php实现类似于pyhon中的Construct库的功能（四）实现do-while功能

引言

在文章

在文章

在文章

这一次要实现的是do-while功能。

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do,while关键字,为了引用内部变量，还需要识别 $ 符号

2，修改语法分析规则，使其可以接受do,while语句

3，修改编码器，生成可运行的php目标代码

4，目标代码的模板文件也要做一些小的修改

其中主要的工作内容还是修改语法分析规则文件。

实现内容

准备解析的结构体定义文件

struct student
{
  char name[2];
  do{
  	int;
  }while($lastError == 0);
};

为了聚焦在do-while功能的实现上，这次只定义了一个结构体 student。循环语句定义如下：

  do{
  	int;
  }while($lastError == 0);

解析过程中有一个内部变量 $lastError，保存每次解析的错误代号，如果为0则表示没有错误。

下面是完整的语法规则处理文件的内容

<?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;
	}
}

//二元操作符的通用处理函数
function biOpertors($stack,$op1Index,$op,$op2Index,$coder){

	$t1= $this->topItem($stack,$op1Index);
	$exp1=$t1[TokenValueIndex];

	$t2= $this->topItem($stack,$op2Index);
	$exp2=$t2[TokenValueIndex];

	$s=$exp1.$op.$exp2;
	return [$s,[]];
}

//处理移进,返回附加信息数组
function handleShift($tokenName,$stack,$coder){

	if($tokenName=='_if'){
		//插入一个空行，空行所在的序号存入附加信息数组，以后可以替换为正确的内容
		return [$coder->pushLine('')];
	}

	if($tokenName=='_else'){
		//插入一个空行，空行所在的序号存入附加信息数组，以后可以替换为正确的内容
		return [$coder->pushLine('')];
	}

	if($tokenName=='_do'){
		//插入一个空行，空行所在的序号存入附加信息数组，以后可以替换为正确的内容
		$coder->isInLoop = True;
		return [$coder->pushLine('')];
	}

	if($tokenName=='_while'){
		//插入一个空行，空行所在的序号存入附加信息数组，以后可以替换为正确的内容
		return [$coder->pushLine('')];
	}	

	return [];
}


//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_wholeExpression_semi($stack,$coder){

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



// statement        }}}


// if          {{{

function _statement_0_ifStatement($stack,$coder){
	
	return $this->pass($stack,1);
}

function _ifStatement_0_ifStatement_else_blockStatement($stack,$coder){	

	//取出_else 记号中保存的空白行所在的地址，替换为正确的内容
	$t1= $this->topItem($stack,2);
	$lineIndex=$t1[TokenExtraIndex][0];

	$content='else{';

	$coder->resetLine($lineIndex,$content);	

	$coder->pushLine('}');	

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

function _ifStatement_0_if_wholeExpression_blockStatement($stack,$coder){
	
	//取出_if 记号中保存的空白行所在的地址，替换为正确的内容
	$t1= $this->topItem($stack,3);
	$lineIndex=$t1[TokenExtraIndex][0];

	$t2= $this->topItem($stack,2);
	$condtionExp=$t2[TokenValueIndex];

	$content='if'.$condtionExp.'{';

	$coder->resetLine($lineIndex,$content);	

	$coder->pushLine('}');

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

//  if        }}}

// do while   {{{

function _statement_0_whileStatement($stack,$coder){
	
	return $this->pass($stack,1);
}

function _whileStatement_0_doBlock_whileExpression_semi($stack,$coder){
	
	$t1= $this->topItem($stack,2);
	
	$condtionExp=$t1[TokenValueIndex];

	$content='while('.$condtionExp.');';

	$coder->pushLine($content);		

	$coder->isInLoop = False;

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

function _whileExpression_0_whileLp_wholeExpression_rp($stack,$coder){
	
	return $this->pass($stack,2);
}

function _whileLp_0_while_lp($stack,$coder){
	
	return $this->pass($stack,2);
}

function _doBlock_0_do_blockStatement($stack,$coder){

	//取出_do 记号中保存的空白行所在的地址，替换为正确的内容
	$t1= $this->topItem($stack,2);
	$lineIndex=$t1[TokenExtraIndex][0];

	$content='do {';

	$coder->resetLine($lineIndex,$content);	

	$coder->pushLine('}');
	
	return $this->pass($stack,1);
}

//  do while    }}}


// 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 }}}


// whole Expression  {{{

function _wholeExpression_0_wholeExpression_bieq_expression($stack,$coder){
	
	return $this->biOpertors($stack,3,'==',1,$coder);
}

function _wholeExpression_0_expression($stack,$coder){
	
	return $this->pass($stack,1);
}

// whole 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];

	$t2= $this->topItem($stack,3);
	$elementName = 	$t2[TokenValueIndex];

	$coder->pushPipeBody($handlerName,$elementName);	
	
	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_int($stack,$coder){	

	$elementName = 	'';
	$parseFuncName = 'parseInt';	
	$coder->pushParseBody($parseFuncName,$elementName,4);	
	
	return ['',[]];
}

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_lp_wholeExpression_rp($stack,$coder){
	
	$t1= $this->topItem($stack,2);
	$s='('.$t1[TokenValueIndex].')';
	return [$s,[]];
}

function _term_0_term_dot_iden($stack,$coder){  
		
	$t1= $this->topItem($stack,3);
	$obj = $t1[TokenValueIndex];
	$t2= $this->topItem($stack,1);
	$var = $t2[TokenValueIndex];
	$exp = '$'.$obj.'[\''.$var.'\']';

	return [$exp,[]];
}

function _term_0_dollar_iden($stack,$coder){
	$t1= $this->topItem($stack,1);	
	$exp = '$'.$t1[TokenValueIndex];
	return [$exp,[]];	
}

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

下面是改进过后的编码器的内容

<?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.');
		}
		$this->isInLoop = False;
	}

	//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 $this->codeLines(); } //添加一个块解析函数头 public function pushLine($content){ array_push($this->codeLines, $content); $lineIndex=$this->lineIndex; $this->lineIndex+=1; return $lineIndex; } //重置一行的内容 public function resetLine($lineIndex,$line){ $this->codeLines[$lineIndex]=$line; } //添加一个块解析函数头 public function pushBlockHeader($structName){ $structName=ucfirst($structName); $content = makeBlockHeader($structName); return $this->pushLine($content); } //添加一个块解析函数体 public function pushParseBody($parseFuncName,$filedName='',$filedSize=0){ $content = makeParseBody($parseFuncName,$filedName,$filedSize); return $this->pushLine($content); } //添加一个管道处理 public function pushPipeBody($handler,$filedName=''){ $content = makePipeBody($handler,$filedName); return $this->pushLine($content); } //添加一个检查结果值的body public function pushCheckBody($filedName=''){ if($this->isInLoop){ $content = makeCheckBodyInLoop($filedName); }else{ $content = makeCheckBody($filedName); } return $this->pushLine($content); } //添加一个块解析类的tail public function pushBlockTail(){ $content = makeblockTail(); return $this->pushLine($content); } }

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\x42\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;
	
		$name = parseFixStr($context,2);
		$lastError = $name['error'];
	
		/*checkBodyInLoop{{*/
		if($name['error']==0){
			$filed = 'name';
			if($filed){
				$valueArray[$filed]=$name['value'];
			}else{
				$valueArray[]=$name['value'];
			}		
			$context['pos']+=$name['size'];
			$totalSize+= $name['size'];
		}
		/*checkBodyInLoop}}*/
		else{
			return ['value'=>False,'size'=>0,'error'=>$name['error'],'msg'=>$name['msg']];
		}
	do {
		$expRes = parseInt($context,4);
		$lastError = $expRes['error'];
	
		if($expRes['error']==0){
			$filed = '';
			if($filed){
				$valueArray[$filed]=$expRes['value'];
			}else{
				$valueArray[]=$expRes['value'];
			}		
			$context['pos']+=$expRes['size'];
			$totalSize+= $expRes['size'];
		}
		}while($lastError==0);
		return ['value'=>$valueArray,'size'=>$totalSize,'error'=>0,'msg'=>'ok'];
	}
}	

可以看出在测试文件中自动生成了 do-while循环结构

运行测试文件的结果

Array
(
    [value] => Array
        (
            [name] => AB
            [0] => 1
            [1] => 2
            [2] => 1094926913
            [3] => 322
            [4] => 1128415488
        )

    [size] => 22
    [error] => 0
    [msg] => ok
)

对比测试数据

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

在解析完两个字节的定长字符串 ‘AB’之后，开始按4个节一段 循环解析 整数值，直到剩下的内容无法解析为一个整数为止。

结论：do-while功能已经实现并通过了验证。

更多相关问题请访问PHP中文网：https://www.gxlcms.com/

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