/*
 * Public Domain Software
 *
 * I (Matthias Ladkau) am the author of the source code in this file.
 * I have placed the source code in this file in the public domain.
 *
 * For further information see: http://creativecommons.org/publicdomain/zero/1.0/
 */

package parser

/*
RuntimeProvider provides runtime components for a parse tree.
*/
type RuntimeProvider interface {

	/*
	   Runtime returns a runtime component for a given ASTNode.
	*/
	Runtime(node *ASTNode) Runtime
}

/*
Runtime provides the runtime for an ASTNode.
*/
type Runtime interface {

	/*
	   Validate this runtime component and all its child components.
	*/
	Validate() error

	/*
		Eval evaluate this runtime component. It gets passed the current variable
		scope and the instance state.

		The instance state is created per execution instance and can be used
		for generator functions to store their current state.
	*/
	Eval(Scope, map[string]interface{}) (interface{}, error)
}

/*
Scope models an environment which stores data.
*/
type Scope interface {

	/*
	   NewChild creates a new child scope.
	*/
	NewChild(name string) Scope

	/*
	   Parent returns the parent scope or nil.
	*/
	Parent() Scope

	/*
	   SetValue sets a new value for a variable.
	*/
	SetValue(varName string, varValue interface{}) error

	/*
	   GetValue gets the current value of a variable.
	*/
	GetValue(varName string) (interface{}, bool, error)

	/*
	   String returns a string representation of this scope.
	*/
	String() string
}