Java example source code file (ArrayAccessExpression.java)
The ArrayAccessExpression.java Java example source code
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
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package sun.tools.tree;
import sun.tools.java.*;
import sun.tools.asm.Assembler;
import java.io.PrintStream;
import java.util.Hashtable;
/**
* WARNING: The contents of this source file are not part of any
* supported API. Code that depends on them does so at its own risk:
* they are subject to change or removal without notice.
*/
public
class ArrayAccessExpression extends UnaryExpression {
/**
* The index expression for the array access. Note that
* ArrayAccessExpression also `moonlights' as a structure for
* storing array types (like Object[]) which are used as part
* of cast expressions. For properly formed array types, the
* value of index is null. We need to be on the lookout for
* null indices in true array accesses, and non-null indices
* in array types. We also need to make sure general purpose
* methods (like copyInline(), which is called for both) are
* prepared to handle either null or non-null indices.
*/
Expression index;
/**
* constructor
*/
public ArrayAccessExpression(long where, Expression right, Expression index) {
super(ARRAYACCESS, where, Type.tError, right);
this.index = index;
}
/**
* Check expression type
*/
public Vset checkValue(Environment env, Context ctx, Vset vset, Hashtable exp) {
vset = right.checkValue(env, ctx, vset, exp);
if (index == null) {
env.error(where, "array.index.required");
return vset;
}
vset = index.checkValue(env, ctx, vset, exp);
index = convert(env, ctx, Type.tInt, index);
if (!right.type.isType(TC_ARRAY)) {
if (!right.type.isType(TC_ERROR)) {
env.error(where, "not.array", right.type);
}
return vset;
}
type = right.type.getElementType();
return vset;
}
public Vset checkAmbigName(Environment env, Context ctx,
Vset vset, Hashtable exp,
UnaryExpression loc) {
if (index == null) {
vset = right.checkAmbigName(env, ctx, vset, exp, this);
if (right.type == Type.tPackage) {
FieldExpression.reportFailedPackagePrefix(env, right);
return vset;
}
// Nope. Is this field expression a type?
if (right instanceof TypeExpression) {
Type atype = Type.tArray(right.type);
loc.right = new TypeExpression(where, atype);
return vset;
}
env.error(where, "array.index.required");
return vset;
}
return super.checkAmbigName(env, ctx, vset, exp, loc);
}
/*
* Check the array if it appears on the LHS of an assignment
*/
public Vset checkLHS(Environment env, Context ctx,
Vset vset, Hashtable exp) {
return checkValue(env, ctx, vset, exp);
}
/*
* Check the array if it appears on the LHS of an op= expression
*/
public Vset checkAssignOp(Environment env, Context ctx,
Vset vset, Hashtable exp, Expression outside) {
return checkValue(env, ctx, vset, exp);
}
/**
* An array access expression never requires the use of an access method to perform
* an assignment to an array element, though an access method may be required to
* fetch the array object itself.
*/
public FieldUpdater getAssigner(Environment env, Context ctx) {
return null;
}
/**
* An array access expression never requires a field updater.
*/
public FieldUpdater getUpdater(Environment env, Context ctx) {
return null;
}
/**
* Convert to a type
*/
Type toType(Environment env, Context ctx) {
return toType(env, right.toType(env, ctx));
}
Type toType(Environment env, Type t) {
if (index != null) {
env.error(index.where, "array.dim.in.type");
}
return Type.tArray(t);
}
/**
* Inline
*/
public Expression inline(Environment env, Context ctx) {
// It isn't possible to simply replace an array access
// with a CommaExpression as happens with many binary
// operators, because array accesses may have side effects
// such as NullPointerException or IndexOutOfBoundsException.
right = right.inlineValue(env, ctx);
index = index.inlineValue(env, ctx);
return this;
}
public Expression inlineValue(Environment env, Context ctx) {
// inlineValue() should not end up being called when the index is
// null. If it is null, we let this method fail with a
// NullPointerException.
right = right.inlineValue(env, ctx);
index = index.inlineValue(env, ctx);
return this;
}
public Expression inlineLHS(Environment env, Context ctx) {
return inlineValue(env, ctx);
}
/**
* Create a copy of the expression for method inlining
*/
public Expression copyInline(Context ctx) {
ArrayAccessExpression e = (ArrayAccessExpression)clone();
e.right = right.copyInline(ctx);
if (index == null) {
// The index can be null when this node is being used to
// represent a type (e.g. Object[]) used in a cast expression.
// We need to copy such structures without complaint.
e.index = null;
} else {
e.index = index.copyInline(ctx);
}
return e;
}
/**
* The cost of inlining this expression
*/
public int costInline(int thresh, Environment env, Context ctx) {
// costInline() should not end up being called when the index is
// null. If it is null, we let this method fail with a
// NullPointerException.
return 1 + right.costInline(thresh, env, ctx)
+ index.costInline(thresh, env, ctx);
}
/**
* Code
*/
int codeLValue(Environment env, Context ctx, Assembler asm) {
// codeLValue() should not end up being called when the index is
// null. If it is null, we let this method fail with a
// NullPointerException.
right.codeValue(env, ctx, asm);
index.codeValue(env, ctx, asm);
return 2;
}
void codeLoad(Environment env, Context ctx, Assembler asm) {
switch (type.getTypeCode()) {
case TC_BOOLEAN:
case TC_BYTE:
asm.add(where, opc_baload);
break;
case TC_CHAR:
asm.add(where, opc_caload);
break;
case TC_SHORT:
asm.add(where, opc_saload);
break;
default:
asm.add(where, opc_iaload + type.getTypeCodeOffset());
}
}
void codeStore(Environment env, Context ctx, Assembler asm) {
switch (type.getTypeCode()) {
case TC_BOOLEAN:
case TC_BYTE:
asm.add(where, opc_bastore);
break;
case TC_CHAR:
asm.add(where, opc_castore);
break;
case TC_SHORT:
asm.add(where, opc_sastore);
break;
default:
asm.add(where, opc_iastore + type.getTypeCodeOffset());
}
}
public void codeValue(Environment env, Context ctx, Assembler asm) {
codeLValue(env, ctx, asm);
codeLoad(env, ctx, asm);
}
/**
* Print
*/
public void print(PrintStream out) {
out.print("(" + opNames[op] + " ");
right.print(out);
out.print(" ");
if (index != null) {
index.print(out);
} else {
out.print("<empty>");
}
out.print(")");
}
}
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