parser

Documentation

Overview

Package parser provides a PEG parser for parsing IFQL. Parsing an IFQL script produces an AST.

Index

• func NewAST(ifql string, opts ...Option) (*ast.Program, error)
• func Parse(filename string, b []byte, opts ...Option) (interface{}, error)
• func ParseFile(filename string, opts ...Option) (i interface{}, err error)
• func ParseReader(filename string, r io.Reader, opts ...Option) (interface{}, error)
• type Option
  • func GlobalStore(key string, value interface{}) Option
  • func MaxExpressions(maxExprCnt uint64) Option
  • func Recover(b bool) Option
• type Stats

Functions

func NewAST

func NewAST(ifql string, opts ...Option) (*ast.Program, error)

NewAST parses ifql query and produces an ast.Program

func Parse

func Parse(filename string, b []byte, opts ...Option) (interface{}, error)

Parse parses the data from b using filename as information in the error messages.

func ParseFile

func ParseFile(filename string, opts ...Option) (i interface{}, err error)

ParseFile parses the file identified by filename.

func ParseReader

func ParseReader(filename string, r io.Reader, opts ...Option) (interface{}, error)

ParseReader parses the data from r using filename as information in the error messages.

Types

type Option

type Option func(*parser) Option

Option is a function that can set an option on the parser. It returns the previous setting as an Option.

func GlobalStore

func GlobalStore(key string, value interface{}) Option

GlobalStore creates an Option to set a key to a certain value in the globalStore.

func MaxExpressions

func MaxExpressions(maxExprCnt uint64) Option

MaxExpressions creates an Option to stop parsing after the provided number of expressions have been parsed, if the value is 0 then the parser will parse for as many steps as needed (possibly an infinite number).

The default for maxExprCnt is 0.

func Recover

func Recover(b bool) Option

Recover creates an Option to set the recover flag to b. When set to true, this causes the parser to recover from panics and convert it to an error. Setting it to false can be useful while debugging to access the full stack trace.

The default is true.

type Stats

type Stats struct {
	// ExprCnt counts the number of expressions processed during parsing
	// This value is compared to the maximum number of expressions allowed
	// (set by the MaxExpressions option).
	ExprCnt uint64

	// ChoiceAltCnt is used to count for each ordered choice expression,
	// which alternative is used how may times.
	// These numbers allow to optimize the order of the ordered choice expression
	// to increase the performance of the parser
	//
	// The outer key of ChoiceAltCnt is composed of the name of the rule as well
	// as the line and the column of the ordered choice.
	// The inner key of ChoiceAltCnt is the number (one-based) of the matching alternative.
	// For each alternative the number of matches are counted. If an ordered choice does not
	// match, a special counter is incremented. The name of this counter is set with
	// the parser option Statistics.
	// For an alternative to be included in ChoiceAltCnt, it has to match at least once.
	ChoiceAltCnt map[string]map[string]int
}

Stats stores some statistics, gathered during parsing