public void atBinExpr(BinExpr expr) throws CompileError {
int token = expr.getOperator();
/* arithmetic operators: +, -, *, /, %, |, ^, &, <<, >>, >>>
*/
int k = lookupBinOp(token);
if (k >= 0) {
expr.oprand1().accept(this);
ASTree right = expr.oprand2();
if (right == null) return; // see TypeChecker.atBinExpr().
int type1 = exprType;
int dim1 = arrayDim;
String cname1 = className;
right.accept(this);
if (dim1 != arrayDim) throw new CompileError("incompatible array types");
if (token == '+' && dim1 == 0 && (type1 == CLASS || exprType == CLASS))
atStringConcatExpr(expr, type1, dim1, cname1);
else atArithBinExpr(expr, token, k, type1);
} else {
/* equation: &&, ||, ==, !=, <=, >=, <, >
*/
if (!booleanExpr(true, expr)) {
bytecode.addIndex(7);
bytecode.addIconst(0); // false
bytecode.addOpcode(Opcode.GOTO);
bytecode.addIndex(4);
}
bytecode.addIconst(1); // true
}
}
protected void arrayAccess(ASTree array, ASTree index) throws CompileError {
array.accept(this);
int type = exprType;
int dim = arrayDim;
if (dim == 0) throw new CompileError("bad array access");
String cname = className;
index.accept(this);
if (typePrecedence(exprType) != P_INT || arrayDim > 0)
throw new CompileError("bad array index");
exprType = type;
arrayDim = dim - 1;
className = cname;
}
private void atStringPlusEq(Expr expr, int type, int dim, String cname, ASTree right)
throws CompileError {
if (!jvmJavaLangString.equals(cname)) badAssign(expr);
convToString(type, dim); // the value might be null.
right.accept(this);
convToString(exprType, arrayDim);
bytecode.addInvokevirtual(javaLangString, "concat", "(Ljava/lang/String;)Ljava/lang/String;");
exprType = CLASS;
arrayDim = 0;
className = jvmJavaLangString;
}
public void atStmnt(Stmnt st) throws CompileError {
if (st == null) return; // empty
int op = st.getOperator();
if (op == EXPR) {
ASTree expr = st.getLeft();
doTypeCheck(expr);
if (expr instanceof AssignExpr) atAssignExpr((AssignExpr) expr, false);
else if (isPlusPlusExpr(expr)) {
Expr e = (Expr) expr;
atPlusPlus(e.getOperator(), e.oprand1(), e, false);
} else {
expr.accept(this);
if (is2word(exprType, arrayDim)) bytecode.addOpcode(POP2);
else if (exprType != VOID) bytecode.addOpcode(POP);
}
} else if (op == DECL || op == BLOCK) {
ASTList list = st;
while (list != null) {
ASTree h = list.head();
list = list.tail();
if (h != null) h.accept(this);
}
} else if (op == IF) atIfStmnt(st);
else if (op == WHILE || op == DO) atWhileStmnt(st, op == WHILE);
else if (op == FOR) atForStmnt(st);
else if (op == BREAK || op == CONTINUE) atBreakStmnt(st, op == BREAK);
else if (op == TokenId.RETURN) atReturnStmnt(st);
else if (op == THROW) atThrowStmnt(st);
else if (op == TRY) atTryStmnt(st);
else if (op == SWITCH) atSwitchStmnt(st);
else if (op == SYNCHRONIZED) atSyncStmnt(st);
else {
// LABEL, SWITCH label stament might be null?.
hasReturned = false;
throw new CompileError("sorry, not supported statement: TokenId " + op);
}
}
private String checkCastExpr(CastExpr expr, String name) throws CompileError {
final String msg = "invalid cast";
ASTree oprand = expr.getOprand();
int dim = expr.getArrayDim();
int type = expr.getType();
oprand.accept(this);
int srcType = exprType;
if (invalidDim(srcType, arrayDim, className, type, dim, name, true)
|| srcType == VOID
|| type == VOID) throw new CompileError(msg);
if (type == CLASS) {
if (!isRefType(srcType)) throw new CompileError(msg);
return toJvmArrayName(name, dim);
} else if (dim > 0) return toJvmTypeName(type, dim);
else return null; // built-in type
}
/* Produces the opcode to branch if the condition is true.
* The oprand (branch offset) is not produced.
*
* @return true if the compiled code is GOTO (always branch).
* GOTO is not produced.
*/
private boolean booleanExpr(boolean branchIf, ASTree expr) throws CompileError {
boolean isAndAnd;
int op = getCompOperator(expr);
if (op == EQ) { // ==, !=, ...
BinExpr bexpr = (BinExpr) expr;
int type1 = compileOprands(bexpr);
// here, arrayDim might represent the array dim. of the left oprand
// if the right oprand is NULL.
compareExpr(branchIf, bexpr.getOperator(), type1, bexpr);
} else if (op == '!') return booleanExpr(!branchIf, ((Expr) expr).oprand1());
else if ((isAndAnd = (op == ANDAND)) || op == OROR) {
BinExpr bexpr = (BinExpr) expr;
if (booleanExpr(!isAndAnd, bexpr.oprand1())) {
exprType = BOOLEAN;
arrayDim = 0;
return true;
} else {
int pc = bytecode.currentPc();
bytecode.addIndex(0); // correct later
if (booleanExpr(isAndAnd, bexpr.oprand2())) bytecode.addOpcode(Opcode.GOTO);
bytecode.write16bit(pc, bytecode.currentPc() - pc + 3);
if (branchIf != isAndAnd) {
bytecode.addIndex(6); // skip GOTO instruction
bytecode.addOpcode(Opcode.GOTO);
}
}
} else if (isAlwaysBranch(expr, branchIf)) {
// Opcode.GOTO is not added here. The caller must add it.
exprType = BOOLEAN;
arrayDim = 0;
return true; // always branch
} else { // others
expr.accept(this);
if (exprType != BOOLEAN || arrayDim != 0) throw new CompileError("boolean expr is required");
bytecode.addOpcode(branchIf ? IFNE : IFEQ);
}
exprType = BOOLEAN;
arrayDim = 0;
return false;
}
protected void atAssignCore(Expr expr, int op, ASTree right, int type, int dim, String cname)
throws CompileError {
if (op == PLUS_E && dim == 0 && type == CLASS) atStringPlusEq(expr, type, dim, cname, right);
else {
right.accept(this);
if (invalidDim(exprType, arrayDim, className, type, dim, cname, false)
|| (op != '=' && dim > 0)) badAssign(expr);
if (op != '=') {
int token = assignOps[op - MOD_E];
int k = lookupBinOp(token);
if (k < 0) fatal();
atArithBinExpr(expr, token, k, type);
}
}
if (op != '=' || (dim == 0 && !isRefType(type))) atNumCastExpr(exprType, type);
// type check should be done here.
}
public void doTypeCheck(ASTree expr) throws CompileError {
if (typeChecker != null) expr.accept(typeChecker);
}
public void compileExpr(ASTree expr) throws CompileError {
doTypeCheck(expr);
expr.accept(this);
}