lang

Documentation

Overview

Package lang is the mcl language frontend that implements the reactive DSL that lets users model their desired state over time.

Index

• Constants
• type Data
• type Lang
  • func (obj *Lang) Cleanup() error
  • func (obj *Lang) Init(ctx context.Context) error
  • func (obj *Lang) Interpret() (*pgraph.Graph, error)
  • func (obj *Lang) Run(ctx context.Context) (reterr error)
  • func (obj *Lang) Stream() <-chan error

Constants

const (
	// EngineStartupStatsTimeout is the amount of time in seconds to wait
	// between engine startup, and loaded event before printing some
	// debugging stats. This is useful for finding bugs in the function
	// engine. Set to zero to disable.
	EngineStartupStatsTimeout = 10
)

Types

type Data

type Data struct {
	// UnificationStrategy is a hack to tune unification performance until
	// we have an overall cleaner unification algorithm in place.
	UnificationStrategy map[string]string
}

Data is some data that is passed into the Lang struct. It is presented here as a single struct with room for multiple fields so that it can be changed or extended in the future without having to re-plumb through all the fields it contains

type Lang

type Lang struct {
	Fs    engine.Fs // connected fs where input dir or metadata exists
	FsURI string

	// Input is a string which specifies what the lang should run. It can
	// accept values in several different forms. If is passed a single dash
	// (-), then it will use `os.Stdin`. If it is passed a single .mcl file,
	// then it will attempt to run that. If it is passed a directory path,
	// then it will attempt to run from there. Instead, if it is passed the
	// path to a metadata file, then it will attempt to parse that and run
	// from that specification. If none of those match, it will attempt to
	// run the raw string as mcl code.
	Input string

	// Data is some additional data for the lang struct.
	Data *Data

	Hostname string
	Local    *local.API
	World    engine.World
	Prefix   string
	Debug    bool
	Logf     func(format string, v ...interface{})
	// contains filtered or unexported fields
}

Lang is the main language lexer/parser object.

func (*Lang) Cleanup

func (obj *Lang) Cleanup() error

Cleanup cleans up and frees memory and resources after everything is done.

func (*Lang) Init

func (obj *Lang) Init(ctx context.Context) error

Init initializes the lang struct, and starts up the initial input parsing. NOTE: The trick is that we need to get the list of funcs to watch AND start watching them, *before* we pull their values, that way we'll know if they changed from the values we wanted.

func (*Lang) Interpret

func (obj *Lang) Interpret() (*pgraph.Graph, error)

Interpret runs the interpreter and returns a graph and corresponding error.

func (*Lang) Run

func (obj *Lang) Run(ctx context.Context) (reterr error)

Run kicks off the function engine. Use the context to shut it down.

func (*Lang) Stream

func (obj *Lang) Stream() <-chan error

Stream returns a channel of graph change requests or errors. These are usually sent when a func output changes.