Class SimpleQueryParser

SimpleQueryParser is used to parse human readable query syntax.

The main idea behind this parser is that a person should be able to type whatever they want to represent a query, and this parser will do its best to interpret what to search for no matter how poorly composed the request may be. Tokens are considered to be any of a term, phrase, or subquery for the operations described below. Whitespace including ' ' '\n' '\r' and '\t' and certain operators may be used to delimit tokens ( ) + | " .

Any errors in query syntax will be ignored and the parser will attempt to decipher what it can; however, this may mean odd or unexpected results.

Query Operators

  • '+' specifies AND operation: token1+token2
  • '|' specifies OR operation: token1|token2
  • '-' negates a single token: -token0
  • '"' creates phrases of terms: "term1 term2 ..."
  • '' at the end of terms specifies prefix query: term
  • '~N' at the end of terms specifies fuzzy query: term~1
  • '~N' at the end of phrases specifies near query: "term1 term2"~5
  • '(' and ')' specifies precedence: token1 + (token2 | token3)

The default operator is OR if no other operator is specified. For example, the following will OR token1 and token2 together: token1 token2

Normal operator precedence will be simple order from right to left. For example, the following will evaluate token1 OR token2 first, then AND with token3:

token1 | token2 + token3

Escaping

An individual term may contain any possible character with certain characters requiring escaping using a '</code>'. The following characters will need to be escaped in terms and phrases: + | " ( ) ' </code>

The '-' operator is a special case. On individual terms (not phrases) the first character of a term that is - must be escaped; however, any '-' characters beyond the first character do not need to be escaped. For example:

  • -term1 -- Specifies NOT operation against term1
  • -term1 -- Searches for the term -term1.
  • term-1 -- Searches for the term term-1.
  • term-1 -- Searches for the term term-1.

The '' operator is a special case. On individual terms (not phrases) the last character of a term that is '' must be escaped; however, any '' characters before the last character do not need to be escaped:

  • term1 -- Searches for the prefix term1
  • term1* -- Searches for the term term1
  • term1 -- Searches for the term term1
  • term*1 -- Searches for the term term1

Note that above examples consider the terms before text processing.

Inheritance
System.Object
QueryBuilder
SimpleQueryParser
Inherited Members
System.Object.ToString()
System.Object.Equals(System.Object)
System.Object.Equals(System.Object, System.Object)
System.Object.ReferenceEquals(System.Object, System.Object)
System.Object.GetHashCode()
System.Object.GetType()
System.Object.MemberwiseClone()
Assembly: Lucene.Net.QueryParser.dll
Syntax
[Serializable]
public class SimpleQueryParser : QueryBuilder

Constructors

Name Description
SimpleQueryParser(Analyzer, IDictionary<String, Single>)

Creates a new parser searching over multiple fields with different weights.
SimpleQueryParser(Analyzer, IDictionary<String, Single>, Operator)

Creates a new parser with custom flags used to enable/disable certain features.
SimpleQueryParser(Analyzer, String)

Creates a new parser searching over a single field.

Fields

Name Description
m_flags

flags to the parser (to turn features on/off)
m_weights

Map of fields to query against with their weights

Properties

Name Description
DefaultOperator

Gets or Sets the implicit operator setting, which will be either SHOULD or MUST.

Methods

Name Description
NewDefaultQuery(String)

Factory method to generate a standard query (no phrase or prefix operators).
NewFuzzyQuery(String, Int32)

Factory method to generate a fuzzy query.
NewPhraseQuery(String, Int32)

Factory method to generate a phrase query with slop.
NewPrefixQuery(String)

Factory method to generate a prefix query.
Parse(String)

Parses the query text and returns parsed query (or null if empty)
Simplify(BooleanQuery)

Helper to simplify boolean queries with 0 or 1 clause

Extension Methods