Operands (projog-core 0.10.0 API)

java.lang.Object
- org.projog.core.parser.Operands

```
public final class Operands
extends Object
```
Collection of operands.
Prolog allows functors (names of predicates) to be defined as "operators". The use of operators allows syntax to be easier to read.
Infix operators are placed between their two arguments. Prefix operators are placed before their single argument. Postfix operators are placed after their single argument.
A common use of operators is in the definition of arithmetic operations. By declaring is and - as infix operators we can write valid prolog syntax like X is 1 + 2. instead of is(X, +(1, 2)).
Each KnowledgeBase has a single unique Operands instance.

See Also:

KnowledgeBase.getOperands()

Constructor Summary

Constructors
Constructor and Description

Operands()

Constructors
Constructor and Description
`Operands()`

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`addOperand(String operandName, String associativityName, int precedence)` Adds a new operator.
`boolean`	`fx(String op)` Returns `true` if `op` represents a prefix operator with associativity of `fx`, else `false`.
`boolean`	`fy(String op)` Returns `true` if `op` represents a prefix operator with associativity of `fy`, else `false`.
`int`	`getInfixPriority(String op)` Returns the priority (precedence/level) of the infix operator represented by `op`.
`int`	`getPostfixPriority(String op)` Returns the priority (precedence/level) of the postfix operator represented by `op`.
`int`	`getPrefixPriority(String op)` Returns the priority (precedence/level) of the prefix operator represented by `op`.
`boolean`	`infix(String op)` Returns `true` if `op` represents an infix operator, else `false`.
`boolean`	`isDefined(String commandName)` Returns `true` if `commandName` represents any known operator, else `false`.
`boolean`	`postfix(String op)` Returns `true` if `op` represents a postfix operator, else `false`.
`boolean`	`prefix(String op)` Returns `true` if `op` represents a prefix operator, else `false`.
`boolean`	`xf(String op)` Returns `true` if `op` represents a postfix operator with associativity of `xf`, else `false`.
`boolean`	`xfx(String op)` Returns `true` if `op` represents an infix operator with associativity of `xfx`, else `false`.
`boolean`	`xfy(String op)` Returns `true` if `op` represents an infix operator with associativity of `xfy`, else `false`.
`boolean`	`yf(String op)` Returns `true` if `op` represents a postfix operator with associativity of `yf`, else `false`.
`boolean`	`yfx(String op)` Returns `true` if `op` represents an infix operator with associativity of `yfx`, else `false`.

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

- Constructor Detail
  - Operands
```
public Operands()
```
- Method Detail
  - addOperand
```
public void addOperand(String operandName,
                       String associativityName,
                       int precedence)
```
    Adds a new operator.
    
    Parameters:
    
    operandName - the name of the new operator
    
    associativityName - the operators associativity (must be one of: xfx, xfy, yfx, fx, fy, xf or yf)
    
    precedence - used to specify the ordering of terms where it is not made explicit by the use of brackets
  - getInfixPriority
```
public int getInfixPriority(String op)
```
    Returns the priority (precedence/level) of the infix operator represented by op.
  - getPrefixPriority
```
public int getPrefixPriority(String op)
```
    Returns the priority (precedence/level) of the prefix operator represented by op.
  - getPostfixPriority
```
public int getPostfixPriority(String op)
```
    Returns the priority (precedence/level) of the postfix operator represented by op.
  - infix
```
public boolean infix(String op)
```
    Returns true if op represents an infix operator, else false.
  - yfx
```
public boolean yfx(String op)
```
    Returns true if op represents an infix operator with associativity of yfx, else false.
  - xfy
```
public boolean xfy(String op)
```
    Returns true if op represents an infix operator with associativity of xfy, else false.
  - xfx
```
public boolean xfx(String op)
```
    Returns true if op represents an infix operator with associativity of xfx, else false.
  - prefix
```
public boolean prefix(String op)
```
    Returns true if op represents a prefix operator, else false.
  - fx
```
public boolean fx(String op)
```
    Returns true if op represents a prefix operator with associativity of fx, else false.
  - fy
```
public boolean fy(String op)
```
    Returns true if op represents a prefix operator with associativity of fy, else false.
  - postfix
```
public boolean postfix(String op)
```
    Returns true if op represents a postfix operator, else false.
  - xf
```
public boolean xf(String op)
```
    Returns true if op represents a postfix operator with associativity of xf, else false.
  - yf
```
public boolean yf(String op)
```
    Returns true if op represents a postfix operator with associativity of yf, else false.
  - isDefined
```
public boolean isDefined(String commandName)
```
    Returns true if commandName represents any known operator, else false.

Class Operands

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

Operands

Method Detail

addOperand

getInfixPriority

getPrefixPriority

getPostfixPriority

infix

yfx

xfy

xfx

prefix

fx

fy

postfix

xf

yf

isDefined