/*

 * Copyright 1994-2003 Sun Microsystems, Inc.  All Rights Reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun 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.

 *

 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package sun.tools.tree;

import sun.tools.java.*;

import sun.tools.asm.Assembler;

import sun.tools.asm.Label;

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 Statement extends Node {

    public static final Vset DEAD_END = Vset.DEAD_END;

    Identifier labels[] = null;

    /**

     * Constructor

     */

    Statement(int op, long where) {

        super(op, where);

    }

    /**

     * An empty statement.  Its costInline is infinite.

     */

    public static final Statement empty = new Statement(STAT, 0);

    /**

     * The largest possible interesting inline cost value.

     */

    public static final int MAXINLINECOST =

                      Integer.getInteger("javac.maxinlinecost",

                                         30).intValue();

    /**

     * Insert a bit of code at the front of a statement.

     * Side-effect s2, if it is a CompoundStatement.

     */

    public static Statement insertStatement(Statement s1, Statement s2) {

        if (s2 == null) {

            s2 = s1;

        } else if (s2 instanceof CompoundStatement) {

            // Do not add another level of block nesting.

            ((CompoundStatement)s2).insertStatement(s1);

        } else {

            Statement body[] = { s1, s2 };

            s2 = new CompoundStatement(s1.getWhere(), body);

        }

        return s2;

    }

    /**

     * Set the label of a statement

     */

    public void setLabel(Environment env, Expression e) {

        if (e.op == IDENT) {

            if (labels == null) {

                labels = new Identifier[1];

            } else {

                // this should almost never happen.  Multiple labels on

                // the same statement.  But handle it gracefully.

                Identifier newLabels[] = new Identifier[labels.length + 1];

                System.arraycopy(labels, 0, newLabels, 1, labels.length);

                labels = newLabels;

            }

            labels[0] = ((IdentifierExpression)e).id;

        } else {

            env.error(e.where, "invalid.label");

        }

    }

    /**

     * Check a statement

     */

    public Vset checkMethod(Environment env, Context ctx, Vset vset, Hashtable exp) {

        // Set up ctx.getReturnContext() for the sake of ReturnStatement.check().

        CheckContext mctx = new CheckContext(ctx, new Statement(METHOD, 0));

        ctx = mctx;

        vset = check(env, ctx, vset, exp);

        // Check for return

        if (!ctx.field.getType().getReturnType().isType(TC_VOID)) {

            // In general, we suppress further error messages due to

            // unreachable statements after reporting the first error

            // along a flow path (using 'clearDeadEnd').   Here, we

            // report an error anyway, because the end of the method

            // should be unreachable despite the earlier error.  The

            // difference in treatment is due to the fact that, in this

            // case, the error is reachability, not unreachability.

            // NOTE: In addition to this subtle difference in the quality

            // of the error diagnostics, this treatment is essential to

            // preserve the correctness of using 'clearDeadEnd' to implement

            // the special-case reachability rules for if-then and if-then-else.

            if (!vset.isDeadEnd()) {

                env.error(ctx.field.getWhere(), "return.required.at.end", ctx.field);

            }

        }

        // Simulate a return at the end.

        vset = vset.join(mctx.vsBreak);

        return vset;

    }

    Vset checkDeclaration(Environment env, Context ctx, Vset vset, int mod, Type t, Hashtable exp) {

        throw new CompilerError("checkDeclaration");

    }

    /**

     * Make sure the labels on this statement do not duplicate the

     * labels on any enclosing statement.  Provided as a convenience

     * for subclasses.

     */

    protected void checkLabel(Environment env, Context ctx) {

        if (labels != null) {

            loop: for (int i = 0; i < labels.length; i++) {

                // Make sure there is not a double label on this statement.

                for (int j = i+1; j < labels.length; j++) {

                    if (labels[i] == labels[j]) {

                        env.error(where, "nested.duplicate.label", labels[i]);

                        continue loop;

                    }

                }

                // Make sure no enclosing statement has the same label.

                CheckContext destCtx =

                    (CheckContext) ctx.getLabelContext(labels[i]);

                if (destCtx != null) {

                    // Check to make sure the label is in not uplevel.

                    if (destCtx.frameNumber == ctx.frameNumber) {

                        env.error(where, "nested.duplicate.label", labels[i]);

                    }

                }

            } // end loop

        }

    }

    Vset check(Environment env, Context ctx, Vset vset, Hashtable exp) {

        throw new CompilerError("check");

    }

    /** This is called in contexts where declarations are valid. */

    Vset checkBlockStatement(Environment env, Context ctx, Vset vset, Hashtable exp) {

        return check(env, ctx, vset, exp);

    }

    Vset reach(Environment env, Vset vset) {

        if (vset.isDeadEnd()) {

            env.error(where, "stat.not.reached");

            vset = vset.clearDeadEnd();

        }

        return vset;

    }

    /**

     * Inline

     */

    public Statement inline(Environment env, Context ctx) {

        return this;

    }

    /**

     * Eliminate this statement, which is only possible if it has no label.

     */

    public Statement eliminate(Environment env, Statement s) {

        if ((s != null) && (labels != null)) {

            Statement args[] = {s};

            s = new CompoundStatement(where, args);

            s.labels = labels;

        }

        return s;

    }

    /**

     * Code

     */

    public void code(Environment env, Context ctx, Assembler asm) {

        throw new CompilerError("code");

    }

    /**

     * Generate the code to call all finally's for a break, continue, or

     * return statement.  We must call "jsr" on all the cleanup code between

     * the current context "ctx", and the destination context "stopctx".

     * If 'save' isn't null, there is also a value on the top of the stack

     */

    void codeFinally(Environment env, Context ctx, Assembler asm,

                        Context stopctx, Type save) {

        Integer num = null;

        boolean haveCleanup = false; // there is a finally or synchronize;

        boolean haveNonLocalFinally = false; // some finally doesn't return;

        for (Context c = ctx; (c != null) && (c != stopctx); c = c.prev) {

            if (c.node == null)

                continue;

            if (c.node.op == SYNCHRONIZED) {

                haveCleanup = true;

            } else if (c.node.op == FINALLY

                          && ((CodeContext)c).contLabel != null) {

                // c.contLabel == null indicates we're in the "finally" part

                haveCleanup = true;

                FinallyStatement st = ((FinallyStatement)(c.node));

                if (!st.finallyCanFinish) {

                    haveNonLocalFinally = true;

                    // after hitting a non-local finally, no need generating

                    // further code, because it won't get executed.

                    break;

                }

            }

        }

        if (!haveCleanup) {

            // there is no cleanup that needs to be done.  Just quit.

            return;

        }

        if (save != null) {

            // This statement has a return value on the stack.

            ClassDefinition def = ctx.field.getClassDefinition();

            if (!haveNonLocalFinally) {

                // Save the return value in the register which should have

                // been reserved.

                LocalMember lf = ctx.getLocalField(idFinallyReturnValue);

                num = new Integer(lf.number);

                asm.add(where, opc_istore + save.getTypeCodeOffset(), num);

            } else {

                // Pop the return value.

                switch(ctx.field.getType().getReturnType().getTypeCode()) {

                    case TC_VOID:

                        break;

                    case TC_DOUBLE: case TC_LONG:

                        asm.add(where, opc_pop2); break;

                    default:

                        asm.add(where, opc_pop); break;

                }

            }

        }

        // Call each of the cleanup functions, as necessary.

        for (Context c = ctx ; (c != null)  && (c != stopctx) ; c = c.prev) {

            if (c.node == null)

                continue;

            if (c.node.op == SYNCHRONIZED) {

                asm.add(where, opc_jsr, ((CodeContext)c).contLabel);

            } else if (c.node.op == FINALLY

                          && ((CodeContext)c).contLabel != null) {

                FinallyStatement st = ((FinallyStatement)(c.node));

                Label label = ((CodeContext)c).contLabel;

                if (st.finallyCanFinish) {

                    asm.add(where, opc_jsr, label);

                } else {

                    // the code never returns, so we're done.

                    asm.add(where, opc_goto, label);

                    break;

                }

            }

        }

        // Move the return value from the register back to the stack.

        if (num != null) {

            asm.add(where, opc_iload + save.getTypeCodeOffset(), num);

        }

    }

    /*

     * Return true if the statement has the given label

     */

    public boolean hasLabel (Identifier lbl) {

        Identifier labels[] = this.labels;

        if (labels != null) {

            for (int i = labels.length; --i >= 0; ) {

                if (labels[i].equals(lbl)) {

                    return true;

                }

            }

        }

        return false;

    }

    /**

     * Check if the first thing is a constructor invocation

     */

    public Expression firstConstructor() {

        return null;

    }

    /**

     * Create a copy of the statement for method inlining

     */

    public Statement copyInline(Context ctx, boolean valNeeded) {

        return (Statement)clone();

    }

    public int costInline(int thresh, Environment env, Context ctx) {

        return thresh;

    }

    /**

     * Print

     */

    void printIndent(PrintStream out, int indent) {

        for (int i = 0 ; i < indent ; i++) {

            out.print("    ");

        }

    }

    public void print(PrintStream out, int indent) {

        if (labels != null) {

            for (int i = labels.length; --i >= 0; )

                out.print(labels[i] + ": ");

        }

    }

    public void print(PrintStream out) {

        print(out, 0);

    }

}