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With inspiration from other libraries
/**
* MVEL 2.0
* Copyright (C) 2007 The Codehaus
* Mike Brock, Dhanji Prasanna, John Graham, Mark Proctor
*
* Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.mvel2.optimizers;
import org.mvel2.CompileException;
import org.mvel2.MVEL;
import org.mvel2.ParserContext;
import org.mvel2.compiler.AbstractParser;
import java.lang.reflect.Method;
import static java.lang.Thread.currentThread;
import static org.mvel2.util.ParseTools.*;
/**
* @author Christopher Brock
*/
public class AbstractOptimizer extends AbstractParser {
protected static final int BEAN = 0;
protected static final int METH = 1;
protected static final int COL = 2;
protected static final int WITH = 3;
protected boolean collection = false;
protected boolean nullSafe = false;
protected Class currType = null;
protected boolean staticAccess = false;
protected int tkStart;
protected AbstractOptimizer() { }
protected AbstractOptimizer(ParserContext pCtx) {
super(pCtx);
}
/**
* Try static access of the property, and return an instance of the Field, Method of Class if successful.
*
* @return - Field, Method or Class instance.
*/
protected Object tryStaticAccess() {
int begin = cursor;
try {
/**
* Try to resolve this *smartly* as a static class reference.
*
* This starts at the end of the token and starts to step backwards to figure out whether
* or not this may be a static class reference. We search for method calls simply by
* inspecting for ()'s. The first union area we come to where no brackets are present is our
* test-point for a class reference. If we find a class, we pass the reference to the
* property accessor along with trailing methods (if any).
*
*/
boolean meth = false;
// int end = start + length;
int last = end;
for (int i = end - 1; i > start; i--) {
switch (expr[i]) {
case '.':
if (!meth) {
ClassLoader classLoader = pCtx != null ? pCtx.getClassLoader() : currentThread().getContextClassLoader();
String test = new String(expr, start, (cursor = last) - start);
try {
if (MVEL.COMPILER_OPT_SUPPORT_JAVA_STYLE_CLASS_LITERALS && test.endsWith(".class"))
test = test.substring(0, test.length() - 6);
return Class.forName(test, true, classLoader);
} catch (ClassNotFoundException cnfe) {
try {
return findInnerClass( test, classLoader, cnfe );
} catch (ClassNotFoundException e) { /* ignore */ }
Class cls = forNameWithInner(new String(expr, start, i - start), classLoader);
String name = new String(expr, i + 1, end - i - 1);
try {
return cls.getField(name);
} catch (NoSuchFieldException nfe) {
for (Method m : cls.getMethods()) {
if (name.equals(m.getName())) return m;
}
return null;
}
}
}
meth = false;
last = i;
break;
case '}':
i--;
for (int d = 1; i > start && d != 0; i--) {
switch (expr[i]) {
case '}':
d++;
break;
case '{':
d--;
break;
case '"':
case '\'':
char s = expr[i];
while (i > start && (expr[i] != s && expr[i - 1] != '\\')) i--;
}
}
break;
case ')':
i--;
for (int d = 1; i > start && d != 0; i--) {
switch (expr[i]) {
case ')':
d++;
break;
case '(':
d--;
break;
case '"':
case '\'':
char s = expr[i];
while (i > start && (expr[i] != s && expr[i - 1] != '\\')) i--;
}
}
meth = true;
last = i++;
break;
case '\'':
while (--i > start) {
if (expr[i] == '\'' && expr[i - 1] != '\\') {
break;
}
}
break;
case '"':
while (--i > start) {
if (expr[i] == '"' && expr[i - 1] != '\\') {
break;
}
}
break;
}
}
}
catch (Exception cnfe) {
cursor = begin;
}
return null;
}
protected int nextSubToken() {
skipWhitespace();
nullSafe = false;
switch (expr[tkStart = cursor]) {
case '[':
return COL;
case '{':
if (expr[cursor - 1] == '.') {
return WITH;
}
break;
case '.':
if ((start + 1) != end) {
switch (expr[cursor = ++tkStart]) {
case '?':
skipWhitespace();
if ((cursor = ++tkStart) == end) {
throw new CompileException("unexpected end of statement", expr, start);
}
nullSafe = true;
fields = -1;
break;
case '{':
return WITH;
default:
if (isWhitespace(expr[tkStart])) {
skipWhitespace();
tkStart = cursor;
}
}
}
else {
throw new CompileException("unexpected end of statement", expr, start);
}
break;
case '?':
if (start == cursor) {
tkStart++;
cursor++;
nullSafe = true;
}
}
//noinspection StatementWithEmptyBody
while (++cursor < end && isIdentifierPart(expr[cursor])) ;
skipWhitespace();
if (cursor < end) {
switch (expr[cursor]) {
case '[':
return COL;
case '(':
return METH;
default:
return BEAN;
}
}
return 0;
}
protected String capture() {
/**
* Trim off any whitespace.
*/
return new String(expr, tkStart = trimRight(tkStart), trimLeft(cursor) - tkStart);
}
/**
* Skip to the next non-whitespace position.
*/
protected void whiteSpaceSkip() {
if (cursor < length)
//noinspection StatementWithEmptyBody
while (isWhitespace(expr[cursor]) && ++cursor != length) ;
}
/**
* @param c - character to scan to.
* @return - returns true is end of statement is hit, false if the scan scar is countered.
*/
protected boolean scanTo(char c) {
for (; cursor < end; cursor++) {
switch (expr[cursor]) {
case '\'':
case '"':
cursor = captureStringLiteral(expr[cursor], expr, cursor, end);
default:
if (expr[cursor] == c) {
return false;
}
}
}
return true;
}
protected int findLastUnion() {
int split = -1;
int depth = 0;
int end = start + length;
for (int i = end - 1; i != start; i--) {
switch (expr[i]) {
case '}':
case ']':
depth++;
break;
case '{':
case '[':
if (--depth == 0) {
split = i;
collection = true;
}
break;
case '.':
if (depth == 0) {
split = i;
}
break;
}
if (split != -1) break;
}
return split;
}
}