[Bug 14702] LCB: Don't try to get head or tail of empty lists.

peter-b · peter-b · commit a97cf273a8ba · 2015-03-02T13:50:55.000Z
diff --git a/libfoundation/src/foundation-proper-list.cpp b/libfoundation/src/foundation-proper-list.cpp
@@ -348,15 +348,19 @@ MCValueRef MCProperListFetchHead(MCProperListRef self)
 {
     if (MCProperListIsIndirect(self))
         self = self -> contents;
-    
+
+	MCAssert (self->length > 0);
+
     return self -> list[0];
 }
 
 MCValueRef MCProperListFetchTail(MCProperListRef self)
 {
     if (MCProperListIsIndirect(self))
         self = self -> contents;
-    
+
+	MCAssert (self->length > 0);
+
     return self -> list[self -> length - 1];
 }
 
diff --git a/libscript/src/module-list.cpp b/libscript/src/module-list.cpp
@@ -20,11 +20,25 @@
 
 extern "C" MC_DLLEXPORT void MCListEvalHeadOf(MCProperListRef p_target, MCValueRef& r_output)
 {
+	if (MCProperListIsEmpty (p_target))
+	{
+		MCErrorCreateAndThrow(kMCGenericErrorTypeInfo, "reason", MCSTR("chunk index out of range"), nil);
+		r_output = nil;
+		return;
+	}
+
     r_output = MCValueRetain(MCProperListFetchHead(p_target));
 }
 
 extern "C" MC_DLLEXPORT void MCListEvalTailOf(MCProperListRef p_target, MCValueRef& r_output)
 {
+	if (MCProperListIsEmpty (p_target))
+	{
+		MCErrorCreateAndThrow(kMCGenericErrorTypeInfo, "reason", MCSTR("chunk index out of range"), nil);
+		r_output = nil;
+		return;
+	}
+
     r_output = MCValueRetain(MCProperListFetchTail(p_target));
 }
 
diff --git a/tests/lcb/stdlib/list.lcb b/tests/lcb/stdlib/list.lcb
@@ -53,8 +53,7 @@ public handler TestHead()
 	test "head" when the head of t is "x"
 	test "first" when the first element of t is "x"
 
-	skip test "head (empty)" because "bug 14702"
-	--MCUnitTestHandlerThrows(TestHead_Empty, "head (empty)")
+	MCUnitTestHandlerThrows(TestHead_Empty, "head (empty)")
 	MCUnitTestHandlerThrows(TestHead_FirstEmpty, "first (empty)")
 end handler
 
@@ -70,8 +69,7 @@ public handler TestTail()
 	test "tail" when the tail of t
 	test "last" when the last element of t
 
-	skip test "tail (empty)" because "bug 14702"
-	--MCUnitTestHandlerThrows(TestTail_Empty, "tail (empty)")
+	MCUnitTestHandlerThrows(TestTail_Empty, "tail (empty)")
 	MCUnitTestHandlerThrows(TestTail_LastEmpty, "last (empty)")
 end handler
 

Original file line number	Diff line number	Diff line change
`@@ -348,15 +348,19 @@ MCValueRef MCProperListFetchHead(MCProperListRef self)`
`348`	`348`	`{`
`349`	`349`	`if (MCProperListIsIndirect(self))`
`350`	`350`	`self = self -> contents;`
`351`		`-`
	`351`	`+`
	`352`	`+ MCAssert (self->length > 0);`
	`353`	`+`
`352`	`354`	`return self -> list[0];`
`353`	`355`	`}`
`354`	`356`
`355`	`357`	`MCValueRef MCProperListFetchTail(MCProperListRef self)`
`356`	`358`	`{`
`357`	`359`	`if (MCProperListIsIndirect(self))`
`358`	`360`	`self = self -> contents;`
`359`		`-`
	`361`	`+`
	`362`	`+ MCAssert (self->length > 0);`
	`363`	`+`
`360`	`364`	`return self -> list[self -> length - 1];`
`361`	`365`	`}`
`362`	`366`
Original file line number	Diff line number	Diff line change
`@@ -20,11 +20,25 @@`
`20`	`20`
`21`	`21`	`extern "C" MC_DLLEXPORT void MCListEvalHeadOf(MCProperListRef p_target, MCValueRef& r_output)`
`22`	`22`	`{`
	`23`	`+ if (MCProperListIsEmpty (p_target))`
	`24`	`+ {`
	`25`	`+ MCErrorCreateAndThrow(kMCGenericErrorTypeInfo, "reason", MCSTR("chunk index out of range"), nil);`
	`26`	`+ r_output = nil;`
	`27`	`+ return;`
	`28`	`+ }`
	`29`	`+`
`23`	`30`	`r_output = MCValueRetain(MCProperListFetchHead(p_target));`
`24`	`31`	`}`
`25`	`32`
`26`	`33`	`extern "C" MC_DLLEXPORT void MCListEvalTailOf(MCProperListRef p_target, MCValueRef& r_output)`
`27`	`34`	`{`
	`35`	`+ if (MCProperListIsEmpty (p_target))`
	`36`	`+ {`
	`37`	`+ MCErrorCreateAndThrow(kMCGenericErrorTypeInfo, "reason", MCSTR("chunk index out of range"), nil);`
	`38`	`+ r_output = nil;`
	`39`	`+ return;`
	`40`	`+ }`
	`41`	`+`
`28`	`42`	`r_output = MCValueRetain(MCProperListFetchTail(p_target));`
`29`	`43`	`}`
`30`	`44`