Package org.codehaus.groovy.classgen.asm

## Class CompileStack

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

- All Implemented Interfaces:
    `org.objectweb.asm.Opcodes`

      public class CompileStack
      extends java.lang.Object
      implements org.objectweb.asm.Opcodes

  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 Also:
    `AsmClassGenerator`

- - ### Nested Class Summary

    Nested Classes
    Modifier and Type | Class | Description
    --- | --- | ---
    `static class` | `CompileStack.BlockRecorder` |
    `protected static class` | `CompileStack.LabelRange` |

  - ### Field Summary

    - ### Fields inherited from interface org.objectweb.asm.Opcodes

      `AALOAD, AASTORE, ACC_ABSTRACT, ACC_ANNOTATION, ACC_BRIDGE, ACC_DEPRECATED, ACC_ENUM, ACC_FINAL, ACC_INTERFACE, ACC_MANDATED, ACC_MODULE, ACC_NATIVE, ACC_OPEN, ACC_PRIVATE, ACC_PROTECTED, ACC_PUBLIC, ACC_STATIC, ACC_STATIC_PHASE, ACC_STRICT, ACC_SUPER, ACC_SYNCHRONIZED, ACC_SYNTHETIC, ACC_TRANSIENT, ACC_TRANSITIVE, ACC_VARARGS, ACC_VOLATILE, ACONST_NULL, ALOAD, ANEWARRAY, ARETURN, ARRAYLENGTH, ASM4, ASM5, ASM6, ASM7, ASTORE, ATHROW, BALOAD, BASTORE, BIPUSH, CALOAD, CASTORE, CHECKCAST, D2F, D2I, D2L, DADD, DALOAD, DASTORE, DCMPG, DCMPL, DCONST_0, DCONST_1, DDIV, DLOAD, DMUL, DNEG, DOUBLE, DREM, DRETURN, DSTORE, DSUB, DUP, DUP_X1, DUP_X2, DUP2, DUP2_X1, DUP2_X2, F_APPEND, F_CHOP, F_FULL, F_NEW, F_SAME, F_SAME1, F2D, F2I, F2L, FADD, FALOAD, FASTORE, FCMPG, FCMPL, FCONST_0, FCONST_1, FCONST_2, FDIV, FLOAD, FLOAT, FMUL, FNEG, FREM, FRETURN, FSTORE, FSUB, GETFIELD, GETSTATIC, GOTO, H_GETFIELD, H_GETSTATIC, H_INVOKEINTERFACE, H_INVOKESPECIAL, H_INVOKESTATIC, H_INVOKEVIRTUAL, H_NEWINVOKESPECIAL, H_PUTFIELD, H_PUTSTATIC, I2B, I2C, I2D, I2F, I2L, I2S, IADD, IALOAD, IAND, IASTORE, ICONST_0, ICONST_1, ICONST_2, ICONST_3, ICONST_4, ICONST_5, ICONST_M1, IDIV, IF_ACMPEQ, IF_ACMPNE, IF_ICMPEQ, IF_ICMPGE, IF_ICMPGT, IF_ICMPLE, IF_ICMPLT, IF_ICMPNE, IFEQ, IFGE, IFGT, IFLE, IFLT, IFNE, IFNONNULL, IFNULL, IINC, ILOAD, IMUL, INEG, INSTANCEOF, INTEGER, INVOKEDYNAMIC, INVOKEINTERFACE, INVOKESPECIAL, INVOKESTATIC, INVOKEVIRTUAL, IOR, IREM, IRETURN, ISHL, ISHR, ISTORE, ISUB, IUSHR, IXOR, JSR, L2D, L2F, L2I, LADD, LALOAD, LAND, LASTORE, LCMP, LCONST_0, LCONST_1, LDC, LDIV, LLOAD, LMUL, LNEG, LONG, LOOKUPSWITCH, LOR, LREM, LRETURN, LSHL, LSHR, LSTORE, LSUB, LUSHR, LXOR, MONITORENTER, MONITOREXIT, MULTIANEWARRAY, NEW, NEWARRAY, NOP, NULL, POP, POP2, PUTFIELD, PUTSTATIC, RET, RETURN, SALOAD, SASTORE, SIPUSH, SWAP, T_BOOLEAN, T_BYTE, T_CHAR, T_DOUBLE, T_FLOAT, T_INT, T_LONG, T_SHORT, TABLESWITCH, TOP, UNINITIALIZED_THIS, V_PREVIEW, V1_1, V1_2, V1_3, V1_4, V1_5, V1_6, V1_7, V1_8, V10, V11, V12, V9`

  - ### Constructor Summary

    Constructors
    Constructor | Description
    --- | ---
    `CompileStack​(WriterController wc)` |

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method | Description
    --- | --- | ---
    `void` | `addExceptionBlock​(org.objectweb.asm.Label start, org.objectweb.asm.Label end, org.objectweb.asm.Label goal, java.lang.String sig)` |
    `void` | `applyBlockRecorder()` |
    `void` | `applyFinallyBlocks​(org.objectweb.asm.Label label, boolean isBreakLabel)` |
    `void` | `clear()` | Clears the state of the class.
    `boolean` | `containsVariable​(java.lang.String name)` |
    `org.objectweb.asm.Label` | `createLocalLabel​(java.lang.String name)` | creates a new named label
    `int` | `defineTemporaryVariable​(java.lang.String name, boolean store)` | creates a temporary variable.
    `int` | `defineTemporaryVariable​(java.lang.String name, ClassNode node, boolean store)` | creates a temporary variable.
    `int` | `defineTemporaryVariable​(Variable var, boolean store)` | creates a temporary variable.
    `BytecodeVariable` | `defineVariable​(Variable v, boolean initFromStack)` | Defines a new Variable using an AST variable.
    `BytecodeVariable` | `defineVariable​(Variable v, ClassNode variableType, boolean initFromStack)` |
    `org.objectweb.asm.Label` | `getBreakLabel()` |
    `org.objectweb.asm.Label` | `getContinueLabel()` |
    `org.objectweb.asm.Label` | `getLabel​(java.lang.String name)` | Returns the label for the given name
    `org.objectweb.asm.Label` | `getNamedBreakLabel​(java.lang.String name)` | Used for `break foo` inside a loop to end the execution of the marked loop.
    `org.objectweb.asm.Label` | `getNamedContinueLabel​(java.lang.String name)` | Used for `continue foo` inside a loop to continue the execution of the marked loop.
    `VariableScope` | `getScope()` |
    `BytecodeVariable` | `getVariable​(java.lang.String variableName)` |
    `BytecodeVariable` | `getVariable​(java.lang.String variableName, boolean mustExist)` | Returns a normal variable.
    `boolean` | `hasBlockRecorder()` |
    `void` | `init​(VariableScope el, Parameter[] parameters)` | initializes this class for a MethodNode.
    `boolean` | `isImplicitThis()` |
    `boolean` | `isInSpecialConstructorCall()` |
    `boolean` | `isLHS()` |
    `void` | `pop()` |
    `void` | `popBlockRecorderVisit​(CompileStack.BlockRecorder finallyBlock)` |
    `void` | `popImplicitThis()` |
    `void` | `popLHS()` |
    `void` | `pushBlockRecorder​(CompileStack.BlockRecorder recorder)` |
    `void` | `pushBlockRecorderVisit​(CompileStack.BlockRecorder finallyBlock)` |
    `void` | `pushBooleanExpression()` | because a boolean Expression may not be evaluated completely it is important to keep the registers clean
    `void` | `pushImplicitThis​(boolean implicitThis)` |
    `void` | `pushInSpecialConstructorCall()` |
    `void` | `pushLHS​(boolean lhs)` |
    `void` | `pushLoop​(java.lang.String labelName)` | Should be called when descending into a loop that does not define a scope.
    `void` | `pushLoop​(java.util.List<java.lang.String> labelNames)` | Should be called when descending into a loop that does not define a scope.
    `void` | `pushLoop​(VariableScope el, java.lang.String labelName)` | Should be called when descending into a loop that defines also a scope.
    `void` | `pushLoop​(VariableScope el, java.util.List<java.lang.String> labelNames)` | Should be called when descending into a loop that defines also a scope.
    `void` | `pushState()` |
    `org.objectweb.asm.Label` | `pushSwitch()` | Creates a new break label and a element for the state stack so pop has to be called later
    `void` | `pushVariableScope​(VariableScope el)` | Causes the state-stack to add an element and sets the given scope as new current variable scope.
    `void` | `removeVar​(int tempIndex)` |
    `void` | `writeExceptionTable​(CompileStack.BlockRecorder block, org.objectweb.asm.Label goal, java.lang.String sig)` |

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- - ### Constructor Detail

    - #### CompileStack

          public CompileStack​(WriterController wc)

  - ### Method Detail

    - #### pushState

          public void pushState()

    - #### getContinueLabel

          public org.objectweb.asm.Label getContinueLabel()

    - #### getBreakLabel

          public org.objectweb.asm.Label getBreakLabel()

    - #### removeVar

          public void removeVar​(int tempIndex)

    - #### pop

          public void pop()

    - #### getScope

          public VariableScope getScope()

    - #### defineTemporaryVariable

          public int defineTemporaryVariable​(Variable var,
                                             boolean store)

      creates a temporary variable.
      Parameters:
        `var` - defines type and name
        `store` - defines if the toplevel argument of the stack should be stored
      Returns:
        the index used for this temporary variable

    - #### getVariable

          public BytecodeVariable getVariable​(java.lang.String variableName)

    - #### getVariable

          public BytecodeVariable getVariable​(java.lang.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.

      Parameters:
        `variableName` - name of the variable
        `mustExist` - throw exception if variable does not exist
      Returns:
        the normal variable or null if not found (and `mustExist` not true)

    - #### defineTemporaryVariable

          public int defineTemporaryVariable​(java.lang.String name,
                                             boolean store)

      creates a temporary variable.
      Parameters:
        `name` - defines type and name
        `store` - defines if the top-level argument of the stack should be stored
      Returns:
        the index used for this temporary variable

    - #### defineTemporaryVariable

          public int defineTemporaryVariable​(java.lang.String name,
                                             ClassNode node,
                                             boolean store)

      creates a temporary variable.
      Parameters:
        `name` - defines the name
        `node` - defines the node
        `store` - defines if the top-level argument of the stack should be stored
      Returns:
        the index used for this temporary variable

    - #### 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

    - #### addExceptionBlock

          public void addExceptionBlock​(org.objectweb.asm.Label start,
                                        org.objectweb.asm.Label end,
                                        org.objectweb.asm.Label goal,
                                        java.lang.String sig)

    - #### init

          public void init​(VariableScope el,
                           Parameter[] parameters)

      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().

    - #### pushVariableScope

          public void pushVariableScope​(VariableScope el)

      Causes the state-stack 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

    - #### pushLoop

          public void pushLoop​(VariableScope el,
                               java.lang.String labelName)

      Should be called when descending 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, TODO: @Deprecate

    - #### pushLoop

          public void pushLoop​(VariableScope el,
                               java.util.List<java.lang.String> labelNames)

      Should be called when descending 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

          public void pushLoop​(java.lang.String labelName)

      Should be called when descending into a loop that does not define a scope. Creates a element for the state stack so pop has to be called later, TODO: @Deprecate

    - #### pushLoop

          public void pushLoop​(java.util.List<java.lang.String> labelNames)

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

    - #### getNamedBreakLabel

          public org.objectweb.asm.Label getNamedBreakLabel​(java.lang.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

          public org.objectweb.asm.Label getNamedContinueLabel​(java.lang.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.

    - #### pushSwitch

          public org.objectweb.asm.Label pushSwitch()

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

    - #### pushBooleanExpression

          public void pushBooleanExpression()

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

    - #### defineVariable

          public BytecodeVariable defineVariable​(Variable v,
                                                 boolean initFromStack)

      Defines a new Variable using an AST variable.
      Parameters:
        `initFromStack` - if true the last element of the stack will be used to initialize the new variable. If false null will be used.

    - #### defineVariable

          public BytecodeVariable defineVariable​(Variable v,
                                                 ClassNode variableType,
                                                 boolean initFromStack)

    - #### containsVariable

          public boolean containsVariable​(java.lang.String name)

      Parameters:
        `name` - the name of the variable of interest
      Returns:
        true if a variable is already defined

    - #### getLabel

          public org.objectweb.asm.Label getLabel​(java.lang.String name)

      Returns the label for the given name

    - #### createLocalLabel

          public org.objectweb.asm.Label createLocalLabel​(java.lang.String name)

      creates a new named label

    - #### applyFinallyBlocks

          public void applyFinallyBlocks​(org.objectweb.asm.Label label,
                                         boolean isBreakLabel)

    - #### applyBlockRecorder

          public void applyBlockRecorder()

    - #### hasBlockRecorder

          public boolean hasBlockRecorder()

    - #### pushBlockRecorder

          public void pushBlockRecorder​(CompileStack.BlockRecorder recorder)

    - #### pushBlockRecorderVisit

          public void pushBlockRecorderVisit​(CompileStack.BlockRecorder finallyBlock)

    - #### popBlockRecorderVisit

          public void popBlockRecorderVisit​(CompileStack.BlockRecorder finallyBlock)

    - #### writeExceptionTable

          public void writeExceptionTable​(CompileStack.BlockRecorder block,
                                          org.objectweb.asm.Label goal,
                                          java.lang.String sig)

    - #### isLHS

          public boolean isLHS()

    - #### pushLHS

          public void pushLHS​(boolean lhs)

    - #### popLHS

          public void popLHS()

    - #### pushImplicitThis

          public void pushImplicitThis​(boolean implicitThis)

    - #### isImplicitThis

          public boolean isImplicitThis()

    - #### popImplicitThis

          public void popImplicitThis()

    - #### isInSpecialConstructorCall

          public boolean isInSpecialConstructorCall()

    - #### pushInSpecialConstructorCall

          public void pushInSpecialConstructorCall()