tomprogers/common-query-parser

A dumb parser for generic query syntax

common query parser

A dumb parser for generic query syntax.

snake plissken -title:"L. A."

I want to find movies with or about Snake Plissken, but not the 1996 movie Escape from L. A.

Query grammar

CQP groks a straightforward query syntax that supports words and phrases, optionally scoped to named fields, with simple negation and escaping.

• terms are separated by spaces, and can contain any other characters

it's pat!

• surround a set of words with quotes to treat it as a single term

the searchers
//> 2 terms: "the" & "searchers"

"the searchers"
//> 1 term: "the searchers"

• prefix any term with a word and a colon to specify a named field for that term

author:niven

title:"The Long ARM of Gil Hamilton"

• as with terms, surround a field name with quotes to treat several words as a single field name

"date modified":2018-02-17

• prefix a term with minus to indicate it is unwanted

-twilight

-"breaking dawn"

-author:"Stephenie Meyer"

• spaces, quotes, colons, and minus signs may be escaped with a backslash (\), which causes them to be treated as normal characters

mission\:impossible
\-273.15°C

Return value

CQP always returns an array, with one element per term recovered from the input string, in source order. Letter case is preserved. Elements are shaped like so:

{
    // only present if term was prefixed with field name & colon
    field: String | undefined

    // the text of the term, excluding any outer quotation marks
    value: String

    // only present if term was prefixed with minus
    negated: true | undefined
}

An example:

import parseQuery from 'common-query-parser'
parseQuery('house of the rising sun -band:"the animals"')

yields:

[
    { value: 'house' },
    { value: 'of' },
    { value: 'the' },
    { value: 'rising' },
    { value: 'sun' },
    { field: 'band', value: 'the animals', negated: true }
]

If no terms could be recovered, an empty array will be returned.

Limitations

CQP does not support boolean operators or logical grouping of any kind.

CQP doesn't doesn't know anything about your data set, and it doesn't provide any logic for filtering a data set.

CQP has not been tested with multi-byte character encodings.

Installation & use

1. Install:

$ yarn add common-query-parser

2. Import & feed it strings:

import parseQuery from 'common-query-parser'

let queryTerms = parseQuery(`house of the rising sun -band:"the animals"`)

Development

Pull requests welcome, as are tickets and good edge cases.

The parser algorithm inspects every character in order in a mode-based way, instead of being built with Regular Expressions or other, more sugary strategies.

Roadmap

The only feature I know I want to add is a second parsing tool that uses boolean-parser-js to parse and recover sets of independently satisfactory criteria from enhanced syntax including boolean operators and grouping with parentheses.

I'm open to other ideas, like better UTF-16 support.

Setup & run

Clone and install dependencies with yarn or npm.

Stylistic stuff

I hate linters. If you intend to submit a PR, make your code look like mine, but above all, format code for clarity.

License

MIT. See the LICENSE file for the legalese.