private static ExpressionChain CombineHighestPriorityLogicalOperatorsIntoSubExpressions(ExpressionChain expressionChain)
{
var operatorPriorities = expressionChain.Operators.Select(GetLogicalOperatorPriority).ToList();
var highestOperatorPriority = operatorPriorities.Max();
var newExpressions = new List <ISearchExpression>();
var newOperators = new List <string>();
var leftExpression = expressionChain.Expressions[0];
for (var operatorIndex = 0; operatorIndex < expressionChain.Operators.Count; operatorIndex++)
{
var logicalOperator = expressionChain.Operators[operatorIndex];
var operatorPriority = GetLogicalOperatorPriority(logicalOperator);
var rightExpression = expressionChain.Expressions[operatorIndex + 1];
if (operatorPriority == highestOperatorPriority)
{
leftExpression = CombineExpressions(leftExpression, logicalOperator, rightExpression);
}
else
{
newExpressions.Add(leftExpression);
newOperators.Add(logicalOperator);
leftExpression = rightExpression;
}
}
newExpressions.Add(leftExpression);
return(new ExpressionChain(newExpressions, newOperators));
}
public ExpressionChain SplitIntoExpressions(string stripped, string[] keywords)
{
var topLevelClause = string.Empty;
var subExpressions = new List <SubSearchExpression>();
var openParenthesisCount = 0;
var currentSubExpression = string.Empty;
const string SubExpressionKeyword = "subexpression";
var subexpressionPattern = $@"\[{SubExpressionKeyword}(?<idx>[0-9]+)\]";
if (Regex.IsMatch(stripped, $".*{subexpressionPattern}.*"))
{
throw new FormatException(); // Query contains our magic subexpression keyword
}
foreach (var c in stripped)
{
if (c == '(')
{
openParenthesisCount++;
if (openParenthesisCount == 1)
{
continue;
}
}
if (c == ')')
{
openParenthesisCount--;
if (openParenthesisCount == 0)
{
topLevelClause += $"[{SubExpressionKeyword}{subExpressions.Count}]";
subExpressions.Add(new SubSearchExpression(currentSubExpression));
currentSubExpression = string.Empty;
continue;
}
}
var isSubExpression = openParenthesisCount > 0;
if (isSubExpression)
{
currentSubExpression += c;
}
else
{
topLevelClause += c;
}
}
var topLevelExpressions = topLevelClause.Split(keywords, StringSplitOptions.None).Select(x => x.Trim()).ToList();
var expressions = new List <ISearchExpression>();
foreach (var topLevelExpression in topLevelExpressions)
{
var pureSubExpressionMatch = Regex.Match(topLevelExpression, $"^{subexpressionPattern}$");
if (pureSubExpressionMatch.Success)
{
var subExpressionIdx = int.Parse(pureSubExpressionMatch.Groups["idx"].Value);
expressions.Add(subExpressions[subExpressionIdx]);
}
else
{
var partialSubExpressionMatch = Regex.Match(topLevelExpression, subexpressionPattern);
if (partialSubExpressionMatch.Success)
{
var subExpressionIdx = int.Parse(partialSubExpressionMatch.Groups["idx"].Value);
var subExpression = subExpressions[subExpressionIdx];
var subExpressionReplaced = Regex.Replace(
topLevelExpression,
subexpressionPattern,
$"({subExpression.Value})");
expressions.Add(new SearchExpression(subExpressionReplaced));
}
else
{
expressions.Add(new SearchExpression(topLevelExpression));
}
}
}
var detectedKeywords = keywords
.SelectMany(keyword => topLevelClause.AllIndicesOf(keyword).Select(idx => new
{
Keyword = keyword.Trim(),
Index = idx
}))
.OrderBy(x => x.Index)
.Select(x => x.Keyword)
.ToList();
var candidateChain = new ExpressionChain(expressions, detectedKeywords);
if (!candidateChain.Operators.Any() &&
candidateChain.Expressions.Count == 1 &&
candidateChain.Expressions.Single() is SubSearchExpression)
{
return(SplitIntoExpressions(candidateChain.Expressions.Single().Value, DataApiSqlOperators.LogicalOperators));
}
return(candidateChain);
}
