de.uka.ilkd.pp.Backend Maven / Gradle / Ivy
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//This file is part of the Java™ Pretty Printer Library (JPPlib)
//Copyright (c) 2009, Martin Giese
//All rights reserved.
//
//Redistribution and use in source and binary forms, with or without
//modification, are permitted provided that the following conditions are met:
//
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package de.uka.ilkd.pp;
/**
* The backend for a {@link Layouter}. An object satisfying this
* interface can act as a receiver for the layed out text produced by
* a {@link Layouter}. A Backend must also provide the
* maximum line width available through the {@link #lineWidth()}
* method. Finally, it is responsible for calculating (with {@link
* #measure(String)} the amount of space it actually needs to print a
* given string. For instance, if strings printed through a {@link
* Layouter} are actually known to be in HTML, {@link
* #measure(String)} can return the size of the text, not including
* markup.
*
* This interface has a type parameter Exc which
* denotes the type of exceptions that might be thrown when output is
* sent to a backend. For instance, a backend like {@link
* WriterBackend}, which ultimately writes output to a {@link
* java.io.Writer} might produce IOExceptions which
* should not be handled by the Backend, but passed through to the
* program calling the {@link Layouter}. So it implements the
* interface Backend<java.io.IOException>. There is a dummy
* exception class {@link NoExceptions} that may be used as parameter
* if no checked exceptions are thrown by a Backend.
*
*
There is currently no provision to handle proportional fonts,
* and there might never be.
*
* @param The type of exceptions that might be thrown by
* this backend.
*
* @author Martin Giese
* @see Layouter
*
*/
public interface Backend {
/** Append a String s to the output. s
* contains no newlines. */
void print(String s) throws Exc;
/** Start a new line. */
void newLine() throws Exc;
/** Closes this backend */
void close() throws Exc;
/** Flushes any buffered output */
void flush() throws Exc;
/** Gets called to record a mark() call in the input. */
void mark(Object o) throws Exc;
/** Returns the available space per line */
int lineWidth();
/** Returns the space required to print the String s */
int measure(String s);
}