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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 groovy.text;
import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
import groovy.lang.Closure;
import groovy.lang.GroovyClassLoader;
import groovy.lang.GroovyCodeSource;
import groovy.lang.GroovyObject;
import groovy.lang.GroovyRuntimeException;
import groovy.lang.Writable;
import org.codehaus.groovy.control.CompilationFailedException;
import org.codehaus.groovy.control.ErrorCollector;
import org.codehaus.groovy.control.MultipleCompilationErrorsException;
import org.codehaus.groovy.control.messages.Message;
import org.codehaus.groovy.control.messages.SyntaxErrorMessage;
import org.codehaus.groovy.runtime.StackTraceUtils;
import org.codehaus.groovy.syntax.SyntaxException;
import java.io.IOException;
import java.io.LineNumberReader;
import java.io.Reader;
import java.io.StringReader;
import java.lang.reflect.InvocationTargetException;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.concurrent.atomic.AtomicInteger;
/**
* Processes template source files substituting variables and expressions into
* placeholders in a template source text to produce the desired output using a
* closure based approach. This engine has equivalent functionality to the
* {@link groovy.text.SimpleTemplateEngine} but creates the template using
* writable closures making it more scalable for large templates.
*
* Specifically this template engine can handle strings larger than 64k which
* still causes problems for the other groovy template engines.
*
*
* The template engine uses JSP style <% %> script and <%= %>
* expression syntax or GString style expressions. The variable
* 'out' is bound to the writer that the template is being written
* to.
*
* Frequently, the template source will be in a file but here is a simple
* example providing the template as a string:
*
*
* def binding = [
* firstname : "Grace",
* lastname : "Hopper",
* accepted : true,
* title : 'Groovy for COBOL programmers'
* ]
* def text = '''\
* Dear {@code <%} out.print firstname {@code %>} ${lastname},
*
* We {@code <%} if (accepted) out.print 'are pleased' else out.print 'regret' {@code %>} \
* to inform you that your paper entitled
* '$title' was ${ accepted ? 'accepted' : 'rejected' }.
*
* The conference committee.
* '''
*
* def template = new groovy.text.StreamingTemplateEngine().createTemplate(text)
*
* print template.make(binding)
*
*
* This example uses a mix of the JSP style and GString style
* placeholders but you can typically use just one style if you wish. Running
* this example will produce this output:
*
*
*
* Dear Grace Hopper,
*
* We are pleased to inform you that your paper entitled
* 'Groovy for COBOL programmers' was accepted.
*
* The conference committee.
*
*
* StreamingTemplateEngine as a servlet engine
* The template engine can also be used as the engine for
* {@link groovy.servlet.TemplateServlet} by placing the following in your
* web.xml file (plus a corresponding servlet-mapping element):
*
*
* <servlet>
* <servlet-name>StreamingTemplate</servlet-name>
* <servlet-class>groovy.servlet.TemplateServlet</servlet-class>
* <init-param>
* <param-name>template.engine</param-name>
* <param-value>groovy.text.StreamingTemplateEngine</param-value>
* </init-param>
* </servlet>
*
In this case, your template source file should be HTML with the
* appropriate embedded placeholders.
*
* Debugging Template Code
* The template engine makes an effort to throw descriptive exceptions with
* context lines, ie:
*
* groovy.text.TemplateExecutionException: Template parse error at line 4:
* 3: We {@code <%} if (accepted) out.print 'are pleased' else out.print 'regret' {@code %>} to inform you that your paper entitled
* {@code -->} 4: '$txitle' was ${ accepted ? 'accepted' : 'rejected' }.
* 5:
* at test.run(test.groovy:18)
*
* Caused by: groovy.lang.MissingPropertyException: No such property: txitle for class: groovy.tmp.templates.StreamingTemplateScript1
* ... 1 more
*
* and sanitize the exceptions to make things readable.
*
* When the exceptions are not enough, it might sometimes be useful to view the actual script source
* generated by the template engine. This would conceptually be equivalent to viewing the
* .java file generated for a jsp page. The source is not currently very readable and
* until we get a built in groovy code pretty printer, we will probably continue to opt for compactness
* rather than readability.
*
* With that being said, viewing the source might still have some value. For this reason the script
* source is accessible via the template.scriptSource property, i.e.:
*
* println template.scriptSource
*
* In the above example.
*
*/
public class StreamingTemplateEngine extends TemplateEngine {
private static final String TEMPLATE_SCRIPT_PREFIX = "StreamingTemplateScript";
private final ClassLoader parentLoader;
private static AtomicInteger counter = new AtomicInteger(0);
/**
* Create a streaming template engine instance using the default class loader
*/
public StreamingTemplateEngine() {
this(StreamingTemplate.class.getClassLoader());
}
/**
* Create a streaming template engine instance using a custom class loader
*
* The custom loader is used when parsing the template code
*
* @param parentLoader The class loader to use when parsing the template code.
*/
public StreamingTemplateEngine(ClassLoader parentLoader) {
this.parentLoader = parentLoader;
}
/**
* Creates a template instance using the template source from the provided Reader.
*
* The template can be applied repeatedly on different bindings to produce custom output.
*
* Technical detail
* Under the hood the returned template is represented as a four argument
* closure where the three first arguments are {@link groovy.lang.Closure#curry curried} in
* while generating the template.
*
* In essence we start with a closure on the form:
*
*
* { parentClass, stringSectionList, binding, out {@code ->}
* //code generated by parsing the template data
* }
*
*
* We then curry in the parentClass and stringSectionList arguments so that the StreamingTemplate
* instance returned from 'createTemplate' internally contains a template closure on the form:
*
*
* { binding, out {@code ->}
* //code generated by parsing the template data
* }
*
*
* Calling {@code template.make(binding)}, curries in the 'binding' argument:
*
*
* public Writable make(final Map map) {
* final Closure template = this.template.curry(new Object[]{map});
* return (Writable) template;
* }
*
*
* This only leaves the 'out' argument unbound. The only method on the {@link groovy.lang.Writable writable} interface is
* {@link groovy.lang.Writable#writeTo writeTo(Writer out)} so groovy rules about casting a closure to a one-method-interface
* apply and the above works. I.e. we return the now one argument closure as the Writable
* which can be serialized to System.out, a file, etc according to the Writable interface contract.
*
* @see groovy.text.TemplateEngine#createTemplate(java.io.Reader)
*/
@Override
public Template createTemplate(final Reader reader) throws CompilationFailedException, ClassNotFoundException, IOException {
return new StreamingTemplate(reader, parentLoader);
}
/**
* The class used to implement the Template interface for the StreamingTemplateEngine
*
*/
private static class StreamingTemplate implements Template {
/**
* The 'header' we use for the resulting groovy script source.
*/
private static final String SCRIPT_HEAD
= "package groovy.tmp.templates;"
+ "def getTemplate() { "
//the below params are:
// _p - parent class, for handling exceptions
// _s - sections, string sections list
// _b - binding map
// out - out stream
//the three first parameters will be curried in as we move along
+ "return { _p, _s, _b, out -> "
+ "int _i = 0;"
+ "try {"
+ "delegate = new Binding(_b);";
/**
* The 'footer' we use for the resulting groovy script source
*/
private static final String SCRIPT_TAIL
= "} catch (Throwable e) { "
+ "_p.error(_i, _s, e);"
+ "}"
+ "}.asWritable()"
+ "}";
private StringBuilder templateSource;
// we use a hard index instead of incrementing the _i variable due to previous
// bug where the increment was not executed when hitting non-executed if branch
private int index = 0;
final Closure template;
String scriptSource;
private static class FinishedReadingException extends Exception {
private static final long serialVersionUID = -3786157136157691230L;
}
//WE USE THIS AS REUSABLE
//CHECKSTYLE.OFF: ConstantNameCheck - special case with a reusable exception
private static final FinishedReadingException finishedReadingException;
//CHECKSTYLE.ON: ConstantNameCheck
public static final StackTraceElement[] EMPTY_STACKTRACE = new StackTraceElement[0];
static {
finishedReadingException = new FinishedReadingException();
finishedReadingException.setStackTrace(EMPTY_STACKTRACE);
}
private static final class Position {
//CHECKSTYLE.OFF: VisibilityModifierCheck - special case, direct access for performance
public int row;
public int column;
//CHECKSTYLE.ON: VisibilityModifierCheck
private Position(int row, int column) {
this.row = row;
this.column = column;
}
private Position(Position p) {
set(p);
}
private void set(Position p) {
this.row = p.row;
this.column = p.column;
}
public String toString() {
return row + ":" + column;
}
}
/**
* A StringSection represent a section in the template source
* with only string data (i.e. no branching, GString references, etc).
* As an example, the following template string:
*
*
* Alice why is a $bird like a writing desk
*
*
* Would produce a string section "Alice why is a " followed by
* a dollar identifier expression followed by another string
* section " like a writing desk".
*/
private static final class StringSection {
StringBuilder data;
Position firstSourcePosition;
Position lastSourcePosition;
Position lastTargetPosition;
private StringSection(Position firstSourcePosition) {
this.data = new StringBuilder();
this.firstSourcePosition = new Position(firstSourcePosition);
}
@Override
public String toString() {
return data.toString();
}
}
/**
* Called to handle the ending of a string section.
*
* @param sections The list of string sections. The current section gets added to this section.
* @param currentSection The current string section.
* @param templateExpressions Template expressions
* @param lastSourcePosition The last read position in the source template stream.
* @param targetPosition The last written to position in the target script stream.
*/
private void finishStringSection(List sections, StringSection currentSection,
StringBuilder templateExpressions,
Position lastSourcePosition, Position targetPosition) {
//when we get exceptions from the parseXXX methods in the main loop, we might try to
//re-finish a section
if (currentSection.lastSourcePosition != null) {
return;
}
currentSection.lastSourcePosition = new Position(lastSourcePosition);
sections.add(currentSection);
append(templateExpressions, targetPosition, "out<<_s[_i=" + index++ + "];");
currentSection.lastTargetPosition = new Position(targetPosition.row, targetPosition.column);
}
public void error(int index, List sections, Throwable e) throws Throwable {
int i = Math.max(0, index);
StringSection precedingSection = sections.get(i);
int traceLine = -1;
for (StackTraceElement element : e.getStackTrace()) {
if (element.getClassName().contains(TEMPLATE_SCRIPT_PREFIX)) {
traceLine = element.getLineNumber();
break;
}
}
if (traceLine != -1) {
int actualLine = precedingSection.lastSourcePosition.row + traceLine - 1;
String message = "Template execution error at line " + actualLine + ":\n" + getErrorContext(actualLine);
TemplateExecutionException unsanitized = new TemplateExecutionException(actualLine, message, StackTraceUtils.sanitize(e));
throw StackTraceUtils.sanitize(unsanitized);
} else {
throw e;
}
}
@SuppressFBWarnings(value = "SR_NOT_CHECKED", justification = "safe to ignore return value of skip from reader backed by StringReader")
private int getLinesInSource() throws IOException {
int result = 0;
try (LineNumberReader reader = new LineNumberReader(new StringReader(templateSource.toString()))) {
reader.skip(Long.MAX_VALUE); // SR_NOT_CHECKED
result = reader.getLineNumber();
}
return result;
}
private String getErrorContext(int actualLine) throws IOException {
int minLine = Math.max(0, actualLine -1);
int maxLine = Math.min(getLinesInSource(), actualLine + 1);
LineNumberReader r = new LineNumberReader(new StringReader(templateSource.toString()));
int lineNr;
StringBuilder result = new StringBuilder();
while ((lineNr = r.getLineNumber()+1) <= maxLine) {
String line = r.readLine();
if (lineNr < minLine) continue;
String nr = Integer.toString(lineNr);
if (lineNr == actualLine) {
nr = " --> " + nr;
}
result.append(padLeft(nr, 10));
result.append(": ");
result.append(line);
result.append('\n');
}
return result.toString();
}
private String padLeft(String s, int len) {
StringBuilder b = new StringBuilder(s);
while (b.length() < len) b.insert(0, " ");
return b.toString();
}
/**
* Turn the template into a writable Closure. When executed the closure
* evaluates all the code embedded in the template and then writes a
* GString containing the fixed and variable items to the writer passed
* as a parameter
*
* For example:
*
* '<%= "test" %> of expr and <% test = 1 %>${test} script.'
*
* would compile into:
*
* { out -> out << "${"test"} of expr and "; test = 1 ; out << "${test} script."}.asWritable()
*
* @param source A reader into the template source data
* @param parentLoader A class loader we use
* @throws CompilationFailedException
* @throws ClassNotFoundException
* @throws IOException
*/
StreamingTemplate(final Reader source, final ClassLoader parentLoader) throws CompilationFailedException, ClassNotFoundException, IOException {
final StringBuilder target = new StringBuilder();
List sections = new ArrayList();
Position sourcePosition = new Position(1, 1);
Position targetPosition = new Position(1, 1);
Position lastSourcePosition = new Position(1, 1);
StringSection currentSection = new StringSection(sourcePosition);
templateSource = new StringBuilder();
//we use the lookAhead to make sure that a template file ending in say "abcdef\\"
//will give a result of "abcdef\\" even though we have special handling for \\
StringBuilder lookAhead = new StringBuilder(10);
append(target, targetPosition, SCRIPT_HEAD);
try {
int skipRead = -1;
//noinspection InfiniteLoopStatement
while (true) {
lastSourcePosition.set(sourcePosition);
int c = (skipRead != -1) ? skipRead : read(source, sourcePosition, lookAhead);
skipRead = -1;
if (c == '\\') {
handleEscaping(source, sourcePosition, currentSection, lookAhead);
continue;
} else if (c == '<') {
c = read(source, sourcePosition, lookAhead);
if (c == '%') {
c = read(source, sourcePosition);
clear(lookAhead);
if (c == '=') {
finishStringSection(sections, currentSection, target, lastSourcePosition, targetPosition);
parseExpression(source, target, sourcePosition, targetPosition);
currentSection = new StringSection(sourcePosition);
continue;
} else {
finishStringSection(sections, currentSection, target, lastSourcePosition, targetPosition);
parseSection(c, source, target, sourcePosition, targetPosition);
currentSection = new StringSection(sourcePosition);
continue;
}
} else {
currentSection.data.append('<');
}
} else if (c == '$') {
c = read(source, sourcePosition);
clear(lookAhead);
if (c == '{') {
finishStringSection(sections, currentSection, target, lastSourcePosition, targetPosition);
parseDollarCurlyIdentifier(source, target, sourcePosition, targetPosition);
currentSection = new StringSection(sourcePosition);
continue;
} else if (Character.isJavaIdentifierStart(c)) {
finishStringSection(sections, currentSection, target, lastSourcePosition, targetPosition);
skipRead = parseDollarIdentifier(c, source, target, sourcePosition, targetPosition);
currentSection = new StringSection(sourcePosition);
continue;
} else {
currentSection.data.append('$');
}
}
currentSection.data.append((char) c);
clear(lookAhead);
}
} catch (FinishedReadingException e) {
if (lookAhead.length() > 0) {
currentSection.data.append(lookAhead);
}
//Ignored here, just used for exiting the read loop. Yeah I know we don't like
//empty catch blocks or expected behavior trowing exceptions, but this just cleaned out the code
//_so_ much that I thought it worth it...this once -Matias Bjarland 20100126
}
finishStringSection(sections, currentSection, target, sourcePosition, targetPosition);
append(target, targetPosition, SCRIPT_TAIL);
scriptSource = target.toString();
this.template = createTemplateClosure(sections, parentLoader, target);
}
private static void clear(StringBuilder lookAhead) {
lookAhead.delete(0, lookAhead.length());
}
private void handleEscaping(final Reader source,
final Position sourcePosition,
final StringSection currentSection,
final StringBuilder lookAhead) throws IOException, FinishedReadingException {
//if we get here, we just read in a back-slash from the source, now figure out what to do with it
int c = read(source, sourcePosition, lookAhead);
/*
The _only_ special escaping this template engine allows is to escape the sequences:
${ and <% and potential slashes in front of these. Escaping in any other sections of the
source string is ignored. The following is a source -> result mapping of a few values, assume a
binding of [alice: 'rabbit'].
Note: we don't do java escaping of slashes in the below
example, i.e. the source string is what you would see in a text editor when looking at your template
file:
source string result
'bob' -> 'bob'
'\bob' -> '\bob'
'\\bob' -> '\\bob'
'${alice}' -> 'rabbit'
'\${alice}' -> '${alice}'
'\\${alice}' -> '\rabbit'
'\\$bob' -> '\\$bob'
'\\' -> '\\'
'\\\' -> '\\\'
'%<= alice %>' -> 'rabbit'
'\%<= alice %>' -> '%<= alice %>'
*/
if (c == '\\') {
//this means we have received a double backslash sequence
//if this is followed by ${ or <% we output one backslash
//and interpret the following sequences with groovy, if followed by anything
//else we output the two backslashes and continue as usual
source.mark(3);
int d = read(source, sourcePosition, lookAhead);
c = read(source, sourcePosition, lookAhead);
clear(lookAhead);
if ((d == '$' && c == '{') ||
(d == '<' && c == '%')) {
source.reset();
currentSection.data.append('\\');
return;
} else {
currentSection.data.append('\\');
currentSection.data.append('\\');
currentSection.data.append((char) d);
}
} else if (c == '$') {
c = read(source, sourcePosition, lookAhead);
if (c == '{') {
currentSection.data.append('$');
} else {
currentSection.data.append('\\');
currentSection.data.append('$');
}
} else if (c == '<') {
c = read(source, sourcePosition, lookAhead);
if (c == '%') {
currentSection.data.append('<');
} else {
currentSection.data.append('\\');
currentSection.data.append('<');
}
} else {
currentSection.data.append('\\');
}
currentSection.data.append((char) c);
clear(lookAhead);
}
private Closure createTemplateClosure(List sections, final ClassLoader parentLoader, StringBuilder target) throws ClassNotFoundException {
final GroovyClassLoader loader = AccessController.doPrivileged((PrivilegedAction) () -> new GroovyClassLoader(parentLoader));
final Class groovyClass;
try {
groovyClass = loader.parseClass(new GroovyCodeSource(target.toString(), TEMPLATE_SCRIPT_PREFIX + counter.incrementAndGet() + ".groovy", "x"));
} catch (MultipleCompilationErrorsException e) {
throw mangleMultipleCompilationErrorsException(e, sections);
} catch (Exception e) {
throw new GroovyRuntimeException("Failed to parse template script (your template may contain an error or be trying to use expressions not currently supported): " + e.getMessage());
}
Closure result;
try {
final GroovyObject object = (GroovyObject) groovyClass.getDeclaredConstructor().newInstance();
Closure chicken = (Closure) object.invokeMethod("getTemplate", null);
//bind the two first parameters of the generated closure to this class and the sections list
result = chicken.curry(this, sections);
} catch (InstantiationException | IllegalAccessException | NoSuchMethodException | InvocationTargetException e) {
throw new ClassNotFoundException(e.getMessage());
}
return result;
}
/**
* Parses a non curly dollar preceded identifier of the type
* '$bird' in the following template example:
*
*
* Alice why is a $bird like a writing desk
*
*
* which would produce the following template data:
*
*
* out << "Alice why is a ";
* out << bird;
* out << " like a writing desk";
*
*
* This method is given the 'b' in 'bird' in argument c, checks if it is a valid
* java identifier start (we assume groovy did not mangle the java
* identifier rules). If so it proceeds to parse characters from the input
* until it encounters a non-java-identifier character. At that point
*
* @param c The first letter of the potential identifier, 'b' in the above example
* @param reader The reader reading from the template source
* @param target The target groovy script source we write to
* @param sourcePosition The reader position in the source stream
* @param targetPosition The writer position in the target stream
* @return true if a valid dollar preceded identifier was found, false otherwise. More
* specifically, returns true if the first character after the dollar sign is
* a valid java identifier. Note that the dollar curly syntax is handled by
* another method.
*
* @throws IOException
* @throws FinishedReadingException If we encountered the end of the source stream.
*/
private int parseDollarIdentifier(int c ,
final Reader reader,
final StringBuilder target,
final Position sourcePosition,
final Position targetPosition) throws IOException, FinishedReadingException {
append(target, targetPosition, "out<<");
append(target, targetPosition, (char) c);
while (true) {
c = read(reader, sourcePosition);
if (!Character.isJavaIdentifierPart(c) || c == '$') {
break;
}
append(target, targetPosition, (char) c);
}
append(target, targetPosition, ";");
return c;
}
/**
* Parses a dollar curly preceded identifier of the type
* '${bird}' in the following template example:
*
*
* Alice why is a ${bird} like a writing desk
*
*
* which would produce the following template data:
*
*
* out << "Alice why is a ";
* out << """${bird}""";
* out << " like a writing desk";
*
*
* This method is given the 'b' in 'bird' in argument c, checks if it is a valid
* java identifier start (we assume groovy did not mangle the java
* identifier rules). If so it proceeds to parse characters from the input
* until it encounters a non-java-identifier character. At that point
*
* @param reader The reader reading from the template source
* @param target The target groovy script source we write to
* @param sourcePosition The reader position in the source stream
* @param targetPosition The writer position in the target stream
* @throws IOException
* @throws FinishedReadingException
*/
private void parseDollarCurlyIdentifier(final Reader reader,
final StringBuilder target,
final Position sourcePosition,
final Position targetPosition) throws IOException, FinishedReadingException {
append(target, targetPosition, "out<<\"\"\"${");
while (true) {
int c = read(reader, sourcePosition);
append(target, targetPosition, (char) c);
if (c == '}') break;
}
append(target, targetPosition, "\"\"\";");
}
/**
* Parse a <% .... %> section if we are writing a GString close and
* append ';' then write the section as a statement
*/
private void parseSection(final int pendingC,
final Reader reader,
final StringBuilder target,
final Position sourcePosition,
final Position targetPosition) throws IOException, FinishedReadingException {
//the below is a quirk, we do this so that every non-string-section is prefixed by
//the same number of characters (the others have "out<<\"\"\"${"), this allows us to
//figure out the exception row and column later on
append(target, targetPosition, " ");
append(target, targetPosition, (char) pendingC);
readAndAppend(reader, target, sourcePosition, targetPosition);
append(target, targetPosition, ';');
}
private void readAndAppend(Reader reader, StringBuilder target, Position sourcePosition, Position targetPosition) throws IOException, FinishedReadingException {
while (true) {
int c = read(reader, sourcePosition);
if (c == '%') {
c = read(reader, sourcePosition);
if (c == '>') break;
append(target, targetPosition, '%');
}
append(target, targetPosition, (char) c);
}
}
/**
* Parse a <%= .... %> expression
*/
private void parseExpression(final Reader reader,
final StringBuilder target,
final Position sourcePosition,
final Position targetPosition) throws IOException, FinishedReadingException {
append(target, targetPosition, "out<<\"\"\"${");
readAndAppend(reader, target, sourcePosition, targetPosition);
append(target, targetPosition, "}\"\"\";");
}
@Override
public Writable make() {
return make(null);
}
@Override
public Writable make(final Map map) {
//we don't need a template.clone here as curry calls clone under the hood
final Closure template = this.template.curry(new Object[]{map});
return (Writable) template;
}
/*
* Create groovy assertion style error message for template error. Example:
*
* Error parsing expression on line 71 column 15, message: no such property jboss for for class DUMMY
* templatedata${jboss}templateddatatemplateddata
* ^------^
* |
* syntax error
*/
private RuntimeException mangleMultipleCompilationErrorsException(MultipleCompilationErrorsException e, List sections) {
RuntimeException result = e;
ErrorCollector collector = e.getErrorCollector();
@SuppressWarnings({"unchecked"})
List errors = (List) collector.getErrors();
if (!errors.isEmpty()) {
Message firstMessage = errors.get(0);
if (firstMessage instanceof SyntaxErrorMessage) {
@SuppressWarnings({"ThrowableResultOfMethodCallIgnored"})
SyntaxException syntaxException = ((SyntaxErrorMessage) firstMessage).getCause();
Position errorPosition = new Position(syntaxException.getLine(), syntaxException.getStartColumn());
//find the string section which precedes the row/col of the thrown exception
StringSection precedingSection = findPrecedingSection(errorPosition, sections);
//and now use the string section to mangle the line numbers so that they refer to the
//appropriate line in the source template data
if (precedingSection != null) {
//if the error was thrown on the same row as where the last string section
//ended, fix column value
offsetPositionFromSection(errorPosition, precedingSection);
//the below being true indicates that we had an unterminated ${ or <% sequence and
//the column is thus meaningless, we reset it to where the %{ or <% starts to at
//least give the user a sporting chance
if (sections.get(sections.size() - 1) == precedingSection) {
errorPosition.column = precedingSection.lastSourcePosition.column;
}
String message = mangleExceptionMessage(e.getMessage(), errorPosition);
result = new TemplateParseException(message, e, errorPosition.row, errorPosition.column);
}
}
}
return result;
}
private String mangleExceptionMessage(String original, Position p) {
String result = original;
int index = result.indexOf("@ line ");
if (index != -1) {
result = result.substring(0, index);
}
int count = 0;
index = 0;
for (char c : result.toCharArray()) {
if (c == ':') {
count++;
if (count == 3) {
result = result.substring(index + 2);
break;
}
}
index++;
}
String msg = "Template parse error '" + result + "' at line " + p.row + ", column " + p.column;
try {
msg += "\n" + getErrorContext(p.row);
} catch (IOException e) {
//we opt for not doing anthing here...we just do not get context if
//this happens
}
return msg;
}
private void offsetPositionFromSection(Position p, StringSection s) {
if (p.row == s.lastTargetPosition.row) {
//The number 8 below represents the number of characters in the header of a non-string-section such as
//<% ... %>. A section like this is represented in the target script as:
//out<<"""......."""
//12345678
p.column -= s.lastTargetPosition.column + 8;
p.column += s.lastSourcePosition.column;
}
p.row += s.lastSourcePosition.row - 1;
}
private StringSection findPrecedingSection(Position p, List sections) {
StringSection result = null;
for (StringSection s : sections) {
if (s.lastTargetPosition.row > p.row
|| (s.lastTargetPosition.row == p.row && s.lastTargetPosition.column > p.column)) {
break;
}
result = s;
}
return result;
}
private void append(final StringBuilder target, Position targetPosition, char c) {
if (c == '\n') {
targetPosition.row++;
targetPosition.column = 1;
} else {
targetPosition.column++;
}
target.append(c);
}
private void append(final StringBuilder target, Position targetPosition, String s) {
int len = s.length();
for (int i = 0; i < len; i++) {
append(target, targetPosition, s.charAt(i));
}
}
private int read(final Reader reader, Position position, StringBuilder lookAhead) throws IOException, FinishedReadingException {
int c = read(reader, position);
lookAhead.append((char) c);
return c;
}
// SEE BELOW
boolean useLastRead = false;
private int lastRead = -1;
/* All \r\n sequences are treated as a single \n. By doing this we
* produce the same output as the GStringTemplateEngine. Otherwise, some
* of our output is on a newline when it should not be.
*
* Instead of using a pushback reader, we just keep a private instance
* variable 'lastRead'.
*/
private int read(final Reader reader, Position position) throws IOException, FinishedReadingException {
int c;
if (useLastRead) {
// use last one if we stored a character
c = lastRead;
// reset last
useLastRead = false;
lastRead = -1;
} else {
c = read(reader);
if (c == '\r') {
// IF CRLF JUST KEEP LF
c = read(reader);
if (c != '\n') {
// ELSE keep original char
// and pushback the one we just read
lastRead = c;
useLastRead = true;
c = '\r';
}
}
}
if (c == -1) {
throw finishedReadingException;
}
if (c == '\n') {
position.row++;
position.column = 1;
} else {
position.column++;
}
return c;
}
private int read(final Reader reader) throws IOException {
int c = reader.read();
templateSource.append((char) c);
return c;
}
}
}