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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.apache.commons.jexl3;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.StringReader;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.UndeclaredThrowableException;
import java.util.ArrayList;
import java.util.List;
import java.util.Objects;
import org.apache.commons.jexl3.internal.Debugger;
import org.apache.commons.jexl3.parser.JavaccError;
import org.apache.commons.jexl3.parser.JexlNode;
import org.apache.commons.jexl3.parser.ParseException;
import org.apache.commons.jexl3.parser.TokenMgrException;
/**
* Wraps any error that might occur during interpretation of a script or expression.
*
* @since 2.0
*/
public class JexlException extends RuntimeException {
/**
* Thrown when parsing fails due to an ambiguous statement.
*
* @since 3.0
*/
public static class Ambiguous extends Parsing {
private static final long serialVersionUID = 20210606123903L;
/** The mark at which ambiguity might stop and recover. */
private final transient JexlInfo recover;
/**
* Creates a new Ambiguous statement exception instance.
* @param begin the start location information
* @param end the end location information
* @param expr the source expression line
*/
public Ambiguous(final JexlInfo begin, final JexlInfo end, final String expr) {
super(begin, expr);
recover = end;
}
/**
* Creates a new Ambiguous statement exception instance.
* @param info the location information
* @param expr the source expression line
*/
public Ambiguous(final JexlInfo info, final String expr) {
this(info, null, expr);
}
@Override
protected String detailedMessage() {
return parserError("ambiguous statement", getDetail());
}
/**
* Tries to remove this ambiguity in the source.
* @param src the source that triggered this exception
* @return the source with the ambiguous statement removed
* or null if no recovery was possible
*/
public String tryCleanSource(final String src) {
final JexlInfo ji = info();
return ji == null || recover == null
? src
: sliceSource(src, ji.getLine(), ji.getColumn(), recover.getLine(), recover.getColumn());
}
}
/**
* Thrown when an annotation handler throws an exception.
*
* @since 3.1
*/
public static class Annotation extends JexlException {
private static final long serialVersionUID = 20210606124101L;
/**
* Creates a new Annotation exception instance.
*
* @param node the annotated statement node
* @param name the annotation name
* @param cause the exception causing the error
*/
public Annotation(final JexlNode node, final String name, final Throwable cause) {
super(node, name, cause);
}
@Override
protected String detailedMessage() {
return "error processing annotation '" + getAnnotation() + "'";
}
/**
* Gets the annotation name
* @return the annotation name
*/
public String getAnnotation() {
return getDetail();
}
}
/**
* Thrown when parsing fails due to an invalid assignment.
*
* @since 3.0
*/
public static class Assignment extends Parsing {
private static final long serialVersionUID = 20210606123905L;
/**
* Creates a new Assignment statement exception instance.
*
* @param info the location information
* @param expr the source expression line
*/
public Assignment(final JexlInfo info, final String expr) {
super(info, expr);
}
@Override
protected String detailedMessage() {
return parserError("assignment", getDetail());
}
}
/**
* Thrown to break a loop.
*
* @since 3.0
*/
public static class Break extends JexlException {
private static final long serialVersionUID = 20210606124103L;
/**
* Creates a new instance of Break.
*
* @param node the break
*/
public Break(final JexlNode node) {
super(node, "break loop", null, false);
}
}
/**
* Thrown to cancel a script execution.
*
* @since 3.0
*/
public static class Cancel extends JexlException {
private static final long serialVersionUID = 7735706658499597964L;
/**
* Creates a new instance of Cancel.
*
* @param node the node where the interruption was detected
*/
public Cancel(final JexlNode node) {
super(node, "execution cancelled", null);
}
}
/**
* Thrown to continue a loop.
*
* @since 3.0
*/
public static class Continue extends JexlException {
private static final long serialVersionUID = 20210606124104L;
/**
* Creates a new instance of Continue.
*
* @param node the continue-node
*/
public Continue(final JexlNode node) {
super(node, "continue loop", null, false);
}
}
/**
* Thrown when parsing fails due to a disallowed feature.
*
* @since 3.2
*/
public static class Feature extends Parsing {
private static final long serialVersionUID = 20210606123906L;
/** The feature code. */
private final int code;
/**
* Creates a new Ambiguous statement exception instance.
* @param info the location information
* @param feature the feature code
* @param expr the source expression line
*/
public Feature(final JexlInfo info, final int feature, final String expr) {
super(info, expr);
this.code = feature;
}
@Override
protected String detailedMessage() {
return parserError(JexlFeatures.stringify(code), getDetail());
}
}
/**
* Thrown when a method or ctor is unknown, ambiguous or inaccessible.
*
* @since 3.0
*/
public static class Method extends JexlException {
private static final long serialVersionUID = 20210606123909L;
/**
* Creates a new Method exception instance.
*
* @param info the location information
* @param name the method name
* @param args the method arguments
* @since 3.2
*/
public Method(final JexlInfo info, final String name, final Object[] args) {
this(info, name, args, null);
}
/**
* Creates a new Method exception instance.
*
* @param info the location information
* @param name the method name
* @param cause the exception causing the error
* @param args the method arguments
* @since 3.2
*/
public Method(final JexlInfo info, final String name, final Object[] args, final Throwable cause) {
super(info, methodSignature(name, args), cause);
}
/**
* Creates a new Method exception instance.
*
* @param info the location information
* @param name the unknown method
* @param cause the exception causing the error
* @deprecated as of 3.2, use call with method arguments
*/
@Deprecated
public Method(final JexlInfo info, final String name, final Throwable cause) {
this(info, name, null, cause);
}
/**
* Creates a new Method exception instance.
*
* @param node the offending ASTnode
* @param name the method name
* @deprecated as of 3.2, use call with method arguments
*/
@Deprecated
public Method(final JexlNode node, final String name) {
this(node, name, null);
}
/**
* Creates a new Method exception instance.
*
* @param node the offending ASTnode
* @param name the method name
* @param args the method arguments
* @since 3.2
*/
public Method(final JexlNode node, final String name, final Object[] args) {
super(node, methodSignature(name, args));
}
@Override
protected String detailedMessage() {
return "unsolvable function/method '" + getMethodSignature() + "'";
}
/**
* Gets the method name
* @return the method name
*/
public String getMethod() {
final String signature = getMethodSignature();
final int lparen = signature.indexOf('(');
return lparen > 0? signature.substring(0, lparen) : signature;
}
/**
* Gets the method signature
* @return the method signature
* @since 3.2
*/
public String getMethodSignature() {
return getDetail();
}
}
/**
* Thrown when an operator fails.
*
* @since 3.0
*/
public static class Operator extends JexlException {
private static final long serialVersionUID = 20210606124100L;
/**
* Creates a new Operator exception instance.
*
* @param node the location information
* @param symbol the operator name
* @param cause the exception causing the error
*/
public Operator(final JexlNode node, final String symbol, final Throwable cause) {
super(node, symbol, cause);
}
@Override
protected String detailedMessage() {
return "error calling operator '" + getSymbol() + "'";
}
/**
* Gets the method name
* @return the method name
*/
public String getSymbol() {
return getDetail();
}
}
/**
* Thrown when parsing fails.
*
* @since 3.0
*/
public static class Parsing extends JexlException {
private static final long serialVersionUID = 20210606123902L;
/**
* Creates a new Parsing exception instance.
*
* @param info the location information
* @param cause the javacc cause
*/
public Parsing(final JexlInfo info, final ParseException cause) {
super(merge(info, cause), Objects.requireNonNull(cause).getAfter(), null);
}
/**
* Creates a new Parsing exception instance.
*
* @param info the location information
* @param msg the message
*/
public Parsing(final JexlInfo info, final String msg) {
super(info, msg, null);
}
@Override
protected String detailedMessage() {
return parserError("parsing", getDetail());
}
}
/**
* Thrown when a property is unknown.
*
* @since 3.0
*/
public static class Property extends JexlException {
private static final long serialVersionUID = 20210606123908L;
/**
* Undefined variable flag.
*/
private final boolean undefined;
/**
* Creates a new Property exception instance.
*
* @param node the offending ASTnode
* @param pty the unknown property
* @deprecated 3.2
*/
@Deprecated
public Property(final JexlNode node, final String pty) {
this(node, pty, true, null);
}
/**
* Creates a new Property exception instance.
*
* @param node the offending ASTnode
* @param pty the unknown property
* @param undef whether the variable is null or undefined
* @param cause the exception causing the error
*/
public Property(final JexlNode node, final String pty, final boolean undef, final Throwable cause) {
super(node, pty, cause);
undefined = undef;
}
/**
* Creates a new Property exception instance.
*
* @param node the offending ASTnode
* @param pty the unknown property
* @param cause the exception causing the error
* @deprecated 3.2
*/
@Deprecated
public Property(final JexlNode node, final String pty, final Throwable cause) {
this(node, pty, true, cause);
}
@Override
protected String detailedMessage() {
return (undefined? "undefined" : "null value") + " property '" + getProperty() + "'";
}
/**
* Gets the property name
* @return the property name
*/
public String getProperty() {
return getDetail();
}
/**
* Tests whether the variable causing an error is undefined or evaluated as null.
*
* @return true if undefined, false otherwise
*/
public boolean isUndefined() {
return undefined;
}
}
/**
* Thrown to return a value.
*
* @since 3.0
*/
public static class Return extends JexlException {
private static final long serialVersionUID = 20210606124102L;
/** The returned value. */
private final transient Object result;
/**
* Creates a new instance of Return.
*
* @param node the return node
* @param msg the message
* @param value the returned value
*/
public Return(final JexlNode node, final String msg, final Object value) {
super(node, msg, null, false);
this.result = value;
}
/**
* Gets the returned value
* @return the returned value
*/
public Object getValue() {
return result;
}
}
/**
* Thrown when reaching stack-overflow.
*
* @since 3.2
*/
public static class StackOverflow extends JexlException {
private static final long serialVersionUID = 20210606123904L;
/**
* Creates a new stack overflow exception instance.
*
* @param info the location information
* @param name the unknown method
* @param cause the exception causing the error
*/
public StackOverflow(final JexlInfo info, final String name, final Throwable cause) {
super(info, name, cause);
}
@Override
protected String detailedMessage() {
return "stack overflow " + getDetail();
}
}
/**
* Thrown to throw a value.
*
* @since 3.3.1
*/
public static class Throw extends JexlException {
private static final long serialVersionUID = 20210606124102L;
/** The thrown value. */
private final transient Object result;
/**
* Creates a new instance of Throw.
*
* @param node the throw node
* @param value the thrown value
*/
public Throw(final JexlNode node, final Object value) {
super(node, null, null, false);
this.result = value;
}
/**
* Gets the thrown value
* @return the thrown value
*/
public Object getValue() {
return result;
}
}
/**
* Thrown when tokenization fails.
*
* @since 3.0
*/
public static class Tokenization extends JexlException {
private static final long serialVersionUID = 20210606123901L;
/**
* Creates a new Tokenization exception instance.
* @param info the location info
* @param cause the javacc cause
*/
public Tokenization(final JexlInfo info, final TokenMgrException cause) {
super(merge(info, cause), Objects.requireNonNull(cause).getAfter(), null);
}
@Override
protected String detailedMessage() {
return parserError("tokenization", getDetail());
}
}
/**
* Thrown when method/ctor invocation fails.
* These wrap InvocationTargetException as runtime exception
* allowing to go through without signature modifications.
* @since 3.2
*/
public static class TryFailed extends JexlException {
private static final long serialVersionUID = 20210606124105L;
/**
* Creates a new instance.
* @param xany the original invocation target exception
*/
TryFailed(final InvocationTargetException xany) {
super((JexlInfo) null, "tryFailed", xany.getCause());
}
}
/**
* Thrown when a variable is unknown.
*
* @since 3.0
*/
public static class Variable extends JexlException {
private static final long serialVersionUID = 20210606123907L;
/**
* Undefined variable flag.
*/
private final VariableIssue issue;
/**
* Creates a new Variable exception instance.
*
* @param node the offending ASTnode
* @param var the unknown variable
* @param undef whether the variable is undefined or evaluated as null
*/
public Variable(final JexlNode node, final String var, final boolean undef) {
this(node, var, undef ? VariableIssue.UNDEFINED : VariableIssue.NULLVALUE);
}
/**
* Creates a new Variable exception instance.
*
* @param node the offending ASTnode
* @param var the unknown variable
* @param vi the variable issue
*/
public Variable(final JexlNode node, final String var, final VariableIssue vi) {
super(node, var, null);
issue = vi;
}
@Override
protected String detailedMessage() {
return issue.message(getVariable());
}
/**
* Gets the variable name
* @return the variable name
*/
public String getVariable() {
return getDetail();
}
/**
* Tests whether the variable causing an error is undefined or evaluated as null.
*
* @return true if undefined, false otherwise
*/
public boolean isUndefined() {
return issue == VariableIssue.UNDEFINED;
}
}
/**
* The various type of variable issues.
*/
public enum VariableIssue {
/** The variable is undefined. */
UNDEFINED,
/** The variable is already declared. */
REDEFINED,
/** The variable has a null value. */
NULLVALUE,
/** THe variable is const and an attempt is made to assign it*/
CONST;
/**
* Stringifies the variable issue.
* @param var the variable name
* @return the issue message
*/
public String message(final String var) {
switch(this) {
case NULLVALUE : return VARQUOTE + var + "' is null";
case REDEFINED : return VARQUOTE + var + "' is already defined";
case CONST : return VARQUOTE + var + "' is const";
case UNDEFINED :
default: return VARQUOTE + var + "' is undefined";
}
}
}
private static final long serialVersionUID = 20210606123900L;
/** Maximum number of characters around exception location. */
private static final int MAX_EXCHARLOC = 128;
/** Used 3 times. */
private static final String VARQUOTE = "variable '";
/**
* Generates a message for an annotation error.
*
* @param node the node where the error occurred
* @param annotation the annotation name
* @return the error message
* @since 3.1
*/
public static String annotationError(final JexlNode node, final String annotation) {
final StringBuilder msg = errorAt(node);
msg.append("error processing annotation '");
msg.append(annotation);
msg.append('\'');
return msg.toString();
}
/**
* Cleans a Throwable from any org.apache.commons.jexl3.internal stack trace element.
*
* @param the throwable type
* @param xthrow the thowable
* @return the throwable
*/
static X clean(final X xthrow) {
if (xthrow != null) {
final List stackJexl = new ArrayList<>();
for (final StackTraceElement se : xthrow.getStackTrace()) {
final String className = se.getClassName();
if (!className.startsWith("org.apache.commons.jexl3.internal")
&& !className.startsWith("org.apache.commons.jexl3.parser")) {
stackJexl.add(se);
}
}
xthrow.setStackTrace(stackJexl.toArray(new StackTraceElement[0]));
}
return xthrow;
}
/**
* Gets the most specific information attached to a node.
*
* @param node the node
* @param info the information
* @return the information or null
*/
static JexlInfo detailedInfo(final JexlNode node, final JexlInfo info) {
if (info != null && node != null) {
final Debugger dbg = new Debugger();
if (dbg.debug(node)) {
return new JexlInfo(info) {
@Override
public JexlInfo.Detail getDetail() {
return dbg;
}
};
}
}
return info;
}
/**
* Creates a string builder pre-filled with common error information (if possible).
*
* @param node the node
* @return a string builder
*/
static StringBuilder errorAt(final JexlNode node) {
final JexlInfo info = node != null ? detailedInfo(node, node.jexlInfo()) : null;
final StringBuilder msg = new StringBuilder();
if (info != null) {
msg.append(info.toString());
} else {
msg.append("?:");
}
msg.append(' ');
return msg;
}
/**
* Gets the most specific information attached to a node.
*
* @param node the node
* @param info the information
* @return the information or null
* @deprecated 3.2
*/
@Deprecated
public static JexlInfo getInfo(final JexlNode node, final JexlInfo info) {
return detailedInfo(node, info);
}
/**
* Merge the node info and the cause info to obtain the best possible location.
*
* @param info the node
* @param cause the cause
* @return the info to use
*/
static JexlInfo merge(final JexlInfo info, final JavaccError cause) {
if (cause == null || cause.getLine() < 0) {
return info;
}
if (info == null) {
return new JexlInfo("", cause.getLine(), cause.getColumn());
}
return new JexlInfo(info.getName(), cause.getLine(), cause.getColumn());
}
/**
* Generates a message for a unsolvable method error.
*
* @param node the node where the error occurred
* @param method the method name
* @return the error message
* @deprecated 3.2
*/
@Deprecated
public static String methodError(final JexlNode node, final String method) {
return methodError(node, method, null);
}
/**
* Generates a message for a unsolvable method error.
*
* @param node the node where the error occurred
* @param method the method name
* @param args the method arguments
* @return the error message
*/
public static String methodError(final JexlNode node, final String method, final Object[] args) {
final StringBuilder msg = errorAt(node);
msg.append("unsolvable function/method '");
msg.append(methodSignature(method, args));
msg.append('\'');
return msg.toString();
}
/**
* Creates a signed-name for a given method name and arguments.
* @param name the method name
* @param args the method arguments
* @return a suitable signed name
*/
static String methodSignature(final String name, final Object[] args) {
if (args != null && args.length > 0) {
final StringBuilder strb = new StringBuilder(name);
strb.append('(');
for (int a = 0; a < args.length; ++a) {
if (a > 0) {
strb.append(", ");
}
final Class clazz = args[a] == null ? Object.class : args[a].getClass();
strb.append(clazz.getSimpleName());
}
strb.append(')');
return strb.toString();
}
return name;
}
/**
* Generates a message for an operator error.
*
* @param node the node where the error occurred
* @param symbol the operator name
* @return the error message
*/
public static String operatorError(final JexlNode node, final String symbol) {
final StringBuilder msg = errorAt(node);
msg.append("error calling operator '");
msg.append(symbol);
msg.append('\'');
return msg.toString();
}
/**
* Generates a message for an unsolvable property error.
*
* @param node the node where the error occurred
* @param var the variable
* @return the error message
* @deprecated 3.2
*/
@Deprecated
public static String propertyError(final JexlNode node, final String var) {
return propertyError(node, var, true);
}
/**
* Generates a message for an unsolvable property error.
*
* @param node the node where the error occurred
* @param pty the property
* @param undef whether the property is null or undefined
* @return the error message
*/
public static String propertyError(final JexlNode node, final String pty, final boolean undef) {
final StringBuilder msg = errorAt(node);
if (undef) {
msg.append("unsolvable");
} else {
msg.append("null value");
}
msg.append(" property '");
msg.append(pty);
msg.append('\'');
return msg.toString();
}
/**
* Removes a slice from a source.
* @param src the source
* @param froml the beginning line
* @param fromc the beginning column
* @param tol the ending line
* @param toc the ending column
* @return the source with the (begin) to (to) zone removed
*/
public static String sliceSource(final String src, final int froml, final int fromc, final int tol, final int toc) {
final BufferedReader reader = new BufferedReader(new StringReader(src));
final StringBuilder buffer = new StringBuilder();
String line;
int cl = 1;
try {
while ((line = reader.readLine()) != null) {
if (cl < froml || cl > tol) {
buffer.append(line).append('\n');
} else {
if (cl == froml) {
buffer.append(line, 0, fromc - 1);
}
if (cl == tol) {
buffer.append(line.substring(toc + 1));
}
} // else ignore line
cl += 1;
}
} catch (final IOException xignore) {
//damn the checked exceptions :-)
}
return buffer.toString();
}
/**
* Wrap an invocation exception.
* Return the cause if it is already a JexlException.
* @param xinvoke the invocation exception
* @return a JexlException
*/
public static JexlException tryFailed(final InvocationTargetException xinvoke) {
final Throwable cause = xinvoke.getCause();
return cause instanceof JexlException
? (JexlException) cause
: new JexlException.TryFailed(xinvoke); // fail
}
/**
* Unwraps the cause of a throwable due to reflection.
*
* @param xthrow the throwable
* @return the cause
*/
static Throwable unwrap(final Throwable xthrow) {
if (xthrow instanceof TryFailed
|| xthrow instanceof InvocationTargetException
|| xthrow instanceof UndeclaredThrowableException) {
return xthrow.getCause();
}
return xthrow;
}
/**
* Generates a message for a variable error.
*
* @param node the node where the error occurred
* @param variable the variable
* @param undef whether the variable is null or undefined
* @return the error message
* @deprecated 3.2
*/
@Deprecated
public static String variableError(final JexlNode node, final String variable, final boolean undef) {
return variableError(node, variable, undef? VariableIssue.UNDEFINED : VariableIssue.NULLVALUE);
}
/**
* Generates a message for a variable error.
*
* @param node the node where the error occurred
* @param variable the variable
* @param issue the variable kind of issue
* @return the error message
*/
public static String variableError(final JexlNode node, final String variable, final VariableIssue issue) {
final StringBuilder msg = errorAt(node);
msg.append(issue.message(variable));
return msg.toString();
}
/** The point of origin for this exception. */
private final transient JexlNode mark;
/** The debug info. */
private final transient JexlInfo info;
/**
* Creates a new JexlException.
*
* @param jinfo the debugging information associated
* @param msg the error message
* @param cause the exception causing the error
*/
public JexlException(final JexlInfo jinfo, final String msg, final Throwable cause) {
super(msg != null ? msg : "", unwrap(cause));
mark = null;
info = jinfo;
}
/**
* Creates a new JexlException.
*
* @param node the node causing the error
* @param msg the error message
*/
public JexlException(final JexlNode node, final String msg) {
this(node, msg, null);
}
/**
* Creates a new JexlException.
*
* @param node the node causing the error
* @param msg the error message
* @param cause the exception causing the error
*/
public JexlException(final JexlNode node, final String msg, final Throwable cause) {
this(node, msg != null ? msg : "", unwrap(cause), true);
}
/**
* Creates a new JexlException.
*
* @param node the node causing the error
* @param msg the error message
* @param cause the exception causing the error
* @param trace whether this exception has a stack trace and can not be suppressed
*/
protected JexlException(final JexlNode node, final String msg, final Throwable cause, final boolean trace) {
super(msg != null ? msg : "", unwrap(cause), !trace, trace);
if (node != null) {
mark = node;
info = node.jexlInfo();
} else {
mark = null;
info = null;
}
}
/**
* Cleans a JexlException from any org.apache.commons.jexl3.internal stack trace element.
*
* @return this exception
*/
public JexlException clean() {
return clean(this);
}
/**
* Accesses detailed message.
*
* @return the message
*/
protected String detailedMessage() {
final Class clazz = getClass();
final String name = clazz == JexlException.class? "JEXL" : clazz.getSimpleName().toLowerCase();
return name + " error : " + getDetail();
}
/**
* Gets the exception specific detail
* @return this exception specific detail
* @since 3.2
*/
public final String getDetail() {
return super.getMessage();
}
/**
* Gets the specific information for this exception.
*
* @return the information
*/
public JexlInfo getInfo() {
return detailedInfo(mark, info);
}
/**
* Detailed info message about this error.
* Format is "debug![begin,end]: string \n msg" where:
* - debug is the debugging information if it exists (@link JexlEngine.setDebug)
* - begin, end are character offsets in the string for the precise location of the error
* - string is the string representation of the offending expression
* - msg is the actual explanation message for this error
*
* @return this error as a string
*/
@Override
public String getMessage() {
final StringBuilder msg = new StringBuilder();
if (info != null) {
msg.append(info.toString());
} else {
msg.append("?:");
}
msg.append(' ');
msg.append(detailedMessage());
final Throwable cause = getCause();
if (cause instanceof JexlArithmetic.NullOperand) {
msg.append(" caused by null operand");
}
return msg.toString();
}
/**
* Pleasing checkstyle.
* @return the info
*/
protected JexlInfo info() {
return info;
}
/**
* Formats an error message from the parser.
*
* @param prefix the prefix to the message
* @param expr the expression in error
* @return the formatted message
*/
protected String parserError(final String prefix, final String expr) {
final int length = expr.length();
if (length < MAX_EXCHARLOC) {
return prefix + " error in '" + expr + "'";
}
final int me = MAX_EXCHARLOC / 2;
int begin = info.getColumn() - me;
if (begin < 0 || length < me) {
begin = 0;
} else if (begin > length) {
begin = me;
}
int end = begin + MAX_EXCHARLOC;
if (end > length) {
end = length;
}
return prefix + " error near '... "
+ expr.substring(begin, end) + " ...'";
}
}