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PHP实现类似于Python中的Construct库功能（二）实现适配器功能

时间：2021-07-01 10:21:17 帮助过：20人阅读

引言

在上一篇文章《PHP实现类似于Python中的Construct库功能（二）实现适配器功能》介绍了用php解析二进制数据的基本思路。接下来要完成两个工作。

1、在上一篇文章中采用解析函数的方式，现在改成用解析类，在类中包含parse方法。

2、在定义结构体数据项时，加上适配器功能，用管道运算符| 连接数据项与适配器，实现数据的变换。

推荐PHP视频教程：https://www.gxlcms.com/course/list/29/type/2.html

基本思路

1，修改词法分析规则，使其可以接受管道运算符 |

2，修改语法分析规则，使其可以接受适配器的调用

3，用php语言实现适配器功能

实现内容

准备解析的结构体定义文件

struct student
{
  char name[2];
  int num|IntOffset(100);
  int age;
  char addr[3];
};

struct teacher
{
  char name[2];
  int num|Int2str; 
  char addr[3];
};

与上一篇文章中的结构体定义最大的不同在于以下这两句

  int num|IntOffset(100); 
  int num|Int2str;  
};

这里通过管道调用了两个适配器，IntOffset(100) 表示在原有值的基础上偏移100,Int2str表示将原有的整数值变成字符串

下面看一下这两个适配器的具体实现

<?php

//将整数值偏移一个定值

namespace Ados;

class IntOffset {

	public function __construct($offset)
	{		
		$this->offset = $offset;		
	}

	function parse($obj){
		if(is_array($obj)){
			return array_map(function($value) {
					    return $value + $this->offset;
					},$obj);
		}
		return $obj+ $this->offset;
	}

	function build($obj){
		throw new \Exception("Int2str build method not implements");
	}

}

class Int2str {

	function parse($obj){
		if(is_array($obj)){
			return array_map(function($value) {
					    return ''.$value;
					},$obj);
		}
		return ''.$obj;
	}

	function build($obj){
		throw new \Exception("Int2str build method not implements");
	}

}

为了集中注意力在二进制数据的解析上，以上两个类中只实现了parse方法，build方法暂未实现。

相应的，模板文件也要有所调整

<?php

//用于进行替换的模板文本

/*blockHeader{{*/
class structName{

	static function parse($context,$size=0){
		$valueArray=[];
		$totalSize = 0;
	/*blockHeader}}*/

	/*parseBody{{*/
		$expRes = parseByte($context,$filedSize);
	/*parseBody}}*/

	/*pipeBody{{*/
		$expRes['value'] = (new Adapter())->parse($expRes['value']);		
	/*pipeBody}}*/

	/*checkBody{{*/
		if($expRes['error']==0){
			$filed = '$filedName';
			if($filed){
				$valueArray[$filed]=$expRes['value'];
			}else{
				$valueArray[]=$expRes['value'];
			}		
			$context['pos']+=$expRes['size'];
			$totalSize+= $expRes['size'];
		}else{
			return ['value'=>False,'size'=>0,'error'=>$expRes['error'],'msg'=>$expRes['msg']];
		}
	/*checkBody}}*/
	

	/*blockTail{{*/
		return ['value'=>$valueArray,'size'=>$totalSize,'error'=>0,'msg'=>'ok'];
	}
}
	/*blockTail}}*/

词法规则文件改动不大，增加对管道运算符的匹配就可以了

['/^\|/','_pipe'		,'|'],

语法规则文件改动得比较大，由于要能够分析这一类语句

 int num|IntOffset(100);

修改后的语法规则文件内容如下：

<?php
/*!
 * structwkr的语法规则处理器
 * 45022300@qq.com
 * Version 0.9.0
 *
 * Copyright 2019, Zhu Hui
 * Released under the MIT license
 */

namespace Ados;

require_once 'const.php';
require_once __SCRIPTCORE__.'syntax_rule/base_rules_handler.php';

class StructwkrRulesHandler extends BaseRulesHandler{

//语法分析的起始记号,归约到最后得到就是若干个结构体定义的列表
function startToken(){

	return '_structList';
}


//求出放在附加信息中的数组长度
function elementSize($extraArray){
	if(count($extraArray)>0){
		return intval($extraArray[0]);
	}else{
		return 0;
	}
}

//语法规则处理函数名由规则右边部分与规则左边部分拼接而成
//语法规则定义的先后决定了归约时匹配的顺序，要根据实际的语法安排
//如果不熟悉语法，随意调整语法规则的先后次序将有可能导致语法错误

// struct list  {{{

function _structList_0_structList_struct($stack,$coder){

	$coder->pushBlockTail();
	return ['#',[]];
	
	
}

function _structList_0_struct($stack,$coder){	
	$coder->pushBlockTail();
	return ['#',[]];
}

// struct list  }}}


// struct   {{{

function _struct_0_structName_blockStatement_semi($stack,$coder){

	$t1= $this->topItem($stack,3);
	$structName = 	$t1[TokenValueIndex];

	$t2= $this->topItem($stack,2);
	$extraArray=$t2[TokenExtraIndex];
	
	return [$structName,$extraArray];
}

// struct   }}}

// struct name     {{{

function _structName_0_strukey_iden($stack,$coder){  

	$t1= $this->topItem($stack,1);
	$structName = 	$t1[TokenValueIndex];

	$coder->pushBlockHeader($structName);	
	return $this->pass($stack,1);
}

// struct name     }}}

// blockStatement    {{{

function _blockStatement_0_lcb_statementList_rcb($stack,$coder){

	return $this->pass($stack,2);

}

// blockStatement    }}}

// statement list  {{{

function _statementList_0_statementList_statement($stack,$coder){
	
	return $this->pass($stack,1);
}

function _statementList_0_statement($stack,$coder){
	//此处0表示statementList是上一级节点，要做特殊处理
	return $this->pass($stack,1);
}

// statement list  }}}


// statement       {{{

function _statement_0_expression_semi($stack,$coder){

	$t1= $this->topItem($stack,2);
	$elementName = 	$t1[TokenValueIndex];	
	$coder->pushCheckBody($elementName);	
	return $this->pass($stack,2);
}

// statement        }}}




// function expression {{{


//函数表达式
function _term_0_funcTerm($stack,$coder){  

	$t1= $this->topItem($stack,1);
	$funcName=$t1[TokenValueIndex];
	$paraArray=$t1[TokenExtraIndex]; 
	$paras = implode(",", $paraArray);
	$exp = $funcName.'('.$paras.')';	
	return [$exp,[]];

}

function _funcTerm_0_funcExpLp_rp($stack,$coder){  

	return $this->pass($stack,2);
}

function _funcTerm_0_funcExpLeft_rp($stack,$coder){  

	return $this->pass($stack,2);
}

function _funcExpLeft_0_funcExpLeft_comma_expression($stack,$coder){  
			
	$t1= $this->topItem($stack,3);
	$t2= $this->topItem($stack,1);

	//函数的参数列表存放在附加信息中
	$paraArray=$t1[TokenExtraIndex]; 
	array_push($paraArray, $t2[TokenValueIndex]);
	
	return [$t1[TokenValueIndex],$paraArray];
}

function _funcExpLeft_0_funcExpLp_expression($stack,$coder){  
	
	$t1= $this->topItem($stack,2);
	$t2= $this->topItem($stack,1);

	//函数的参数列表存放在附加信息中
	$paraArray=$t1[TokenExtraIndex]; 
	array_push($paraArray, $t2[TokenValueIndex]);
	
	return [$t1[TokenValueIndex],$paraArray];
}

function _funcExpLp_0_iden_lp($stack,$coder){  
	
	return $this->pass($stack,2);

}

// function expression }}}


//    Expression         {{{

//表达式可以进行管道运算
function _expression_0_expression_pipe_factor($stack,$coder){

	$t1= $this->topItem($stack,1);
	$handlerName = 	$t1[TokenValueIndex];

	$coder->pushPipeBody($handlerName);	
	
	return $this->pass($stack,3);
}


function _expression_0_double_factor($stack,$coder){	

	$t1= $this->topItem($stack,1);
	$elementName = 	$t1[TokenValueIndex];
	$parseFuncName = 'parseDouble';	
	$coder->pushParseBody($parseFuncName,$elementName);	
	
	return $this->pass($stack,1);
}

function _expression_0_float_factor($stack,$coder){	

	$t1= $this->topItem($stack,1);
	$elementName = 	$t1[TokenValueIndex];
	$parseFuncName = 'parseFloat';	
	$coder->pushParseBody($parseFuncName,$elementName);	
	
	return $this->pass($stack,1);
}


function _expression_0_char_factor($stack,$coder){

	$t1= $this->topItem($stack,1);
	$elementName = 	$t1[TokenValueIndex];
	$size = $this->elementSize($t1[TokenExtraIndex]);
	
	$parseFuncName = 'parseFixStr';	
	$coder->pushParseBody($parseFuncName,$elementName,$size);		
	
	return $this->pass($stack,1);
}

function _expression_0_int_factor($stack,$coder){	

	$t1= $this->topItem($stack,1);
	$elementName = 	$t1[TokenValueIndex];
	$parseFuncName = 'parseInt';	
	$coder->pushParseBody($parseFuncName,$elementName,4);	
	
	return $this->pass($stack,1);
}

function _expression_0_factor($stack,$coder){
	
	return $this->pass($stack,1);
}

//   Expression         }}}

// factor       {{{

function _factor_0_term($stack,$coder){
	
	return $this->pass($stack,1);
}

//  factor        }}}

//   term    {{{

function _term_0_iden($stack,$coder){
	$t1= $this->topItem($stack,1);
	//未指定数据长度时将长度值设为0 
	$valLen = 	'0';	
	$t2= $this->topItem($stack,2);
	return [$t1[TokenValueIndex],[$valLen]];	
}

function _term_0_num($stack,$coder){
	return $this->pass($stack,1);
}

function _term_0_array($stack,$coder){
	return $this->pass($stack,1);
}

//   term     }}}


// array 	  {{{

function _array_0_arrayLb_num_rb($stack,$coder){

	$t1= $this->topItem($stack,2);
	$valLen = 	$t1[TokenValueIndex];	
	
	$t2= $this->topItem($stack,3);
	//将数据长度放入附加信息 
	return [$t2[TokenValueIndex],[$valLen]];		
}

function _arrayLb_0_iden_lb($stack,$coder){  
	return $this->pass($stack,2);
}

// array 	   }}}


}// end of class

编码器也要做相应的调整，增加对管道运算的处理

<?php
/*!
 * structwkr编码器，
 *
 * 45022300@qq.com
 * Version 0.9.0
 *
 * Copyright 2019, Zhu Hui
 * Released under the MIT license
 */

namespace Ados;

require_once __SCRIPTCORE__.'coder/base_coder.php';
require_once __STRUCT_PARSE_TEMP__.'templateReplaceFuncs.php';


class StructwkrCoder extends BaseCoder{

	public function __construct($engine)
	{
		if($engine){ 
			$this->engine = $engine;
		}else{ 
			exit('the engine is not valid in StructwkrCoder construct.');
		}
	}

	//编译得到的最终结果
	public function codeLines(){
		if(count($this->codeLines)<1){
			return '';
		}
		$script='';		
		for ($i=0;$i< count($this->codeLines);$i+=1) {
			$script.=$this->codeLines[$i];
		}	
		return $script;
	}	

	//
输出编译后的结果 public function printCodeLines(){ echo $this->codeLines(); } //添加一个块解析函数头 public function pushBlockHeader($structName){ $structName=ucfirst($structName); $content = makeBlockHeader($structName); array_push($this->codeLines, $content); $lineIndex=$this->lineIndex; $this->lineIndex+=1; return $lineIndex; } //添加一个块解析函数体 public function pushParseBody($parseFuncName,$filedName='',$filedSize=0){ $content = makeParseBody($parseFuncName,$filedName,$filedSize); array_push($this->codeLines, $content); $lineIndex=$this->lineIndex; $this->lineIndex+=1; return $lineIndex; } //添加一个管道处理 public function pushPipeBody($handler){ $content = makePipeBody($handler); array_push($this->codeLines, $content); $lineIndex=$this->lineIndex; $this->lineIndex+=1; return $lineIndex; } //添加一个检查结果值的body public function pushCheckBody($filedName=''){ $content = makeCheckBody($filedName); array_push($this->codeLines, $content); $lineIndex=$this->lineIndex; $this->lineIndex+=1; return $lineIndex; } //添加一个块解析类的tail public function pushBlockTail(){ $content = makeblockTail(); array_push($this->codeLines, $content); $lineIndex=$this->lineIndex; $this->lineIndex+=1; return $lineIndex; } }

实现结果

自动生成的测试文件如下

<?php

namespace Ados;

//加载常量定义文件
require_once 'const.php';
require_once __STRUCT_PARSE_TEMP__.'templateBuidinFuncs.php';
require_once __STRUCT_PARSE_ADAPTER__.'int2str.adapter.php';
require_once __STRUCT_PARSE_ADAPTER__.'intoffset.adapter.php';

$context['pos']=0;
$context['data']="\x41\x43\x01\x00\x00\x00\x02\x00\x00\x00\x41\x42\x43\x41\x42\x01\x00\x00\x00\x41\x42\x43";

$expRes = Student::parse($context);
$context['pos']+=$expRes['size'];
print_r($expRes);


$expRes = Teacher::parse($context);
$context['pos']+=$expRes['size'];
print_r($expRes);



class Student{

	static function parse($context,$size=0){
		$valueArray=[];
		$totalSize = 0;
	
		$expRes = parseFixStr($context,2);
	
		if($expRes['error']==0){
			$filed = 'name';
			if($filed){
				$valueArray[$filed]=$expRes['value'];
			}else{
				$valueArray[]=$expRes['value'];
			}		
			$context['pos']+=$expRes['size'];
			$totalSize+= $expRes['size'];
		}else{
			return ['value'=>False,'size'=>0,'error'=>$expRes['error'],'msg'=>$expRes['msg']];
		}
	
		$expRes = parseInt($context,4);
	
		$expRes['value'] = (new IntOffset(100))->parse($expRes['value']);		
	
		if($expRes['error']==0){
			$filed = 'num';
			if($filed){
				$valueArray[$filed]=$expRes['value'];
			}else{
				$valueArray[]=$expRes['value'];
			}		
			$context['pos']+=$expRes['size'];
			$totalSize+= $expRes['size'];
		}else{
			return ['value'=>False,'size'=>0,'error'=>$expRes['error'],'msg'=>$expRes['msg']];
		}
	
		$expRes = parseInt($context,4);
	
		if($expRes['error']==0){
			$filed = 'age';
			if($filed){
				$valueArray[$filed]=$expRes['value'];
			}else{
				$valueArray[]=$expRes['value'];
			}		
			$context['pos']+=$expRes['size'];
			$totalSize+= $expRes['size'];
		}else{
			return ['value'=>False,'size'=>0,'error'=>$expRes['error'],'msg'=>$expRes['msg']];
		}
	
		$expRes = parseFixStr($context,3);
	
		if($expRes['error']==0){
			$filed = 'addr';
			if($filed){
				$valueArray[$filed]=$expRes['value'];
			}else{
				$valueArray[]=$expRes['value'];
			}		
			$context['pos']+=$expRes['size'];
			$totalSize+= $expRes['size'];
		}else{
			return ['value'=>False,'size'=>0,'error'=>$expRes['error'],'msg'=>$expRes['msg']];
		}
	
		return ['value'=>$valueArray,'size'=>$totalSize,'error'=>0,'msg'=>'ok'];
	}
}
	
class Teacher{

	static function parse($context,$size=0){
		$valueArray=[];
		$totalSize = 0;
	
		$expRes = parseFixStr($context,2);
	
		if($expRes['error']==0){
			$filed = 'name';
			if($filed){
				$valueArray[$filed]=$expRes['value'];
			}else{
				$valueArray[]=$expRes['value'];
			}		
			$context['pos']+=$expRes['size'];
			$totalSize+= $expRes['size'];
		}else{
			return ['value'=>False,'size'=>0,'error'=>$expRes['error'],'msg'=>$expRes['msg']];
		}
	
		$expRes = parseInt($context,4);
	
		$expRes['value'] = (new Int2str)->parse($expRes['value']);		
	
		if($expRes['error']==0){
			$filed = 'num';
			if($filed){
				$valueArray[$filed]=$expRes['value'];
			}else{
				$valueArray[]=$expRes['value'];
			}		
			$context['pos']+=$expRes['size'];
			$totalSize+= $expRes['size'];
		}else{
			return ['value'=>False,'size'=>0,'error'=>$expRes['error'],'msg'=>$expRes['msg']];
		}
	
		$expRes = parseFixStr($context,3);
	
		if($expRes['error']==0){
			$filed = 'addr';
			if($filed){
				$valueArray[$filed]=$expRes['value'];
			}else{
				$valueArray[]=$expRes['value'];
			}		
			$context['pos']+=$expRes['size'];
			$totalSize+= $expRes['size'];
		}else{
			return ['value'=>False,'size'=>0,'error'=>$expRes['error'],'msg'=>$expRes['msg']];
		}
	
		return ['value'=>$valueArray,'size'=>$totalSize,'error'=>0,'msg'=>'ok'];
	}
}

运行测试文件的结果

Array
(
    [value] => Array
        (
            [name] => AC
            [num] => 101
            [age] => 2
            [addr] => ABC
        )

    [size] => 13
    [error] => 0
    [msg] => ok
)
Array
(
    [value] => Array
        (
            [name] => AB
            [num] => 1
            [addr] => ABC
        )

    [size] => 9
    [error] => 0
    [msg] => ok
)

对比测试数据

$context['data']="\x41\x43\x01\x00\x00\x00\x02\x00\x00\x00\x41\x42\x43\x41\x42\x01\x00\x00\x00\x41\x42\x43";

如果不加适配器
第一个结构体的num字段的结果应是：
[num] => 1

现在加上了适配器
int num|IntOffset(100);

所以结果变成了：
[num] => 101

适配器功能已经实现并得到了验证。

更多相关问题请访问PHP中文网相关视频教程：https://www.gxlcms.com/

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