/**
* conditional-expression:
* logical-OR-expression
* logical-OR-expression ? expression : conditional-expression
*/
static AstExpression ParseConditionalExpression(void)
{
AstExpression expr;
expr = ParseBinaryExpression(Prec[OP_OR]);
if (CurrentToken == TK_QUESTION)
{
AstExpression condExpr;
CREATE_AST_NODE(condExpr, Expression);
condExpr->op = OP_QUESTION;
condExpr->kids[0] = expr;
NEXT_TOKEN;
CREATE_AST_NODE(condExpr->kids[1], Expression);
condExpr->kids[1]->op = OP_COLON;
condExpr->kids[1]->kids[0] = ParseExpression();
Expect(TK_COLON);
condExpr->kids[1]->kids[1] = ParseConditionalExpression();
return condExpr;
}
return expr;
}
/**
* Check if the initializer expression is address constant.
* e.g.
* int a;
* int b = &a;
*/
static AstExpression CheckAddressConstant(AstExpression expr)
{
AstExpression addr;
AstExpression p;
int offset = 0;
if (! IsPtrType(expr->ty))
return NULL;
if (expr->op == OP_ADD || expr->op == OP_SUB)
{
addr = CheckAddressConstant(expr->kids[0]);
if (addr == NULL || expr->kids[1]->op != OP_CONST)
return NULL;
expr->kids[0] = addr->kids[0];
expr->kids[1]->val.i[0] += (expr->op == OP_ADD ? 1 : -1) * addr->kids[1]->val.i[0];
return expr;
}
if (expr->op == OP_ADDRESS)
addr = expr->kids[0];
else
addr = expr;
while (addr->op == OP_INDEX || addr->op == OP_MEMBER)
{
if (addr->op == OP_INDEX)
{
if (addr->kids[1]->op != OP_CONST)
return NULL;
offset += addr->kids[1]->val.i[0] * addr->ty->size;
}
else
{
Field fld = addr->val.p;
offset += fld->offset;
}
addr = addr->kids[0];
}
if (addr->op != OP_ID || (expr->op != OP_ADDRESS && ! addr->isarray && ! addr->isfunc))
return NULL;
((Symbol)addr->val.p)->ref++;
CREATE_AST_NODE(p, Expression);
p->op = OP_ADD;
p->ty = expr->ty;
p->kids[0] = addr;
p->kids[1] = Constant(addr->coord, T(INT), p->val);
return p;
}
static AstExpression CastExpression(Type ty, AstExpression expr)
{
AstExpression cast;
if (expr->op == OP_CONST && ty->categ != VOID)
return FoldCast(ty, expr);
CREATE_AST_NODE(cast, Expression);
cast->coord = expr->coord;
cast->op = OP_CAST;
cast->ty = ty;
cast->kids[0] = expr;
return cast;
}
/**
* Construct an expression to divide diff by size
*/
static AstExpression PointerDifference(AstExpression diff, int size)
{
AstExpression expr;
union value val;
CREATE_AST_NODE(expr, Expression);
expr->ty = diff->ty;
expr->op = OP_DIV;
expr->kids[0] = diff;
val.i[1] = 0;
val.i[0] = size;
expr->kids[1] = Constant(diff->coord, diff->ty, val);
return expr;
}
/**
* Construct an expression to multiply offset by scale.
*/
static AstExpression ScalePointerOffset(AstExpression offset, int scale)
{
AstExpression expr;
union value val;
CREATE_AST_NODE(expr, Expression);
expr->ty = offset->ty;
expr->op = OP_MUL;
expr->kids[0] = offset;
val.i[1] = 0;
val.i[0] = scale;
expr->kids[1] = Constant(offset->coord, offset->ty, val);
return FoldConstant(expr);
}
static AstExpression TransformIncrement(AstExpression expr)
{
AstExpression casgn;
union value val;
val.i[1] = 0; val.i[0] = 1;
CREATE_AST_NODE(casgn, Expression);
casgn->coord = expr->coord;
casgn->op = (expr->op == OP_POSTINC || expr->op == OP_PREINC) ? OP_ADD_ASSIGN : OP_SUB_ASSIGN;
casgn->kids[0] = expr->kids[0];
casgn->kids[1] = Constant(expr->coord, T(INT), val);
expr->kids[0] = CheckExpression(casgn);
expr->ty = expr->kids[0]->ty;
return expr;
}
/**
* expression:
* assignment-expression
* expression , assignment-expression
*/
AstExpression ParseExpression(void)
{
AstExpression expr, comaExpr;
expr = ParseAssignmentExpression();
while(CurrentToken == TK_COMMA)
{
CREATE_AST_NODE(comaExpr, Expression);
comaExpr->op = OP_COMMA;
comaExpr->kids[0] = expr;
NEXT_TOKEN;
comaExpr->kids[1] = ParseAssignmentExpression();
expr = comaExpr;
}
return expr;
}
static AstExpression BORBitField(AstExpression expr1, AstExpression expr2)
{
AstExpression bor;
if (expr1->op == OP_CONST && expr2->op == OP_CONST)
{
expr1->val.i[0] |= expr2->val.i[0];
return expr1;
}
CREATE_AST_NODE(bor, Expression);
bor->coord = expr1->coord;
bor->ty = expr1->ty;
bor->op = OP_BITOR;
bor->kids[0] = expr1;
bor->kids[1] = expr2;
return bor;
}
static AstExpression CheckAssignmentExpression(AstExpression expr)
{
int ops[] =
{
OP_BITOR, OP_BITXOR, OP_BITAND, OP_LSHIFT, OP_RSHIFT,
OP_ADD, OP_SUB, OP_MUL, OP_DIV, OP_MOD
};
Type ty;
expr->kids[0] = Adjust(CheckExpression(expr->kids[0]), 0);
expr->kids[1] = Adjust(CheckExpression(expr->kids[1]), 1);
if (! CanModify(expr->kids[0]))
{
Error(&expr->coord, "The left operand cannot be modified");
}
if (expr->op != OP_ASSIGN)
{
AstExpression lopr;
CREATE_AST_NODE(lopr, Expression);
lopr->coord = expr->coord;
lopr->op = ops[expr->op - OP_BITOR_ASSIGN];
lopr->kids[0] = expr->kids[0];
lopr->kids[1] = expr->kids[1];
expr->kids[1] = (*BinaryOPCheckers[lopr->op - OP_OR])(lopr);
}
ty = expr->kids[0]->ty;
if (! CanAssign(ty, expr->kids[1]))
{
Error(&expr->coord, "Wrong assignment");
}
else
{
expr->kids[1] = Cast(ty, expr->kids[1]);
}
expr->ty = ty;
return expr;
}
/**
* assignment-expression:
* conditional-expression
* unary-expression assignment-operator assignment-expression
* assignment-operator:
* = *= /= %= += -= <<= >>= &= ^= |=
* There is a little twist here: the parser always treats the first nonterminal
* as a conditional expression.
*/
AstExpression ParseAssignmentExpression(void)
{
AstExpression expr;
expr = ParseConditionalExpression();
if (CurrentToken >= TK_ASSIGN && CurrentToken <= TK_MOD_ASSIGN)
{
AstExpression asgnExpr;
CREATE_AST_NODE(asgnExpr, Expression);
asgnExpr->op = BINARY_OP;
asgnExpr->kids[0] = expr;
NEXT_TOKEN;
asgnExpr->kids[1] = ParseAssignmentExpression();
return asgnExpr;
}
return expr;
}
static AstExpression PlaceBitField(Field fld, AstExpression expr)
{
AstExpression lsh;
union value val;
if (expr->op == OP_CONST)
{
expr->val.i[0] <<= fld->pos;
return expr;
}
CREATE_AST_NODE(lsh, Expression);
lsh->coord = expr->coord;
lsh->ty = expr->ty;
lsh->op = OP_LSHIFT;
lsh->kids[0] = expr;
val.i[1] = 0;
val.i[0] = fld->pos;
lsh->kids[1] = Constant(expr->coord, T(INT), val);
return lsh;
}
/**
* Parse a binary expression, from logical-OR-expresssion to multiplicative-expression
*/
static AstExpression ParseBinaryExpression(int prec)
{
AstExpression binExpr;
AstExpression expr;
int newPrec;
expr = ParseUnaryExpression();
/// while the following binary operater's precedence is higher than current
/// binary operator's precedence, parses a higer precedence expression
while (IsBinaryOP(CurrentToken) && (newPrec = Prec[BINARY_OP]) >= prec)
{
CREATE_AST_NODE(binExpr, Expression);
binExpr->op = BINARY_OP;
binExpr->kids[0] = expr;
NEXT_TOKEN;
binExpr->kids[1] = ParseBinaryExpression(newPrec + 1);
expr = binExpr;
}
return expr;
}
/**
* primary-expression:
* ID
* constant
* string-literal
* ( expression )
*/
static AstExpression ParsePrimaryExpression(void)
{
AstExpression expr;
switch (CurrentToken)
{
case TK_ID:
CREATE_AST_NODE(expr, Expression);
expr->op = OP_ID;
expr->val = TokenValue;
NEXT_TOKEN;
return expr;
/// Notice: Only when parsing constant and string literal,
/// ty member in astExpression is used since from OP_CONST
/// and OP_STR alone the expression's type can't be determined
case TK_INTCONST:
case TK_UINTCONST:
case TK_LONGCONST:
case TK_ULONGCONST:
case TK_LLONGCONST:
case TK_ULLONGCONST:
case TK_FLOATCONST:
case TK_DOUBLECONST:
case TK_LDOUBLECONST:
CREATE_AST_NODE(expr, Expression);
if (CurrentToken >= TK_FLOATCONST)
CurrentToken++;
/// nasty, requires that both from TK_INTCONST to TK_LDOUBLECONST
/// and from INT to LDOUBLE are consecutive
expr->ty = T(INT + CurrentToken - TK_INTCONST);
expr->op = OP_CONST;
expr->val = TokenValue;
NEXT_TOKEN;
return expr;
case TK_STRING:
case TK_WIDESTRING:
CREATE_AST_NODE(expr, Expression);
expr->ty = ArrayOf(((String)TokenValue.p)->len + 1, CurrentToken == TK_STRING ? T(CHAR) : WCharType);
expr->op = OP_STR;
expr->val = TokenValue;
NEXT_TOKEN;
return expr;
case TK_LPAREN:
NEXT_TOKEN;
expr = ParseExpression();
Expect(TK_RPAREN);
return expr;
default:
Error(&TokenCoord, "Expect identifier, string, constant or (");
return Constant0;
}
}
/**
* unary-expression:
* postfix-expression
* unary-operator unary-expression
* ( type-name ) unary-expression
* sizeof unary-expression
* sizeof ( type-name )
*
* unary-operator:
* ++ -- & * + - ! ~
*/
static AstExpression ParseUnaryExpression()
{
AstExpression expr;
int t;
switch (CurrentToken)
{
case TK_INC:
case TK_DEC:
case TK_BITAND:
case TK_MUL:
case TK_ADD:
case TK_SUB:
case TK_NOT:
case TK_COMP:
CREATE_AST_NODE(expr, Expression);
expr->op = UNARY_OP;
NEXT_TOKEN;
expr->kids[0] = ParseUnaryExpression();
return expr;
case TK_LPAREN:
/// When current token is (, it may be a type cast expression
/// or a primary expression, we need to look ahead one token,
/// if next token is type name, the expression is treated as
/// a type cast expression; otherwise a primary expresion
BeginPeekToken();
t = GetNextToken();
if (IsTypeName(t))
{
EndPeekToken();
CREATE_AST_NODE(expr, Expression);
expr->op = OP_CAST;
NEXT_TOKEN;
expr->kids[0] = (AstExpression)ParseTypeName();
Expect(TK_RPAREN);
expr->kids[1] = ParseUnaryExpression();
return expr;
}
else
{
EndPeekToken();
return ParsePostfixExpression();
}
break;
case TK_SIZEOF:
/// this case hase the same issue with TK_LPAREN case
CREATE_AST_NODE(expr, Expression);
expr->op = OP_SIZEOF;
NEXT_TOKEN;
if (CurrentToken == TK_LPAREN)
{
BeginPeekToken();
t = GetNextToken();
if (IsTypeName(t))
{
EndPeekToken();
NEXT_TOKEN;
/// In this case, the first kid is not an expression,
/// but thanks to both type name and expression have a
/// kind member to discriminate them.
expr->kids[0] = (AstExpression)ParseTypeName();
Expect(TK_RPAREN);
}
else
{
EndPeekToken();
expr->kids[0] = ParseUnaryExpression();
}
}
else
{
expr->kids[0] = ParseUnaryExpression();
}
return expr;
default:
return ParsePostfixExpression();
}
}
/**
* postfix-expression:
* primary-expression
* postfix-expression [ expression ]
* postfix-expression ( [argument-expression-list] )
* postfix-expression . identifier
* postfix-expression -> identifier
* postfix-expression ++
* postfix-expression --
*/
static AstExpression ParsePostfixExpression(void)
{
AstExpression expr, p;
expr = ParsePrimaryExpression();
while (1)
{
switch (CurrentToken)
{
case TK_LBRACKET:
CREATE_AST_NODE(p, Expression);
p->op = OP_INDEX;
p->kids[0] = expr;
NEXT_TOKEN;
p->kids[1] = ParseExpression();
Expect(TK_RBRACKET);
expr = p;
break;
case TK_LPAREN:
CREATE_AST_NODE(p, Expression);
p->op = OP_CALL;
p->kids[0] = expr;
NEXT_TOKEN;
if (CurrentToken != TK_RPAREN)
{
AstNode *tail;
/// function call expression's second kid is actually
/// a list of expression instead of a single expression
p->kids[1] = ParseAssignmentExpression();
tail = &p->kids[1]->next;
while (CurrentToken == TK_COMMA)
{
NEXT_TOKEN;
*tail = (AstNode)ParseAssignmentExpression();
tail = &(*tail)->next;
}
}
Expect(TK_RPAREN);
expr = p;
break;
case TK_DOT:
case TK_POINTER:
CREATE_AST_NODE(p, Expression);
p->op = (CurrentToken == TK_DOT ? OP_MEMBER : OP_PTR_MEMBER);
p->kids[0] = expr;
NEXT_TOKEN;
if (CurrentToken != TK_ID)
{
Error(&p->coord, "Expect identifier as struct or union member");
}
else
{
p->val = TokenValue;
NEXT_TOKEN;
}
expr = p;
break;
case TK_INC:
case TK_DEC:
CREATE_AST_NODE(p, Expression);
p->op = (CurrentToken == TK_INC) ? OP_POSTINC : OP_POSTDEC;
p->kids[0] = expr;
NEXT_TOKEN;
expr = p;
break;
default:
return expr;
}
}
}
