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Give the parser knowledge of constants for unary - and +

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- Since the tokenizer never gives the parser negative numbers but always a
  unary minus followed by a positive number, it seems reasonable to make
  the parser smart enough to turn these into negative constants without
  generating extra tree nodes.
- And since we're doing it for unary -, we might as well do it for unary +
  as well and avoid extra nodes when we know we don't need them.
This commit is contained in:
Randy Heit 2013-09-12 22:22:43 -05:00
parent 2a1414ad66
commit 743b05189e
1 changed files with 29 additions and 4 deletions
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25
src/zscript/zcc-parse.lemon
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@ -884,16 +884,41 @@ unary_expr(X) ::= primary(A).
}
unary_expr(X) ::= SUB unary_expr(A). [UNARY]
{
ZCC_ExprConstant *con = static_cast<ZCC_ExprConstant *>(A);
if (A->Operation == PEX_ConstValue && (con->Type->IsA(RUNTIME_CLASS(PInt)) || con->Type->IsA(RUNTIME_CLASS(PFloat))))
{ // For constants, manipulate the child node directly, and don't create a new node.
if (con->Type->IsA(RUNTIME_CLASS(PInt)))
{
con->IntVal = -con->IntVal;
}
else
{
con->DoubleVal = -con->DoubleVal;
}
X = A;
}
else
{ // For everything else, create a new node and do the negation later.
UNARY_EXPR(A,PEX_Negate);
X = expr;
}
}
unary_expr(X) ::= ADD unary_expr(A). [UNARY]
{
// Even though this is really a no-op, we still need to make a node for
// it so we can type check that it is being applied to something numeric.
// But we can do that right now for constant numerals.
ZCC_ExprConstant *con = static_cast<ZCC_ExprConstant *>(A);
if (A->Operation != PEX_ConstValue || (!con->Type->IsA(RUNTIME_CLASS(PInt)) && !con->Type->IsA(RUNTIME_CLASS(PFloat))))
{
UNARY_EXPR(A,PEX_AntiNegate);
X = expr;
}
else
{
X = A;
}
}
unary_expr(X) ::= SUBSUB unary_expr(A). [UNARY]
{
UNARY_EXPR(A,PEX_PreDec);