/*
* Copyright 2002-2008 the original author or authors.
*
* 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 org.springframework.beans.factory.parsing;
import java.util.Stack;
/**
* Simple {@link Stack}-based structure for tracking the logical position during
* a parsing process. {@link Entry entries} are added to the stack at
* each point during the parse phase in a reader-specific manner.
*
* <p>Calling {@link #toString()} will render a tree-style view of the current logical
* position in the parse phase. This representation is intended for use in
* error messages.
*
* @author Rob Harrop
* @since 2.0
*/
public final class ParseState {
/**
* Tab character used when rendering the tree-style representation.
*/
private static final char TAB = '\t';
/**
* Internal {@link Stack} storage.
*/
private final Stack state;
/**
* Create a new <code>ParseState</code> with an empty {@link Stack}.
*/
public ParseState() {
this.state = new Stack();
}
/**
* Create a new <code>ParseState</code> whose {@link Stack} is a {@link Object#clone clone}
* of that of the passed in <code>ParseState</code>.
*/
private ParseState(ParseState other) {
this.state = (Stack) other.state.clone();
}
/**
* Add a new {@link Entry} to the {@link Stack}.
*/
public void push(Entry entry) {
this.state.push(entry);
}
/**
* Remove an {@link Entry} from the {@link Stack}.
*/
public void pop() {
this.state.pop();
}
/**
* Return the {@link Entry} currently at the top of the {@link Stack} or
* <code>null</code> if the {@link Stack} is empty.
*/
public Entry peek() {
return (Entry) (this.state.empty() ? null : this.state.peek());
}
/**
* Create a new instance of {@link ParseState} which is an independent snapshot
* of this instance.
*/
public ParseState snapshot() {
return new ParseState(this);
}
/**
* Returns a tree-style representation of the current <code>ParseState</code>.
*/
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
for (int x = 0; x < this.state.size(); x++) {
if (x > 0) {
sb.append('\n');
for (int y = 0; y < x; y++) {
sb.append(TAB);
}
sb.append("-> ");
}
sb.append(this.state.get(x));
}
return sb.toString();
}
/**
* Marker interface for entries into the {@link ParseState}.
*/
public interface Entry {
}
}
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