如何在 AST 中获取变量名和值

这比您提出的其他问题要复杂得多PHP变量，但是了解如何编写它很有趣。

我已经在代码中添加了注释，但基本上它会分析代码并查找分配（PhpParser\Node\Expr\Assign节点实例）。然后它将它分成左右两部分，并递归地提取两部分中的任何变量。

该代码允许在表达式的任一侧嵌套变量，我更改了示例代码以提供一些更广泛的示例。

代码中的注释（假定了解解析器如何与节点等一起工作）...

$traverser = new NodeTraverser;

class ExtractVars extends NodeVisitorAbstract {

private $prettyPrinter = null;

private $variables = [];

private $expressions = [];

public function __construct() {

$this->prettyPrinter = new PhpParser\PrettyPrinter\Standard;

}

public function leaveNode(Node $node) {

if ( $node instanceof PhpParser\Node\Expr\Assign ) {

$assignVars = $this->extractVarRefs ( $node->var );

// Get string of what assigned to actually is

$assign = $this->prettyPrinter->prettyPrintExpr($node->var);

// Store the variables associated with the left hand side

$this->expressions[$assign]["to"] = $assignVars;

// Store variables from right

$this->expressions[$assign][] = $this->extractVarRefs ( $node->expr );

}

}

private function extractVarRefs ( Node $node ) : array {

$variableList = [];

// If it's a variable, store the name

if ( $node instanceof PhpParser\Node\Expr\Variable ) {

$variable = $this->prettyPrinter->prettyPrintExpr($node);

$this->variables[] = $variable;

$variableList[] = $variable;

}

// Look for any further variables in the node

foreach ( $node->getSubNodeNames() as $newNodeName ) {

$newNode = $node->$newNodeName;

if ( $newNode instanceof Node && $newNode->getSubNodeNames()) {

// Recursive call to extract variables

$toAdd = $this->extractVarRefs ( $newNode );

// Add new list to current list

$variableList = array_merge($variableList, $toAdd);

}

}

return $variableList;

}

public function getVariables() : array {

return array_unique($this->variables);

}

public function getExpressions() : array {

return $this->expressions;

}

}

$varExtract = new ExtractVars();

$traverser->addVisitor ($varExtract);

$traverser->traverse($ast);

print_r($varExtract->getVariables());

print_r($varExtract->getExpressions());

其中给出了变量列表...

Array

(

[0] => $_POST

[1] => $b

[3] => $new

[4] => $nonexist

)

表达式列表为

Array

(

[$_POST[$b]] => Array

(

[to] => Array

(

[0] => $_POST

[1] => $b

)

[0] => Array

(

[0] => $_POST

)

)

[$new] => Array

(

[to] => Array

(

[0] => $new

)

[0] => Array

(

[0] => $nonexist

)

[1] => Array

(

[0] => $_POST

[1] => $b

)

)

)

请注意，[to]数组的元素包含 . 左侧涉及的所有变量=。

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