nativestring.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):
 *   Tom Beauvais
 *   Norris Boyd
 *   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;

/**
 * This class implements the String native object.
 *
 * See ECMA 15.5.
 *
 * String methods for dealing with regular expressions are
 * ported directly from C. Latest port is from version 1.40.12.19
 * in the JSFUN13_BRANCH.
 *
 * @author Mike McCabe
 * @author Norris Boyd
 */
final class NativeString extends IdScriptableObject
{
    static final long serialVersionUID = 920268368584188687L;

    private static final Object STRING_TAG = new Object();

    static void init(Scriptable scope, boolean sealed)
    {
        NativeString obj = new NativeString("");
        obj.exportAsJSClass(MAX_PROTOTYPE_ID, scope, sealed);
    }

    private NativeString(String s) {
        string = s;
    }

    public String getClassName() {
        return "String";
    }

    private static final int
        Id_length                    =  1,
        MAX_INSTANCE_ID              =  1;

    protected int getMaxInstanceId()
    {
        return MAX_INSTANCE_ID;
    }

    protected int findInstanceIdInfo(String s)
    {
        if (s.equals("length")) {
            return instanceIdInfo(DONTENUM | READONLY | PERMANENT, Id_length);
        }
        return super.findInstanceIdInfo(s);
    }

    protected String getInstanceIdName(int id)
    {
        if (id == Id_length) { return "length"; }
        return super.getInstanceIdName(id);
    }

    protected Object getInstanceIdValue(int id)
    {
        if (id == Id_length) {
            return ScriptRuntime.wrapInt(string.length());
        }
        return super.getInstanceIdValue(id);
    }

    protected void fillConstructorProperties(IdFunctionObject ctor)
    {
        addIdFunctionProperty(ctor, STRING_TAG, ConstructorId_fromCharCode,
                              "fromCharCode", 1);
        super.fillConstructorProperties(ctor);
    }

    protected void initPrototypeId(int id)
    {
        String s;
        int arity;
        switch (id) {
          case Id_constructor:      arity=1; s="constructor";      break;
          case Id_toString:         arity=0; s="toString";         break;
          case Id_toSource:         arity=0; s="toSource";         break;
          case Id_valueOf:          arity=0; s="valueOf";          break;
          case Id_charAt:           arity=1; s="charAt";           break;
          case Id_charCodeAt:       arity=1; s="charCodeAt";       break;
          case Id_indexOf:          arity=1; s="indexOf";          break;
          case Id_lastIndexOf:      arity=1; s="lastIndexOf";      break;
          case Id_split:            arity=2; s="split";            break;
          case Id_substring:        arity=2; s="substring";        break;
          case Id_toLowerCase:      arity=0; s="toLowerCase";      break;
          case Id_toUpperCase:      arity=0; s="toUpperCase";      break;
          case Id_substr:           arity=2; s="substr";           break;
          case Id_concat:           arity=1; s="concat";           break;
          case Id_slice:            arity=2; s="slice";            break;
          case Id_bold:             arity=0; s="bold";             break;
          case Id_italics:          arity=0; s="italics";          break;
          case Id_fixed:            arity=0; s="fixed";            break;
          case Id_strike:           arity=0; s="strike";           break;
          case Id_small:            arity=0; s="small";            break;
          case Id_big:              arity=0; s="big";              break;
          case Id_blink:            arity=0; s="blink";            break;
          case Id_sup:              arity=0; s="sup";              break;
          case Id_sub:              arity=0; s="sub";              break;
          case Id_fontsize:         arity=0; s="fontsize";         break;
          case Id_fontcolor:        arity=0; s="fontcolor";        break;
          case Id_link:             arity=0; s="link";             break;
          case Id_anchor:           arity=0; s="anchor";           break;
          case Id_equals:           arity=1; s="equals";           break;
          case Id_equalsIgnoreCase: arity=1; s="equalsIgnoreCase"; break;
          case Id_match:            arity=1; s="match";            break;
          case Id_search:           arity=1; s="search";           break;
          case Id_replace:          arity=1; s="replace";          break;
          default: throw new IllegalArgumentException(String.valueOf(id));
        }
        initPrototypeMethod(STRING_TAG, id, s, arity);
    }

    public Object execIdCall(IdFunctionObject f, Context cx, Scriptable scope,
                             Scriptable thisObj, Object[] args)
    {
        if (!f.hasTag(STRING_TAG)) {
            return super.execIdCall(f, cx, scope, thisObj, args);
        }
        int id = f.methodId();
        switch (id) {
          case ConstructorId_fromCharCode: {
            int N = args.length;
            if (N < 1)
                return "";
            StringBuffer sb = new StringBuffer(N);
            for (int i = 0; i != N; ++i) {
                sb.append(ScriptRuntime.toUint16(args[i]));
            }
            return sb.toString();
          }

          case Id_constructor: {
            String s = (args.length >= 1)
                ? ScriptRuntime.toString(args[0]) : "";
            if (thisObj == null) {
                // new String(val) creates a new String object.
                return new NativeString(s);
            }
            // String(val) converts val to a string value.
            return s;
          }

          case Id_toString:
          case Id_valueOf:
            // ECMA 15.5.4.2: 'the toString function is not generic.
            return realThis(thisObj, f).string;

          case Id_toSource: {
            String s = realThis(thisObj, f).string;
            return "(new String(\""+ScriptRuntime.escapeString(s)+"\"))";
          }

          case Id_charAt:
          case Id_charCodeAt: {
             // See ECMA 15.5.4.[4,5]
            String target = ScriptRuntime.toString(thisObj);
            double pos = ScriptRuntime.toInteger(args, 0);
            if (pos < 0 || pos >= target.length()) {
                if (id == Id_charAt) return "";
                else return ScriptRuntime.NaNobj;
            }
            char c = target.charAt((int)pos);
            if (id == Id_charAt) return String.valueOf(c);
            else return ScriptRuntime.wrapInt(c);
          }

          case Id_indexOf:
            return ScriptRuntime.wrapInt(js_indexOf(
                ScriptRuntime.toString(thisObj), args));

          case Id_lastIndexOf:
            return ScriptRuntime.wrapInt(js_lastIndexOf(
                ScriptRuntime.toString(thisObj), args));

          case Id_split:
            return js_split(cx, scope, ScriptRuntime.toString(thisObj), args);

          case Id_substring:
            return js_substring(cx, ScriptRuntime.toString(thisObj), args);

          case Id_toLowerCase:
            // See ECMA 15.5.4.11
            return ScriptRuntime.toString(thisObj).toLowerCase();

          case Id_toUpperCase:
            // See ECMA 15.5.4.12
            return ScriptRuntime.toString(thisObj).toUpperCase();

          case Id_substr:
            return js_substr(ScriptRuntime.toString(thisObj), args);

          case Id_concat:
            return js_concat(ScriptRuntime.toString(thisObj), args);

          case Id_slice:
            return js_slice(ScriptRuntime.toString(thisObj), args);

          case Id_bold:
            return tagify(thisObj, "b", null, null);

          case Id_italics:
            return tagify(thisObj, "i", null, null);

          case Id_fixed:
            return tagify(thisObj, "tt", null, null);

          case Id_strike:
            return tagify(thisObj, "strike", null, null);

          case Id_small:
            return tagify(thisObj, "small", null, null);

          case Id_big:
            return tagify(thisObj, "big", null, null);

          case Id_blink:
            return tagify(thisObj, "blink", null, null);

          case Id_sup:
            return tagify(thisObj, "sup", null, null);

          case Id_sub:
            return tagify(thisObj, "sub", null, null);

          case Id_fontsize:
            return tagify(thisObj, "font", "size", args);

          case Id_fontcolor:
            return tagify(thisObj, "font", "color", args);

          case Id_link:
            return tagify(thisObj, "a", "href", args);

          case Id_anchor:
            return tagify(thisObj, "a", "name", args);

          case Id_equals:
          case Id_equalsIgnoreCase: {
            String s1 = ScriptRuntime.toString(thisObj);
            String s2 = ScriptRuntime.toString(args, 0);
            return ScriptRuntime.wrapBoolean(
                (id == Id_equals) ? s1.equals(s2) : s1.equalsIgnoreCase(s2));
          }

          case Id_match:
          case Id_search:
          case Id_replace:
            {
                int actionType;
                if (id == Id_match) {
                    actionType = RegExpProxy.RA_MATCH;
                } else if (id == Id_search) {
                    actionType = RegExpProxy.RA_SEARCH;
                } else {
                    actionType = RegExpProxy.RA_REPLACE;
                }
                return ScriptRuntime.checkRegExpProxy(cx).
                    action(cx, scope, thisObj, args, actionType);
            }
        }
        throw new IllegalArgumentException(String.valueOf(id));
    }

    private static NativeString realThis(Scriptable thisObj, IdFunctionObject f)
    {
        if (!(thisObj instanceof NativeString))
            throw incompatibleCallError(f);
        return (NativeString)thisObj;
    }

    /*
     * HTML composition aids.
     */
    private static String tagify(Object thisObj, String tag,
                                 String attribute, Object[] args)
    {
        String str = ScriptRuntime.toString(thisObj);
        StringBuffer result = new StringBuffer();
        result.append('<');
        result.append(tag);
        if (attribute != null) {
            result.append(' ');
            result.append(attribute);
            result.append("=\"");
            result.append(ScriptRuntime.toString(args, 0));
            result.append('"');
        }
        result.append('>');
        result.append(str);
        result.append("</");
        result.append(tag);
        result.append('>');
        return result.toString();
    }

    public String toString() {
        return string;
    }

    /* Make array-style property lookup work for strings.
     * XXX is this ECMA?  A version check is probably needed. In js too.
     */
    public Object get(int index, Scriptable start) {
        if (0 <= index && index < string.length()) {
            return string.substring(index, index + 1);
        }
        return super.get(index, start);
    }

    public void put(int index, Scriptable start, Object value) {
        if (0 <= index && index < string.length()) {
            return;
        }
        super.put(index, start, value);
    }

    /*
     *
     * See ECMA 15.5.4.6.  Uses Java String.indexOf()
     * OPT to add - BMH searching from jsstr.c.
     */
    private static int js_indexOf(String target, Object[] args) {
        String search = ScriptRuntime.toString(args, 0);
        double begin = ScriptRuntime.toInteger(args, 1);

        if (begin > target.length()) {
            return -1;
        } else {
            if (begin < 0)
                begin = 0;
            return target.indexOf(search, (int)begin);
        }
    }

    /*
     *
     * See ECMA 15.5.4.7
     *
     */
    private static int js_lastIndexOf(String target, Object[] args) {
        String search = ScriptRuntime.toString(args, 0);
        double end = ScriptRuntime.toNumber(args, 1);

        if (end != end || end > target.length())
            end = target.length();
        else if (end < 0)
            end = 0;

        return target.lastIndexOf(search, (int)end);
    }

    /*
     * Used by js_split to find the next split point in target,
     * starting at offset ip and looking either for the given
     * separator substring, or for the next re match.  ip and
     * matchlen must be reference variables (assumed to be arrays of
     * length 1) so they can be updated in the leading whitespace or
     * re case.
     *
     * Return -1 on end of string, >= 0 for a valid index of the next
     * separator occurrence if found, or the string length if no
     * separator is found.
     */
    private static int find_split(Context cx, Scriptable scope, String target,
                                  String separator, int version,
                                  RegExpProxy reProxy, Scriptable re,
                                  int[] ip, int[] matchlen, boolean[] matched,
                                  String[][] parensp)
    {
        int i = ip[0];
        int length = target.length();

        /*
         * Perl4 special case for str.split(' '), only if the user has selected
         * JavaScript1.2 explicitly.  Split on whitespace, and skip leading w/s.
         * Strange but true, apparently modeled after awk.
         */
        if (version == Context.VERSION_1_2 &&
            re == null && separator.length() == 1 && separator.charAt(0) == ' ')
        {
            /* Skip leading whitespace if at front of str. */
            if (i == 0) {
                while (i < length && Character.isWhitespace(target.charAt(i)))
                    i++;
                ip[0] = i;
            }