https://github.com/baranasoftware/query-parser
A Go library (lexer and parser) for parsing query parameters.
https://github.com/baranasoftware/query-parser
Last synced: 3 months ago
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A Go library (lexer and parser) for parsing query parameters.
- Host: GitHub
- URL: https://github.com/baranasoftware/query-parser
- Owner: baranasoftware
- Created: 2024-09-30T17:33:27.000Z (8 months ago)
- Default Branch: main
- Last Pushed: 2025-03-13T01:27:05.000Z (3 months ago)
- Last Synced: 2025-03-13T01:31:36.611Z (3 months ago)
- Language: Go
- Homepage:
- Size: 7.81 KB
- Stars: 0
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
# Reference Materials
* [Let's make a Teeny Tiny compiler series](https://austinhenley.com/blog/teenytinycompiler1.html)
* [Writing A Compiler In Go](https://compilerbook.com/)
* [Crafting Interpreters](https://craftinginterpreters.com/)
* [Pratt Parsers](https://journal.stuffwithstuff.com/2011/03/19/pratt-parsers-expression-parsing-made-easy/)
* [Demystifying Pratt Parsers](https://martin.janiczek.cz/2023/07/03/demystifying-pratt-parsers.html)
# Lexer and Parser for Parsing Query Parameters
A lexer and parser (API) for parsing REST query parameters.
`?filter=expression`
| Operation | Function | Example |
|-----------------------------------|-------------------|-------------------------------------------------------|
| Equality | `equals` | `?filter=equals(lastName,'Smith')` |
| Less than | `lessThan` | `?filter=lessThan(age,'25')` |
| Less than or equal to | `lessOrEqual` | `?filter=lessOrEqual(lastModified,'2001-01-01')` |
| Greater than | `greaterThan` | `?filter=greaterThan(duration,'6:12:14')` |
| Greater than or equal to | `greaterOrEqual` | `?filter=greaterOrEqual(percentage,'33.33')`
| Contains text | `contains` | `?filter=contains(description,'cooking')` |
| Starts with text | `startsWith` | `?filter=startsWith(description,'The')`
| Ends with text | `endsWith` | `?filter=endsWith(description,'End')` |
| Equals one value from set | `any` | `?filter=any(chapter,'Intro','Summary','Conclusion')` |
| Collection contains items | `has` | `?filter=has(articles)` |
| Negation | `not` | `?filter=not(equals(lastName,null))` |
| Conditional logical OR | `or` | `?filter=or(has(orders),has(invoices))` |
| Conditional logical AND | `and` | `?filter=and(has(orders),has(invoices))` |
## Notes
* Comparison operators compare an attribute against a constant value (between quotes), null or another attribute:
`GET /users?filter=equals(displayName,'Brian Connor') HTTP/1.1`
`GET /users?filter=equals(displayName,null) HTTP/1.1`
`GET /users?filter=equals(displayName,lastName) HTTP/1.1`
* Comparison operators can be combined with the count function, which acts on to-many relationships:
`GET /customers?filter=greaterThan(count(orders),count(invoices)) HTTP/1.1`
`GET /blogs?filter=lessThan(count(owner.articles),'10') HTTP/1.1`
* Complex filter:
`GET /blogs?include=owner.articles.revisions&filter=and(or(equals(title,'Technology'),has(owner.articles)),not(equals(owner.lastName,null)))&filter[owner.articles]=equals(caption,'Two')&filter[owner.articles.revisions]=greaterThan(publishTime,'2005-05-05') HTTP/1.1`
## Grammar
```
grammar Filter;
filterExpression:
notExpression
| logicalExpression
| comparisonExpression
| matchTextExpression
| anyExpression
| hasExpression;
notExpression:
'not' LPAREN filterExpression RPAREN;
logicalExpression:
( 'and' | 'or' ) LPAREN filterExpression ( COMMA filterExpression )* RPAREN;
comparisonExpression:
( 'equals' | 'greaterThan' | 'greaterOrEqual' | 'lessThan' | 'lessOrEqual' ) LPAREN (
countExpression | fieldChain
) COMMA (
countExpression | literalConstant | 'null' | fieldChain
) RPAREN;
matchTextExpression:
( 'contains' | 'startsWith' | 'endsWith' ) LPAREN fieldChain COMMA literalConstant RPAREN;
anyExpression:
'any' LPAREN fieldChain ( COMMA literalConstant )+ RPAREN;
hasExpression:
'has' LPAREN fieldChain ( COMMA filterExpression )? RPAREN;
countExpression:
'count' LPAREN fieldChain RPAREN;
fieldChain:
FIELD ( '.' FIELD )*;
literalConstant:
ESCAPED_TEXT;
LPAREN: '(';
RPAREN: ')';
COMMA: ',';
fragment OUTER_FIELD_CHARACTER: [A-Za-z0-9];
fragment INNER_FIELD_CHARACTER: [A-Za-z0-9_-];
FIELD: OUTER_FIELD_CHARACTER ( INNER_FIELD_CHARACTER* OUTER_FIELD_CHARACTER )?;
ESCAPED_TEXT: '\'' ( ~['] | '\'\'' )* '\'' ;
LINE_BREAKS: [\r\n]+ -> skip;
```