static SilikoSyntaxTreeNode *GetExprAddSub(SilikoLexer *lexer)
{
SilikoSyntaxTreeNode *leftValue = NULL;
SilikoSyntaxTreeNode *rest = NULL;
leftValue = GetExprMulDiv(lexer);
if (leftValue == NULL)
return NULL;
if (!(rest = GetExprAddSubRest(lexer)))
{
SilikoSyntaxTreeDelete(leftValue);
return NULL;
}
if (rest->Type == SILIKO_AST_NOTHING)
{
SilikoSyntaxTreeDelete(rest);
return leftValue;
}
if (SilikoSyntaxTreeGraftLeft(rest, leftValue))
return rest;
SilikoSyntaxTreeDelete(rest);
SilikoSyntaxTreeDelete(leftValue);
return SilikoSyntaxTreeNewError();
}
static SilikoSyntaxTreeNode *GetExprAddSubRest(SilikoLexer *lexer)
{
char *operation = NULL;
SilikoSyntaxTreeNode *leftValue = NULL;
SilikoSyntaxTreeNode *rest = NULL;
SilikoSyntaxTreeNode *branchNode = NULL;
switch (lexer->Token.Type)
{
case '+':
operation = "add";
break;
case '-':
operation = "subtract";
break;
default:
return SilikoSyntaxTreeNewNothing();
}
SilikoLexerNext(lexer);
if (!(leftValue = GetExprMulDiv(lexer)))
goto memerr;
if (!(rest = GetExprAddSubRest(lexer)))
goto memerr;
if (!(branchNode = SilikoSyntaxTreeNewBranch(operation)))
goto memerr;
SilikoSyntaxTreePushRight(branchNode, NULL);
SilikoSyntaxTreePushRight(branchNode, leftValue);
if (rest->Type != SILIKO_AST_NOTHING)
{
SilikoSyntaxTreeGraftLeft(rest, branchNode);
return rest;
}
SilikoSyntaxTreeDelete(rest);
return branchNode;
memerr:
SilikoSyntaxTreeDelete(leftValue);
SilikoSyntaxTreeDelete(rest);
return NULL;
}
int SilikoSyntaxTreeGraftLeft(SilikoSyntaxTreeNode *Tree, SilikoSyntaxTreeNode *NewBranch)
{
if (Tree->Type == SILIKO_AST_BRANCH)
{
if (Tree->Branch->Count == 0)
{
return 0;
}
else if (Tree->Branch->Children[0] == NULL)
{
Tree->Branch->Children[0] = NewBranch;
return -1;
}
else
{
return SilikoSyntaxTreeGraftLeft
(Tree->Branch->Children[0], NewBranch);
}
}
else
{
return 0;
}
}