PHP peut également implémenter une analyse lexicale et des langages personnalisés !

                                                                                                           

Il y avait une exigence dans le projet précédent. L'équipe commerciale a écrit des formules personnalisées en chinois, puis nous avons dû les exécuter en arrière-plan pour renvoyer les résultats à l'interface. Nous avons donc écrit cet analyseur lexical basé sur le fini. machine d'état. C'est relativement simple. J'espère que cela pourra inspirer d'autres.

1. Analysez les exigences

Entrez la formule chinoise et renvoyez le résultat, tel que :

现有薪资=10000;
个税起点=3000;
当前年份=2021;
如果(当前年份=2022){
    个税起点=5000;
}
返回 (现有薪资-个税起点) * 0.2;

2. Implémentez les exigences

L'idée originale est d'utiliser le remplacement de chaîne pour remplacer le chinois mots-clés avec le mot-clé PHP, puis appelez eval pour exécuter C'est en effet possible, mais j'ai toujours l'impression que ce n'est pas très beau et ne peut pas réaliser une analyse dynamique. Je viens de penser à implémenter moi-même une simple analyse lexicale, puis à la combiner avec ast pour convertir le lexique en code php pour l'exécution, ne serait-ce pas amusant ? La version actuelle n'utilise pas d'arbres de syntaxe abstraite pour générer du code et utilise toutes la concaténation de chaînes. [Apprentissage recommandé : Tutoriel vidéo PHP]

<?php

/**
 * Class Lexer
 * @package Sett\OaLang
 * 词法分析器
 */
class Lexer {
    // 内置关键字集合
    public $keywordList = [];
    // 内置操作符集合
    public $operatorList = [
        "+", "-", "*", "/", "=", ">", "<", "!", "(", ")", "{", "}", ",", ";"
    ];
    // 源代码
    private $input;
    // 当前的字符
    private $currChar;
    // 当前字符位置
    private $currCharPos = 0;
    // 结束符
    private $eof = "eof";
    // 当前编码
    private $currEncode  = "UTF-8";

    // 内置关键字
    public const VAR = "variable";
    public const STR = "string";
    public const KW  = "keyword";
    public const OPR = "operator";
    public const INT = "integer";
    public const NIL = "null";


    /**
     * Lexer constructor.
     * @param string $input
     */
    public function __construct(string $input) {
        $this->input    = $input;
        $this->currChar = mb_substr($this->input, $this->currCharPos, 1);
    }

    /**
     * @param array $keywordList
     */
    public function setKeywordList($keywordList) {
        $this->keywordList = $keywordList;
    }

    /**
     * @return array
     * @throws Exception
     */
    public function parseInput() {
        if ($this->input == "") {
            throw new Exception("code can not be empty");
        }
        $tokens = [];
        do {
            $token = $this->nextToken();
            if ($token["type"] != "eof") {
                $tokens[] = $token;
            }
            if ($token["type"] == self::KW) {
                $tokens[] = $this->makeToken(self::NIL, " ");
            }
        } while ($token["type"] != "eof");
        return $tokens;
    }

    /**
     * @return array
     */
    public function nextToken() {
        $this->skipBlankChar();
        $this->currChar == "" && $this->currChar = $this->eof;
        if ($this->isCnLetter()) {
            $word = $this->matchUntilNextCharIsNotCn();
            if ($this->isKeyword($word)) {
                $this->currCharPos -= 1;
                return $this->currToken(static::KW, $word);
            }
            // 不是关键字的全部归为变量
            return $this->makeToken(static::VAR, $word);
        }
        // 如果是操作符
        if ($this->isOperator()) {
            return $this->currToken(static::OPR, $this->currChar);
        }
        // 如果是数字
        if ($this->isNumber()) {
            return $this->currToken(static::INT, $this->currChar);
        }
        // 如果是字符串
        if ($str = $this->isStr()) {
            return $this->currToken(static::STR, $str);
        }
        // 如果是变量
        if ($this->isVar()) {
            $word = $this->matchVar();
            if ($this->isKeyword($word)) {
                return $this->currToken(static::KW, $word);
            }
            return $this->makeToken(static::VAR, $word);
        }
        if ($this->currChar == $this->eof) {
            return $this->currToken(&#39;eof&#39;, $this->currChar);
        }
        return $this->currToken(static::VAR, $this->currChar);
    }

    /**
     * @param string $input
     * @return string
     */
    private function matchVar(string $input = "") {
        $word = $input ?: &#39;&#39;;
        while ($this->isVar()) {
            $word .= $this->currChar;
            $this->nextChar();
        }
        return $word;
    }

    /**
     * @return bool
     * 是否为普通变量
     */
    private function isVar() {
        return $this->isCnLetter() || $this->isEnLetter();
    }


    /**
     * 跳过空白字符
     */
    private function skipBlankChar() {
        while (ord($this->currChar) == 10 ||
            ord($this->currChar) == 13 ||
            ord($this->currChar) == 32) {
            $this->nextChar();
        }
    }

    /**
     * @param string $type
     * @param $word
     * @return array
     * 记录当前token和下一个字符
     */
    private function currToken(string $type, $word) {
        $token = $this->makeToken($type, $word);
        $this->nextChar();
        return $token;
    }

    /**
     * @param string $type
     * @param string $char
     * @return array
     */
    private function makeToken(string $type, string $char) {
        return ["type" => $type, "char" => $char, "pos" => $this->currCharPos];
    }


    /**
     * @return bool
     * 判断是否是英文字符
     */
    private function isEnLetter() {
        if ($this->currChar == "" || $this->currChar == $this->eof) {
            return false;
        }
        $ord = mb_ord($this->currChar, $this->currEncode);
        if ($ord > ord(&#39;a&#39;) && $ord < ord(&#39;z&#39;)) {
            return true;
        }
        return false;
    }

    /**
     * @return false|int
     * 是否中文字符
     */
    private function isCnLetter() {
        return preg_match("/^[\x{4e00}-\x{9fa5}]+$/u", $this->currChar);
    }

    /**
     * @return bool
     * 是否为数字
     */
    private function isNumber() {
        return is_numeric($this->currChar);
    }

    /**
     * @return bool
     * 是否是字符串
     */
    private function isStr() {
        return $this->matchCompleteStr();
    }

    /**
     * @return string
     * 匹配完整字符串
     */
    private function matchCompleteStr() {
        $char = "";
        if ($this->currChar == "\"") {
            $this->nextChar();
            while ($this->currChar != "\"") {
                if ($this->currChar != "\"") {
                    $char .= $this->currChar;
                }
                $this->nextChar();
            }
            return $char;
        }
        return $char;
    }

    /**
     * @return bool
     * 是否是操作符
     */
    private function isOperator() {
        return in_array($this->currChar, $this->operatorList);
    }

    /**
     * @return string
     * 匹配中文字符
     */
    private function matchUntilNextCharIsNotCn() {
        $char = "";
        while ($this->isCnLetter()) {
            $char .= $this->currChar;
            $this->nextChar();
        }
        return $char;
    }

    /**
     * @return void 获取下一个字符
     * 获取下一个字符
     */
    private function nextChar() {
        $this->currCharPos += 1;
        $this->currChar    = mb_substr($this->input, $this->currCharPos, 1);
        if ($this->currChar == "") {
            $this->currChar = $this->eof;
        }
    }

    /**
     * @param string $input
     * @return bool
     * 是否是关键字
     */
    private function isKeyword(string $input) {
        return ($this->keywordList[$input] ?? "") != "";
    }

    public function convert(array $tokens) {
        $code = "";
        foreach ($this->lexerIterator($tokens) as $generator) {
            switch ($generator["type"]) {
                case static::KW:
                    $code .= $this->keywordList[$generator["char"]];
                    break;
                case static::VAR:
                    $code .= sprintf("$%s", $generator["char"]);
                    break;
                case static::OPR:
                    $code .= $this->replace($generator["char"]);
                    break;
                case static::INT:
                    $code .= $generator["char"];
                    break;
                case static::STR:
                    $code .= sprintf("\"%s\"", $generator["char"]);
                    break;
                default:
                    $code .= $generator["char"];
            }
        }
        return $code;
    }

    private function replace(string $char) {
        return str_replace("+", ".", $char);
    }

    /**
     * @param array $tokens
     * @return \Generator
     */
    private function lexerIterator(array $tokens) {
        foreach ($tokens as $index => $token) {
            yield $token;
        }
    }
}

3. Comment utiliser

require __DIR__ . "/vendor/autoload.php";
// 定义一段代码
$code = <<<EOF
姓名="腕豪";
问候="你好啊";
地址=(1+2) * 3;
如果(地址 > 3){
    地址=1;
}否则{
    地址="艾欧尼亚"
}
说话 = ("我"+"爱")+"你";
返回 姓名+年龄;
EOF;
$lexer = new Lexer($code);
// 自定义你的关键字
$kwMap = [
    "如果" => "if", "否则" => "else", "返回" => "return", "否则如果" => "elseif"
];
$lexer->setKeywordList($kwMap);
// 这里是生成的词
$tokens = $lexer->parseInput();
// 将生成的词转成php,当然你也可以尝试用php-parse转ast再转成php，这里只是简单的拼接
var_dump($lexer->convert($tokens));

pour générer des mots

[{
    "type": "variable",
    "char": "姓名",
    "pos": 2}, {
    "type": "operator",
    "char": "=",
    "pos": 2}, {
    "type": "string",
    "char": "腕豪",
    "pos": 7}, {
    "type": "operator",
    "char": ";",
    "pos": 8}, {
    "type": "variable",
    "char": "问候",
    "pos": 13}, {
    "type": "operator",
    "char": "=",
    "pos": 13}, {
    "typ e": "string",
    "char": "你好啊",
    "pos": 17}, {
    "type": "operator",
    "char": ";",
    "pos": 18}, {
    "type": "variable",
    "char": "地址",
    "pos": 23}, {
    "type": "operator",
    "char": "=",
    "pos": 23}, {
    "type": "operator",
    "char": "(",
    "pos": 24}, {
    "type": "integer",
    "char": "1",
    "pos": 25}, {
    "type": "operator",
    "char": " +",
    "pos": 26}, {
    "type": "integer",
    "char": "2",
    "pos": 27}, {
    "type": "operator",
    "char": ")",
    "pos": 28}, {
    "type": "operator",
    "char": "*",
    "pos": 30}, {
    "type": "integer",
    "char": "3",
    "pos": 32}, {
    "type": "operator",
    "char": ";",
    "pos": 33}, {
    "type": "keyword",
    "char": "如果",
    "pos": 37}, {
    "type": "nul l",
    "char": " ",
    "pos": 38}, {
    "type": "operator",
    "char": "(",
    "pos": 38}, {
    "type": "variable",
    "char": "地址",
    "pos": 41}, {
    "type": "operator",
    "char": ">",
    "pos": 42}, {
    "type": "integer",
    "char": "3",
    "pos": 44}, {
    "type": "operator",
    "char": ")",
    "pos": 45}, {
    "type": "operator",
    "char": "{",
    "pos": 46}, {
    "type": "variable",
    "char": "地址",
    "pos": 55}, {
    "type": "operator",
    "char": "=",
    "pos": 55}, {
    "type": "integer",
    "char": "1",
    "pos": 56}, {
    "type": "operator",
    "char": ";",
    "pos": 57}, {
    "type": "operator",
    "char": "}",
    "pos": 60}, {
    "type": "keyword",
    "char": "否则",
    "pos": 62}, {
    "type": "null",
    "char ": " ",
    "pos": 63}, {
    "type": "operator",
    "char": "{",
    "pos": 63}, {
    "type": "variable",
    "char": "地址",
    "pos": 72}, {
    "type": "operator",
    "char": "=",
    "pos": 72}, {
    "type": "string",
    "char": "艾欧尼亚",
    "pos": 78}, {
    "type": "operator",
    "char": ";",
    "pos": 79}, {
    "type": "operator",
    "char": "}",
    "pos": 82}, {
    "type": "variable",
    "char": "说话",
    "pos": 87}, {
    "type": "operator",
    "char": "=",
    "pos": 88}, {
    "type": "operator",
    "char": "(",
    "pos": 90}, {
    "type": "string",
    "char": "我",
    "pos": 93}, {
    "type": "operator",
    "char": "+",
    "pos": 94}, {
    "type": "string",
    "char": "爱",
    "pos": 97}, {
    "type": "operator",
    "char": ")",
    "pos": 98}, {
    "type": "operator",
    "char": "+",
    "pos": 99}, {
    "type": "string",
    "char": "你",
    "pos": 102}, {
    "type": "operator",
    "char": ";",
    "pos": 103}, {
    "type": "keyword",
    "char": "返回",
    "pos": 107}, {
    "type": "null",
    "char": " ",
    "pos": 108}, {
    "type": "variable",
    "char": "姓名",
    "pos": 111}, {
    "typ e": "operator",
    "char": "+",
    "pos": 111}, {
    "type": "variable",
    "char": "年龄",
    "pos": 114}, {
    "type": "operator",
    "char": ";",
    "pos": 114}]

Sortie :

$姓名="腕豪";$问候="你好啊";$地址=(1.2)*3;if ($地址>3){$地址=1;}else {$地址="艾欧尼亚";}$说话=("我"."爱")."你";return $姓名.$年龄;

Peut-il être exécuté ? Bien sûr que vous le pouvez. Il y a encore quelques petits bugs que je ne souhaite pas changer.

4. Scénarios d'utilisation

Quoi, certaines personnes disent en fait que c'est inutile ? Le système oa sera toujours utile.

Ce qui précède est le contenu détaillé de. pour plus d'informations, suivez d'autres articles connexes sur le site Web de PHP en chinois!