// Six possible causes of exceptions in the builder:
// 1. Undefined prefix in a node test.
// 2. Undefined prefix in a variable reference, or unknown variable.
// 3. Undefined prefix in a function call, or unknown function, or wrong number/types of arguments.
// 4. Argument of Union operator is not a node-set.
// 5. First argument of Predicate is not a node-set.
// 6. Argument of Axis is not a node-set.
public Node Parse(string xpathExpr, IXPathBuilder <Node> builder)
{
Debug.Assert(this.scanner == null && this.builder == null);
Debug.Assert(builder != null);
Node result = default(Node);
this.scanner = new XPathScanner(xpathExpr);
this.builder = builder;
this.posInfo.Clear();
try {
builder.StartBuild();
result = ParseExpr();
scanner.CheckToken(LexKind.Eof);
}
catch (XPathParserException e) {
if (e.queryString == null)
{
e.queryString = scanner.Source;
PopPosInfo(out e.startChar, out e.endChar);
}
throw;
}
finally {
result = builder.EndBuild(result);
#if DEBUG
this.builder = null;
this.scanner = null;
#endif
}
Debug.Assert(posInfo.Count == 0, "PushPosInfo() and PopPosInfo() calls have been unbalanced");
return(result);
}
/*
* PrimaryExpr ::= Literal | Number | VariableReference | '(' Expr ')' | FunctionCall
*/
private Node ParsePrimaryExpr()
{
Debug.Assert(IsPrimaryExpr());
Node opnd;
switch (scanner.Kind)
{
case LexKind.String:
opnd = builder.String(scanner.StringValue);
scanner.NextLex();
break;
case LexKind.Number:
opnd = builder.Number(scanner.RawValue);
scanner.NextLex();
break;
case LexKind.Dollar:
int startChar = scanner.LexStart;
scanner.NextLex();
scanner.CheckToken(LexKind.Name);
PushPosInfo(startChar, scanner.LexStart + scanner.LexSize);
opnd = builder.Variable(scanner.Prefix, scanner.Name);
PopPosInfo();
scanner.NextLex();
break;
case LexKind.LParens:
scanner.NextLex();
opnd = ParseExpr();
scanner.PassToken(LexKind.RParens);
break;
default:
Debug.Assert(
scanner.Kind == LexKind.Name && scanner.CanBeFunction && !IsNodeType(scanner),
"IsPrimaryExpr() returned true, but the lexeme is not recognized"
);
opnd = ParseFunctionCall();
break;
}
return(opnd);
}
private static void InternalParseNodeTest(XPathScanner scanner, XPathAxis axis, out XPathNodeType nodeType, out string nodePrefix, out string nodeName)
{
switch (scanner.Kind)
{
case LexKind.Name:
if (scanner.CanBeFunction && IsNodeType(scanner))
{
nodePrefix = null;
nodeName = null;
switch (scanner.Name)
{
case "comment": nodeType = XPathNodeType.Comment; break;
case "text": nodeType = XPathNodeType.Text; break;
case "node": nodeType = XPathNodeType.All; break;
default:
Debug.Assert(scanner.Name == "processing-instruction");
nodeType = XPathNodeType.ProcessingInstruction;
break;
}
scanner.NextLex();
scanner.PassToken(LexKind.LParens);
if (nodeType == XPathNodeType.ProcessingInstruction)
{
if (scanner.Kind != LexKind.RParens) // 'processing-instruction' '(' Literal ')'
{
scanner.CheckToken(LexKind.String);
// It is not needed to set nodePrefix here, but for our current implementation
// comparing whole QNames is faster than comparing just local names
nodePrefix = string.Empty;
nodeName = scanner.StringValue;
scanner.NextLex();
}
}
scanner.PassToken(LexKind.RParens);
}
else
{
nodePrefix = scanner.Prefix;
nodeName = scanner.Name;
nodeType = PrincipalNodeType(axis);
scanner.NextLex();
if (nodeName == "*")
{
nodeName = null;
}
}
break;
case LexKind.Star:
nodePrefix = null;
nodeName = null;
nodeType = PrincipalNodeType(axis);
scanner.NextLex();
break;
default:
throw scanner.NodeTestExpectedException(scanner.RawValue);
}
}