AND qb64prefix_set = 1) THEN a$ = "No label allowed after _LASTHANDLER": GOTO errmes
+                IF hhc$ <> "_NEWHANDLER" AND (hhc$ <> "NEWHANDLER" AND qb64prefix_set = 1) THEN a$ = "Expected: ON ERROR GOTO [_NEWHANDLER] label": GOTO errmes
+                lbl$ = getelement$(ca$, 5)
+                IF lbl$ = "0" THEN a$ = "Zero not allowed after _NEWHANDLER": GOTO errmes
+            END IF
+            IF lbl$ = "0" THEN 'independent from hhc$ (i.e. always clear history)
                 WriteBufLine MainTxtBuf, "error_goto_line=0;"
                 WriteBufLine MainTxtBuf, "qbs_set(error_handler_history, qbs_new_txt_len(" + MKI$(&H2222) + ", 0));"
                 WriteBufLine MainTxtBuf, "qbs_cleanup(qbs_tmp_base, 0);"
                 l$ = l$ + sp + "0"
                 layoutdone = 1: IF LEN(layout$) THEN layout$ = layout$ + sp + l$ ELSE layout$ = l$
                 GOTO finishedline
-            ELSEIF UCASE$(lbl$) = "_LASTHANDLER" OR (UCASE$(lbl$) = "LASTHANDLER" AND qb64prefix_set = 1) THEN
+            ELSEIF hhc$ = "_NEWHANDLER" OR (hhc$ = "NEWHANDLER" AND qb64prefix_set = 1) THEN
+                IF n = 4 THEN a$ = "Expected: ON ERROR GOTO [_NEWHANDLER] label": GOTO errmes
+                IF ASC(hhc$, 1) = 95 THEN l$ = l$ + sp + SCase$("_NewHandler") ELSE l$ = l$ + sp + SCase$("NewHandler")
+            ELSEIF hhc$ = "_LASTHANDLER" OR (hhc$ = "LASTHANDLER" AND qb64prefix_set = 1) THEN
                 WriteBufLine MainTxtBuf, "error_goto_line = qbr(func_val(error_handler_history));"
                 WriteBufLine MainTxtBuf, "qbs_set(error_handler_history, func_mid(error_handler_history, func_instr(NULL, error_handler_history, qbs_new_txt_len(" + CHR$(34) + "|" + CHR$(34) + ", 1), 0) + 1 , NULL, 0));"
                 WriteBufLine MainTxtBuf, "qbs_cleanup(qbs_tmp_base, 0);"
-                IF ASC(lbl$, 1) = 95 THEN l$ = l$ + sp + SCase$("_LastHandler") ELSE l$ = l$ + sp + SCase$("LastHandler")
+                IF ASC(hhc$, 1) = 95 THEN l$ = l$ + sp + SCase$("_LastHandler") ELSE l$ = l$ + sp + SCase$("LastHandler")
                 layoutdone = 1: IF LEN(layout$) THEN layout$ = layout$ + sp + l$ ELSE layout$ = l$
                 GOTO finishedline
             END IF
@@ -9148,12 +9158,13 @@ DO
                 Labels(r).Scope_Restriction = subfuncn
             END IF 'x
 
-
             l$ = l$ + sp + tlayout$
             layoutdone = 1: IF LEN(layout$) THEN layout$ = layout$ + sp + l$ ELSE layout$ = l$
             errorlabels = errorlabels + 1
-            WriteBufLine MainTxtBuf, "qbs_set(error_handler_history, qbs_add(qbs_add(qbs_str((int32)(error_goto_line)), qbs_new_txt_len(" + CHR$(34) + "|" + CHR$(34) + ", 1)), error_handler_history));"
-            WriteBufLine MainTxtBuf, "qbs_cleanup(qbs_tmp_base, 0);"
+            IF hhc$ = "_NEWHANDLER" OR (hhc$ = "NEWHANDLER" AND qb64prefix_set = 1) THEN
+                WriteBufLine MainTxtBuf, "qbs_set(error_handler_history, qbs_add(qbs_add(qbs_str((int32)(error_goto_line)), qbs_new_txt_len(" + CHR$(34) + "|" + CHR$(34) + ", 1)), error_handler_history));"
+                WriteBufLine MainTxtBuf, "qbs_cleanup(qbs_tmp_base, 0);"
+            END IF
             WriteBufLine MainTxtBuf, "error_goto_line=" + str2(errorlabels) + ";"
             WriteBufLine ErrTxtBuf, "if (error_goto_line==" + str2(errorlabels) + "){error_handling=1; goto LABEL_" + lbl$ + ";}"
             GOTO finishedline

source/subs_functions/syntax_highlighter_list.bas

@@ -3,7 +3,7 @@ listOfKeywords$ = "@?@$CHECKING@$ERROR@$CONSOLE@ONLY@$DYNAMIC@$ELSE@$ELSEIF@$END
 listOfKeywords$ = listOfKeywords$ + "_ERRORLINE@_ERRORMESSAGE$@_EXIT@_EXPLICIT@_EXPLICITARRAY@_FILEEXISTS@_FLOAT@_FONT@_FONTHEIGHT@_FONTWIDTH@_FREEFONT@_FREEIMAGE@_FREETIMER@_FULLSCREEN@_G2D@_G2R@_GLRENDER@_GREEN@_GREEN32@_HEIGHT@_HIDE@_HYPOT@_ICON@_INCLERRORFILE$@_INCLERRORLINE@_INTEGER64@_KEYCLEAR@_KEYDOWN@_KEYHIT@_LASTAXIS@_LASTBUTTON@_LASTWHEEL@_LIMIT@_LOADFONT@_LOADIMAGE@_MAPTRIANGLE@_MAPUNICODE@_MEM@_MEMCOPY@_MEMELEMENT@_MEMEXISTS@_MEMFILL@_MEMFREE@_MEMGET@_MEMIMAGE@_MEMSOUND@_MEMNEW@_MEMPUT@_MIDDLE@_MK$@_MOUSEBUTTON@_MOUSEHIDE@_MOUSEINPUT@_MOUSEMOVE@_MOUSEMOVEMENTX@_MOUSEMOVEMENTY@_MOUSEPIPEOPEN@_MOUSESHOW@_MOUSEWHEEL@_MOUSEX@_MOUSEY@_NEWIMAGE@_OFFSET@_OPENCLIENT@_OPENCONNECTION@_OPENHOST@_OS$@_PALETTECOLOR@_PI@_PIXELSIZE@_PRESERVE@_PRINTIMAGE@_PRINTMODE@_PRINTSTRING@_PRINTWIDTH@_PUTIMAGE@_R2D@_R2G@_RED@_RED32@_RESIZE@_RESIZEHEIGHT@_RESIZEWIDTH@_RGB@_RGB32@_RGBA@_RGBA32@_ROUND@_SCREENCLICK@_SCREENEXISTS@_SCREENHIDE@_SCREENICON@_SCREENIMAGE@_SCREENMOVE@_SCREENPRINT@_SCREENSHOW@_SCREENX@_SCREENY@_SEC@_SECH@_SETALPHA@_SHELLHIDE@_SINH@_SNDBAL@_SNDCLOSE@_SNDCOPY@_SNDGETPOS@_SNDLEN@_SNDLIMIT@_SNDLOOP@_SNDOPEN@_SNDOPENRAW@_SNDPAUSE@_SNDPAUSED@_SNDPLAY@_SNDPLAYCOPY@_SNDPLAYFILE@_SNDPLAYING@_SNDRATE@_SNDRAW@_SNDRAWDONE@_SNDRAWLEN@_SNDSETPOS@_SNDSTOP@_SNDVOL@_SOURCE@_STARTDIR$@_STRCMP@_STRICMP@_TANH@_TITLE@_TITLE$@_UNSIGNED@_WHEEL@_WIDTH@_WINDOWHANDLE@_WINDOWHASFOCUS@_GLACCUM@_GLALPHAFUNC@_GLARETEXTURESRESIDENT@_GLARRAYELEMENT@_GLBEGIN@_GLBINDTEXTURE@_GLBITMAP@_GLBLENDFUNC@_GLCALLLIST@_GLCALLLISTS@_GLCLEAR@_GLCLEARACCUM@_GLCLEARCOLOR@_GLCLEARDEPTH@_GLCLEARINDEX@_GLCLEARSTENCIL@_GLCLIPPLANE@_GLCOLOR3B@_GLCOLOR3BV@_GLCOLOR3D@_GLCOLOR3DV@_GLCOLOR3F@_GLCOLOR3FV@_GLCOLOR3I@_GLCOLOR3IV@_GLCOLOR3S@_GLCOLOR3SV@_GLCOLOR3UB@_GLCOLOR3UBV@_GLCOLOR3UI@_GLCOLOR3UIV@_GLCOLOR3US@_GLCOLOR3USV@_GLCOLOR4B@_GLCOLOR4BV@_GLCOLOR4D@_GLCOLOR4DV@_GLCOLOR4F@_GLCOLOR4FV@_GLCOLOR4I@_GLCOLOR4IV@_GLCOLOR4S@_GLCOLOR4SV@_GLCOLOR4UB@_GLCOLOR4UBV@_GLCOLOR4UI@_GLCOLOR4UIV@_GLCOLOR4US@_GLCOLOR4USV@_GLCOLORMASK@_GLCOLORMATERIAL@_GLCOLORPOINTER@_GLCOPYPIXELS@_GLCOPYTEXIMAGE1D@_GLCOPYTEXIMAGE2D@_GLCOPYTEXSUBIMAGE1D@"
 listOfKeywords$ = listOfKeywords$ + "_GLCOPYTEXSUBIMAGE2D@_GLCULLFACE@_GLDELETELISTS@_GLDELETETEXTURES@_GLDEPTHFUNC@_GLDEPTHMASK@_GLDEPTHRANGE@_GLDISABLE@_GLDISABLECLIENTSTATE@_GLDRAWARRAYS@_GLDRAWBUFFER@_GLDRAWELEMENTS@_GLDRAWPIXELS@_GLEDGEFLAG@_GLEDGEFLAGPOINTER@_GLEDGEFLAGV@_GLENABLE@_GLENABLECLIENTSTATE@_GLEND@_GLENDLIST@_GLEVALCOORD1D@_GLEVALCOORD1DV@_GLEVALCOORD1F@_GLEVALCOORD1FV@_GLEVALCOORD2D@_GLEVALCOORD2DV@_GLEVALCOORD2F@_GLEVALCOORD2FV@_GLEVALMESH1@_GLEVALMESH2@_GLEVALPOINT1@_GLEVALPOINT2@_GLFEEDBACKBUFFER@_GLFINISH@_GLFLUSH@_GLFOGF@_GLFOGFV@_GLFOGI@_GLFOGIV@_GLFRONTFACE@_GLFRUSTUM@_GLGENLISTS@_GLGENTEXTURES@_GLGETBOOLEANV@_GLGETCLIPPLANE@_GLGETDOUBLEV@_GLGETERROR@_GLGETFLOATV@_GLGETINTEGERV@_GLGETLIGHTFV@_GLGETLIGHTIV@_GLGETMAPDV@_GLGETMAPFV@_GLGETMAPIV@_GLGETMATERIALFV@_GLGETMATERIALIV@_GLGETPIXELMAPFV@_GLGETPIXELMAPUIV@_GLGETPIXELMAPUSV@_GLGETPOINTERV@_GLGETPOLYGONSTIPPLE@_GLGETSTRING@_GLGETTEXENVFV@_GLGETTEXENVIV@_GLGETTEXGENDV@_GLGETTEXGENFV@_GLGETTEXGENIV@_GLGETTEXIMAGE@_GLGETTEXLEVELPARAMETERFV@_GLGETTEXLEVELPARAMETERIV@_GLGETTEXPARAMETERFV@_GLGETTEXPARAMETERIV@_GLHINT@_GLINDEXMASK@_GLINDEXPOINTER@_GLINDEXD@_GLINDEXDV@_GLINDEXF@_GLINDEXFV@_GLINDEXI@_GLINDEXIV@_GLINDEXS@_GLINDEXSV@_GLINDEXUB@_GLINDEXUBV@_GLINITNAMES@_GLINTERLEAVEDARRAYS@_GLISENABLED@_GLISLIST@_GLISTEXTURE@_GLLIGHTMODELF@_GLLIGHTMODELFV@_GLLIGHTMODELI@_GLLIGHTMODELIV@_GLLIGHTF@_GLLIGHTFV@_GLLIGHTI@_GLLIGHTIV@_GLLINESTIPPLE@_GLLINEWIDTH@_GLLISTBASE@_GLLOADIDENTITY@_GLLOADMATRIXD@_GLLOADMATRIXF@_GLLOADNAME@_GLLOGICOP@_GLMAP1D@_GLMAP1F@_GLMAP2D@_GLMAP2F@_GLMAPGRID1D@_GLMAPGRID1F@_GLMAPGRID2D@_GLMAPGRID2F@_GLMATERIALF@_GLMATERIALFV@_GLMATERIALI@_GLMATERIALIV@_GLMATRIXMODE@_GLMULTMATRIXD@_GLMULTMATRIXF@_GLNEWLIST@_GLNORMAL3B@_GLNORMAL3BV@_GLNORMAL3D@_GLNORMAL3DV@_GLNORMAL3F@_GLNORMAL3FV@_GLNORMAL3I@_GLNORMAL3IV@_GLNORMAL3S@_GLNORMAL3SV@_GLNORMALPOINTER@_GLORTHO@_GLPASSTHROUGH@_GLPIXELMAPFV@_GLPIXELMAPUIV@_GLPIXELMAPUSV@_GLPIXELSTOREF@_GLPIXELSTOREI@_GLPIXELTRANSFERF@_GLPIXELTRANSFERI@_GLPIXELZOOM@_GLPOINTSIZE@_GLPOLYGONMODE@_GLPOLYGONOFFSET@_GLPOLYGONSTIPPLE@"
 listOfKeywords$ = listOfKeywords$ + "_GLPOPATTRIB@_GLPOPCLIENTATTRIB@_GLPOPMATRIX@_GLPOPNAME@_GLPRIORITIZETEXTURES@_GLPUSHATTRIB@_GLPUSHCLIENTATTRIB@_GLPUSHMATRIX@_GLPUSHNAME@_GLRASTERPOS2D@_GLRASTERPOS2DV@_GLRASTERPOS2F@_GLRASTERPOS2FV@_GLRASTERPOS2I@_GLRASTERPOS2IV@_GLRASTERPOS2S@_GLRASTERPOS2SV@_GLRASTERPOS3D@_GLRASTERPOS3DV@_GLRASTERPOS3F@_GLRASTERPOS3FV@_GLRASTERPOS3I@_GLRASTERPOS3IV@_GLRASTERPOS3S@_GLRASTERPOS3SV@_GLRASTERPOS4D@_GLRASTERPOS4DV@_GLRASTERPOS4F@_GLRASTERPOS4FV@_GLRASTERPOS4I@_GLRASTERPOS4IV@_GLRASTERPOS4S@_GLRASTERPOS4SV@_GLREADBUFFER@_GLREADPIXELS@_GLRECTD@_GLRECTDV@_GLRECTF@_GLRECTFV@_GLRECTI@_GLRECTIV@_GLRECTS@_GLRECTSV@_GLRENDERMODE@_GLROTATED@_GLROTATEF@_GLSCALED@_GLSCALEF@_GLSCISSOR@_GLSELECTBUFFER@_GLSHADEMODEL@_GLSTENCILFUNC@_GLSTENCILMASK@_GLSTENCILOP@_GLTEXCOORD1D@_GLTEXCOORD1DV@_GLTEXCOORD1F@_GLTEXCOORD1FV@_GLTEXCOORD1I@_GLTEXCOORD1IV@_GLTEXCOORD1S@_GLTEXCOORD1SV@_GLTEXCOORD2D@_GLTEXCOORD2DV@_GLTEXCOORD2F@_GLTEXCOORD2FV@_GLTEXCOORD2I@_GLTEXCOORD2IV@_GLTEXCOORD2S@_GLTEXCOORD2SV@_GLTEXCOORD3D@_GLTEXCOORD3DV@_GLTEXCOORD3F@_GLTEXCOORD3FV@_GLTEXCOORD3I@_GLTEXCOORD3IV@_GLTEXCOORD3S@_GLTEXCOORD3SV@_GLTEXCOORD4D@_GLTEXCOORD4DV@_GLTEXCOORD4F@_GLTEXCOORD4FV@_GLTEXCOORD4I@_GLTEXCOORD4IV@_GLTEXCOORD4S@_GLTEXCOORD4SV@_GLTEXCOORDPOINTER@_GLTEXENVF@_GLTEXENVFV@_GLTEXENVI@_GLTEXENVIV@_GLTEXGEND@_GLTEXGENDV@_GLTEXGENF@_GLTEXGENFV@_GLTEXGENI@_GLTEXGENIV@_GLTEXIMAGE1D@_GLTEXIMAGE2D@_GLTEXPARAMETERF@_GLTEXPARAMETERFV@_GLTEXPARAMETERI@_GLTEXPARAMETERIV@_GLTEXSUBIMAGE1D@_GLTEXSUBIMAGE2D@_GLTRANSLATED@_GLTRANSLATEF@_GLVERTEX2D@_GLVERTEX2DV@_GLVERTEX2F@_GLVERTEX2FV@_GLVERTEX2I@_GLVERTEX2IV@_GLVERTEX2S@_GLVERTEX2SV@_GLVERTEX3D@_GLVERTEX3DV@_GLVERTEX3F@_GLVERTEX3FV@_GLVERTEX3I@_GLVERTEX3IV@_GLVERTEX3S@_GLVERTEX3SV@_GLVERTEX4D@_GLVERTEX4DV@_GLVERTEX4F@_GLVERTEX4FV@_GLVERTEX4I@_GLVERTEX4IV@_GLVERTEX4S@_GLVERTEX4SV@_GLVERTEXPOINTER@_GLVIEWPORT@SMOOTH@STRETCH@_ANTICLOCKWISE@_BEHIND@_CLEAR@_FILLBACKGROUND@_GLUPERSPECTIVE@_HARDWARE@_HARDWARE1@_KEEPBACKGROUND@_NONE@_OFF@_ONLY@_ONLYBACKGROUND@_ONTOP@_SEAMLESS@_SMOOTH@_SMOOTHSHRUNK@_SMOOTHSTRETCHED@"
-listOfKeywords$ = listOfKeywords$ + "_SOFTWARE@_SQUAREPIXELS@_STRETCH@_ALLOWFULLSCREEN@_ALL@_ECHO@_READFILE$@_WRITEFILE@_INSTRREV@_LASTHANDLER@_TRIM$@_ACCEPTFILEDROP@_FINISHDROP@_TOTALDROPPEDFILES@_DROPPEDFILE@_DROPPEDFILE$@_SHR@_SHL@_ROR@_ROL@"
+listOfKeywords$ = listOfKeywords$ + "_SOFTWARE@_SQUAREPIXELS@_STRETCH@_ALLOWFULLSCREEN@_ALL@_ECHO@_READFILE$@_WRITEFILE@_INSTRREV@_LASTHANDLER@_NEWHANDLER@_TRIM$@_ACCEPTFILEDROP@_FINISHDROP@_TOTALDROPPEDFILES@_DROPPEDFILE@_DROPPEDFILE$@_SHR@_SHL@_ROR@_ROL@"
 listOfKeywords$ = listOfKeywords$ + "_ADLER32@_CRC32@_MD5$@_DEFLATE$@_INFLATE$@_READBIT@_RESETBIT@_SETBIT@_TOGGLEBIT@$INCLUDEONCE@$ASSERTS@CONSOLE@_ASSERT@_CAPSLOCK@_NUMLOCK@_SCROLLLOCK@_TOGGLE@_CONSOLEFONT@_CONSOLECURSOR@_CONSOLEINPUT@_CINP@$NOPREFIX@$COLOR@$DEBUG@$EMBED@_EMBEDDED$@_ENVIRONCOUNT@$UNSTABLE@$MIDISOUNDFONT@"
 listOfKeywords$ = listOfKeywords$ + "_NOTIFYPOPUP@_MESSAGEBOX@_INPUTBOX$@_SELECTFOLDERDIALOG$@_COLORCHOOSERDIALOG@_OPENFILEDIALOG$@_SAVEFILEDIALOG$@_SAVEIMAGE@_FILES$@_FULLPATH$@_NEGATE@_ANDALSO@_ORELSE@"
 listOfKeywords$ = listOfKeywords$ + "_STATUSCODE@_SNDNEW@_SCALEDWIDTH@_SCALEDHEIGHT@_UFONTHEIGHT@_UPRINTWIDTH@_ULINESPACING@_UPRINTSTRING@_UCHARPOS@_MIDISOUNDBANK@"

tests/compile_tests/on_error/errtest.bas

@@ -8,14 +8,14 @@ END DECLARE
 
 'testing handler behavior
 Status
-ON ERROR GOTO mainHandler
+ON ERROR GOTO mainHandler 'set w/o history entry
 Status
 ERROR 5
 NormalTest
 ERROR 5
 RecursiveTest 3
 ERROR 5
-ON ERROR GOTO _LASTHANDLER
+ON ERROR GOTO _LASTHANDLER 'no more history entries => silent fallback to "unhandled"
 Status
 
 'return to test script
@@ -36,30 +36,30 @@ RESUME NEXT
 
 '-----------------------------------------------------------------------
 SUB NormalTest
-ON ERROR GOTO nSubHandler
-Status
-ERROR 5
-ON ERROR GOTO _LASTHANDLER
-Status
+    ON ERROR GOTO _NEWHANDLER nSubHandler 'set with history entry
+    Status
+    ERROR 5
+    ON ERROR GOTO _LASTHANDLER 'restore to the last handler from history
+    Status
 END SUB
 '-----
 SUB RecursiveTest (n%)
-ON ERROR GOTO rSubHandler
-Status
-ERROR 5
-IF n% > 1 THEN RecursiveTest n% - 1
-ON ERROR GOTO _LASTHANDLER
-Status
+    ON ERROR GOTO _NEWHANDLER rSubHandler 'set with history entry
+    Status
+    ERROR 5
+    IF n% > 1 THEN RecursiveTest n% - 1
+    ON ERROR GOTO _LASTHANDLER 'restore to the last handler from history
+    Status
 END SUB
 
 '-----------------------------------------------------------------------
 SUB Status
-PRINT: PRINT "HISTORY: "; "<"; GetErrorHistory$; ">"
-SELECT CASE GetErrorGotoLine&
-    CASE 0: PRINT " ACTIVE: unhandled"
-    CASE 1: PRINT " ACTIVE: main handler"
-    CASE 2: PRINT " ACTIVE: normal sub handler"
-    CASE 3: PRINT " ACTIVE: recursive sub handler"
-END SELECT
+    PRINT: PRINT "HISTORY: "; "<"; GetErrorHistory$; ">"
+    SELECT CASE GetErrorGotoLine&
+        CASE 0: PRINT " ACTIVE: unhandled"
+        CASE 1: PRINT " ACTIVE: main handler"
+        CASE 2: PRINT " ACTIVE: normal sub handler"
+        CASE 3: PRINT " ACTIVE: recursive sub handler"
+    END SELECT
 END SUB
 

tests/compile_tests/on_error/errtest.output

@@ -2,37 +2,37 @@
 HISTORY: <>
  ACTIVE: unhandled
 
-HISTORY: < 0|>
+HISTORY: <>
  ACTIVE: main handler
  CALLED: main handler
 
-HISTORY: < 1| 0|>
+HISTORY: < 1|>
  ACTIVE: normal sub handler
  CALLED: normal sub handler
 
-HISTORY: < 0|>
+HISTORY: <>
  ACTIVE: main handler
  CALLED: main handler
 
-HISTORY: < 1| 0|>
+HISTORY: < 1|>
  ACTIVE: recursive sub handler
  CALLED: recursive sub handler
 
-HISTORY: < 3| 1| 0|>
+HISTORY: < 3| 1|>
  ACTIVE: recursive sub handler
  CALLED: recursive sub handler
 
-HISTORY: < 3| 3| 1| 0|>
+HISTORY: < 3| 3| 1|>
  ACTIVE: recursive sub handler
  CALLED: recursive sub handler
 
-HISTORY: < 3| 1| 0|>
+HISTORY: < 3| 1|>
  ACTIVE: recursive sub handler
 
-HISTORY: < 1| 0|>
+HISTORY: < 1|>
  ACTIVE: recursive sub handler
 
-HISTORY: < 0|>
+HISTORY: <>
  ACTIVE: main handler
  CALLED: main handler