mirror of
https://gerrit.wikimedia.org/r/mediawiki/extensions/AbuseFilter.git
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483 lines
13 KiB
C++
483 lines
13 KiB
C++
/*
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* Copyright (c) 2008 Andrew Garrett.
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* Copyright (c) 2008 River Tarnell <river@wikimedia.org>
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* Derived from public domain code contributed by Victor Vasiliev.
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*
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* Permission is granted to anyone to use this software for any purpose,
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* including commercial applications, and to alter it and redistribute it
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* freely. This software is provided 'as-is', without any express or
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* implied warranty.
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*/
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#ifndef EXPRESSOR_H
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#define EXPRESSOR_H
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#include <string>
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#include <vector>
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#include <stdexcept>
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#include <iostream>
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#include <boost/noncopyable.hpp>
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#include <boost/function.hpp>
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#include <boost/spirit/core.hpp>
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#include <boost/spirit/utility/confix.hpp>
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#include <boost/spirit/utility/chset.hpp>
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#include <boost/spirit/tree/ast.hpp>
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#include <boost/spirit/tree/tree_to_xml.hpp>
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#include <boost/spirit/symbols.hpp>
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#include <boost/spirit/utility/escape_char.hpp>
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#include <boost/function.hpp>
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#include <boost/noncopyable.hpp>
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#include <boost/format.hpp>
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#include <boost/regex/icu.hpp>
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#include <unicode/uchar.h>
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#include "aftypes.h"
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#include "afstring.h"
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#include "affunctions.h"
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#include "fray.h"
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#include "ast.h"
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namespace afp {
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template<typename T> struct parser_grammar;
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template<typename charT>
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struct basic_expressor : boost::noncopyable {
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typedef boost::function<basic_datum<charT> (std::vector<basic_datum<charT> >)> func_t;
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basic_expressor();
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~basic_expressor();
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basic_datum<charT> evaluate(basic_fray<charT> const &expr) const;
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void print_xml(std::ostream &strm, basic_fray<charT> const &expr) const;
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void add_variable(basic_fray<charT> const &name, basic_datum<charT> const &value);
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void add_function(basic_fray<charT> const &name, func_t value);
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void clear();
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void clear_functions();
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void clear_variables();
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private:
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parser_grammar<charT> *grammar_;
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};
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typedef basic_expressor<char> expressor;
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typedef basic_expressor<UChar32> u32expressor;
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using namespace boost::spirit;
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/*
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* ABUSEFILTER EXPRESSION PARSER
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* =============================
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*
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* This is the basic expression parser. It doesn't contain any AF logic
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* itself, but rather presents an interface for the user to add custom
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* functions and variables.
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*
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* The interface to the parser is the 'expressor' class. Use it like this:
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*
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* expressor e;
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* e.add_variable("ONE", 1);
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* e.evaluate("ONE + 2"); -- returns 3
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*
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* Custom functions should have the following prototype:
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*
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* datum (std::vector<afp::datum) const &args);
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*
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* Functions must return a value; they cannot be void. The arguments passed to
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* the function are stored in the 'args' array in left-to-right order.
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*
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* The parser implements a C-like grammar with some differences. The following
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* operators are available:
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*
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* a & b true if a and b are both true
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* a | b true if either a or b is true
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* a ^ b true if either a or b is true, but not if both are true
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* a + b arithmetic
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* a - b
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* a * b
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* a / b
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* a % b
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* a ** b power-of (a^b)
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* a in b true if the string "b" contains the substring "a"
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* !a true if a is false
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* (a) same value as a
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* a ? b : c if a is true, returns the value of b, otherwise c
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* a == b comparison operators
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* a != b
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* a < b
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* a <= b
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* a > b
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* a >= b
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* a === b returns true if a==b and both are the same type
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* a !== b return true if a != b or they are different types
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*
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* The parser uses afp::datum for its variables. This means it supports
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* strings, ints and floats, with automatic conversion between types.
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*/
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struct parse_error : std::runtime_error {
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parse_error(char const *what) : std::runtime_error(what) {}
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};
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/*
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* The grammar itself.
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*/
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template<typename charT>
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struct parser_grammar : public grammar<parser_grammar<charT> >
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{
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static const int id_value = 1;
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static const int id_variable = 2;
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static const int id_basic = 3;
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static const int id_bool_expr = 4;
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static const int id_ord_expr = 5;
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static const int id_eq_expr = 6;
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static const int id_pow_expr = 7;
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static const int id_mult_expr = 8;
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static const int id_plus_expr = 9;
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static const int id_in_expr = 10;
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static const int id_function = 12;
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static const int id_tern_expr = 13;
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static const int id_string = 14;
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/* User-defined variables. */
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symbols<basic_datum<charT>, charT > variables;
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void add_variable(basic_fray<charT> const &name, basic_datum<charT> const &value) {
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variables.add(name.c_str(), value);
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}
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/* User-defined functions. */
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symbols<boost::function<basic_datum<charT> (std::vector<basic_datum<charT> >)>, charT > functions;
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void add_function(
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basic_fray<charT> const &name,
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boost::function<basic_datum<charT> (std::vector<basic_datum<charT> >)> func) {
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functions.add(name.c_str(), func);
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}
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symbols<int, charT> eq_opers, ord_opers, plus_opers, mult_opers, in_opers, bool_opers;
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parser_grammar() {
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eq_opers.add("=", 0);
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eq_opers.add("==", 0);
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eq_opers.add("===", 0);
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eq_opers.add("!=", 0);
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eq_opers.add("!==", 0);
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eq_opers.add("/=", 0);
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ord_opers.add("<", 0);
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ord_opers.add("<=", 0);
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ord_opers.add(">", 0);
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ord_opers.add(">=", 0);
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plus_opers.add("+", 0);
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plus_opers.add("-", 0);
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mult_opers.add("*", 0);
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mult_opers.add("/", 0);
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mult_opers.add("%", 0);
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bool_opers.add("&", 0);
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bool_opers.add("|", 0);
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bool_opers.add("^", 0);
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in_opers.add("in", 0);
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in_opers.add("contains", 0);
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in_opers.add("matches", 0);
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in_opers.add("like", 0);
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in_opers.add("rlike", 0);
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in_opers.add("regex", 0);
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}
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template<typename ScannerT>
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struct definition
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{
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parser_grammar const &self_;
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definition(parser_grammar const &self)
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: self_(self)
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{
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/*
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* A literal value. Either a string, a floating
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* pointer number or an integer.
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*/
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value =
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strict_real_p
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| as_lower_d[ leaf_node_d[
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oct_p >> 'o'
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| hex_p >> 'x'
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| bin_p >> 'b'
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| int_p
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] ]
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| string
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;
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/*
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* config_p can't be used here, because it will rewrite
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* *(c_escape_ch_p[x]) into (*c_escape_ch_p)[x]
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*/
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string = inner_node_d[
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'"'
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>> leaf_node_d[ *(lex_escape_ch_p - '"') ]
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>> '"'
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]
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;
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/*
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* A variable. If the variable is found in the
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* user-supplied variable list, we use that.
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* Otherwise, unknown variables (containing uppercase
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* letters and underscore only) are returned as the
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* empty string.
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*/
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variable = longest_d[
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self.variables
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| leaf_node_d[ (+ (upper_p | '_') ) ]
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]
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;
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/*
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* A function call: func([arg[, arg...]]).
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*/
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function =
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(
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root_node_d[self.functions]
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>> inner_node_d[
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'('
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>> ( tern_expr % discard_node_d[ch_p(',')] )
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>> ')'
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]
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)
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;
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/*
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* A basic atomic value. Either a variable, function
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* or literal, or a negated expression !a, or a
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* parenthesised expression (a).
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*/
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basic =
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value
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| variable
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| function
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| inner_node_d[ '(' >> tern_expr >> ')' ]
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| root_node_d[ch_p('!')] >> tern_expr
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| root_node_d[ch_p('+')] >> tern_expr
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| root_node_d[ch_p('-')] >> tern_expr
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;
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/*
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* "a in b" operator
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*/
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in_expr =
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basic
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>> *( root_node_d[ self.in_opers ] >> basic )
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;
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/*
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* power-of. This is right-associative.
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*/
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pow_expr =
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in_expr
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>> !( root_node_d[ str_p("**") ] >> pow_expr )
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;
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/*
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* Multiplication and operators with the same
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* precedence.
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*/
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mult_expr =
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pow_expr
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>> *( root_node_d[ self.mult_opers ] >> pow_expr )
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;
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/*
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* Additional and operators with the same precedence.
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*/
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plus_expr =
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mult_expr
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>> *( root_node_d[ self.plus_opers ] >> mult_expr )
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;
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/*
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* Ordinal comparisons and operators with the same
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* precedence.
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*/
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ord_expr =
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plus_expr
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>> *( root_node_d[ self.ord_opers ] >> plus_expr )
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;
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/*
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* Equality comparisons.
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*/
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eq_expr =
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ord_expr
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>> *( root_node_d[ self.eq_opers ] >> ord_expr )
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;
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/*
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* Boolean expressions.
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*/
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bool_expr =
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eq_expr
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>> *( root_node_d[ self.bool_opers ] >> eq_expr )
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;
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/*
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* The ternary operator. Notice this is
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* right-associative: a ? b ? c : d : e
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* is supported.
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*/
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tern_expr =
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bool_expr
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>> !(
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root_node_d[ch_p('?')] >> tern_expr
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>> discard_node_d[ch_p(':')] >> tern_expr
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)
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;
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}
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rule<ScannerT, parser_context<>, parser_tag<id_tern_expr> >
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const &start() const {
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return tern_expr;
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}
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rule<ScannerT, parser_context<>, parser_tag<id_value> > value;
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rule<ScannerT, parser_context<>, parser_tag<id_variable> > variable;
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rule<ScannerT, parser_context<>, parser_tag<id_basic> > basic;
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rule<ScannerT, parser_context<>, parser_tag<id_bool_expr> > bool_expr;
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rule<ScannerT, parser_context<>, parser_tag<id_ord_expr> > ord_expr;
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rule<ScannerT, parser_context<>, parser_tag<id_eq_expr> > eq_expr;
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rule<ScannerT, parser_context<>, parser_tag<id_pow_expr> > pow_expr;
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rule<ScannerT, parser_context<>, parser_tag<id_mult_expr> > mult_expr;
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rule<ScannerT, parser_context<>, parser_tag<id_plus_expr> > plus_expr;
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rule<ScannerT, parser_context<>, parser_tag<id_in_expr> > in_expr;
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rule<ScannerT, parser_context<>, parser_tag<id_function> > function;
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rule<ScannerT, parser_context<>, parser_tag<id_tern_expr> > tern_expr;
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rule<ScannerT, parser_context<>, parser_tag<id_string> > string;
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};
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};
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template<typename charT>
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basic_expressor<charT>::basic_expressor()
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: grammar_(new parser_grammar<charT>)
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{
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/*
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* We provide a couple of standard variables everyone wants.
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*/
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add_variable(make_astring<charT>("true"), afp::basic_datum<charT>::from_int(true));
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add_variable(make_astring<charT>("false"), afp::basic_datum<charT>::from_int(false));
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/*
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* The cast functions.
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*/
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add_function(make_astring<charT>("int"), &f_int<charT>);
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add_function(make_astring<charT>("string"), &f_string<charT>);
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add_function(make_astring<charT>("float"), &f_float<charT>);
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}
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template<typename charT>
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basic_expressor<charT>::~basic_expressor()
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{
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delete grammar_;
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}
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/*
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* The user interface to evaluate an expression. It returns the result, or
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* throws an exception if an error occurs.
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*/
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template<typename charT>
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basic_datum<charT>
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basic_expressor<charT>::evaluate(basic_fray<charT> const &filter) const
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{
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using namespace boost::spirit;
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typedef typename basic_fray<charT>::const_iterator iterator_t;
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basic_datum<charT> ret;
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tree_parse_info<iterator_t> info = ast_parse(filter.begin(), filter.end(), *grammar_,
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+chset<>("\n\t ") | comment_p("/*", "*/"));
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if (info.full) {
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ast_evaluator<charT, typename tree_match<iterator_t>::tree_iterator> ae(*grammar_);
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return ae.tree_eval(info.trees.begin());
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} else {
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throw parse_error("parsing failed");
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}
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}
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template<typename charT>
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void
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basic_expressor<charT>::print_xml(std::ostream &strm, basic_fray<charT> const &filter) const
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{
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using namespace boost::spirit;
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typedef typename basic_fray<charT>::const_iterator iterator_t;
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tree_parse_info<iterator_t> info = ast_parse(filter.begin(), filter.end(), *grammar_,
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+chset<>("\n\t ") | comment_p("/*", "*/"));
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if (info.full) {
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std::map<parser_id, std::string> rule_names;
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rule_names[parser_grammar<charT>::id_value] = "value";
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rule_names[parser_grammar<charT>::id_variable] = "variable";
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rule_names[parser_grammar<charT>::id_basic] = "basic";
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rule_names[parser_grammar<charT>::id_bool_expr] = "bool_expr";
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rule_names[parser_grammar<charT>::id_ord_expr] = "ord_expr";
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rule_names[parser_grammar<charT>::id_eq_expr] = "eq_expr";
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rule_names[parser_grammar<charT>::id_pow_expr] = "pow_expr";
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rule_names[parser_grammar<charT>::id_mult_expr] = "mult_expr";
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rule_names[parser_grammar<charT>::id_plus_expr] = "plus_expr";
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rule_names[parser_grammar<charT>::id_in_expr] = "in_expr";
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rule_names[parser_grammar<charT>::id_function] = "function";
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rule_names[parser_grammar<charT>::id_tern_expr] = "tern_expr";
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rule_names[parser_grammar<charT>::id_string] = "string";
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tree_to_xml(strm, info.trees, "", rule_names);
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} else {
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throw parse_error("parsing failed");
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}
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}
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template<typename charT>
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void
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basic_expressor<charT>::clear()
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{
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clear_variables();
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clear_functions();
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}
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template<typename charT>
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void
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basic_expressor<charT>::clear_variables()
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{
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symbols<basic_datum<charT>, charT > variables;
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grammar_->variables = variables;
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}
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template<typename charT>
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void
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basic_expressor<charT>::clear_functions()
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{
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symbols<boost::function<basic_datum<charT> (std::vector<basic_datum<charT> >)>, charT > functions;
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grammar_->functions = functions;
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}
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template<typename charT>
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void
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basic_expressor<charT>::add_variable(basic_fray<charT> const &name, basic_datum<charT> const &value)
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{
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grammar_->add_variable(name, value);
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}
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template<typename charT>
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void
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basic_expressor<charT>::add_function(basic_fray<charT> const &name, func_t value)
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{
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grammar_->add_function(name, value);
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}
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} // namespace afp
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#endif /* !EXPRESSOR_H */
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