ESCEnvironment

Extends: Object

Description

Class to track variables and their associated scopes within a script.

Scoping is implemented using this class, including traditional scoping rules. Scope binding and resolution are handled in this class.

Members

Methods

init

func init(enclosing: Variant) -> void

Initializes the scope and sets the scope which encloses this one.

Parameters

Name	Type	Description	Required?
enclosing	`Variant`	Optional parent environment used to resolve lookups outside this scope.	yes

Returns

Returns nothing.

cleanup

func cleanup() -> void

is_valid_key

func is_valid_key(name: ESCToken) -> Variant

Determines whether the specified key (i.e. the script variable’s name) is valid either within this scope or an enclosing scope.

Parameters

Name	Type	Description	Required?
name	`ESCToken`	Token describing the variable name to look up.	yes

Returns

Returns true if the variable exists in this scope or an enclosing scope, otherwise false. (bool)

get_value

func get_value(name: ESCToken) -> Variant

Fetches the value of the specified key (i.e. the script variable) from this scope or an enclosing one. otherwise, an error is produced

Parameters

Name	Type	Description	Required?
name	`ESCToken`	Token describing the variable name whose value is requested.	yes

Returns

Returns the value associated with the variable name, or produces an error if undefined. (Variant)

assign

func assign(name: ESCToken, value: Variant) -> Variant

Assigns a value to the specified key (i.e. the script variable) from this scope or an enclosing one.

Parameters

Name	Type	Description	Required?
name	`ESCToken`	Token describing the variable name to assign.	yes
value	`Variant`	the value to be assigned to the script variable	yes

Returns

Returns nothing on success, or produces an error if the variable is undefined in all scopes.

define

func define(name: String, value: Variant) -> void

Defines a script variable in this scope and assigns it a value.

Parameters

Name	Type	Description	Required?
name	`String`	Variable name to register in this scope.	yes
value	`Variant`	the value to be assigned to the script variable	yes

Returns

Returns nothing.

ancestor

func ancestor(distance: int) -> Variant

Fetches the scope (environment) that is distance levels up the enclosing scope chain.

Parameters

Name	Type	Description	Required?
distance	`int`	The number of levels up the scope chain to traverse. `distance == 0` returns this scope (self); `distance == 1` returns the immediate enclosing scope; `distance == 2` returns the enclosing scope’s enclosing scope, etc.	yes

Returns

Returns the environment (scope) at the specified distance up the enclosing scope chain. (ESCEnvironment)

get_at

func get_at(distance: int, name: String) -> Variant

Gets the value of the script variable (if it exists) that is at most distance levels above this one.

Parameters

Name	Type	Description	Required?
distance	`int`	The number of scope levels to traverse; e.g. `distance == 0` is this scope, `distance == 1` is the enclosing scope, `distance == 2` is the enclosing scope’s enclosing scope, etc.	yes
name	`String`	Variable name to resolve at the requested scope depth.	yes

Returns

Returns the value of the variable at the specified scope distance. (Variant)

assign_at

func assign_at(distance: int, name: ESCToken, value: Variant) -> void

Assigns the specified value to the script variable (if it exists) that is at most distance levels above this one.

Parameters

Name	Type	Description	Required?
distance	`int`	the number of scope levels to traverse; e.g. `distance == 0` is this scope, `distance == 1` is the enclosing scope, `distance == 2` is the enclosing scope’s enclosing scope, etc.	yes
name	`ESCToken`	Token describing the variable name to modify at the requested scope depth.	yes
value	`Variant`	the value to assign to the script variable	yes

Returns

Returns nothing. (void)

get_enclosing

func get_enclosing() -> Variant

The enclosing scope (environment) for this scope.

Parameters

None.

Returns

Returns the enclosing scope (environment) for this scope. (Variant)

get_values

func get_values() -> Variant

The dictionary storing all script variables and their associated values located at this scope’s level.

Parameters

None.

Returns

Returns the dictionary storing all script variables and their associated values located at this scope’s level. (Dictionary)