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|
<?php
namespace Micropoly\Search;
use Generator;
use Iterator;
class Parser
{
public const TOK_PAROPEN = "(";
public const TOK_PARCLOSE = ")";
public const TOK_TAG = "#";
public const TOK_WORD = '"';
public const TOK_OP = "op";
public const TOK_PROP = ":";
private static function iterChars(string $input): Iterator
{
for ($i = 0; $i < mb_strlen($input); $i++)
yield mb_substr($input, $i, 1);
}
/**
* @param string $input
* @return Iterator
* @throws ParseError
*/
public static function tokenize(string $input): Iterator
{
$chars = new CharSource($input);
yield from self::tokenize_normal($chars);
}
private static function getItemAndAdvance(Iterator $input)
{
if (!$input->valid())
return null;
$out = $input->current();
$input->next();
return $out;
}
/**
* @return Iterator
* @throws ParseError
*/
private static function tokenize_normal(CharSource $input): Iterator
{
$buf = "";
$yieldBufAndClear = function () use (&$buf) {
if ($buf !== "") {
switch ($buf) {
case "and":
case "or":
case "not":
yield [self::TOK_OP, $buf];
break;
default:
yield [self::TOK_WORD, $buf];
}
}
$buf = "";
};
for (;;) {
$c = $input->getNext();
if ($c === null) {
break;
}
switch ($c) {
case '\\':
$next = $input->getNext();
if ($next === null) {
$buf .= $c;
break 2;
}
$buf .= $next;
break;
case ' ':
case "\t":
yield from $yieldBufAndClear();
break;
case '"':
yield from $yieldBufAndClear();
yield from self::tokenize_string($input);
break;
case ':':
if ($buf !== "") {
yield [self::TOK_PROP, $buf];
$buf = "";
}
break;
case '(':
yield from $yieldBufAndClear();
yield [self::TOK_PAROPEN, null];
break;
case ')':
yield from $yieldBufAndClear();
yield [self::TOK_PARCLOSE, null];
break;
case '#':
yield from $yieldBufAndClear();
yield from self::tokenize_tag($input);
break;
default:
$buf .= $c;
}
}
yield from $yieldBufAndClear();
return;
}
/**
* @param string $input
* @return SearchExpr|null
* @throws ParseError
*/
public static function parse(string $input): ?SearchExpr
{
$tokens = self::tokenize($input);
$stack = [];
$cur = null;
$binOp = null;
$negated = false;
$putExpr = function (SearchExpr $expr) use (&$cur, &$binOp, &$negated) {
if ($negated) {
$expr = new NotOp($expr);
}
$cur = $cur === null
? $expr
: LogicOp::build($binOp ?? LogicOp::OP_AND, $cur, $expr);
$binOp = null;
$negated = false;
};
$setBinOp = function ($op) use (&$binOp) {
if ($binOp !== null)
throw new ParseError("Unexpected logic operator $op");
$binOp = $op;
};
for (;;) {
$token = self::getItemAndAdvance($tokens);
if ($token === null)
break;
[$ttyp, $tdata] = $token;
switch ($ttyp) {
case self::TOK_TAG:
$putExpr(new TagExpr($tdata));
break;
case self::TOK_OP:
switch ($tdata) {
case "and":
$setBinOp(LogicOp::OP_AND);
break;
case "or":
$setBinOp(LogicOp::OP_OR);
break;
case "not":
$negated = !$negated;
break;
default:
throw new \DomainException("Unexpected data for TOK_OP: $tdata");
}
break;
case self::TOK_WORD:
$putExpr(new FTSExpr($tdata));
break;
case self::TOK_PROP:
// TODO(laria): Implement this
throw new ParseError("Not yet supported");
case self::TOK_PAROPEN:
$stack[] = [$cur, $binOp, $negated];
$cur = $binOp = $negated = null;
break;
case self::TOK_PARCLOSE:
if (empty($stack))
throw new ParseError("Unexpected closing parenthesis");
$parContent = $cur;
[$cur, $binOp, $negated] = array_pop($stack);
$putExpr($parContent);
break;
}
}
if (!empty($stack))
throw new ParseError("Unclosed parenthesis");
return $cur;
}
/**
* @param CharSource $input
* @return Generator
* @throws ParseError
*/
private static function tokenize_string(CharSource $input): Generator
{
$content = "";
for (;;) {
$c = $input->getNext();
if ($c === null)
throw new ParseError("Unclosed string encountered");
switch ($c) {
case '\\':
$next = $input->getNext();
if ($next === null)
throw new ParseError("Unclosed string encountered");
$content .= $next;
break;
case '"':
yield [self::TOK_WORD, $content];
return;
default:
$content .= $c;
}
}
}
/**
* @param CharSource $input
* @return Iterator
*/
private static function tokenize_tag(CharSource $input): Iterator
{
$tag = "";
$yieldTag = function () use (&$tag) {
if ($tag === "")
yield [self::TOK_WORD, "#"];
else
yield [self::TOK_TAG, $tag];
};
for (;;) {
$c = $input->getNext();
if ($c === null) {
yield from $yieldTag();
return;
}
switch ($c) {
case '\\':
$next = $input->getNext();
if ($c === null) {
$tag .= '\\';
yield [self::TOK_TAG, $tag];
return;
}
$tag .= $next;
break;
case ' ':
case "\t":
yield from $yieldTag();
return;
case '(':
case ')':
case '#':
$input->unget();
yield from $yieldTag();
return;
default:
$tag .= $c;
}
}
}
}
|
