    001// Copyright 2011 The Apache Software Foundation
    002//
    003// Licensed under the Apache License, Version 2.0 (the "License");
    004// you may not use this file except in compliance with the License.
    005// You may obtain a copy of the License at
    006//
    007// http://www.apache.org/licenses/LICENSE-2.0
    008//
    009// Unless required by applicable law or agreed to in writing, software
    010// distributed under the License is distributed on an "AS IS" BASIS,
    011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    012// See the License for the specific language governing permissions and
    013// limitations under the License.
    014
    015package org.apache.tapestry5.internal.plastic;
    016
    017import java.util.Map;
    018
    019import org.apache.tapestry5.internal.plastic.asm.Label;
    020import org.apache.tapestry5.internal.plastic.asm.MethodVisitor;
    021import org.apache.tapestry5.internal.plastic.asm.Opcodes;
    022import org.apache.tapestry5.plastic.LocalVariable;
    023import org.apache.tapestry5.plastic.MethodDescription;
    024
    025/**
    026 * Stores information about the method whose instructions are being constructed, to make it easier
    027 * to share data across multiple instances.
    028 */
    029public class InstructionBuilderState implements Opcodes
    030{
    031    final MethodDescription description;
    032
    033    final MethodVisitor visitor;
    034
    035    final NameCache nameCache;
    036
    037    int localIndex;
    038
    039    int varSuffix;
    040
    041    static class LVInfo
    042    {
    043        final int width, offset, loadOpcode, storeOpcode;
    044
    045        final Label end;
    046
    047        public LVInfo(int width, int offset, int loadOpcode, int storeOpcode, Label end)
    048        {
    049            this.width = width;
    050            this.offset = offset;
    051            this.loadOpcode = loadOpcode;
    052            this.storeOpcode = storeOpcode;
    053            this.end = end;
    054        }
    055    }
    056
    057    /** Map from LocalVariable to Integer offset. */
    058    final Map<LocalVariable, LVInfo> locals = PlasticInternalUtils.newMap();
    059
    060    /** Index for argument (0 is first true argument); allows for double-width primitive types. */
    061    final int[] argumentIndex;
    062
    063    /** Opcode used to load argument (0 is first true argument). */
    064    final int[] argumentLoadOpcode;
    065
    066    protected InstructionBuilderState(MethodDescription description, MethodVisitor visitor, NameCache nameCache)
    067    {
    068        this.description = description;
    069        this.visitor = visitor;
    070        this.nameCache = nameCache;
    071
    072        // TODO: Account for static methods?
    073
    074        int argCount = description.argumentTypes.length;
    075
    076        argumentIndex = new int[argCount];
    077        argumentLoadOpcode = new int[argCount];
    078
    079        // first argument index is for "this"
    080
    081        int offset = 1;
    082
    083        for (int i = 0; i < argCount; i++)
    084        {
    085            PrimitiveType type = PrimitiveType.getByName(description.argumentTypes[i]);
    086
    087            argumentIndex[i] = offset++;
    088            argumentLoadOpcode[i] = type == null ? ALOAD : type.loadOpcode;
    089
    090            if (type != null && type.isWide())
    091                offset++;
    092        }
    093
    094        localIndex = offset;
    095    }
    096
    097    /** Creates a new Label and adds it to the method. */
    098    Label newLabel()
    099    {
    100        Label result = new Label();
    101
    102        visitor.visitLabel(result);
    103
    104        return result;
    105    }
    106
    107    LocalVariable startVariable(String type)
    108    {
    109        Label start = newLabel();
    110        Label end = new Label();
    111
    112        PrimitiveType ptype = PrimitiveType.getByName(type);
    113
    114        int width = (ptype != null && ptype.isWide()) ? 2 : 1;
    115
    116        int loadOpcode = ptype == null ? ALOAD : ptype.loadOpcode;
    117        int storeOpcode = ptype == null ? ASTORE : ptype.storeOpcode;
    118
    119        LVInfo info = new LVInfo(width, localIndex, loadOpcode, storeOpcode, end);
    120
    121        localIndex += width;
    122
    123        LocalVariable var = new LocalVariableImpl(type);
    124
    125        locals.put(var, info);
    126
    127        visitor.visitLocalVariable(nextVarName(), nameCache.toDesc(type), null, start, end, info.offset);
    128
    129        return var;
    130    }
    131
    132    void load(LocalVariable var)
    133    {
    134        LVInfo info = locals.get(var);
    135
    136        visitor.visitVarInsn(info.loadOpcode, info.offset);
    137    }
    138
    139    void store(LocalVariable var)
    140    {
    141        LVInfo info = locals.get(var);
    142
    143        visitor.visitVarInsn(info.storeOpcode, info.offset);
    144    }
    145
    146    void stopVariable(LocalVariable variable)
    147    {
    148        LVInfo info = locals.get(variable);
    149
    150        visitor.visitLabel(info.end);
    151
    152        locals.remove(variable);
    153
    154        localIndex -= info.width;
    155    }
    156
    157    private String nextVarName()
    158    {
    159        return "var" + varSuffix++;
    160    }
    161}