/// <summary>
/// This constructor takes a Boolean expression in infix format.
/// Some examples
/// are shown below. Assume <b>T</b> is an instance of the
/// <see cref="Tags"/>
/// class.
/// <list type="table">
/// <item>
/// T[CommonPropertyNames.title] contains "foo"
/// <term>
/// </term>
/// <description>
/// <see cref="MediaComparer.IsMatch"/> will return
/// true on media objects that have <i>foo</i> in the title.
/// </description>
/// </item>
///
/// <item>
/// T[CommonPropertyNames.creator] doesNotContain "\"HappyBand\""
/// <term>
/// </term>
/// <description>
/// <see cref="MediaComparer.IsMatch"/> will return
/// true on media objects that do not have <i>"HappyBand"</i> in the title.
/// </description>
/// </item>
///
/// <item>
/// (T[CommonPropertyNames.Class] = "object.item.audioItem.musicTrack" and Tags.PropertyAttributes.res_size > "40") or (T[CommonPropertyNames.author] exists true)
/// <term>
/// </term>
/// <description>
/// <see cref="MediaComparer.IsMatch"/> will return
/// true on media objects that are music tracks with at least one resource greater than 40 bytes
/// OR on media objects that have a value set for the author metadata.
/// </description>
/// </item>
/// </list>
/// </summary>
/// <param name="infix">The boolean infix expression conforming to the syntax and semantics of ContentDirectory's boolean query language.</param>
/// <exception cref="OpenSource.UPnP.AV.CdsMetadata.Error_MalformedSearchCriteria">
/// Thrown if the infix expression has a syntax error.
/// </exception>
public MediaComparer(string infix)
{
string allstring = infix.Trim();
if ((allstring == "") || (allstring == "*"))
{
this.m_AlwaysMatch = true;
return;
}
//Initialize an empty stack and empty result string variable.
//
Stack stack = new Stack();
m_Postfix = new Queue();
RelExpStates state = RelExpStates.unknown;
TokenResult token;
while (infix.Length > 0)
{
infix = infix.Trim();
token = GetToken(ref infix, state);
switch (state)
{
case RelExpStates.unknown:
if (token.TokenType == Tokens.PropertyName)
{
state = RelExpStates.expectOp;
}
break;
case RelExpStates.expectOp:
if (token.TokenType != Tokens.Operator)
{
throw new UPnPCustomException(402, "Invalid Args: Invalid operator " + token.Data);
}
state = RelExpStates.expectValue;
break;
case RelExpStates.expectValue:
if (token.TokenType != Tokens.PropertyValue)
{
throw new UPnPCustomException(402, "Invalid Args: Unexpected value " + token.Data);
}
state = RelExpStates.unknown;
break;
}
switch (token.TokenType)
{
case Tokens.Operator:
if (token.OpToken == OperatorTokens.LParen)
{
//left paren
//
stack.Push(token);
}
else if (token.OpToken == OperatorTokens.RParen)
{
//right paren
//
TokenResult tr = new TokenResult(false);
do
{
if (stack.Count > 0)
{
tr = (TokenResult)stack.Pop();
if (tr.OpToken != OperatorTokens.LParen)
{
m_Postfix.Enqueue(tr);
}
}
else
{
throw new UPnPCustomException(402, "Invalid Args: Missing Left Parenthesis.");
}
}while (tr.OpToken != OperatorTokens.LParen);
}
else
{
//standard operator
//
if (token.OpToken == OperatorTokens.Invalid)
{
throw new Exception("bad code");
}
while
(
(stack.Count > 0) &&
(((TokenResult)stack.Peek()).Precedence >= token.Precedence) &&
(((TokenResult)stack.Peek()).OpToken != OperatorTokens.LParen)
)
{
// While stack is not empty &&
// top operator has higher or equal precedence...
// pop operator and stuff into queue
m_Postfix.Enqueue(stack.Pop());
}
stack.Push(token);
}
break;
case Tokens.PropertyName:
m_Postfix.Enqueue(token);
TagExtractor te = new TagExtractor(token.Data);
this.m_PE[token.Data] = te;
break;
case Tokens.PropertyValue:
m_Postfix.Enqueue(token);
break;
}
}
// pop remaining items in stack and stuff into queue
//
while (stack.Count > 0)
{
TokenResult tr = (TokenResult)stack.Pop();
if (tr.OpToken != OperatorTokens.LParen)
{
m_Postfix.Enqueue(tr);
}
}
}
/// <summary>
/// Obtains the next token, given the current state and the expression.
/// </summary>
/// <param name="exp">the remaining portion of the infix expression to translate into a postfix expression</param>
/// <param name="state">the state determines what types of tokens can be accepted.</param>
/// <returns></returns>
private TokenResult GetToken(ref string exp, RelExpStates state)
{
TokenResult token = new TokenResult(false);
bool searchOps1 = false;
bool searchOps2 = false;
bool searchOps3 = false;
bool parsePropName = false;
bool parsePropValue = false;
switch (state)
{
case RelExpStates.unknown:
//look for everything
searchOps1 = true;
searchOps3 = true;
parsePropName = true;
break;
case RelExpStates.expectOp:
//look for relop, stringop, derived-op
searchOps2 = true;
break;
case RelExpStates.expectValue:
parsePropValue = true;
break;
}
//remove any preceding whitespace chars
exp = exp.Trim();
if (exp != "")
{
if ((searchOps1) && (token.TokenType == Tokens.Invalid))
{
token = this.SeachOperators(ref exp, Operators1);
}
if ((searchOps2) && (token.TokenType == Tokens.Invalid))
{
token = this.SeachOperators(ref exp, Operators2);
}
if ((searchOps3) && (token.TokenType == Tokens.Invalid))
{
token = this.SeachOperators(ref exp, Operators3);
}
if (token.TokenType == Tokens.Invalid)
{
if (parsePropValue)
{
//it must be an operand... so parse the next whitespace delimited string or
//extract the next string enclosed by quotes
if ((exp.StartsWith("true")) || (exp.StartsWith("false")))
{
// This is a value for an existence-op operation
token = new TokenResult(exp, false);
exp = exp.Substring(exp.Length);
}
else if (exp.StartsWith("\""))
{
// This is a value operand that is delimited
// by another double-quote
int endQuote = 1;
int escape = 0;
bool endQuoteFound = false;
// find the next end-quote that is not
// an escaped end-quote.
while (!endQuoteFound)
{
endQuote = exp.IndexOf("\"", endQuote);
escape = exp.IndexOf("\\\"", escape);
if (
(escape < 0) ||
(escape == endQuote - 1) ||
(escape > endQuote)
)
{
endQuoteFound = true;
}
}
if (endQuote <= 0)
{
StringBuilder msg = new StringBuilder(exp.Length);
msg.AppendFormat("Invalid Args: Unterminated end-quote in SearchCriteria, near \"{0}\"", exp);
throw new UPnPCustomException(402, msg.ToString());
}
string unescaped = exp.Substring(1, endQuote - 1);
string escaped = unescaped.Replace("\\\\", "\\").Replace("\\\"", "\"");
token = new TokenResult(escaped, false);
exp = exp.Substring(endQuote + 1);
}
else
{
// Assume the CP provided a white-space delimited value without quotes
//int endPos = exp.IndexOf(" ");
int endPos = this.FindNextIndexOf(exp, WHITESPACESANDENDPAREN);
string str = exp;
if (endPos > 0)
{
str = exp.Substring(0, endPos);
}
token = new TokenResult(str, false);
exp = exp.Substring(str.Length);
}
}
else
{
// This is a property name, that is delimited by
// a whitespace.
//int endPos = exp.IndexOf(" ");
int endPos = this.FindNextIndexOf(exp, WHITESPACES);
if (endPos > 0)
{
string prop = exp.Substring(0, endPos);
token = new TokenResult(prop, true);
exp = exp.Substring(prop.Length);
}
else
{
throw new Error_MalformedSearchCriteria("Property name has not been properly delimited.");
}
}
}
}
if (
(token.TokenType == Tokens.Invalid)
)
{
throw new UPnPCustomException(402, "Invalid Args: Invalid SearchCriteria string.");
}
return(token);
}
/// <summary>
/// Obtains the next token, given the current state and the expression.
/// </summary>
/// <param name="exp">the remaining portion of the infix expression to translate into a postfix expression</param>
/// <param name="state">the state determines what types of tokens can be accepted.</param>
/// <returns></returns>
private TokenResult GetToken(ref string exp, RelExpStates state)
{
TokenResult token = new TokenResult(false);
bool searchOps1 = false;
bool searchOps2 = false;
bool searchOps3 = false;
bool parsePropName = false;
bool parsePropValue = false;
switch (state)
{
case RelExpStates.unknown:
//look for everything
searchOps1 = true;
searchOps3 = true;
parsePropName = true;
break;
case RelExpStates.expectOp:
//look for relop, stringop, derived-op
searchOps2 = true;
break;
case RelExpStates.expectValue:
parsePropValue = true;
break;
}
//remove any preceding whitespace chars
exp = exp.Trim();
if (exp != "")
{
if ((searchOps1) && (token.TokenType == Tokens.Invalid))
{
token = this.SeachOperators(ref exp, Operators1);
}
if ((searchOps2) && (token.TokenType == Tokens.Invalid))
{
token = this.SeachOperators(ref exp, Operators2);
}
if ((searchOps3) && (token.TokenType == Tokens.Invalid))
{
token = this.SeachOperators(ref exp, Operators3);
}
if (token.TokenType == Tokens.Invalid)
{
if (parsePropValue)
{
//it must be an operand... so parse the next whitespace delimited string or
//extract the next string enclosed by quotes
if ((exp.StartsWith("true")) || (exp.StartsWith("false")))
{
// This is a value for an existence-op operation
token = new TokenResult(exp, false);
exp = exp.Substring(exp.Length);
}
else if (exp.StartsWith("\""))
{
// This is a value operand that is delimited
// by another double-quote
int endQuote = 1;
int escape = 0;
bool endQuoteFound = false;
// find the next end-quote that is not
// an escaped end-quote.
while (!endQuoteFound)
{
endQuote = exp.IndexOf("\"", endQuote);
escape = exp.IndexOf("\\\"", escape);
if (
(escape < 0) ||
(escape == endQuote - 1) ||
(escape > endQuote)
)
{
endQuoteFound = true;
}
}
if (endQuote <= 0)
{
StringBuilder msg = new StringBuilder(exp.Length);
msg.AppendFormat("Invalid Args: Unterminated end-quote in SearchCriteria, near \"{0}\"", exp);
throw new UPnPCustomException(402, msg.ToString());
}
string unescaped = exp.Substring(1, endQuote-1);
string escaped = unescaped.Replace("\\\\", "\\").Replace("\\\"", "\"");
token = new TokenResult(escaped, false);
exp = exp.Substring(endQuote+1);
}
else
{
// Assume the CP provided a white-space delimited value without quotes
//int endPos = exp.IndexOf(" ");
int endPos = this.FindNextIndexOf(exp, WHITESPACESANDENDPAREN);
string str = exp;
if (endPos > 0)
{
str = exp.Substring(0, endPos);
}
token = new TokenResult(str, false);
exp = exp.Substring(str.Length);
}
}
else
{
// This is a property name, that is delimited by
// a whitespace.
//int endPos = exp.IndexOf(" ");
int endPos = this.FindNextIndexOf(exp, WHITESPACES);
if (endPos > 0)
{
string prop = exp.Substring(0, endPos);
token = new TokenResult(prop, true);
exp = exp.Substring(prop.Length);
}
else
{
throw new Error_MalformedSearchCriteria("Property name has not been properly delimited.");
}
}
}
}
if (
(token.TokenType == Tokens.Invalid)
)
{
throw new UPnPCustomException(402, "Invalid Args: Invalid SearchCriteria string.");
}
return token;
}
