SearchEngine

Data Object Search Engine

Query Syntax

1. Normal Search

Just inputs the normal words that want to performed in the search action, example by using this statement as query:

Hello world!

And then it will be tokenlize as two words: hello and world, these two words will match any text that contains the string hello or world by default.

1.1 Using Wildcards

This search engine allowed wildcards search: * for any length any characters match, and % allowed just one any character match, example as:

abc*d
abc%d

• abc*d will match abc...blabla...d
• abc%d will match abc.d, and this text abc...blabla...d will match failure.

1.2 Using Regexp

If your query expression its first char is #, then query will be translate as regexp search, for example:

#\d+

this query expression will translate as regexp \d+ match any number string.

1.3 Using Levenshtein

If your query expression its first char is ~, then query will be translate as Levenshtein calculate for string similarity match:

~abcd

~abcd will match any string that looks like to abcd with similarity score 0.85 cutoff.

2. Must have Search

"ABC D"

"ABC D" will match EEEABC DEE as it contains the entire query string ABC D, ABC+D will match failure, as it can not contains ABC D

3. Logical Expression

Query can also using the logical expression for advance search, allowed operators are AND, OR, NOT, and you can also using brackets ( and ) to changes the calculate priority, example:

'#\d+' AND ("ABC D" OR NOT 22)

This query expression can be explained as: the result should match an any length numeric string (\d+) andalso the result should contains the entire string ABC D or not contains number string 22.

4. Field Search

This search engine can specific the search field in the object by specifc the field name, example:

Name:'#\d+' OR ID:55

This query expression can explain as: the query result should found a numeric sub string in the Property which named Name or ID property contains string 55.

Code Usage

1. Build Query Expression

Imports Microsoft.VisualBasic.Data.IO.SearchEngine

' Using the ``Build`` extension function for compile your query string into expression model
Dim query = "#\d+".Build(anyDefault:=Tokens.op_OR, allowInStr:=False)

2. Expression Query

The you can performance the string or object match by using the function in the resulted Expression model:

For test match a string:

Dim result As Boolean = query.Match(text:="23333")

For test match a .NET object:

Dim obj As New NamedValue(Of String) With {
    .Name = "Hello world!",
    .Value = "23333",
    .Description = "Test Object"
}
Dim def As New IObject(GetType(NamedValue(Of String)))

result = query.Evaluate(def, obj)

Then this will makes very easy for integrated this engine into your application if you search for a search engine, example as for test match from a .NET object collection:

Dim def As New IObject(GetType(NamedValue(Of String)))
Dim source As IEnumerable(Of NamedValue(Of String))
Dim query = <user_inputs>.Build(anyDefault:=Tokens.op_OR, allowInStr:=False)

Dim out = From x
          In source
          Where query.Evaluate(def, x)
          Select x

For Each x In out
    ' Display on your Form to show result to your user.
    ' blablabla
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