public ParserIssue[] TryParse(string text, out IContentExpression result)
{
if (text == null)
{
throw new ArgumentNullException(nameof(text));
}
result = null;
var tokens = _tokenizer.Tokenize(text);
try
{
var q = new Queue <DslToken>(tokens);
result = ParseExpression(q, t => false);
return(new ParserIssue[] { });
}
catch (ParserException ex)
{
return(new ParserIssue[]
{
new ParserIssue
{
CodeOrMessage = ex.Message,
Index = ex.Token?.Match.StartIndex ?? (text.Length - 1),
Value = ex.Token?.Value
}
});
}
}
void Test(string text, IContentExpression expected)
{
var parser = new ContentExpressionParser(new Tokenizer());
var issues = parser.TryParse(text, out IContentExpression actual);
Assert.AreEqual(expected, actual);
}
public RegexFilter(IContentExpression value, string regex)
{
if (regex == null)
{
throw new ArgumentNullException(nameof(regex));
}
Value = value ?? throw new ArgumentNullException(nameof(value));
Regex = new Regex(regex, RegexOptions.Compiled);
}
public EqualToFilter(IContentExpression left, IContentExpression right)
{
Left = left ?? throw new ArgumentNullException(nameof(left));
Right = right ?? throw new ArgumentNullException(nameof(right));
}
public OfTypeFilter(IContentExpression value, ContentType contentType)
{
Value = value ?? throw new ArgumentNullException(nameof(value));
ContentType = contentType;
}
IContentExpression ParseExpression(Queue <DslToken> q, Func <DslToken, bool> terminate)
{
IContentExpression exp = null;
while (q.Count > 0)
{
var lookAhead = q.Peek();
if (terminate(lookAhead))
{
break;
}
else if (lookAhead.IsConstant())
{
if (exp != null)
{
throw new ParserException($"Unexpected token", lookAhead);
}
var token = q.DequeueAndValidate(Utils.ConstantTokens);
exp = CreateConstant(token);
}
else if (lookAhead.TokenType == TokenType.Equals)
{
if (exp == null)
{
throw new ParserException($"Unexpected token", lookAhead);
}
var token = q.DequeueAndValidate(TokenType.Equals);
exp = new EqualToFilter(exp,
ParseExpression(q, t => t.TokenType == TokenType.And || t.TokenType == TokenType.Or || terminate(t)));
}
else if (lookAhead.TokenType == TokenType.Contains)
{
if (exp == null)
{
throw new ParserException($"Unexpected token", lookAhead);
}
var token = q.DequeueAndValidate(TokenType.Contains);
exp = new ContainsFilter(exp,
ParseExpression(q, t => t.TokenType == TokenType.And || t.TokenType == TokenType.Or || terminate(t)));
}
else if (lookAhead.TokenType == TokenType.MatchRegex)
{
if (exp == null)
{
throw new ParserException($"Unexpected token", lookAhead);
}
var token = q.DequeueAndValidate(TokenType.MatchRegex);
var pattern = q.DequeueAndValidate(TokenType.String);
exp = new RegexFilter(exp, pattern.Value);
}
else if (lookAhead.TokenType == TokenType.And)
{
if (exp == null)
{
throw new ParserException($"Unexpected token", lookAhead);
}
var token = q.DequeueAndValidate(TokenType.And);
if (exp is IContentFilter leftBool)
{
var right = ParseExpression(q, terminate);
if (right is IContentFilter rightBool)
{
exp = new AndFilter(leftBool, rightBool);
}
else
{
throw new ParserException("AND cannot have a right operand that does not yield boolean", token);
}
}
else
{
throw new ParserException("AND cannot have a left operand that does not yield boolean", token);
}
}
else if (lookAhead.TokenType == TokenType.Or)
{
if (exp == null)
{
throw new ParserException($"Unexpected token", lookAhead);
}
var token = q.DequeueAndValidate(TokenType.Or);
if (exp is IContentFilter leftBool)
{
var right = ParseExpression(q, terminate);
if (right is IContentFilter rightBool)
{
exp = new OrFilter(leftBool, rightBool);
}
else
{
throw new ParserException("OR cannot have a right operand that does not yield boolean", token);
}
}
else
{
throw new ParserException("OR cannot have a left operand that does not yield boolean", token);
}
}
else if (lookAhead.TokenType == TokenType.Path)
{
if (exp == null)
{
throw new ParserException($"Unexpected token", lookAhead);
}
var token = q.DequeueAndValidate(TokenType.Path);
exp = new PathExpression(exp, ContentPath.Parse($"$.{token.Value.TrimStart('.')}"));
}
else if (lookAhead.TokenType == TokenType.DollarSign)
{
if (exp != null)
{
throw new ParserException($"Unexpected token", lookAhead);
}
q.DequeueAndValidate(TokenType.DollarSign);
exp = new ScopeRootExpression();
}
else if (lookAhead.TokenType == TokenType.OpenCurly)
{
if (exp != null)
{
throw new ParserException($"Unexpected token", lookAhead);
}
exp = CreateObjectExpression(q);
}
else if (lookAhead.TokenType == TokenType.OpenSquareBracket)
{
if (exp != null)
{
throw new ParserException($"Unexpected token", lookAhead);
}
exp = CreateListExpression(q);
}
else if (lookAhead.TokenType == TokenType.OpenBracket)
{
if (exp != null)
{
throw new ParserException($"Unexpected token", lookAhead);
}
q.DequeueAndValidate(TokenType.OpenBracket); // open bracket (
exp = ParseExpression(q, t => t.TokenType == TokenType.CloseBracket);
q.DequeueAndValidate(TokenType.CloseBracket); // close bracket )
}
else
{
throw new ParserException($"Unexpected token", lookAhead);
}
}
if (exp == null)
{
throw new ParserException($"Unexpected end", null);
}
return(exp);
}
public ContainsWhereFilter(IContentExpression list, IContentFilter item)
{
List = list ?? throw new ArgumentNullException(nameof(list));
ItemFilter = item ?? throw new ArgumentNullException(nameof(item));
}
