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Groovy: A powerful, dynamic language for the JVM
/*
* 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.util;
import groovy.lang.GroovyRuntimeException;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.Writer;
/**
* A helper class for printing indented text. This can be used stand-alone or, more commonly, from Builders.
*
* By default, a PrintWriter to System.out is used as the Writer, but it is possible
* to change the Writer by passing a new one as a constructor argument.
*
* Indention by default is 2 characters but can be changed by passing a
* different value as a constructor argument.
*
* The following is an example usage. Note that within a "with" block you need to
* specify a parameter name so that this.println is not called instead of IndentPrinter.println:
*
* new IndentPrinter(new PrintWriter(out)).with { p ->
* p.printIndent()
* p.println('parent1')
* p.incrementIndent()
* p.printIndent()
* p.println('child 1')
* p.printIndent()
* p.println('child 2')
* p.decrementIndent()
* p.printIndent()
* p.println('parent2')
* p.flush()
* }
*
* The above example prints this to standard output:
*
* parent1
* child 1
* child 2
* parent2
*
*
* @author James Strachan
*/
public class IndentPrinter {
private int indentLevel;
private String indent;
private Writer out;
private final boolean addNewlines;
private boolean autoIndent;
/**
* Creates an IndentPrinter backed by a PrintWriter pointing to System.out, with an indent of two spaces.
*
* @see #IndentPrinter(Writer, String)
*/
public IndentPrinter() {
this(new PrintWriter(System.out), " ");
}
/**
* Creates an IndentPrinter backed by the supplied Writer, with an indent of two spaces.
*
* @param out Writer to output to
* @see #IndentPrinter(Writer, String)
*/
public IndentPrinter(Writer out) {
this(out, " ");
}
/**
* Creates an IndentPrinter backed by the supplied Writer,
* with a user-supplied String to be used for indenting.
*
* @param out Writer to output to
* @param indent character(s) used to indent each line
*/
public IndentPrinter(Writer out, String indent) {
this(out, indent, true);
}
/**
* Creates an IndentPrinter backed by the supplied Writer,
* with a user-supplied String to be used for indenting
* and the ability to override newline handling.
*
* @param out Writer to output to
* @param indent character(s) used to indent each line
* @param addNewlines set to false to gobble all new lines (default true)
*/
public IndentPrinter(Writer out, String indent, boolean addNewlines) {
this(out, indent, addNewlines, false);
}
/**
* Create an IndentPrinter to the given PrintWriter
* @param out Writer to output to
* @param indent character(s) used to indent each line
* @param addNewlines set to false to gobble all new lines (default true)
* @param autoIndent set to true to make println() prepend the indent automatically (default false)
*/
public IndentPrinter(Writer out, String indent, boolean addNewlines, boolean autoIndent) {
this.addNewlines = addNewlines;
if (out == null) {
throw new IllegalArgumentException("Must specify a Writer");
}
this.out = out;
this.indent = indent;
this.autoIndent = autoIndent;
}
/**
* Prints a string followed by an end of line character.
*
* @param text String to be written
*/
public void println(String text) {
try {
if(autoIndent) printIndent();
out.write(text);
println();
} catch(IOException ioe) {
throw new GroovyRuntimeException(ioe);
}
}
/**
* Prints a string.
*
* @param text String to be written
*/
public void print(String text) {
try {
out.write(text);
} catch(IOException ioe) {
throw new GroovyRuntimeException(ioe);
}
}
/**
* Prints a character.
*
* @param c char to be written
*/
public void print(char c) {
try {
out.write(c);
} catch(IOException ioe) {
throw new GroovyRuntimeException(ioe);
}
}
/**
* Prints the current indent level.
*/
public void printIndent() {
for (int i = 0; i < indentLevel; i++) {
try {
out.write(indent);
} catch(IOException ioe) {
throw new GroovyRuntimeException(ioe);
}
}
}
/**
* Prints an end-of-line character (if enabled via addNewLines property).
* Defaults to outputting a single '\n' character but by using a custom
* Writer, e.g. PlatformLineWriter, you can get platform-specific
* end-of-line characters.
*
* @see #IndentPrinter(Writer, String, boolean)
*/
public void println() {
if (addNewlines) {
try {
out.write("\n");
} catch(IOException ioe) {
throw new GroovyRuntimeException(ioe);
}
}
}
public void incrementIndent() {
++indentLevel;
}
public void decrementIndent() {
--indentLevel;
}
public int getIndentLevel() {
return indentLevel;
}
public void setIndentLevel(int indentLevel) {
this.indentLevel = indentLevel;
}
public boolean getAutoIndent(){
return this.autoIndent;
}
public void setAutoIndent(boolean autoIndent){
this.autoIndent = autoIndent;
}
public void flush() {
try {
out.flush();
} catch(IOException ioe) {
throw new GroovyRuntimeException(ioe);
}
}
}