org.eclipse.epsilon.eol.execute.context

Class FrameStack

java.lang.Object

org.eclipse.epsilon.eol.execute.context.FrameStack

public class FrameStack
extends Object

A FrameStack is a stack of frames that stores the variables created during the execution of an EOL program.

A FrameStack is divided into two distinct regions, one for global variables and one for local variables. The global region always contains at least one frame, while the local region can be empty.

Version:

1.1

Author:

Dimitrios Kolovos, Antonio García-Domínguez

See Also:

Frame

Field Summary

Fields

Modifier and Type	Field and Description
protected HashMap<String,Variable>	builtInVariables
protected org.eclipse.epsilon.eol.execute.context.FrameStackRegion	globals
protected org.eclipse.epsilon.eol.execute.context.FrameStackRegion	locals

Constructor Summary

Constructors

Constructor and Description
FrameStack() Creates a new frame stack

Method Summary

Modifier and Type	Method and Description
FrameStack	clone()
boolean	contains(String name) Returns true if a variable with the specified name exists in the scope
boolean	containsGlobal(String name) Returns true if a global variable with the specified name exists.
boolean	containsLocal(String name) Returns true if a local variable with the specified name exists.
protected int	countGlobalFrames()
void	dispose()
Frame	enter(FrameType type, ModuleElement entryPoint, Variable... variables) Deprecated. Use #enterLocal(FrameType, AST, Variable...) instead. This method will be removed from a future version of Epsilon.
Frame	enterGlobal(FrameType type, ModuleElement entryPoint, Variable... variables) Enters a new global frame.
Frame	enterLocal(FrameType type, ModuleElement entryPoint, Variable... variables) Enters a new local frame.
Variable	get(String name) Returns the variable with the specified name and if it does not exist returns null.
ModuleElement	getCurrentStatement()
int	getDepth()
List<SingleFrame>	getFrames() Returns a list with all local (from top to bottom) and global (from top to bottom) stack frames, in that order.
Variable	getGlobal(String name) Returns the global variable with the specified name If the global variable does not exist, this method returns null.
Frame	getGlobals() Deprecated. Use the designated methods for manipulating global variables (e.g. #enterGlobal(FrameType, AST, Variable...), putGlobal(Variable) and getGlobal(String)). If no appropriate method exists, please open a bug report to request it. This method will be removed in a future version of Epsilon.
Variable	getLocal(String name) Returns the local variable with the specified name If the local variable does not exist, this method returns null.
Frame	getTopFrame()
boolean	isInLoop()
void	leave(ModuleElement entryPoint) Deprecated. Use #leaveLocal(AST) instead. This method will be removed from a future version of Epsilon.
void	leave(ModuleElement entryPoint, boolean dispose) Deprecated. Use #leaveLocal(AST, boolean) instead. This method will be removed from a future version of Epsilon.
void	leaveGlobal(ModuleElement entryPoint) Convenience method for #leaveGlobal(AST, boolean) which disposes of the global stack frame that was left.
void	leaveGlobal(ModuleElement entryPoint, boolean dispose) Leaves the current global stack frame and returns to the previous frame in the stack.
void	leaveLocal(ModuleElement entryPoint) Convenience method for #leaveLocal(AST, boolean)) which disposes of the stack frame that was left.
void	leaveLocal(ModuleElement entryPoint, boolean dispose) Leaves the current local frame and returns to the previous frame in the stack.
void	put(Variable... variables) Puts one or more new variables in the topmost frame of the scope.
void	put(Variable variable) Puts a new variable in the topmost frame of the scope.
void	putGlobal(Variable... variables) Puts one or more new variables in the topmost global stack frame.
void	putGlobal(Variable variable) Puts a new variable in the topmost global stack frame.
void	remove(String variable) Removes a variable by name from the topmost frame of the scope.
void	setCurrentStatement(ModuleElement ast)
String	toString()

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

globals

protected org.eclipse.epsilon.eol.execute.context.FrameStackRegion globals

locals

protected org.eclipse.epsilon.eol.execute.context.FrameStackRegion locals

builtInVariables

protected HashMap<String,Variable> builtInVariables

Constructor Detail

FrameStack

public FrameStack()

Creates a new frame stack

Method Detail

dispose

public void dispose()

enterGlobal

public Frame enterGlobal(FrameType type,
                         ModuleElement entryPoint,
                         Variable... variables)

Enters a new global frame.

Parameters:

type - The type of the frame: variables in lower stack frames are visible from an FrameType.UNPROTECTED frame, and invisible from a FrameType.PROTECTED frame.

entryPoint - The AST from which the entry is performed

variables - Zero or more variables that will be added to the new frame.

enterLocal

public Frame enterLocal(FrameType type,
                        ModuleElement entryPoint,
                        Variable... variables)

Enters a new local frame.

Parameters:

type - The type of the frame: variables in lower stack frames are visible from an FrameType.UNPROTECTED frame, and invisible from a FrameType.PROTECTED frame.

entryPoint - The AST from which the entry is performed

variables - Zero or more variables that will be added to the new frame.

Returns:

enter

public Frame enter(FrameType type,
                   ModuleElement entryPoint,
                   Variable... variables)

Deprecated. Use #enterLocal(FrameType, AST, Variable...) instead. This method will be removed from a future version of Epsilon.

Enters a new local frame.

leaveLocal

public void leaveLocal(ModuleElement entryPoint,
                       boolean dispose)

Leaves the current local frame and returns to the previous frame in the stack. This method cannot leave a global stack frame: use #leaveGlobal(AST, boolean) for that.

leaveLocal

public void leaveLocal(ModuleElement entryPoint)

Convenience method for #leaveLocal(AST, boolean)) which disposes of the stack frame that was left.

leaveGlobal

public void leaveGlobal(ModuleElement entryPoint,
                        boolean dispose)

Leaves the current global stack frame and returns to the previous frame in the stack. This method cannot leave a local stack frame: use #leaveLocal(AST, boolean) for that. This method will not leave the last remaining global stack frame.

leaveGlobal

public void leaveGlobal(ModuleElement entryPoint)

Convenience method for #leaveGlobal(AST, boolean) which disposes of the global stack frame that was left.

leave

public void leave(ModuleElement entryPoint,
                  boolean dispose)

Deprecated. Use #leaveLocal(AST, boolean) instead. This method will be removed from a future version of Epsilon.

Leaves the current local frame and returns to the previous frame in the stack.

leave

public void leave(ModuleElement entryPoint)

Deprecated. Use #leaveLocal(AST) instead. This method will be removed from a future version of Epsilon.

Convenience method for #leaveLocal(AST) which disposes of the stack frame that was left.

put

public void put(Variable... variables)

Puts one or more new variables in the topmost frame of the scope. Note that the topmost frame can be either a local or a global frame, depending on the current state of the FrameStack.

put

public void put(Variable variable)

Puts a new variable in the topmost frame of the scope. Note that the topmost frame can be either a local or a global frame, depending on the current state of the FrameStack.

putGlobal

public void putGlobal(Variable... variables)

Puts one or more new variables in the topmost global stack frame.

putGlobal

public void putGlobal(Variable variable)

Puts a new variable in the topmost global stack frame.

remove

public void remove(String variable)

Removes a variable by name from the topmost frame of the scope. Note that the topmost frame can be either a local or a global frame, depending on the current state of the FrameStack.

get

public Variable get(String name)

Returns the variable with the specified name and if it does not exist returns null. Note that variables in a higher frame shadow variables with the same name in lower frames. Similarly, local variables shadow global variables with the same name.

Parameters:

name - The name of the variable

Returns:

The variable with the specified name or null

getLocal

public Variable getLocal(String name)

Returns the local variable with the specified name If the local variable does not exist, this method returns null.

Note: this method does not respect the usual shadowing semantics of the FrameStack, and consequently most clients should call get(String) (i.e., only call this method if you really know what you are doing!)

Parameters:

name - The name of the local variable

Returns:

The local variable with the specified name or null

getGlobal

public Variable getGlobal(String name)

Returns the global variable with the specified name If the global variable does not exist, this method returns null.

Note: this method does not respect the usual shadowing semantics of the FrameStack, and consequently most clients should call get(String) (i.e., only call this method if you really know what you are doing!)

Parameters:

name - The name of the global variable

Returns:

The global variable with the specified name or null

isInLoop

public boolean isInLoop()

contains

public boolean contains(String name)

Returns true if a variable with the specified name exists in the scope

Parameters:

name -

Returns:

containsLocal

public boolean containsLocal(String name)

Returns true if a local variable with the specified name exists.

Note: this method does not respect the usual shadowing semantics of the FrameStack, and consequently most clients should call contains(String) (i.e., only call this method if you really know what you are doing!)

Parameters:

name -

Returns:

containsGlobal

public boolean containsGlobal(String name)

Returns true if a global variable with the specified name exists.

Note: this method does not respect the usual shadowing semantics of the FrameStack, and consequently most clients should call contains(String) (i.e., only call this method if you really know what you are doing!)

Parameters:

name -

Returns:

getGlobals

@Deprecated
public Frame getGlobals()

Deprecated. Use the designated methods for manipulating global variables (e.g. #enterGlobal(FrameType, AST, Variable...), putGlobal(Variable) and getGlobal(String)). If no appropriate method exists, please open a bug report to request it. This method will be removed in a future version of Epsilon.

Returns a single frame containing all global variables. Note that this representation does not allow clients to determine in which global frame a variable resides. This method is provided only for backwards-compatibility reasons: previous version of EOL did not support multiple global variable frames.

getFrames

public List<SingleFrame> getFrames()

Returns a list with all local (from top to bottom) and global (from top to bottom) stack frames, in that order.

getDepth

public int getDepth()

clone

public FrameStack clone()

Overrides:

clone in class Object

toString

public String toString()

Overrides:

toString in class Object

getTopFrame

public Frame getTopFrame()

getCurrentStatement

public ModuleElement getCurrentStatement()

setCurrentStatement

public void setCurrentStatement(ModuleElement ast)

countGlobalFrames

protected int countGlobalFrames()