<?php
namespace JmesPath;
/**
* Dispatches to named JMESPath functions using a single function that has the
* following signature:
*
* mixed $result = fn(string $function_name, array $args)
*/
class FnDispatcher
{
/**
* Gets a cached instance of the default function implementations.
*
* @return FnDispatcher
*/
public static function getInstance()
{
static $instance = null;
if (!$instance) {
$instance = new self();
}
return $instance;
}
/**
* @param string $fn Function name.
* @param array $args Function arguments.
*
* @return mixed
*/
public function __invoke($fn, array $args)
{
return $this->{'fn_' . $fn}($args);
}
private function fn_abs(array $args)
{
$this->validate('abs', $args, [['number']]);
return abs($args[0]);
}
private function fn_avg(array $args)
{
$this->validate('avg', $args, [['array']]);
$sum = $this->reduce('avg:0', $args[0], ['number'], function ($a, $b) {
return $a + $b;
});
return $args[0] ? ($sum / count($args[0])) : null;
}
private function fn_ceil(array $args)
{
$this->validate('ceil', $args, [['number']]);
return ceil($args[0]);
}
private function fn_contains(array $args)
{
$this->validate('contains', $args, [['string', 'array'], ['any']]);
if (is_array($args[0])) {
return in_array($args[1], $args[0]);
} elseif (is_string($args[1])) {
return strpos($args[0], $args[1]) !== false;
} else {
return null;
}
}
private function fn_ends_with(array $args)
{
$this->validate('ends_with', $args, [['string'], ['string']]);
list($search, $suffix) = $args;
return $suffix === '' || substr($search, -strlen($suffix)) === $suffix;
}
private function fn_floor(array $args)
{
$this->validate('floor', $args, [['number']]);
return floor($args[0]);
}
private function fn_not_null(array $args)
{
if (!$args) {
throw new \RuntimeException(
"not_null() expects 1 or more arguments, 0 were provided"
);
}
return array_reduce($args, function ($carry, $item) {
return $carry !== null ? $carry : $item;
});
}
private function fn_join(array $args)
{
$this->validate('join', $args, [['string'], ['array']]);
$fn = function ($a, $b, $i) use ($args) {
return $i ? ($a . $args[0] . $b) : $b;
};
return $this->reduce('join:0', $args[1], ['string'], $fn);
}
private function fn_keys(array $args)
{
$this->validate('keys', $args, [['object']]);
return array_keys((array) $args[0]);
}
private function fn_length(array $args)
{
$this->validate('length', $args, [['string', 'array', 'object']]);
return is_string($args[0]) ? strlen($args[0]) : count((array) $args[0]);
}
private function fn_max(array $args)
{
$this->validate('max', $args, [['array']]);
$fn = function ($a, $b) { return $a >= $b ? $a : $b; };
return $this->reduce('max:0', $args[0], ['number', 'string'], $fn);
}
private function fn_max_by(array $args)
{
$this->validate('max_by', $args, [['array'], ['expression']]);
$expr = $this->wrapExpression('max_by:1', $args[1], ['number', 'string']);
$fn = function ($carry, $item, $index) use ($expr) {
return $index
? ($expr($carry) >= $expr($item) ? $carry : $item)
: $item;
};
return $this->reduce('max_by:1', $args[0], ['any'], $fn);
}
private function fn_min(array $args)
{
$this->validate('min', $args, [['array']]);
$fn = function ($a, $b, $i) { return $i && $a <= $b ? $a : $b; };
return $this->reduce('min:0', $args[0], ['number', 'string'], $fn);
}
private function fn_min_by(array $args)
{
$this->validate('min_by', $args, [['array'], ['expression']]);
$expr = $this->wrapExpression('min_by:1', $args[1], ['number', 'string']);
$i = -1;
$fn = function ($a, $b) use ($expr, &$i) {
return ++$i ? ($expr($a) <= $expr($b) ? $a : $b) : $b;
};
return $this->reduce('min_by:1', $args[0], ['any'], $fn);
}
private function fn_reverse(array $args)
{
$this->validate('reverse', $args, [['array', 'string']]);
if (is_array($args[0])) {
return array_reverse($args[0]);
} elseif (is_string($args[0])) {
return strrev($args[0]);
} else {
throw new \RuntimeException('Cannot reverse provided argument');
}
}
private function fn_sum(array $args)
{
$this->validate('sum', $args, [['array']]);
$fn = function ($a, $b) { return $a + $b; };
return $this->reduce('sum:0', $args[0], ['number'], $fn);
}
private function fn_sort(array $args)
{
$this->validate('sort', $args, [['array']]);
$valid = ['string', 'number'];
return Utils::stableSort($args[0], function ($a, $b) use ($valid) {
$this->validateSeq('sort:0', $valid, $a, $b);
return strnatcmp($a, $b);
});
}
private function fn_sort_by(array $args)
{
$this->validate('sort_by', $args, [['array'], ['expression']]);
$expr = $args[1];
$valid = ['string', 'number'];
return Utils::stableSort(
$args[0],
function ($a, $b) use ($expr, $valid) {
$va = $expr($a);
$vb = $expr($b);
$this->validateSeq('sort_by:0', $valid, $va, $vb);
return strnatcmp($va, $vb);
}
);
}
private function fn_starts_with(array $args)
{
$this->validate('starts_with', $args, [['string'], ['string']]);
list($search, $prefix) = $args;
return $prefix === '' || strpos($search, $prefix) === 0;
}
private function fn_type(array $args)
{
$this->validateArity('type', count($args), 1);
return Utils::type($args[0]);
}
private function fn_to_string(array $args)
{
$this->validateArity('to_string', count($args), 1);
$v = $args[0];
if (is_string($v)) {
return $v;
} elseif (is_object($v)
&& !($v instanceof \JsonSerializable)
&& method_exists($v, '__toString')
) {
return (string) $v;
}
return json_encode($v);
}
private function fn_to_number(array $args)
{
$this->validateArity('to_number', count($args), 1);
$value = $args[0];
$type = Utils::type($value);
if ($type == 'number') {
return $value;
} elseif ($type == 'string' && is_numeric($value)) {
return strpos($value, '.') ? (float) $value : (int) $value;
} else {
return null;
}
}
private function fn_values(array $args)
{
$this->validate('values', $args, [['array', 'object']]);
return array_values((array) $args[0]);
}
private function fn_merge(array $args)
{
if (!$args) {
throw new \RuntimeException(
"merge() expects 1 or more arguments, 0 were provided"
);
}
return call_user_func_array('array_replace', $args);
}
private function fn_to_array(array $args)
{
$this->validate('to_array', $args, [['any']]);
return Utils::isArray($args[0]) ? $args[0] : [$args[0]];
}
private function fn_map(array $args)
{
$this->validate('map', $args, [['expression'], ['any']]);
$result = [];
foreach ($args[1] as $a) {
$result[] = $args[0]($a);
}
return $result;
}
private function typeError($from, $msg)
{
if (strpos($from, ':')) {
list($fn, $pos) = explode(':', $from);
throw new \RuntimeException(
sprintf('Argument %d of %s %s', $pos, $fn, $msg)
);
} else {
throw new \RuntimeException(
sprintf('Type error: %s %s', $from, $msg)
);
}
}
private function validateArity($from, $given, $expected)
{
if ($given != $expected) {
$err = "%s() expects {$expected} arguments, {$given} were provided";
throw new \RuntimeException(sprintf($err, $from));
}
}
private function validate($from, $args, $types = [])
{
$this->validateArity($from, count($args), count($types));
foreach ($args as $index => $value) {
if (!isset($types[$index]) || !$types[$index]) {
continue;
}
$this->validateType("{$from}:{$index}", $value, $types[$index]);
}
}
private function validateType($from, $value, array $types)
{
if ($types[0] == 'any'
|| in_array(Utils::type($value), $types)
|| ($value === [] && in_array('object', $types))
) {
return;
}
$msg = 'must be one of the following types: ' . implode(', ', $types)
. '. ' . Utils::type($value) . ' found';
$this->typeError($from, $msg);
}
/**
* Validates value A and B, ensures they both are correctly typed, and of
* the same type.
*
* @param string $from String of function:argument_position
* @param array $types Array of valid value types.
* @param mixed $a Value A
* @param mixed $b Value B
*/
private function validateSeq($from, array $types, $a, $b)
{
$ta = Utils::type($a);
$tb = Utils::type($b);
if ($ta !== $tb) {
$msg = "encountered a type mismatch in sequence: {$ta}, {$tb}";
$this->typeError($from, $msg);
}
$typeMatch = ($types && $types[0] == 'any') || in_array($ta, $types);
if (!$typeMatch) {
$msg = 'encountered a type error in sequence. The argument must be '
. 'an array of ' . implode('|', $types) . ' types. '
. "Found {$ta}, {$tb}.";
$this->typeError($from, $msg);
}
}
/**
* Reduces and validates an array of values to a single value using a fn.
*
* @param string $from String of function:argument_position
* @param array $values Values to reduce.
* @param array $types Array of valid value types.
* @param callable $reduce Reduce function that accepts ($carry, $item).
*
* @return mixed
*/
private function reduce($from, array $values, array $types, callable $reduce)
{
$i = -1;
return array_reduce(
$values,
function ($carry, $item) use ($from, $types, $reduce, &$i) {
if (++$i > 0) {
$this->validateSeq($from, $types, $carry, $item);
}
return $reduce($carry, $item, $i);
}
);
}
/**
* Validates the return values of expressions as they are applied.
*
* @param string $from Function name : position
* @param callable $expr Expression function to validate.
* @param array $types Array of acceptable return type values.
*
* @return callable Returns a wrapped function
*/
private function wrapExpression($from, callable $expr, array $types)
{
list($fn, $pos) = explode(':', $from);
$from = "The expression return value of argument {$pos} of {$fn}";
return function ($value) use ($from, $expr, $types) {
$value = $expr($value);
$this->validateType($from, $value, $types);
return $value;
};
}
/** @internal Pass function name validation off to runtime */
public function __call($name, $args)
{
$name = str_replace('fn_', '', $name);
throw new \RuntimeException("Call to undefined function {$name}");
}
}
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