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/*
* Copyright (C) 2009 Nokia Corporation.
*
* Author: Zeeshan Ali (Khattak) <zeeshanak@gnome.org>
*
* This file is part of Rygel.
*
* Rygel is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* Rygel is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
using GUPnP;
using Gee;
errordomain Rygel.SearchCriteriaError {
SYNTAX_ERROR
}
private enum Rygel.SearchCriteriaSymbol {
EQ = SearchCriteriaOp.EQ,
NEQ,
LESS,
LEQ,
GREATER,
GEQ,
CONTAINS,
DOES_NOT_CONTAIN,
DERIVED_FROM,
EXISTS,
ASTERISK,
AND,
OR,
TRUE,
FALSE
}
private struct Rygel.SearchCriteriaToken {
public string str_symbol;
public SearchCriteriaSymbol symbol;
}
/**
* Parses a search criteria string and creates SearchExpression as a result.
*/
internal class Rygel.SearchCriteriaParser : Object, StateMachine {
// The original string representation received from client
public string str;
public SearchExpression expression; // The root expression
public Error err;
public Cancellable cancellable { get; set; }
private SearchCriteriaSymbol token {
get {
return (SearchCriteriaSymbol) this.scanner.token;
}
}
private string context {
owned get {
return this.scanner.line.to_string () + "." +
this.scanner.position.to_string ();
}
}
private Scanner scanner;
private const SearchCriteriaToken[] TOKENS = {
{ "=", SearchCriteriaSymbol.EQ },
{ "!=", SearchCriteriaSymbol.NEQ },
{ "<", SearchCriteriaSymbol.LESS },
{ "<=", SearchCriteriaSymbol.LEQ },
{ ">", SearchCriteriaSymbol.GREATER },
{ ">=", SearchCriteriaSymbol.GEQ },
{ "contains", SearchCriteriaSymbol.CONTAINS },
{ "doesNotContain", SearchCriteriaSymbol.DOES_NOT_CONTAIN },
{ "derivedfrom", SearchCriteriaSymbol.DERIVED_FROM },
{ "exists", SearchCriteriaSymbol.EXISTS },
{ "*", SearchCriteriaSymbol.ASTERISK },
{ "and", SearchCriteriaSymbol.AND },
{ "or", SearchCriteriaSymbol.OR },
{ "true", SearchCriteriaSymbol.TRUE },
{ "false", SearchCriteriaSymbol.FALSE }
};
public SearchCriteriaParser (string str) throws Error {
this.str = str;
scanner = new Scanner (null);
scanner.config.cset_skip_characters = " \t\n\r\012" +
"\013\014\015";
scanner.config.scan_identifier_1char = true;
scanner.config.cset_identifier_first = CharacterSet.a_2_z +
"_*<>=!@" +
CharacterSet.A_2_Z;
scanner.config.cset_identifier_nth = CharacterSet.a_2_z + "_" +
CharacterSet.DIGITS + "=:@" +
CharacterSet.A_2_Z +
CharacterSet.LATINS +
CharacterSet.LATINC;
scanner.config.symbol_2_token = true;
foreach (var token in TOKENS) {
scanner.scope_add_symbol (0,
token.str_symbol,
((int) token.symbol).to_pointer ());
}
}
// This implementation is not really async
public async void run () {
if (this.str == "*") {
// Wildcard
this.completed ();
return;
}
this.scanner.input_text (this.str, (uint) this.str.length);
this.scanner.get_next_token ();
try {
this.expression = this.parse_or_expression ();
} catch (Error err) {
this.err = err;
}
this.completed ();
}
private SearchExpression? parse_and_expression () throws Error {
var exp = this.parse_rel_expression ();
while (this.token == SearchCriteriaSymbol.AND) {
this.scanner.get_next_token ();
var exp2 = new LogicalExpression();
exp2.operand1 = exp;
exp2.op = LogicalOperator.AND;
exp2.operand2 = this.parse_rel_expression ();
exp = exp2;
}
return exp;
}
private SearchExpression? parse_rel_expression () throws Error {
var exp = new RelationalExpression ();
if (this.scanner.token == TokenType.IDENTIFIER) {
exp.operand1 = this.scanner.value.identifier;
this.scanner.get_next_token ();
if (this.token == SearchCriteriaSymbol.EQ ||
this.token == SearchCriteriaSymbol.NEQ ||
this.token == SearchCriteriaSymbol.LESS ||
this.token == SearchCriteriaSymbol.LEQ ||
this.token == SearchCriteriaSymbol.GREATER ||
this.token == SearchCriteriaSymbol.GEQ ||
this.token == SearchCriteriaSymbol.CONTAINS ||
this.token == SearchCriteriaSymbol.DOES_NOT_CONTAIN ||
this.token == SearchCriteriaSymbol.DERIVED_FROM) {
exp.op = (SearchCriteriaOp) this.scanner.token;
this.scanner.get_next_token ();
if (this.scanner.token == TokenType.STRING) {
exp.operand2 = this.scanner.value.string;
this.scanner.get_next_token ();
return exp;
} else {
throw new SearchCriteriaError.SYNTAX_ERROR (this.context +
": expected " +
"\"STRING\"");
}
} else if (this.token == SearchCriteriaSymbol.EXISTS) {
exp.op = (SearchCriteriaOp) this.scanner.token;
this.scanner.get_next_token ();
if (this.token == SearchCriteriaSymbol.TRUE) {
exp.operand2 = "true";
this.scanner.get_next_token ();
return exp;
} else if (this.token == SearchCriteriaSymbol.FALSE) {
exp.operand2 = "false";
this.scanner.get_next_token ();
return exp;
} else {
throw new SearchCriteriaError.SYNTAX_ERROR (this.context +
": expected " +
"\"true\"|\"" +
"false\"");
}
} else {
throw new SearchCriteriaError.SYNTAX_ERROR (this.context +
": expected " +
"operator");
}
} else if (this.scanner.token == TokenType.LEFT_PAREN) {
this.scanner.get_next_token ();
var exp2 = this.parse_or_expression ();
if (this.scanner.token != TokenType.RIGHT_PAREN) {
throw new SearchCriteriaError.SYNTAX_ERROR (this.context +
": expected ')'");
} else {
this.scanner.get_next_token ();
return exp2;
}
} else {
throw new SearchCriteriaError.SYNTAX_ERROR (this.context +
": expected " +
"identifier or '('");
}
}
private SearchExpression? parse_or_expression () throws Error {
var exp = this.parse_and_expression ();
while (this.token == SearchCriteriaSymbol.OR) {
this.scanner.get_next_token ();
var exp2 = new LogicalExpression();
exp2.operand1 = exp;
exp2.op = LogicalOperator.OR;
exp2.operand2 = this.parse_and_expression ();
exp = exp2;
}
return exp;
}
}
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