activations

Documentation

Overview

Package activations implements data structures that can be used when dealing with program scopes.

Index

• type Activation
  • func NewActivation(parent *Activation) *Activation
  • func (a *Activation) Find(name string) interface{}
  • func (a *Activation) ForEach(cb func(string, interface{}) error) error
  • func (a *Activation) Set(name string, value interface{})
• type Activations
  • func (a *Activations) Current() *Activation
  • func (a *Activations) CurrentOrNew() *Activation
  • func (a *Activations) Depth() int
  • func (a *Activations) Find(key string) interface{}
  • func (a *Activations) Pop()
  • func (a *Activations) Push(activation *Activation)
  • func (a *Activations) PushNewWithCurrent()
  • func (a *Activations) PushNewWithParent(parent *Activation) *Activation
  • func (a *Activations) Set(name string, value interface{})

Types

type Activation

type Activation struct {
	Depth  int
	Parent *Activation
	// contains filtered or unexported fields
}

An Activation is a map of strings to arbitrary values. It can be used to represent an active scope in a program, i.e. it can be used as a symbol table during semantic analysis, or as an activation record during interpretation.

func NewActivation

func NewActivation(parent *Activation) *Activation

func (*Activation) Find

func (a *Activation) Find(name string) interface{}

Find returns the value for a given key in the activation. It returns nil if no value is found.

func (*Activation) ForEach

func (a *Activation) ForEach(cb func(string, interface{}) error) error

ForEach calls the given function for each entry (key-value pair) in the activation. It can be used to iterate over all entries of the activation.

func (*Activation) Set

func (a *Activation) Set(name string, value interface{})

Set sets the given key-value pair in the activation.

type Activations

type Activations struct {
	// contains filtered or unexported fields
}

Activations is a stack of activation records. Each entry represents a new ac.

The current / most nested activation record can be found at the top of the stack (see function `current`).

Each activation in the stack contains *all* active records – there is no need to traverse to parent records. This is implemented efficiently by using immutable maps that share data with their parents.

func (*Activations) Current

func (a *Activations) Current() *Activation

Current returns the current / most nested activation, which can be found at the top of the stack. It returns nil if there is no active activation.

func (*Activations) CurrentOrNew

func (a *Activations) CurrentOrNew() *Activation

CurrentOrNew returns the current activation, or if it does not exists, a new activation

func (*Activations) Depth

func (a *Activations) Depth() int

Depth returns the depth (size) of the activation stack.

func (*Activations) Find

func (a *Activations) Find(key string) interface{}

Find returns the value for a given key in the current activation. It returns nil if no value is found or if there is no current activation.

func (*Activations) Pop

func (a *Activations) Pop()

Pop pops the top-most (current) activation from the top of the activation stack.

func (*Activations) Push

func (a *Activations) Push(activation *Activation)

Push pushes the given activation onto the top of the activation stack.

func (*Activations) PushNewWithCurrent

func (a *Activations) PushNewWithCurrent()

PushNewWithCurrent pushes a new empty activation to the top of the activation stack. The new activation has the current activation as its parent.

func (*Activations) PushNewWithParent

func (a *Activations) PushNewWithParent(parent *Activation) *Activation

PushNewWithParent pushes a new empty activation to the top of the activation stack. The new activation has the given parent as its parent.

func (*Activations) Set

func (a *Activations) Set(name string, value interface{})

Set sets the key value pair int the current scope.