com.flagwind.commands.CommandExpressionParser Maven / Gradle / Ivy
package com.flagwind.commands;
import com.flagwind.commons.CharUtils;
import com.flagwind.commons.StringUtils;
import com.flagwind.io.PathAnchor;
import org.apache.commons.lang3.tuple.MutableTriple;
import java.io.IOException;
import java.io.StringReader;
import java.util.*;
import static com.flagwind.io.PathAnchor.*;
/**
* 命令表达式解析类
* @author chendb
*/
public class CommandExpressionParser {
//#region 单例字段
public static CommandExpressionParser Instance = new CommandExpressionParser();
//#endregion
//#region 私有枚举
private enum CommandPathState {
/**
* 无
*/
None,
/**
* 单点
*/
Dot,
/**
* 双点
*/
DoubleDot,
/**
* 斜杠
*/
Slash,
/**
* 部分
*/
Part,
}
private enum CommandPairState {
None,
Slash,
Assign,
Part,
}
//#endregion
//#region 私有构造
private CommandExpressionParser() {
}
//#endregion
//#region 解析方法
public CommandExpression parse(String text) throws IOException {
if (StringUtils.isBlank(text)) {
return null;
}
CommandExpression result = null;
CommandExpression current = null;
StringReader reader = new StringReader(text);
while (reader.read() > 0) {
current = parse(reader);
if (result != null) {
CommandExpression previous = result;
while (previous.getNext() != null) {
previous = previous.getNext();
}
previous.setNext(current);
} //线性查找命令表达式的管道链，并更新其指向
else {
result = current;
}
}
return result;
}
private CommandExpression parse(StringReader reader) throws IOException {
PathAnchor anchor;
String name, path;
List arguments = new ArrayList<>();
HashMap options = new HashMap<>();
//解析命令表达式中的路径部分，如果表达式有误则该解析方法内部抛出异常
MutableTriple result = parsePath(reader);
anchor = result.getLeft();
name = result.getMiddle();
path = result.getRight();
Map.Entry pair;
//依次解析命令表达式中的选项和参数
while ((pair = parsePair(reader)) != null) {
if (pair != null) {
if (StringUtils.isBlank(pair.getKey())) {
arguments.add(pair.getValue());
} else {
options.put(pair.getKey(), pair.getValue());
}
}
}
String[] args = arguments.toArray(new String[arguments.size()]);
//返回一个命令表达式
return new CommandExpression(anchor, name, path, options.entrySet(), args);
}
//#endregion
//#region 私有方法
/**
* 路径解析
* @param reader
* @return
* @throws CommandExpressionException
* @throws IOException
*/
private static MutableTriple parsePath(StringReader reader) throws IOException {
if (reader == null) {
throw new NullPointerException("reader");
}
MutableTriple result = new MutableTriple<>();
CommandPathState state = CommandPathState.None;
List parts = new ArrayList();
int valueRead = 0;
//设置输出参数的默认值
PathAnchor anchor = None;
String name = "";
String path = "";
while ((valueRead = reader.read()) > 0) {
char chr = (char) valueRead;
//首先对位于路径中间的点号进行转换，以方便后续的处理
if (chr == '.' && state == CommandPathState.Part) {
chr = '/';
}
if (chr == '.') {
switch (state) {
case None:
state = CommandPathState.Dot;
anchor = Current;
break;
case Dot:
state = CommandPathState.DoubleDot;
anchor = Parent;
break;
case DoubleDot:
break;
case Slash:
break;
case Part:
break;
default:
throw new CommandExpressionException("Invalid anchor of command path.");
}
} else if (chr == '/') {
if (state == CommandPathState.Slash) {
throw new CommandExpressionException("Duplicate '/' slash characters.");
}
if (state == CommandPathState.None) {
anchor = Root;
} else if (state == CommandPathState.Part) {
parts.add(name);
name = "";
}
state = CommandPathState.Slash;
} else if (Character.isLetterOrDigit(chr) || chr == '_') {
if (state == CommandPathState.Dot || state == CommandPathState.DoubleDot) {
throw new CommandExpressionException("Missing '/' slash character between dot and letter or digit.");
}
name += chr;
state = CommandPathState.Part;
} else if (CharUtils.isWhiteSpace(chr)) {
if (state == CommandPathState.None) {
continue;
} else {
break;
}
} else {
throw new CommandExpressionException("Contains '{chr}' illegal character(s) in the command path.");
}
}
reader.close();
//如果路径以斜杠符结尾，即为非法路径格式
if (state == CommandPathState.Slash && ((parts != null && parts.size() > 0) || anchor != Root)) {
throw new CommandExpressionException("The command path can not at the end of '/' character.");
}
if (parts != null && parts.size() > 0) {
path = String.join(".", parts);
} else if (StringUtils.isBlank(name)) {
switch (anchor) {
case Root:
name = "/";
break;
case Current:
name = ".";
break;
case Parent:
name = "..";
break;
}
anchor = None;
}
result.setLeft(anchor);
result.setMiddle(name);
result.setRight(path);
return result;
}
private static Collection> parsePairs(String text) throws IOException {
List> result = new ArrayList<>();
if (text == null) {
return null;
}
StringReader reader = new StringReader(text);
do {
result.add(parsePair(reader));
} while (reader.read() > 0);
reader.close();
return result;
}
private static Map.Entry parsePair(StringReader reader) throws IOException {
if (reader == null) {
throw new NullPointerException("reader");
}
char quote = '\0';
boolean isEscaping = false;
String key = StringUtils.EMPTY;
String value = StringUtils.EMPTY;
CommandPairState state = CommandPairState.None;
int valueRead;
while ((valueRead = reader.read()) > 0) {
char chr = (char) valueRead;
if (chr == '-' || chr == '/') {
if (state == CommandPairState.Slash) {
throw new CommandExpressionException("Duplicate '{chr}' option indicator of command expression.");
}
if (state == CommandPairState.None && quote == '\0') {
state = CommandPairState.Slash;
continue;
}
} else if (chr == ':' || chr == '=') {
if (state == CommandPairState.Part
&& !StringUtils.isBlank(key)
&& (quote == '\0' && !isEscaping)) {
state = CommandPairState.Assign;
continue;
}
} else if (chr == '|') {
if (quote == '\0') {
if (StringUtils.isBlank(key) && StringUtils.isBlank(value)) {
return null;
}
return new AbstractMap.SimpleEntry(key, value);
}
} else if (CharUtils.isWhiteSpace(chr)) {
if (state == CommandPairState.Slash) {
throw new CommandExpressionException("A white-space character at the back of the option indicator.");
}
if (state == CommandPairState.None) {
continue;
} else if (quote == '\0') {
return new AbstractMap.SimpleEntry(key, value);
}
} else if (isQuote(chr) && !isEscaping) {
if (quote != '\0') {
quote = '\0';
continue;
} else if (state != CommandPairState.Part) {
quote = chr;
continue;
}
}
//设置转义状态：即当前字符为转义符并且当前状态不为转义状态
isEscaping = chr == '\\' && (!isEscaping);
if (isEscaping) {
continue;
}
switch (state) {
case Slash:
key += chr;
break;
case None:
case Assign:
value += chr;
break;
default:
if (StringUtils.isBlank(value)) {
key += chr;
} else {
value += chr;
}
break;
}
state = CommandPairState.Part;
}
if (StringUtils.isBlank(key) && StringUtils.isBlank(value)) {
return null;
}
return new AbstractMap.SimpleEntry(key, value);
}
private static boolean isQuote(char chr) {
return (chr == '"' || chr == '\'');
}
private static char escapeChar(char chr) {
switch (chr) {
case 's':
return ' ';
case 't':
return '\t';
case '\\':
return '\\';
default:
return '\0';
}
}
//#endregion
}
© 2015 - 2025 Weber Informatics LLC | Privacy Policy