README
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Arc API filter parser
This package contains a parser to transform the filter syntax exposed by the API to a filter expression that can by used by the underlying fact storage system.
As we currently store the facts in a postgresql cloumn of type jsonb the parser currently produces a WHERE clause that uses postgresql specifc json operators.
Example:
fact1 = "1" OR fact2 != 2
is transformed to
( facts->>'fact1' = '1' OR (facts->>'fact2')::numeric <> 2 )
Implementation details
Both the lexer and parser are auto generated. The generated output parser.go and lexer.go are checked into version control, so unless you want to change the parser you don't need to bother with the following.
The lexer is generated using nex from the file filter.nex. It can be installed with go get https://github.com/blynn/nex
The parser is generated using go's yacc implmentation go tool yacc from the file filter.y. It comes with a standard go installation.
The filter.go file contains //go:generate stanzas to generate both the lexer and the parser for you. To modify the parser you just need to edit filter.y or filter.nex and run go generate in the package directory.
Documentation
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Index ¶
Constants ¶
const AND = 57351
const FIELD = 57346
const NEQ = 57349
const NLIKE = 57350
const NOT = 57353
const NUMBER = 57348
const OR = 57352
const STRING = 57347
Variables ¶
This section is empty.
Functions ¶
func Postgresql ¶
Types ¶
type Lexer ¶
type Lexer struct {
// contains filtered or unexported fields
}
func NewLexerWithInit ¶
NewLexerWithInit creates a new Lexer object, runs the given callback on it, then returns it.
func (*Lexer) Lex ¶
Lex runs the lexer. Always returns 0. When the -s option is given, this function is not generated; instead, the NN_FUN macro runs the lexer.
Source Files