nativeglobal.java

java中比较著名的js引擎当属mozilla开源的rhino

/* -*- Mode: java; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 *
 * ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Rhino code, released
 * May 6, 1999.
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 1997-1999
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   Norris Boyd
 *   Igor Bukanov
 *   Mike McCabe
 *
 * Alternatively, the contents of this file may be used under the terms of
 * the GNU General Public License Version 2 or later (the "GPL"), in which
 * case the provisions of the GPL are applicable instead of those above. If
 * you wish to allow use of your version of this file only under the terms of
 * the GPL and not to allow others to use your version of this file under the
 * MPL, indicate your decision by deleting the provisions above and replacing
 * them with the notice and other provisions required by the GPL. If you do
 * not delete the provisions above, a recipient may use your version of this
 * file under either the MPL or the GPL.
 *
 * ***** END LICENSE BLOCK ***** */

package org.mozilla.javascript;

import java.io.Serializable;

import org.mozilla.javascript.xml.XMLLib;

/**
 * This class implements the global native object (function and value
 * properties only).
 *
 * See ECMA 15.1.[12].
 *
 * @author Mike Shaver
 */

public class NativeGlobal implements Serializable, IdFunctionCall
{
    static final long serialVersionUID = 6080442165748707530L;

    public static void init(Context cx, Scriptable scope, boolean sealed) {
        NativeGlobal obj = new NativeGlobal();

        for (int id = 1; id <= LAST_SCOPE_FUNCTION_ID; ++id) {
            String name;
            int arity = 1;
            switch (id) {
              case Id_decodeURI:
                name = "decodeURI";
                break;
              case Id_decodeURIComponent:
                name = "decodeURIComponent";
                break;
              case Id_encodeURI:
                name = "encodeURI";
                break;
              case Id_encodeURIComponent:
                name = "encodeURIComponent";
                break;
              case Id_escape:
                name = "escape";
                break;
              case Id_eval:
                name = "eval";
                break;
              case Id_isFinite:
                name = "isFinite";
                break;
              case Id_isNaN:
                name = "isNaN";
                break;
              case Id_isXMLName:
                name = "isXMLName";
                break;
              case Id_parseFloat:
                name = "parseFloat";
                break;
              case Id_parseInt:
                name = "parseInt";
                arity = 2;
                break;
              case Id_unescape:
                name = "unescape";
                break;
              case Id_uneval:
                name = "uneval";
                break;
              default:
                  throw Kit.codeBug();
            }
            IdFunctionObject f = new IdFunctionObject(obj, FTAG, id, name,
                                                      arity, scope);
            if (sealed) {
                f.sealObject();
            }
            f.exportAsScopeProperty();
        }

        ScriptableObject.defineProperty(
            scope, "NaN", ScriptRuntime.NaNobj,
            ScriptableObject.DONTENUM);
        ScriptableObject.defineProperty(
            scope, "Infinity",
            ScriptRuntime.wrapNumber(Double.POSITIVE_INFINITY),
            ScriptableObject.DONTENUM);
        ScriptableObject.defineProperty(
            scope, "undefined", Undefined.instance,
            ScriptableObject.DONTENUM);

        String[] errorMethods = Kit.semicolonSplit(""
                                    +"ConversionError;"
                                    +"EvalError;"
                                    +"RangeError;"
                                    +"ReferenceError;"
                                    +"SyntaxError;"
                                    +"TypeError;"
                                    +"URIError;"
                                    +"InternalError;"
                                    +"JavaException;"
                                    );

        /*
            Each error constructor gets its own Error object as a prototype,
            with the 'name' property set to the name of the error.
        */
        for (int i = 0; i < errorMethods.length; i++) {
            String name = errorMethods[i];
            Scriptable errorProto = ScriptRuntime.
                                        newObject(cx, scope, "Error",
                                                  ScriptRuntime.emptyArgs);
            errorProto.put("name", errorProto, name);
            if (sealed) {
                if (errorProto instanceof ScriptableObject) {
                    ((ScriptableObject)errorProto).sealObject();
                }
            }
            IdFunctionObject ctor = new IdFunctionObject(obj, FTAG,
                                                         Id_new_CommonError,
                                                         name, 1, scope);
            ctor.markAsConstructor(errorProto);
            if (sealed) {
                ctor.sealObject();
            }
            ctor.exportAsScopeProperty();
        }
    }

    public Object execIdCall(IdFunctionObject f, Context cx, Scriptable scope,
                             Scriptable thisObj, Object[] args)
    {
        if (f.hasTag(FTAG)) {
            int methodId = f.methodId();
            switch (methodId) {
                case Id_decodeURI:
                case Id_decodeURIComponent: {
                    String str = ScriptRuntime.toString(args, 0);
                    return decode(str, methodId == Id_decodeURI);
                }

                case Id_encodeURI:
                case Id_encodeURIComponent: {
                    String str = ScriptRuntime.toString(args, 0);
                    return encode(str, methodId == Id_encodeURI);
                }

                case Id_escape:
                    return js_escape(args);

                case Id_eval:
                    return js_eval(cx, scope, args);

                case Id_isFinite: {
                    boolean result;
                    if (args.length < 1) {
                        result = false;
                    } else {
                        double d = ScriptRuntime.toNumber(args[0]);
                        result = (d == d
                                  && d != Double.POSITIVE_INFINITY
                                  && d != Double.NEGATIVE_INFINITY);
                    }
                    return ScriptRuntime.wrapBoolean(result);
                }

                case Id_isNaN: {
                    // The global method isNaN, as per ECMA-262 15.1.2.6.
                    boolean result;
                    if (args.length < 1) {
                        result = true;
                    } else {
                        double d = ScriptRuntime.toNumber(args[0]);
                        result = (d != d);
                    }
                    return ScriptRuntime.wrapBoolean(result);
                }

                case Id_isXMLName: {
                    Object name = (args.length == 0)
                                  ? Undefined.instance : args[0];
                    XMLLib xmlLib = XMLLib.extractFromScope(scope);
                    return ScriptRuntime.wrapBoolean(
                        xmlLib.isXMLName(cx, name));
                }

                case Id_parseFloat:
                    return js_parseFloat(args);

                case Id_parseInt:
                    return js_parseInt(args);

                case Id_unescape:
                    return js_unescape(args);

                case Id_uneval: {
                    Object value = (args.length != 0)
                                   ? args[0] : Undefined.instance;
                    return ScriptRuntime.uneval(cx, scope, value);
                }

                case Id_new_CommonError:
                    // The implementation of all the ECMA error constructors
                    // (SyntaxError, TypeError, etc.)
                    return NativeError.make(cx, scope, f, args);
            }
        }
        throw f.unknown();
    }

    /**
     * The global method parseInt, as per ECMA-262 15.1.2.2.
     */
    private Object js_parseInt(Object[] args) {
        String s = ScriptRuntime.toString(args, 0);
        int radix = ScriptRuntime.toInt32(args, 1);

        int len = s.length();
        if (len == 0)
            return ScriptRuntime.NaNobj;

        boolean negative = false;
        int start = 0;
        char c;
        do {
            c = s.charAt(start);
            if (!Character.isWhitespace(c))
                break;
            start++;
        } while (start < len);

        if (c == '+' || (negative = (c == '-')))
            start++;

        final int NO_RADIX = -1;
        if (radix == 0) {
            radix = NO_RADIX;
        } else if (radix < 2 || radix > 36) {
            return ScriptRuntime.NaNobj;
        } else if (radix == 16 && len - start > 1 && s.charAt(start) == '0') {
            c = s.charAt(start+1);
            if (c == 'x' || c == 'X')
                start += 2;
        }

        if (radix == NO_RADIX) {
            radix = 10;
            if (len - start > 1 && s.charAt(start) == '0') {
                c = s.charAt(start+1);
                if (c == 'x' || c == 'X') {
                    radix = 16;
                    start += 2;
                } else if ('0' <= c && c <= '9') {
                    radix = 8;
                    start++;
                }
            }
        }

        double d = ScriptRuntime.stringToNumber(s, start, radix);
        return ScriptRuntime.wrapNumber(negative ? -d : d);
    }

    /**
     * The global method parseFloat, as per ECMA-262 15.1.2.3.
     *
     * @param cx unused
     * @param thisObj unused
     * @param args the arguments to parseFloat, ignoring args[>=1]
     * @param funObj unused
     */
    private Object js_parseFloat(Object[] args)
    {
        if (args.length < 1)
            return ScriptRuntime.NaNobj;

        String s = ScriptRuntime.toString(args[0]);
        int len = s.length();
        int start = 0;
        // Scan forward to skip whitespace
        char c;
        for (;;) {
            if (start == len) {
                return ScriptRuntime.NaNobj;
            }
            c = s.charAt(start);
            if (!TokenStream.isJSSpace(c)) {
                break;
            }
            ++start;
        }

        int i = start;
        if (c == '+' || c == '-') {
            ++i;
            if (i == len) {
                return ScriptRuntime.NaNobj;
            }
            c = s.charAt(i);
        }

        if (c == 'I') {
            // check for "Infinity"
            if (i+8 <= len && s.regionMatches(i, "Infinity", 0, 8)) {
                double d;
                if (s.charAt(start) == '-') {
                    d = Double.NEGATIVE_INFINITY;
                } else {
                    d = Double.POSITIVE_INFINITY;
                }
                return ScriptRuntime.wrapNumber(d);
            }
            return ScriptRuntime.NaNobj;
        }

        // Find the end of the legal bit
        int decimal = -1;
        int exponent = -1;
        for (; i < len; i++) {
            switch (s.charAt(i)) {
              case '.':
                if (decimal != -1) // Only allow a single decimal point.
                    break;
                decimal = i;
                continue;

              case 'e':
              case 'E':
                if (exponent != -1)
                    break;
                exponent = i;
                continue;

              case '+':
              case '-':
                 // Only allow '+' or '-' after 'e' or 'E'
                if (exponent != i-1)
                    break;
                continue;

              case '0': case '1': case '2': case '3': case '4':
              case '5': case '6': case '7': case '8': case '9':
                continue;

              default:
                break;
            }
            break;
        }
        s = s.substring(start, i);
        try {
            return Double.valueOf(s);
        }
        catch (NumberFormatException ex) {
            return ScriptRuntime.NaNobj;
        }
    }

    /**
     * The global method escape, as per ECMA-262 15.1.2.4.