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Enhance ConstExprEvaluator by evaluating new type of expressions or enhancing some (hopefully) #1107

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Enhance ConstExprEvaluator by evaluating new type of expressions or enhancing some (hopefully) #1107

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fe64d1a
Enhance/Add expression evaluations for iTop project: https://github.c…
odain-cbd Sep 5, 2025
8ffc123
code cleanup: fix formatting/php doc
odain-cbd Sep 9, 2025
f5f324a
move non-constant evaluation in ExprEvaluator dedicated class
odain-cbd Sep 18, 2025
b2cd073
php-cs-fixer cleanup
odain-cbd Sep 18, 2025
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342 changes: 330 additions & 12 deletions lib/PhpParser/ConstExprEvaluator.php
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Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,10 @@
namespace PhpParser;

use PhpParser\Node\Expr;
use PhpParser\Node\Identifier;
use PhpParser\Node\Name;
use PhpParser\Node\Scalar;
use Exception;

use function array_merge;

Expand All @@ -30,6 +33,12 @@ class ConstExprEvaluator {
/** @var callable|null */
private $fallbackEvaluator;

/** @var array $functionsWhiteList */
private $functionsWhiteList;

/** @var array $staticCallsWhitelist */
private $staticCallsWhitelist;

/**
* Create a constant expression evaluator.
*
Expand All @@ -44,6 +53,17 @@ public function __construct(?callable $fallbackEvaluator = null) {
"Expression of type {$expr->getType()} cannot be evaluated"
);
};

$this->functionsWhiteList = [];
$this->staticCallsWhitelist = [];
}

public function setFunctionsWhitelist(array $functionsWhiteList): void {
$this->functionsWhiteList = $functionsWhiteList;
}

public function setStaticCallsWhitelist(array $staticCallsWhitelist): void {
$this->staticCallsWhitelist = $staticCallsWhitelist;
}

/**
Expand Down Expand Up @@ -115,6 +135,10 @@ private function evaluate(Expr $expr) {
return $this->evaluateArray($expr);
}

if ($expr instanceof Expr\Variable) {
return $this->evaluateVariable($expr);
}

// Unary operators
if ($expr instanceof Expr\UnaryPlus) {
return +$this->evaluate($expr->expr);
Expand Down Expand Up @@ -145,6 +169,38 @@ private function evaluate(Expr $expr) {
return $this->evaluateConstFetch($expr);
}

if ($expr instanceof Expr\Isset_) {
return $this->evaluateIsset($expr);
}

if ($expr instanceof Expr\ClassConstFetch) {
return $this->evaluateClassConstFetch($expr);
}

if ($expr instanceof Expr\Cast) {
return $this->evaluateCast($expr);
}

if ($expr instanceof Expr\StaticPropertyFetch) {
return $this->evaluateStaticPropertyFetch($expr);
}

if ($expr instanceof Expr\FuncCall) {
return $this->evaluateFuncCall($expr);
}

if ($expr instanceof Expr\StaticCall) {
return $this->evaluateStaticCall($expr);
}

if ($expr instanceof Expr\NullsafePropertyFetch||$expr instanceof Expr\PropertyFetch) {
return $this->evaluatePropertyFetch($expr);
}

if ($expr instanceof Expr\NullsafeMethodCall||$expr instanceof Expr\MethodCall) {
return $this->evaluateMethodCall($expr);
}

return ($this->fallbackEvaluator)($expr);
}

Expand Down Expand Up @@ -175,12 +231,15 @@ private function evaluateTernary(Expr\Ternary $expr) {

/** @return mixed */
private function evaluateBinaryOp(Expr\BinaryOp $expr) {
if ($expr instanceof Expr\BinaryOp\Coalesce
&& $expr->left instanceof Expr\ArrayDimFetch
) {
// This needs to be special cased to respect BP_VAR_IS fetch semantics
return $this->evaluate($expr->left->var)[$this->evaluate($expr->left->dim)]
?? $this->evaluate($expr->right);
if ($expr instanceof Expr\BinaryOp\Coalesce) {
try {
$var = $this->evaluate($expr->left);
} catch(\Throwable $t) {
//left expression cannot be evaluated (! isset for exeample)
return $this->evaluate($expr->right);
}

return $var ?? $this->evaluate($expr->right);
}

// The evaluate() calls are repeated in each branch, because some of the operators are
Expand Down Expand Up @@ -225,13 +284,272 @@ private function evaluateBinaryOp(Expr\BinaryOp $expr) {

/** @return mixed */
private function evaluateConstFetch(Expr\ConstFetch $expr) {
$name = $expr->name->toLowerString();
switch ($name) {
case 'null': return null;
case 'false': return false;
case 'true': return true;
}
try {
$name = $expr->name;
if(! is_string($name)) {
//PHP_VERSION_ID usecase
$name = $name->name;
}

if (defined($name)) {
return constant($name);
}
} catch(\Throwable $t) {}

return ($this->fallbackEvaluator)($expr);
}

/** @return bool */
private function evaluateIsset(Expr\Isset_ $expr) {
try {
foreach ($expr->vars as $var) {
$var = $this->evaluate($var);
if (! isset($var)) {
return false;
}
}

return true;
} catch(\Throwable $t) {
return false;
}
}

/** @return mixed */
private function evaluateClassConstFetch(Expr\ClassConstFetch $expr) {
try {
$classname = $expr->class->name;
$property = $expr->name->name;

if ('class' === $property) {
return $classname;
}

if (class_exists($classname)) {
$class = new \ReflectionClass($classname);
if (array_key_exists($property, $class->getConstants())) {
$oReflectionConstant = $class->getReflectionConstant($property);
if ($oReflectionConstant->isPublic()) {
return $class->getConstant($property);
}
}
}
} catch(\Throwable $t) {}

return ($this->fallbackEvaluator)($expr);
}

/** @return mixed */
private function evaluateCast(Expr\Cast $expr) {
try {
$subexpr = $this->evaluate($expr->expr);
$type = get_class($expr);
switch ($type) {
case Expr\Cast\Array_::class:
return (array) $subexpr;

case Expr\Cast\Bool_::class:
return (bool) $subexpr;

case Expr\Cast\Double::class:
switch ($expr->getAttribute("kind")) {
case Expr\Cast\Double::KIND_DOUBLE:
return (double) $subexpr;

case Expr\Cast\Double::KIND_FLOAT:
case Expr\Cast\Double::KIND_REAL:
return (float) $subexpr;
}

break;

case Expr\Cast\Int_::class:
return (int) $subexpr;

case Expr\Cast\Object_::class:
return (object) $subexpr;

case Expr\Cast\String_::class:
return (string) $subexpr;
}
} catch(\Throwable $t) {}

return ($this->fallbackEvaluator)($expr);
}

/** @return mixed */
private function evaluateStaticPropertyFetch(Expr\StaticPropertyFetch $expr) {
try {
$classname = $expr->class->name;
if ($expr->name instanceof Identifier) {
$property = $expr->name->name;
} else {
$property = $this->evaluate($expr->name);
}

if (class_exists($classname)) {
$class = new \ReflectionClass($classname);
if (array_key_exists($property, $class->getStaticProperties())) {
$oReflectionProperty = $class->getProperty($property);
if ($oReflectionProperty->isPublic()) {
return $class->getStaticPropertyValue($property);
}
}
}
}
catch (\Throwable $t) {}

return ($this->fallbackEvaluator)($expr);
}

/** @return mixed */
private function evaluateFuncCall(Expr\FuncCall $expr) {
try {
$name = $expr->name;
if ($name instanceof Name) {
$function = $name->name;
} else {
$function = $this->evaluate($name);
}

if (! in_array($function, $this->functionsWhiteList)) {
throw new Exception("FuncCall $function not supported");
}

$args=[];
foreach ($expr->args as $arg) {
/** @var \PhpParser\Node\Arg $arg */
$args[]=$arg->value->value;
}

$reflection_function = new \ReflectionFunction($function);
return $reflection_function->invoke(...$args);
}
catch (\Throwable $t) {}

return ($this->fallbackEvaluator)($expr);
}

/** @return mixed */
private function evaluateVariable(Expr\Variable $expr) {
try {
$name = $expr->name;
if (array_key_exists($name, get_defined_vars())) {
return $$name;
}

if (array_key_exists($name, $GLOBALS)) {
global $$name;
return $$name;
}
} catch (\Throwable $t) {
}

return ($this->fallbackEvaluator)($expr);
}

/** @return mixed */
private function evaluateStaticCall(Expr\StaticCall $expr) {
try {
$class = $expr->class->name;
if ($expr->name instanceof Identifier) {
$method = $expr->name->name;
} else {
$method = $this->evaluate($expr->name);
}

$static_call_description = "$class::$method";
if (! in_array($static_call_description, $this->staticCallsWhitelist)) {
throw new Exception("StaticCall $static_call_description not supported");
}

$args=[];
foreach ($expr->args as $arg) {
/** @var \PhpParser\Node\Arg $arg */
$args[]=$arg->value->value;
}

$class = new \ReflectionClass($class);
$method = $class->getMethod($method);
if ($method->isPublic()) {
return $method->invokeArgs(null, $args);
}
} catch (\Throwable $t) {}

return ($this->fallbackEvaluator)($expr);
}

/**
* @param \PhpParser\Node\Expr\NullsafePropertyFetch|\PhpParser\Node\Expr\PropertyFetch $expr
*
* @return mixed
*/
private function evaluatePropertyFetch($expr) {
try {
$var = $this->evaluate($expr->var);
} catch (\Throwable $t) {
$var = null;
}

if (! is_null($var)) {
try {
if ($expr->name instanceof Identifier) {
$name = $expr->name->name;
} else {
$name = $this->evaluate($expr->name);
}

$reflectionClass = new \ReflectionClass(get_class($var));
$property = $reflectionClass->getProperty($name);
if ($property->isPublic()) {
return $property->getValue($var);
}
}
catch (\Throwable $t) {}
} else if ($expr instanceof Expr\NullsafePropertyFetch) {
return null;
}

return ($this->fallbackEvaluator)($expr);
}

/**
* @param \PhpParser\Node\Expr\MethodCall|\PhpParser\Node\Expr\NullsafeMethodCall $expr
*
* @return mixed
*/
private function evaluateMethodCall($expr) {
try {
$var = $this->evaluate($expr->var);
} catch (\Throwable $t) {
$var = null;
}

if (! is_null($var)) {
try {
$args = [];
foreach ($expr->args as $arg) {
/** @var \PhpParser\Node\Arg $arg */
$args[] = $arg->value->value;
}

if ($expr->name instanceof Identifier) {
$name = $expr->name->name;
} else {
$name = $this->evaluate($expr->name);
}

$reflectionClass = new \ReflectionClass(get_class($var));
$method = $reflectionClass->getMethod($name);
if ($method->isPublic()) {
return $method->invokeArgs($var, $args);
}
}
catch (\Throwable $t) {}
} else if ($expr instanceof Expr\NullsafeMethodCall) {
return null;
}

return ($this->fallbackEvaluator)($expr);
}
}
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