Expression

java.lang.Object
- cetus.hir.Expression

All Implemented Interfaces:

Printable, Traversable, java.lang.Cloneable, java.lang.Comparable<Expression>

Direct Known Subclasses:

AlignofExpression, ArrayAccess, BinaryExpression, CommaExpression, CompoundLiteral, ConditionalExpression, DeleteExpression, FunctionCall, IDExpression, InfExpression, Literal, MinMaxExpression, NewExpression, OffsetofExpression, RangeExpression, SizeofExpression, SomeExpression, StatementExpression, ThrowExpression, Typecast, UnaryExpression, VaArgExpression
```
public abstract class Expression
extends java.lang.Object
implements java.lang.Cloneable, java.lang.Comparable<Expression>, Traversable
```
Base class for all expressions. Expressions are compared lexically against other expressions when used in collections.

Method Summary

Methods
Modifier and Type	Method and Description
`Expression`	`clone()` Creates and returns a deep copy of this expression.
`int`	`compareTo(Expression e)`
`boolean`	`equals(java.lang.Object o)` Checks if the given object is has the same type with this expression and its children is same with this expression's.
`java.util.List<Expression>`	`findExpression(Expression expr)` Returns a list of subexpressions of this expression that match `expr` using its equals method.
`java.util.List<Traversable>`	`getChildren()` Provides access to the children of this object as a list.
`Traversable`	`getParent()` Provides access to the parent of this object.
`Statement`	`getStatement()` Get the parent Statement containing this Expression.
`int`	`hashCode()` Returns the hash code of the expression.
`boolean`	`needsParens()` Checks if the expression needs parentheses around itself when printed.
`void`	`print(java.io.PrintWriter o)` Prints the expression on the specified print writer.
`void`	`printSelf()`
`void`	`removeChild(Traversable child)` This operation is not allowed.
`void`	`setChild(int index, Traversable t)` Sets the `index`th child of this object to `t`.
`void`	`setParens(boolean f)` Sets whether the expression needs to have an outer set of parentheses printed around it.
`void`	`setParent(Traversable t)` Sets the parent of this object.
`void`	`setPrintMethod(java.lang.reflect.Method m)` Overrides the print method for this object only.
`void`	`swapWith(Expression expr)` Swaps two expression on the IR tree.
`java.lang.String`	`toString()` Returns a string representation of the expression
`void`	`verify()` Verifies three properties of this object: (1) All children are not null, (2) the parent object has this object as a child, (3) all children have this object as the parent.

Methods inherited from class java.lang.Object
getClass, notify, notifyAll, wait, wait, wait

- Method Detail
  - clone
```
public Expression clone()
```
    Creates and returns a deep copy of this expression.
    
    Overrides:
    
    clone in class java.lang.Object
    
    Returns:
    a deep copy of this expression.
  - compareTo
```
public int compareTo(Expression e)
```
    Specified by:
    
    compareTo in interface java.lang.Comparable<Expression>
  - equals
```
public boolean equals(java.lang.Object o)
```
    Checks if the given object is has the same type with this expression and its children is same with this expression's. The sub classes of expression should call this method first and proceed with more checking if they have additional fields to be checked.
    
    Overrides:
    
    equals in class java.lang.Object
    
    Parameters:
    o - the object to be compared with.
    
    Returns:
    true if o!=null, this.getClass()==o.getClass(), and this.children.equals(o.children) || this.children==o.children==null
  - hashCode
```
public int hashCode()
```
    Returns the hash code of the expression. It returns the hash code of the string representation since expressions are compared lexically.
    
    Overrides:
    
    hashCode in class java.lang.Object
    
    Returns:
    the integer hash code of the expression.
  - findExpression
```
public java.util.List<Expression> findExpression(Expression expr)
```
    Returns a list of subexpressions of this expression that match expr using its equals method.
    
    Parameters:
    expr - The subexpression sought.
    
    Returns:
    a list of matching subexpressions, which may be empty.
  - getChildren
```
public java.util.List<Traversable> getChildren()
```
    Description copied from interface: Traversable
    
    Provides access to the children of this object as a list. This object is free to internally implement its list as a LinkedList or an ArrayList. It is generally not good practice to call this method yourself; the ordering of children is not guaranteed so instead you should use the methods of the particular class whose children you wish to access.
    
    Specified by:
    
    getChildren in interface Traversable
    
    Returns:
    the children as a list.
  - getParent
```
public Traversable getParent()
```
    Description copied from interface: Traversable
    
    Provides access to the parent of this object. Every IR object has at most one parent. (The parent relationship is the same as the parent relationship in the parse tree, and is not to be confused with the base class of a derived class declaration.)
    
    Specified by:
    
    getParent in interface Traversable
    
    Returns:
    the parent of this object.
  - getStatement
```
public Statement getStatement()
```
    Get the parent Statement containing this Expression.
    
    Returns:
    the enclosing Statement or null if this Expression is not inside a Statement.
  - print
```
public void print(java.io.PrintWriter o)
```
    Prints the expression on the specified print writer.
    
    Specified by:
    
    print in interface Printable
    
    Parameters:
    o - the target print writer.
  - printSelf
```
public void printSelf()
```
  - removeChild
```
public void removeChild(Traversable child)
```
    This operation is not allowed.
    
    Specified by:
    
    removeChild in interface Traversable
    
    Parameters:
    child - a reference to a child object that must match with ==.
    
    Throws:
    
    java.lang.UnsupportedOperationException - always
  - setChild
```
public void setChild(int index,
            Traversable t)
```
    Description copied from interface: Traversable
    
    Sets the indexth child of this object to t. By calling this method, the old child located at the position i will have a null parent. It is generally not good practice to call this method yourself; the ordering of children is not guaranteed so instead you should use the methods of the particular class whose children you wish to access. There are checks to prevent such actions as making a statement a child of an expression, but you still may be able to do some damage with this method if you are not careful.
    
    Specified by:
    
    setChild in interface Traversable
    
    Throws:
    
    NotAnOrphanException - if t has a parent object.
    
    java.lang.IllegalArgumentException - if index is out-of-range or t is not an expression.
  - setParens
```
public void setParens(boolean f)
```
    Sets whether the expression needs to have an outer set of parentheses printed around it.
    
    Parameters:
    f - True to use parens, false to not use parens.
  - needsParens
```
public boolean needsParens()
```
    Checks if the expression needs parentheses around itself when printed.
  - setParent
```
public void setParent(Traversable t)
```
    Description copied from interface: Traversable
    
    Sets the parent of this object. Cetus checks that the parent already considers this object a child. The intent is to maintain an ordering where first this object becomes a child of another object, and then this object is told who its parent is. Enforcing this order makes it easier for Cetus to enforce other invariants and ensure the IR is correct.
    
    Specified by:
    
    setParent in interface Traversable
  - setPrintMethod
```
public void setPrintMethod(java.lang.reflect.Method m)
```
    Overrides the print method for this object only.
    
    Parameters:
    m - The new print method.
  - swapWith
```
public void swapWith(Expression expr)
```
    Swaps two expression on the IR tree. If neither this expression nor expr has a parent, then this function has no effect. Otherwise, each expression ends up with the other's parent and exchange positions in the parents' lists of children.
    
    Parameters:
    expr - The expression with which to swap this expression.
    
    Throws:
    
    java.lang.IllegalArgumentException - if expr is null.
    
    java.lang.IllegalStateException - if the types of the expressions are such that they would create inconsistent IR when swapped.
  - toString
```
public java.lang.String toString()
```
    Returns a string representation of the expression
    
    Overrides:
    
    toString in class java.lang.Object
  - verify
```
public void verify()
            throws java.lang.IllegalStateException
```
    Verifies three properties of this object: (1) All children are not null, (2) the parent object has this object as a child, (3) all children have this object as the parent.
    
    Throws:
    
    java.lang.IllegalStateException - if any of the properties are not true.

Class Expression

Method Summary

Methods inherited from class java.lang.Object

Method Detail

clone

compareTo

equals

hashCode

findExpression

getChildren

getParent

getStatement

print

printSelf

removeChild

setChild

setParens

needsParens

setParent

setPrintMethod

swapWith

toString

verify