codegen.java

這是一個javascript 的 interpreter是了解 web browser的好材料

                             (short)(ClassFileWriter.ACC_STATIC
                                     | ClassFileWriter.ACC_PRIVATE));
                cfw.addALoad(0); // proxy
                cfw.addALoad(1); // context
                cfw.addPush(reString);
                if (reFlags == null) {
                    cfw.add(ByteCode.ACONST_NULL);
                } else {
                    cfw.addPush(reFlags);
                }
                cfw.addInvoke(ByteCode.INVOKEINTERFACE,
                              "org/mozilla/javascript/RegExpProxy",
                              "compileRegExp",
                              "(Lorg/mozilla/javascript/Context;"
                              +"Ljava/lang/String;Ljava/lang/String;"
                              +")Ljava/lang/Object;");
                cfw.add(ByteCode.PUTSTATIC, mainClassName,
                        reFieldName, reFieldType);
            }
        }

        cfw.addPush(1);
        cfw.add(ByteCode.PUTSTATIC, mainClassName, "_reInitDone", "Z");
        cfw.add(ByteCode.RETURN);
        cfw.stopMethod((short)2);
    }

    private void emitConstantDudeInitializers(ClassFileWriter cfw)
    {
        int N = itsConstantListSize;
        if (N == 0)
            return;

        cfw.startMethod("<clinit>", "()V",
            (short)(ClassFileWriter.ACC_STATIC | ClassFileWriter.ACC_FINAL));

        double[] array = itsConstantList;
        for (int i = 0; i != N; ++i) {
            double num = array[i];
            String constantName = "_k" + i;
            String constantType = getStaticConstantWrapperType(num);
            cfw.addField(constantName, constantType,
                         (short)(ClassFileWriter.ACC_STATIC
                                 | ClassFileWriter.ACC_PRIVATE));
            int inum = (int)num;
            if (inum == num) {
                cfw.add(ByteCode.NEW, "java/lang/Integer");
                cfw.add(ByteCode.DUP);
                cfw.addPush(inum);
                cfw.addInvoke(ByteCode.INVOKESPECIAL, "java/lang/Integer",
                              "<init>", "(I)V");
            } else {
                cfw.addPush(num);
                addDoubleWrap(cfw);
            }
            cfw.add(ByteCode.PUTSTATIC, mainClassName,
                    constantName, constantType);
        }

        cfw.add(ByteCode.RETURN);
        cfw.stopMethod((short)0);
    }

    void pushRegExpArray(ClassFileWriter cfw, ScriptOrFnNode n,
                         int contextArg, int scopeArg)
    {
        int regexpCount = n.getRegexpCount();
        if (regexpCount == 0) throw badTree();

        cfw.addPush(regexpCount);
        cfw.add(ByteCode.ANEWARRAY, "java/lang/Object");

        cfw.addALoad(contextArg);
        cfw.addInvoke(ByteCode.INVOKESTATIC,
                      "org/mozilla/javascript/ScriptRuntime",
                      "checkRegExpProxy",
                      "(Lorg/mozilla/javascript/Context;"
                      +")Lorg/mozilla/javascript/RegExpProxy;");
        // Stack: proxy, array
        cfw.add(ByteCode.DUP);
        cfw.addALoad(contextArg);
        cfw.addInvoke(ByteCode.INVOKESTATIC, mainClassName,
                      REGEXP_INIT_METHOD_NAME, REGEXP_INIT_METHOD_SIGNATURE);
        for (int i = 0; i != regexpCount; ++i) {
            // Stack: proxy, array
            cfw.add(ByteCode.DUP2);
            cfw.addALoad(contextArg);
            cfw.addALoad(scopeArg);
            cfw.add(ByteCode.GETSTATIC, mainClassName,
                    getCompiledRegexpName(n, i), "Ljava/lang/Object;");
            // Stack: compiledRegExp, scope, cx, proxy, array, proxy, array
            cfw.addInvoke(ByteCode.INVOKEINTERFACE,
                          "org/mozilla/javascript/RegExpProxy",
                          "wrapRegExp",
                          "(Lorg/mozilla/javascript/Context;"
                          +"Lorg/mozilla/javascript/Scriptable;"
                          +"Ljava/lang/Object;"
                          +")Lorg/mozilla/javascript/Scriptable;");
            // Stack: wrappedRegExp, array, proxy, array
            cfw.addPush(i);
            cfw.add(ByteCode.SWAP);
            cfw.add(ByteCode.AASTORE);
            // Stack: proxy, array
        }
        // remove proxy
        cfw.add(ByteCode.POP);
    }

    void pushNumberAsObject(ClassFileWriter cfw, double num)
    {
        if (num == 0.0) {
            if (1 / num > 0) {
                // +0.0
                cfw.add(ByteCode.GETSTATIC,
                        "org/mozilla/javascript/optimizer/OptRuntime",
                        "zeroObj", "Ljava/lang/Double;");
            } else {
                cfw.addPush(num);
                addDoubleWrap(cfw);
            }

        } else if (num == 1.0) {
            cfw.add(ByteCode.GETSTATIC,
                    "org/mozilla/javascript/optimizer/OptRuntime",
                    "oneObj", "Ljava/lang/Double;");
            return;

        } else if (num == -1.0) {
            cfw.add(ByteCode.GETSTATIC,
                    "org/mozilla/javascript/optimizer/OptRuntime",
                    "minusOneObj", "Ljava/lang/Double;");

        } else if (num != num) {
            cfw.add(ByteCode.GETSTATIC,
                    "org/mozilla/javascript/ScriptRuntime",
                    "NaNobj", "Ljava/lang/Double;");

        } else if (itsConstantListSize >= 2000) {
            // There appears to be a limit in the JVM on either the number
            // of static fields in a class or the size of the class
            // initializer. Either way, we can't have any more than 2000
            // statically init'd constants.
            cfw.addPush(num);
            addDoubleWrap(cfw);

        } else {
            int N = itsConstantListSize;
            int index = 0;
            if (N == 0) {
                itsConstantList = new double[64];
            } else {
                double[] array = itsConstantList;
                while (index != N && array[index] != num) {
                    ++index;
                }
                if (N == array.length) {
                    array = new double[N * 2];
                    System.arraycopy(itsConstantList, 0, array, 0, N);
                    itsConstantList = array;
                }
            }
            if (index == N) {
                itsConstantList[N] = num;
                itsConstantListSize = N + 1;
            }
            String constantName = "_k" + index;
            String constantType = getStaticConstantWrapperType(num);
            cfw.add(ByteCode.GETSTATIC, mainClassName,
                    constantName, constantType);
        }
    }

    private static void addDoubleWrap(ClassFileWriter cfw)
    {
        cfw.addInvoke(ByteCode.INVOKESTATIC,
                      "org/mozilla/javascript/optimizer/OptRuntime",
                      "wrapDouble", "(D)Ljava/lang/Double;");
    }

    private static String getStaticConstantWrapperType(double num)
    {
        int inum = (int)num;
        if (inum == num) {
            return "Ljava/lang/Integer;";
        } else {
            return "Ljava/lang/Double;";
        }
    }
    static void pushUndefined(ClassFileWriter cfw)
    {
        cfw.add(ByteCode.GETSTATIC, "org/mozilla/javascript/Undefined",
                "instance", "Ljava/lang/Object;");
    }

    int getIndex(ScriptOrFnNode n)
    {
        return scriptOrFnIndexes.getExisting(n);
    }

    static String getDirectTargetFieldName(int i)
    {
        return "_dt" + i;
    }

    String getDirectCtorName(ScriptOrFnNode n)
    {
        return "_n"+getIndex(n);
    }

    String getBodyMethodName(ScriptOrFnNode n)
    {
        return "_c"+getIndex(n);
    }

    String getBodyMethodSignature(ScriptOrFnNode n)
    {
        StringBuffer sb = new StringBuffer();
        sb.append('(');
        sb.append(mainClassSignature);
        sb.append("Lorg/mozilla/javascript/Context;"
                  +"Lorg/mozilla/javascript/Scriptable;"
                  +"Lorg/mozilla/javascript/Scriptable;");
        if (n.getType() == Token.FUNCTION) {
            OptFunctionNode ofn = OptFunctionNode.get(n);
            if (ofn.isTargetOfDirectCall()) {
                int pCount = ofn.fnode.getParamCount();
                for (int i = 0; i != pCount; i++) {
                    sb.append("Ljava/lang/Object;D");
                }
            }
        }
        sb.append("[Ljava/lang/Object;)Ljava/lang/Object;");
        return sb.toString();
    }

    String getFunctionInitMethodName(OptFunctionNode ofn)
    {
        return "_i"+getIndex(ofn.fnode);
    }

    String getCompiledRegexpName(ScriptOrFnNode n, int regexpIndex)
    {
        return "_re"+getIndex(n)+"_"+regexpIndex;
    }

    static RuntimeException badTree()
    {
        throw new RuntimeException("Bad tree in codegen");
    }

     void setMainMethodClass(String className)
     {
         mainMethodClass = className;
     }

     static final String DEFAULT_MAIN_METHOD_CLASS
        = "org.mozilla.javascript.optimizer.OptRuntime";

    private static final String SUPER_CLASS_NAME
        = "org.mozilla.javascript.NativeFunction";

    static final String DIRECT_CALL_PARENT_FIELD = "_dcp";
    private static final String ID_FIELD_NAME = "_id";

    private static final String REGEXP_INIT_METHOD_NAME = "_reInit";
    private static final String REGEXP_INIT_METHOD_SIGNATURE
        =  "(Lorg/mozilla/javascript/RegExpProxy;"
           +"Lorg/mozilla/javascript/Context;"
           +")V";
    static final String REGEXP_ARRAY_FIELD_NAME = "_re";
    static final String REGEXP_ARRAY_FIELD_TYPE = "[Ljava/lang/Object;";

    static final String FUNCTION_INIT_SIGNATURE
        =  "(Lorg/mozilla/javascript/Context;"
           +"Lorg/mozilla/javascript/Scriptable;"
           +")V";

   static final String FUNCTION_CONSTRUCTOR_SIGNATURE
        = "(Lorg/mozilla/javascript/Scriptable;"
          +"Lorg/mozilla/javascript/Context;I)V";

    private static final Object globalLock = new Object();
    private static int globalSerialClassCounter;

    private CompilerEnvirons compilerEnv;

    private ObjArray directCallTargets;
    ScriptOrFnNode[] scriptOrFnNodes;
    private ObjToIntMap scriptOrFnIndexes;

    private String mainMethodClass = DEFAULT_MAIN_METHOD_CLASS;

    String mainClassName;
    String mainClassSignature;

    private double[] itsConstantList;
    private int itsConstantListSize;
}


class BodyCodegen
{
    void generateBodyCode()
    {
        isGenerator = Codegen.isGenerator(scriptOrFn);
        
        // generate the body of the current function or script object
        initBodyGeneration();

        if (isGenerator) {

            // All functions in the generated bytecode have a unique name. Every
            // generator has a unique prefix followed by _gen
            String type = "(" +
                          codegen.mainClassSignature +
                          "Lorg/mozilla/javascript/Context;" +
                          "Lorg/mozilla/javascript/Scriptable;" +
                          "Ljava/lang/Object;" +
                          "Ljava/lang/Object;I)Ljava/lang/Object;"; 
            cfw.startMethod(codegen.getBodyMethodName(scriptOrFn) + "_gen",
                    type,
                    (short)(ClassFileWriter.ACC_STATIC
                            | ClassFileWriter.ACC_PRIVATE));
        } else {
            cfw.startMethod(codegen.getBodyMethodName(scriptOrFn),
                    codegen.getBodyMethodSignature(scriptOrFn),
                    (short)(ClassFileWriter.ACC_STATIC
                            | ClassFileWriter.ACC_PRIVATE));
        }

        generatePrologue();
        Node treeTop;
        if (fnCurrent != null) {
            treeTop = scriptOrFn.getLastChild();
        } else {
            treeTop = scriptOrFn;
        }
        generateStatement(treeTop);
        generateEpilogue();

        cfw.stopMethod((short)(localsMax + 1));