infra.beans.factory.parsing.ParseState Maven / Gradle / Ivy
/*
* Copyright 2017 - 2024 the original author or authors.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see [https://www.gnu.org/licenses/]
*/
package infra.beans.factory.parsing;
import java.util.ArrayDeque;
import infra.lang.Nullable;
/**
* Simple {@link ArrayDeque}-based structure for tracking the logical position during
* a parsing process. {@link Entry entries} are added to the ArrayDeque at each point
* during the parse phase in a reader-specific manner.
*
* 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
* @author Juergen Hoeller
* @since 4.0
*/
public final class ParseState {
/**
* Internal {@link ArrayDeque} storage.
*/
private final ArrayDeque state;
/**
* Create a new {@code ParseState} with an empty {@link ArrayDeque}.
*/
public ParseState() {
this.state = new ArrayDeque<>();
}
/**
* Create a new {@code ParseState} whose {@link ArrayDeque} is a clone
* of the state in the passed-in {@code ParseState}.
*/
private ParseState(ParseState other) {
this.state = other.state.clone();
}
/**
* Add a new {@link Entry} to the {@link ArrayDeque}.
*/
public void push(Entry entry) {
this.state.push(entry);
}
/**
* Remove an {@link Entry} from the {@link ArrayDeque}.
*/
public void pop() {
this.state.pop();
}
/**
* Return the {@link Entry} currently at the top of the {@link ArrayDeque} or
* {@code null} if the {@link ArrayDeque} is empty.
*/
@Nullable
public Entry peek() {
return 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}.
*/
@Override
public String toString() {
StringBuilder sb = new StringBuilder(64);
int i = 0;
for (Entry entry : this.state) {
if (i > 0) {
sb.append('\n');
for (int j = 0; j < i; j++) {
sb.append('\t');
}
sb.append("-> ");
}
sb.append(entry);
i++;
}
return sb.toString();
}
/**
* Marker interface for entries into the {@link ParseState}.
*/
public interface Entry {
}
}