com.google.gwt.thirdparty.streamhtmlparser.impl.InternalState Maven / Gradle / Ivy
/*
* Copyright (C) 2010 Google Inc.
*
* 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 com.google.gwt.thirdparty.streamhtmlparser.impl;
import com.google.gwt.thirdparty.guava.common.base.Preconditions;
import java.util.concurrent.atomic.AtomicInteger;
/**
* A very simple representation of the parser internal state. The state
* contains a small integer identifier (from 1 to 255) to allow for
* the implementation of a simple finite state machine. The name is
* purely informational.
*
* In order to eliminate the possibility that different states have
* the same identifier, this class manages the idenitifiers themselves.
* The HTML and Javascript parser states are managed elsewhere in different
* "namespaces" hence will not clash and there is no current need for this
* class to disambiguate them further.
*
*
The methods to create new InternalState
instances are
* package-scope only as they are only needed by HtmlParserImpl
* and JavascriptParserImpl
.
*/
class InternalState {
// An InternalState to represent an error condition for all parsers.
static final InternalState INTERNAL_ERROR_STATE = new InternalState();
// MAX_ID and FIRST_ID are only used for asserts against developer error.
private static final int MAX_ID = 255;
private static final int FIRST_ID = 1;
private static AtomicInteger htmlStates = new AtomicInteger(FIRST_ID);
private static AtomicInteger javascriptStates = new AtomicInteger(FIRST_ID);
private final String name;
private final int id;
/**
* @param name the {@code String} identifier for this state
* @param id the integer identiifer for this state, guaranteed to be unique
*/
private InternalState(String name, int id) {
Preconditions.checkNotNull(name);
Preconditions.checkArgument(id >= FIRST_ID);
Preconditions.checkArgument(id <= MAX_ID);
this.name = name;
this.id = id;
}
/**
* Used only for the error state. Bypasses assert checks.
*/
private InternalState() {
name = "InternalStateError";
id = 0;
}
/**
* @return {@code String} name of that state.
*/
public String getName() {
return name;
}
/**
* @return {@code int} id of that state.
*/
public int getId() {
return id;
}
/**
* @return {@code String} representation of that object, the format
* may change.
*/
@Override
public String toString() {
return String.format("InternalState: Name: %s; Id: %d", name, id);
}
/**
* Obtain a new {@code InternalState} instance for the HTML parser.
*
* @param name a unique identifier for this state useful during debugging
* @return a new {@code InternalState} object
*/
static InternalState getInstanceHtml(String name) {
int htmlStateId = htmlStates.getAndIncrement();
return new InternalState(name, htmlStateId);
}
/**
* Obtain a new InternalState
instance for the Javascript parser.
*
* @param name A unique identifier for this state useful during debugging
* @return a new {@code InternalState} object
*/
static InternalState getInstanceJavascript(String name) {
int javascriptStateId = javascriptStates.getAndIncrement();
return new InternalState(name, javascriptStateId);
}
}