com.google.javascript.rhino.TokenStream Maven / Gradle / Ivy
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/*
*
* ***** 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):
* Roger Lawrence
* Mike McCabe
* Igor Bukanov
* Ethan Hugg
* Bob Jervis
* Terry Lucas
* Milen Nankov
* Pascal-Louis Perez
*
* 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 com.google.javascript.rhino;
/**
* This class implements the JavaScript scanner.
*
* It is based on the C source files jsscan.c and jsscan.h in the jsref package.
*
*
IMPORTANT: As of 2018-03-09 it is still not possible to use Java 8 features in this file due
* to limitations on some internal Google projects that depend on it.
*/
public final class TokenStream {
/**
* Is the string an ES3 keyword?
*
*
Keywords for versions of JavaScript after ES3 are not included, because the parser would
* reject valid ES3 code that happened to newer keywords if we did that.
*
*
Since isKeyword() is used repeatedly in scanning, for performance reasons, it is implemented
* to do the minimum number of character comparisons to ascertain whether the given name is a
* keyword, instead of doing string search of the name against JS keywords.
*/
public static boolean isKeyword(String name) {
boolean id = false;
String s = name;
complete: {
String X = null;
int c;
partial: switch (s.length()) {
case 2: c=s.charAt(1);
if (c=='f') {
if (s.charAt(0)=='i') {id=true; break complete;}
} else if (c=='n') {
if (s.charAt(0)=='i') {id=true; break complete;}
} else if (c=='o') {
if (s.charAt(0)=='d') {id=true; break complete;}
}
break partial;
case 3: switch (s.charAt(0)) {
case 'f':
if (s.charAt(2)=='r' && s.charAt(1)=='o') {
id=true; break complete;
} break partial;
case 'i':
if (s.charAt(2)=='t' && s.charAt(1)=='n') {
id=true; break complete;
} break partial;
case 'n':
if (s.charAt(2)=='w' && s.charAt(1)=='e') {
id=true; break complete;
} break partial;
case 't':
if (s.charAt(2)=='y' && s.charAt(1)=='r') {
id=true; break complete;
} break partial;
case 'v':
if (s.charAt(2)=='r' && s.charAt(1)=='a') {
id=true; break complete;
} break partial;
} break partial;
case 4: switch (s.charAt(0)) {
case 'b': X="byte";id=true; break partial;
case 'c': c=s.charAt(3);
if (c=='e') { if (s.charAt(2)=='s' && s.charAt(1)=='a') {
id=true; break complete;} }
else if (c=='r') {
if (s.charAt(2)=='a' && s.charAt(1)=='h') {
id=true; break complete;
}
}
break partial;
case 'e': c=s.charAt(3);
if (c=='e') { if (s.charAt(2)=='s' && s.charAt(1)=='l') {
id=true; break complete;} }
else if (c=='m') {
if (s.charAt(2)=='u' && s.charAt(1)=='n') {
id=true; break complete;} }
break partial;
case 'g': X="goto";id=true; break partial;
case 'l': X="long";id=true; break partial;
case 'n': X="null";id=true; break partial;
case 't': c=s.charAt(3);
if (c=='e') { if (s.charAt(2)=='u' && s.charAt(1)=='r') {
id=true; break complete;} }
else if (c=='s') {
if (s.charAt(2)=='i' && s.charAt(1)=='h') {
id=true; break complete;} }
break partial;
case 'v': X="void";id=true; break partial;
case 'w': X="with";id=true; break partial;
} break partial;
case 5: switch (s.charAt(2)) {
case 'a': X="class";id=true; break partial;
case 'e': X="break";id=true; break partial;
case 'i': X="while";id=true; break partial;
case 'l': X="false";id=true; break partial;
case 'n': c=s.charAt(0);
if (c=='c') { X="const";id=true; }
else if (c=='f') { X="final";id=true; }
break partial;
case 'o': c=s.charAt(0);
if (c=='f') { X="float";id=true; }
else if (c=='s') { X="short";id=true; }
break partial;
case 'p': X="super";id=true; break partial;
case 'r': X="throw";id=true; break partial;
case 't': X="catch";id=true; break partial;
} break partial;
case 6: switch (s.charAt(1)) {
case 'a': X="native";id=true; break partial;
case 'e': c=s.charAt(0);
if (c=='d') { X="delete";id=true; }
else if (c=='r') { X="return";id=true; }
break partial;
case 'h': X="throws";id=true; break partial;
case 'm': X="import";id=true; break partial;
case 'o': X="double";id=true; break partial;
case 't': X="static";id=true; break partial;
case 'u': X="public";id=true; break partial;
case 'w': X="switch";id=true; break partial;
case 'x': X="export";id=true; break partial;
case 'y': X="typeof";id=true; break partial;
} break partial;
case 7: switch (s.charAt(1)) {
case 'a': X="package";id=true; break partial;
case 'e': X="default";id=true; break partial;
case 'i': X="finally";id=true; break partial;
case 'o': X="boolean";id=true; break partial;
case 'r': X="private";id=true; break partial;
case 'x': X="extends";id=true; break partial;
} break partial;
case 8: switch (s.charAt(0)) {
case 'a': X="abstract";id=true; break partial;
case 'c': X="continue";id=true; break partial;
case 'd': X="debugger";id=true; break partial;
case 'f': X="function";id=true; break partial;
case 'v': X="volatile";id=true; break partial;
} break partial;
case 9: c=s.charAt(0);
if (c=='i') { X="interface";id=true; }
else if (c=='p') { X="protected";id=true; }
else if (c=='t') { X="transient";id=true; }
break partial;
case 10: c=s.charAt(1);
if (c=='m') { X="implements";id=true; }
else if (c=='n') { X="instanceof";id=true; }
break partial;
case 12: X="synchronized";id=true; break partial;
}
// partial match validate the entire string the one possibility
if (X != null && X != s && !X.equals(s)) {
return false;
}
}
return id;
}
public static boolean isJSIdentifier(String s) {
return JSIdentifier.isJSIdentifier(s);
}
private TokenStream() {}
}