org.codehaus.groovy.classgen
Class CompileStack

java.lang.Object
  org.codehaus.groovy.classgen.CompileStack

All Implemented Interfaces:

org.objectweb.asm.Opcodes

class CompileStack
extends Object

This class is a helper for AsmClassGenerator. It manages different aspects of the code of a code block like handling labels, defining variables, and scopes. After a MethodNode is visited clear should be called, for initialization the method init should be used.

Some Notes:

• every push method will require a later pop call
• method parameters may define a category 2 variable, so don't ignore the type stored in the variable object
• the index of the variable may not be as assumed when the variable is a parameter of a method because the parameter may be used in a closure, so don't ignore the stored variable index
• the names of temporary variables can be ignored. The names are only used for debugging and do not conflict with each other or normal variables. For accessing, the index of the variable must be used.
• never mix temporary and normal variables by changes to this class. While the name is very important for a normal variable, it is only a helper construct for temporary variables. That means for example a name for a temporary variable can be used multiple times without conflict. So mixing them both may lead to the problem that a normal or temporary variable is hidden or even removed. That must not happen!

see:

AsmClassGenerator

author:

Jochen Theodorou

CompileStack

CompileStack()

applyFinallyBlocks

public void applyFinallyBlocks(Label label, boolean isBreakLabel)

applyFinallyBlocks

public void applyFinallyBlocks()

clear

public void clear()

Clears the state of the class. This method should be called after a MethodNode is visited. Note that a call to init will fail if clear is not called before

containsVariable

public boolean containsVariable(String name)

param:

name the name of the variable of interest

return:

true if a variable is already defined

createLocalLabel

public Label createLocalLabel(String name)

creates a new named label

defineTemporaryVariable

public int defineTemporaryVariable(def var, boolean store)

creates a temporary variable.

param:

var defines type and name

param:

store defines if the toplevel argument of the stack should be stored

return:

the index used for this temporary variable

defineTemporaryVariable

public int defineTemporaryVariable(String name, boolean store)

creates a temporary variable.

param:

name defines type and name

param:

store defines if the toplevel argument of the stack should be stored

return:

the index used for this temporary variable

defineTemporaryVariable

public int defineTemporaryVariable(String name, ClassNode node, boolean store)

creates a temporary variable.

param:

name defines the name

param:

node defines the node

param:

store defines if the toplevel argument of the stack should be stored

return:

the index used for this temporary variable

defineVariable

public Variable defineVariable(def v, boolean initFromStack)

Defines a new Variable using an AST variable.

param:

initFromStack if true the last element of the stack will be used to initilize the new variable. If false null will be used.

getBreakLabel

public Label getBreakLabel()

getContinueLabel

public Label getContinueLabel()

getLabel

public Label getLabel(String name)

Returns the label for the given name

getNamedBreakLabel

protected Label getNamedBreakLabel(String name)

Used for break foo inside a loop to end the execution of the marked loop. This method will return the break label of the loop if there is one found for the name. If not, the current break label is returned.

getNamedContinueLabel

protected Label getNamedContinueLabel(String name)

Used for continue foo inside a loop to continue the execution of the marked loop. This method will return the break label of the loop if there is one found for the name. If not, getLabel is used.

getScope

public VariableScope getScope()

getVariable

public Variable getVariable(String variableName)

getVariable

public Variable getVariable(String variableName, boolean mustExist)

Returns a normal variable.

If mustExist is true and the normal variable doesn't exist, then this method will throw a GroovyBugError. It is not the intention of this method to let this happen! And the exception should not be used for flow control - it is just acting as an assertion. If the exception is thrown then it indicates a bug in the class using CompileStack. This method can also not be used to return a temporary variable. Temporary variables are not normal variables.

param:

variableName name of the variable

param:

mustExist throw exception if variable does not exist

return:

the normal variable or null if not found (and mustExist not true)

hasFinallyBlocks

public boolean hasFinallyBlocks()

init

protected void init(VariableScope el, Parameter[] parameters, MethodVisitor mv, ClassNode cn)

initializes this class for a MethodNode. This method will automatically define variables for the method parameters and will create references if needed. The created variables can be accessed by calling getVariable().

pop

public void pop()

popFinallyBlock

public void popFinallyBlock()

popFinallyBlockVisit

public void popFinallyBlockVisit(Runnable block)

pushBooleanExpression

protected void pushBooleanExpression()

because a boolean Expression may not be evaluated completly it is important to keep the registers clean

pushFinallyBlock

public void pushFinallyBlock(Runnable block)

pushFinallyBlockVisit

public void pushFinallyBlockVisit(Runnable block)

pushLoop

protected void pushLoop(VariableScope el, String labelName)

Should be called when decending into a loop that defines also a scope. Calls pushVariableScope and prepares labels for a loop structure. Creates a element for the state stack so pop has to be called later

pushLoop

protected void pushLoop(String labelName)

Should be called when decending into a loop that does not define a scope. Creates a element for the state stack so pop has to be called later

pushState

protected void pushState()

pushSwitch

protected Label pushSwitch()

Creates a new break label and a element for the state stack so pop has to be called later

pushVariableScope

protected void pushVariableScope(VariableScope el)

Causes the statestack to add an element and sets the given scope as new current variable scope. Creates a element for the state stack so pop has to be called later

removeVar

public void removeVar(int tempIndex)

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