From 2eb5a432d2229788ce2fdb09f36c6f4bebdea813 Mon Sep 17 00:00:00 2001
From: Laria Carolin Chabowski <laria@laria.me>
Date: Fri, 7 Feb 2020 09:44:59 +0100
Subject: Initial commit

---
 src/Search/Parser.php | 295 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 295 insertions(+)
 create mode 100644 src/Search/Parser.php

(limited to 'src/Search/Parser.php')

diff --git a/src/Search/Parser.php b/src/Search/Parser.php
new file mode 100644
index 0000000..a8efdfd
--- /dev/null
+++ b/src/Search/Parser.php
@@ -0,0 +1,295 @@
+<?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;
+            }
+        }
+    }
+}
\ No newline at end of file
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