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## 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

Nested Class Summary
`class` | `CompileStack.StateStackElement`

Constructor Summary
`CompileStack()`

Method Summary
`void` | `applyFinallyBlocks(Label label, boolean isBreakLabel)`
`void` | `applyFinallyBlocks()`
`void` | `clear()` Clears the state of the class.
`boolean` | `containsVariable(String name)`
`Label` | `createLocalLabel(String name)` creates a new named label
`int` | `defineTemporaryVariable(def var, boolean store)` creates a temporary variable.
`int` | `defineTemporaryVariable(String name, boolean store)` creates a temporary variable.
`int` | `defineTemporaryVariable(String name, ClassNode node, boolean store)` creates a temporary variable.
`Variable` | `defineVariable(def v, boolean initFromStack)` Defines a new Variable using an AST variable.
`Label` | `getBreakLabel()`
`Label` | `getContinueLabel()`
`Label` | `getLabel(String name)` Returns the label for the given name
`protected Label` | `getNamedBreakLabel(String name)` Used for `break foo` inside a loop to end the execution of the marked loop.
`protected Label` | `getNamedContinueLabel(String name)` Used for `continue foo` inside a loop to continue the execution of the marked loop.
`VariableScope` | `getScope()`
`Variable` | `getVariable(String variableName)`
`Variable` | `getVariable(String variableName, boolean mustExist)` Returns a normal variable.
`boolean` | `hasFinallyBlocks()`
`protected void` | `init(VariableScope el, Parameter[] parameters, MethodVisitor mv, ClassNode cn)` initializes this class for a MethodNode.
`void` | `pop()`
`void` | `popFinallyBlock()`
`void` | `popFinallyBlockVisit(Runnable block)`
`protected void` | `pushBooleanExpression()` because a boolean Expression may not be evaluated completly it is important to keep the registers clean
`void` | `pushFinallyBlock(Runnable block)`
`void` | `pushFinallyBlockVisit(Runnable block)`
`protected void` | `pushLoop(VariableScope el, String labelName)` Should be called when decending into a loop that defines also a scope.
`protected void` | `pushLoop(String labelName)` Should be called when decending into a loop that does not define a scope.
`protected void` | `pushState()`
`protected Label` | `pushSwitch()` Creates a new break label and a element for the state stack so pop has to be called later
`protected void` | `pushVariableScope(VariableScope el)` Causes the statestack to add an element and sets the given scope as new current variable scope.
`void` | `removeVar(int tempIndex)`

Methods inherited from class Object
wait, wait, wait, hashCode, getClass, equals, toString, notify, notifyAll

Constructor Detail

### CompileStack

    CompileStack()

Method Detail

### 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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