Term (Java API Reference for Oracle® Coherence Community Edition)

java.lang.Object
- com.tangosol.coherence.dsltools.termtrees.Term

All Implemented Interfaces:

Iterable<Term>

Direct Known Subclasses:

AtomicTerm, NodeTerm
```
public abstract class Term
extends Object
implements Iterable<Term>
```
Term is the abstract class used to represent trees of Terms (term-trees). A term (a node of a term tree) consists of a special label called a functor and a sequence of child terms (called arguments). Strings, Numbers, and Symbols are atomic-terms and are the leaves of a term-tree, i.e. they have no children. Trees of symbols lie midway between sequences of symbols and graphs of symbols in expressiveness and therefor represent somewhat of a sweet-spot in representation space. Historically, term-trees can be found in Prolog and Mathematica and are used for many of the same purposes that others use S-Expressions or XML. All are generic means for representing trees of symbols, and are useful for representing a great variety of kinds of data There exist encodings that freely go between S-Expressions or XML into term-trees. Powerful matching techniques exist that operate over term-trees and at this point in time are 50 years old. Techniques that are 60 years old show how powerful term-trees can be as the implementation vehicle for interpreters and compilers. Finally, "Term Language" (TL), the literal expression of term-trees is much more readable and writable than either S-expressions or XML and is an excelent. way to test the output of a parser by comparing a simple literal. The Term protocol distunguishes between atoms (such as literals) and nodes with children, and leaf nodes that are atoms or nodes without children. All Terms have a functor which acts somewhat like a type or classifier. Term-trees are especially useful as Abstract Syntax Trees (AST) and in implementing expression languages.

Author:

djl 2009.08.31

Nested Class Summary

Nested Classes
Modifier and Type Class and Description

class Term.TermIterator
This Iterator implementation iterates over the child Terms of a given Term.

Nested Classes
Modifier and Type	Class and Description
`class`	`Term.TermIterator` This `Iterator` implementation iterates over the child `Term`s of a given `Term`.

Constructor Summary

Constructors
Constructor and Description

Term()

Constructors
Constructor and Description
`Term()`

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`accept(TermWalker walker)` Do a dispatch back to the given walker.
`abstract Term[]`	`children()` Obtain the childern Terms
`boolean`	`childrenTermEqual(Term t)` Answer whether the receiver's children is equal to the given Terms children.
`Term`	`findAttribute(String sFunctor)` Find the Term amoungst the children whose functor equals the given functor that has a singleton child.
`Term`	`findChild(String sFunctor)` Find the Term amoungst the children whose functor equals the given functor.
`abstract String`	`fullFormString()` Answer a String representation of the Term that is allowed to show more internal details than toString() which does not compress information.
`abstract String`	`getFunctor()` Obtain the functor representation of the Term.
`boolean`	`headChildrenTermEqual(Term t)` Find the Term amongst the children whose functor equals the given functor.
`boolean`	`isAtom()` Answer whether the receiver is an Atomic Term.
`boolean`	`isLeaf()` Answer whether the receiver has children.
`boolean`	`isNumber()` Answer whether the receiver is an Atomic Term representing a Number.
`Iterator<Term>`	`iterator()`
`int`	`length()` Answer whether the length of the receivers children
`abstract Term`	`termAt(int index)` Obtain the child term at the given index.
`abstract boolean`	`termEqual(Term t)` Answer whether the receiver is equal to the given Term.
`abstract Term`	`withChild(Term t)` Join the receiver with the given child Term.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface java.lang.Iterable
forEach, spliterator

- Constructor Detail
  - Term
```
public Term()
```
- Method Detail
  - getFunctor
```
public abstract String getFunctor()
```
    Obtain the functor representation of the Term.
    
    Returns:
    
    the functor
  - termAt
```
public abstract Term termAt(int index)
```
    Obtain the child term at the given index. The index is 1 based for children and with at(0) returning the functor as an AtomicTerm. Beware, your 0 based habits can cause problems but 1 based indexing is useful since the functor is an interesting part of the information space. We are bowing here to the wisdom of Mathematica Expressions.
    
    Parameters:
    
    index - index of the child or functor to return
    
    Returns:
    
    the child Term or functor as AtomicTerm if index is 0
  - children
```
public abstract Term[] children()
```
    Obtain the childern Terms
    
    Returns:
    
    the children of the receiver
  - withChild
```
public abstract Term withChild(Term t)
```
    Join the receiver with the given child Term. AtomicTerms will construct a general list term (functor .list.) and NodeTerms may be mutated.
    
    Parameters:
    
    t - the term to join with
    
    Returns:
    
    the Term resulting from joining.
  - termEqual
```
public abstract boolean termEqual(Term t)
```
    Answer whether the receiver is equal to the given Term. Terms are equal if their functors are equal and their children are termEqual to the children of the given term.
    
    Parameters:
    
    t - the Term to check for termEqual
    
    Returns:
    
    the boolean result of the comparison
  - fullFormString
```
public abstract String fullFormString()
```
    Answer a String representation of the Term that is allowed to show more internal details than toString() which does not compress information. Similar to Object.toString().
    
    Returns:
    
    a String representation of the receiver
  - isLeaf
```
public boolean isLeaf()
```
    Answer whether the receiver has children.
    
    Returns:
    
    the boolean result of the isLeaf() test
  - isAtom
```
public boolean isAtom()
```
    Answer whether the receiver is an Atomic Term.
    
    Returns:
    
    the boolean result of the isAtom() test
  - isNumber
```
public boolean isNumber()
```
    Answer whether the receiver is an Atomic Term representing a Number.
    
    Returns:
    
    the boolean result of the isNumber() test
  - length
```
public int length()
```
    Answer whether the length of the receivers children
    
    Returns:
    
    the length
  - findChild
```
public Term findChild(String sFunctor)
```
    Find the Term amoungst the children whose functor equals the given functor.
    
    Parameters:
    
    sFunctor - the functor to search for
    
    Returns:
    
    the found Term or null if not found
  - findAttribute
```
public Term findAttribute(String sFunctor)
```
    Find the Term amoungst the children whose functor equals the given functor that has a singleton child.
    
    Parameters:
    
    sFunctor - the functor to search for
    
    Returns:
    
    the found Term's first child or null if not found
  - childrenTermEqual
```
public boolean childrenTermEqual(Term t)
```
    Answer whether the receiver's children is equal to the given Terms children. Terms are equal if their functors are equal and their children are termEqual to the children of the given term.
    
    Parameters:
    
    t - term whose children are to be checked for equality
    
    Returns:
    
    the found Term or null if not found
  - headChildrenTermEqual
```
public boolean headChildrenTermEqual(Term t)
```
    Find the Term amongst the children whose functor equals the given functor.
    
    Parameters:
    
    t - the functor to search for
    
    Returns:
    
    the found Term or null if not found
  - accept
```
public void accept(TermWalker walker)
```
    Do a dispatch back to the given walker.
    
    Parameters:
    
    walker - the TermWalker that implements the visitor for Terms
  - iterator
```
public Iterator<Term> iterator()
```
    Specified by:
    
    iterator in interface Iterable<Term>

Class Term

Nested Class Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Methods inherited from interface java.lang.Iterable

Constructor Detail

Term

Method Detail

getFunctor

termAt

children

withChild

termEqual

fullFormString

isLeaf

isAtom

isNumber

length

findChild

findAttribute

childrenTermEqual

headChildrenTermEqual

accept

iterator