/**
* Use a parser to parse an input sequence.
*
* @param Parser $p
* A parser.
* @param Positional[] $input
* An input sequence.
* @return \Parco\Result Parse result.
*/
public function parse(Parser $p, array $input)
{
if ($this->atEnd($input)) {
$pos = array(1, 1);
} else {
$pos = $this->head($input)->getPosition();
}
return $p->parse($input, $pos);
}
/**
* A parser that returns the `$i`th group of a regex parse result.
*
* @param int $i
* Group number starting from 0, where 0 is the entire matched
* string.
* @param Parser $p
* A regex parser, see {@see regex}.
* @return Parser A parser that returns the group or null if the group is
* empty.
*/
public function group($i, Parser $p)
{
return new FuncParser(function ($input, array $pos) use($i, $p) {
$r = $p->parse($input, $pos);
if (!$r->successful) {
return $r;
}
$group = $r->group($i);
$offset = $r->offset($i);
if (isset($offset)) {
$pos[1] += $offset;
}
return new Success($group, $pos, $r->nextInput, $r->nextPos);
});
}
/**
* A parser for right-associative chaining.
*
* @param Parser $p
* A parser.
* @param Parser $sep
* A parser that parses the elements that separate the elements
* parsed by `$p` and returns a right-associative function that
* combines two elements returned by `$p`.
*/
public function chainr(Parser $p, Parser $sep)
{
return new FuncParser(function ($input, array $pos) use($p, $sep) {
$r = $p->parse($input, $pos);
if (!$r->successful) {
return $r;
}
$ops = array(array($r->result, null));
$input = $r->nextInput;
$nextPos = $r->nextPos;
while (true) {
$s = $sep->parse($input, $nextPos);
if (!$s->successful) {
break;
}
$r = $p->parse($s->nextInput, $s->nextPos);
if (!$r->successful) {
break;
}
$f = $s->result;
$ops[] = array($r->result, $f);
$input = $r->nextInput;
$nextPos = $r->nextPos;
}
$length = count($ops);
$rightOperand = $ops[$length - 1][0];
for ($i = $length - 2; $i >= 0; $i--) {
$f = $ops[$i + 1][1];
$leftOperand = $ops[$i][0];
$rightOperand = call_user_func($f, $leftOperand, $rightOperand);
}
return new Success($rightOperand, $pos, $input, $nextPos);
});
}