A simple example of PHP interpreter pattern sharing

A simple example of PHP interpreter pattern sharing

<?php//Interpreter mode abstract class Expression{private static $keyCount = 0;private $key = null;abstract function Interpret (Int Erpretercontext $ctx);/** * as array key * @return Auto increment value */public function GetKey () {if (!isset ($this->key ) {self:: $keyCount + +; $this->key = self:: $keyCount;} return $this->key;}} /** * Context */class interpretercontext{private $expressionstore = Array ()/** * Store value */public function replace (Ex Pression $exp, $value) {$this->expressionstore[$exp->getkey ()] = $value;} /** * Find value */public function lookup (Expression $exp) {return $this->expressionstore[$exp->getkey ()];}} /** * Literal expression */class literalexpression extends expression{private $value;p ublic function construct ($value) {$ This->value = $value;} Public function interpret (Interpretercontext $ctx) {$ctx->replace ($this, $this->value);}} /** * Var=value expression */class variableexpression extends Expression{private $name;p rivate $val;p ublic function const Ruct ($name, $val =null) {$this->name = $name; $this->val = $val;} Public function interpret (Interpretercontext $ctx) {if (!is_null ($this->val)) {$ctx->replace ($this, $this- val); $this->val = null;}} Public Function SetValue ($value) {$this->val = $value;} /** * @override */public function GetKey () {return $this->name;}} Abstract class Operatorexpression extends expression{protected $l _op;protected $r _op;public function construct ( Expression $l, expression $r) {$this->l_op = $l; $this->r_op = $r;} /** * @param $ctx interpretercontext * @param $result _l expression $l ' s result * @param $result _r expression $r ' s Resul T */protected abstract function Dointerpret (Interpretercontext $ctx, $result _l, $result _r);p ublic function interpret ( Interpretercontext $ctx) {$this->l_op->interpret ($ctx); $this->r_op->interpret ($CTX); $result _l = $ctx- >lookup ($this->l_op); $result _r = $ctx->lookup ($this->r_op); $this->dointerpret ($ctx, $result _l, $ Result_r);}} /** * equals * *Class Equalsexpression extends operatorexpression{protected function Dointerpret (interpretercontext $ctx, $result _l, $ Result_r) {$ctx->replace ($this, $result _l = = $result _r);}} /** * or */class booleanorexpression extends operatorexpression{protected function Dointerpret (Interpretercontext $ctx, $result _l, $result _r) {$ctx->replace ($this, $result _l | | $result _r);}} /** * and */class booleanandexpression extends operatorexpression{protected function Dointerpret (Interpretercontext $ CTX, $result _l, $result _r) {$ctx->replace ($this, $result _l && $result _r);}} /** * Not */class booleannotexpression extends expression{private $expr;p ublic function construct (Expression $e) {$this-& gt;expr = $e;} Public function interpret (Interpretercontext $ctx) {$this->expr->interpret ($ctx); $ctx->replace ($this,!$ Ctx->lookup ($this->expr));}} Test code/* $ctx = new Interpretercontext () $literarl = new Literalexpression (' four '); $literarl->interpret ($CTX) ;//Echo $ctx->lookup ($litErarl); $variable = new VariableExpression (' Input ', ' 444 '); $variable->interpret ($CTX);//Echo $ctx->lookup ($ variable); $answer = new VariableExpression (' input '); $answer->interpret ($CTX); Echo $ctx->lookup ($answer); */// $input Equas four or $input equals 4$ctx = new Interpretercontext (); $input = new VariableExpression (' input '); $statement = New Booleanorexpression (New Equalsexpression ($input, New Literalexpression (' Four ')), new Equalsexpression ($input, new Literalexpression (4)); $input->setvalue (' four '); $statement->interpret ($CTX); Var_dump ($ctx->lookup ($ statement)); True$input->setvalue (4); $statement->interpret ($CTX); Var_dump ($ctx->lookup ($statement)); True$input->setvalue, $statement->interpret ($ctx), Var_dump ($ctx->lookup ($statement)); False$not = new Booleannotexpression ($statement); True$not->interpret ($CTX); Var_dump ($ctx->lookup ($not));