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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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 * accompanied this code).
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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.
/**
 * 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.
/**
     * 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
/**
     * constructor
     */
    public ArrayAccessExpression(long where, Expression right, Expression index) {
        super(ARRAYACCESS, where, Type.tError, right);
        this.index = index;
    }

    
Check expression type
/**
     * 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.
/**
     * 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.
/**
     * An array access expression never requires a field updater.
     */
    public FieldUpdater getUpdater(Environment env, Context ctx) {
        return null;
    }

    
Convert to a type
/**
     * 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
/**
     * 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
/**
     * 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
/**
     * 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
/**
     * 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
/**
     * 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(")");
    }
}