/*
* Copyright 2003-2015 JetBrains s.r.o.
*
* 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 jetbrains.mps.text.impl;
import jetbrains.mps.text.BufferLayout;
import jetbrains.mps.text.BufferSnapshot;
import jetbrains.mps.text.TextBuffer;
import jetbrains.mps.text.TextUnit;
import org.jetbrains.annotations.NotNull;
/**
* Facility to describe layout of TextBuffer, i.e. areas and their location in respect to other.
* The class needs {@link TextBuffer}/{@link BufferLayout}, but since unit layout is generally known
* before {@link TextBuffer} is available, parameterizes {@link jetbrains.mps.text.impl.RegularTextUnit2#setBufferLayout(BufferLayoutConfiguration)} TextUnit}
* implementation instead.
* TODO Perhaps, it's an overkill, and we shall expose TextBuffer from TextUnit, and configure BufferLayout directly, without this extra layer?
*
*
* Instances of this class are supplied by client when {@link TextUnit} is constructed, and implementation consults this class the moment
* buffer for the unit is available and requires configuration. Clients could re-use same configuration for multiple units, just need to
* act accordingly if there's any state (i.e. distinguish by {@link TextBuffer} argument).
*
* Before any text is generated into buffer, this class gets a chance to configure buffer with {@link #prepareBuffer(TextBuffer)}.
* Once generation is over, to get final text snapshot, {@link #prepareSnapshot(TextBuffer)} is consulted.
*
* @author Artem Tikhomirov
* @since 3.3
*/
public class BufferLayoutConfiguration {
/**
* Initialize buffer/layout according to this configuration.
* Default implementation is no-op.
* In case of simple layout, may declare all areas here at once (no need for overridden #prepareSnapshot() then)
*
* @param buffer actual text buffer, uninitialized (there's single top-most text area only)
*/
public void prepareBuffer(@NotNull TextBuffer buffer) {
// no-op. may prepare initial active area.
}
/**
* Finalize text presentation according to desired layout.
* Default implementation uses blank layout, which outputs all text areas in the order they were registered with the buffer.
*
* @param buffer same instance as in preceding {@link #prepareSnapshot(TextBuffer)} call
* @return text according to layout configured by this class
*/
@NotNull
public BufferSnapshot prepareSnapshot(@NotNull TextBuffer buffer) {
return buffer.snapshot(buffer.newLayout());
}
}