Package com.singularsys.jep

Class Operator

java.lang.Object
com.singularsys.jep.Operator
All Implemented Interfaces:
Serializable
Direct Known Subclasses:
TernaryOperator, TernaryOperator.RhsTernaryOperator
public class Operator extends Object implements Serializable
An Operator with additional information about its commutativity etc.

Operators have a number of properties:

  • A symbol or name of the operator "+".
  • The number of arguments NO_ARGS 0, UNARY 1 (e.g. UMINUS -x), BINARY 2 (e.g. x+y), and NARY either 3 ( a>b ? a : b) or unspecified like a list [x,y,z,w].
  • The binding of the operator, LEFT 1+2+3 -> (1+2)+3 or RIGHT 1=2=3 -> 1=(2=3).
  • Whether the operator is ASSOCIATIVE or COMMUTATIVE.
  • The precedence of the operators + has a higher precedence than *.
  • For unary operators they can either be PREFIX like -x or SUFFIX like x%.
  • Comparative operators can be REFLEXIVE, SYMMETRIC, TRANSITIVE or EQUIVALENCE which has all three properties.
  • A reference to a PostfixtMathCommandI object which is used to evaluate an equation containing the operator.
Various is... and get... methods are provided to query the properties of the operator.
Author:
Rich Morris Created on 19-Oct-2003
See Also:

  • Field Details

    • NO_ARGS

      public static final int NO_ARGS
      No arguments to operator
      See Also:

    • UNARY

      public static final int UNARY
      Unary operators, such as -x !x ~x
      See Also:

    • BINARY

      public static final int BINARY
      Binary operators, such as x+y, x>y
      See Also:

    • NARY

      public static final int NARY
      Trinary ops such as ?: and or higher like [x,y,z,w]
      See Also:

    • LEFT

      public static final int LEFT
      Left binding like +: 1+2+3 -> (1+2)+3
      See Also:

    • ASSOCIATIVE

      public static final int ASSOCIATIVE
      Associative operators x*(y*z) == (x*y)*z .
      See Also:

    • COMMUTATIVE

      public static final int COMMUTATIVE
      Commutative operators x*y = y*x.
      See Also:

    • REFLEXIVE

      public static final int REFLEXIVE
      Reflective relations x=x for all x.
      See Also:

    • SYMMETRIC

      public static final int SYMMETRIC
      Symmetric relation x=y implies y=x.
      See Also:

    • TRANSITIVE

      public static final int TRANSITIVE
      Transitive relations x=y and y=z implies x=z
      See Also:

    • EQUIVALENCE

      public static final int EQUIVALENCE
      Equivalence relations = reflexive, transitive and symmetric.
      See Also:

    • PREFIX

      public static final int PREFIX
      prefix operators -x
      See Also:

    • SUFFIX

      public static final int SUFFIX
      postfix operators x%
      See Also:

    • SELF_INVERSE

      public static final int SELF_INVERSE
      self inverse operators like -(-x) !(!x)
      See Also:

    • COMPOSITE

      public static final int COMPOSITE
      composite operators, like a-b which is a+(-b)
      See Also:

    • USE_BINDING_FOR_PRINT

      public static final int USE_BINDING_FOR_PRINT
      For non-commutative operators printing can be determined by the left or right binding. For example (a-b)-c is printed as a-b-c (flag set). But a/b/c could be ambiguous so (a/b)/c is printed with brackets (flag not set).
      See Also:

    • NOT_IN_PARSER

      public static final int NOT_IN_PARSER
      Non-standard operators, like array access. These will typically require the PrintRulesI interface to print and require special parsing options.
      See Also:

    • TERNARY

      public static final int TERNARY
      three argument operators like java's cond?tval:fval
      See Also:

    • name

      protected final String name
      A unique name defining the operator. Access level changed to protected in version 3.5

    • symbol

      protected String symbol
      The symbol for the operator, used for printing. Access level changed to protected in version 3.5

    • printSymbol

      protected String printSymbol
      The symbol for the operator, used for printing. Access level changed to protected in version 3.5

    • pfmc

      protected PostfixMathCommandI pfmc
      The PostfixMathCommandI for evaluating Access level changed to protected in version 3.5

    • flags

      protected int flags
      Flags for type of operator Access level changed to protected in version 3.5

    • precedence

      protected int precedence
      Precedence of operator, 0 is most tightly bound, so prec("*") < prec("+"). Access level changed to protected in version 3.5

    • key

      protected int key
      Key used to identify the operator in the operator table Access level changed to protected in version 3.5

  • Constructor Details

    • Operator

      public Operator(String name, PostfixMathCommandI pfmc, int flags)
      Construct a new operator with no precedence set.
      Parameters:
      name - printable name of the operator
      pfmc - postfix math command for the operator
      flags - set of flags defining the properties of the operator.

    • Operator

      public Operator(String name, PostfixMathCommandI pfmc, int flags, int precedence)
      Constructs a new operator with a given precedence.
      Parameters:
      name - printable name of the operator
      pfmc - postfix math command for the operator
      flags - set of flags defining the properties of the operator
      precedence - operator precedence to be set

    • Operator

      public Operator(String name, String symbol, PostfixMathCommandI pfmc, int flags)
      Constructs a new operator, with a different name and symbol
      Parameters:
      name - name of operator, must be unique, used when describing operator
      symbol - printable name of operator, used for printing equations
      pfmc - postfix math command for operator
      flags - set of flags defining the properties of the operator

    • Operator

      public Operator(String name, String symbol, PostfixMathCommandI pfmc, int flags, int precedence)
      Constructs a new operator, with a different name and symbol and allows a given precedence to be set.
      Parameters:
      name - name of operator, must be unique, used when describing operator
      symbol - printable name of operator, used for printing equations
      pfmc - postfix math command for operator
      flags - set of flags defining the properties of the operator.
      precedence - operator precedence to be set

  • Method Details

    • getSymbol

      public final String getSymbol()
      returns the symbol used by this operator.
      Returns:
      The symbol

    • setSymbol

      public final void setSymbol(String sym)
      Sets the symbol used by the operator. Note Jep.reinitializeComponents() must be called after using this method.
      Parameters:
      sym - the new symbol to use.

    • getName

      public final String getName()
      returns a unique name defining this operator.
      Returns:
      the name

    • getPrintSymbol

      public String getPrintSymbol()
      The symbol used for printing. If null the symbol is used instead.
      Returns:
      the symbol used for printing or null if no special symbol is used

    • setPrintSymbol

      public void setPrintSymbol(String printSymbol)
      The symbol used for printing. If null the symbol is used instead.

    • getPFMC

      public final PostfixMathCommandI getPFMC()

    • setPFMC

      public final void setPFMC(PostfixMathCommandI pfmc)

    • getPrecedence

      public final int getPrecedence()
      Get the precedence of the operator. Lower values correspond to tighter binding, that is * gives a lower value than + and 1+2*3 is 1+(2*3).
      Returns:
      the precedence

    • setPrecedence

      public void setPrecedence(int i)
      Set the precedence of the operator. Lower values correspond to tighter binding, that is * gives a lower value than + and 1+2*3 is 1+(2*3).
      Parameters:
      i - the precedence

    • setDistributiveOver

      public final void setDistributiveOver(Operator op)

    • isDistributiveOver

      public boolean isDistributiveOver(Operator op)

    • setRootOp

      public void setRootOp(Operator root)
      For composite operators like a-b which can be considered as a+(-b) there is a root operator (+) and an inverse operator (UMinus). Typically, this is set for both the inverse and the composite
      Parameters:
      root - the root operator

    • setInverseOp

      public void setInverseOp(Operator inv)
      For composite operators like a-b which can be considered as a+(-b) there is a root operator (+) and an inverse operator (UMinus). Typically, set for the root and the composite operators.
      Parameters:
      inv - the unary inverse operator

    • setBinaryInverseOp

      public void setBinaryInverseOp(Operator inv)
      In a mathematical group with operator + and inverse uminus (-y) the binary inverse operator is the composition x + (-y) in other words subtraction -. Typically, set for the root and the inverse.
      Parameters:
      inv -

    • getRootOp

      public Operator getRootOp()
      The basic group operator associated with the inverse or composite operator.
      Returns:
      the root operator or null if this is the root operator or if none defined.

    • getInverseOp

      public Operator getInverseOp()
      The unary inverse operator associated with a root or composite operator.
      Returns:
      the inverse operator or null if this is the inverse operator or if none defined.

    • getBinaryInverseOp

      public Operator getBinaryInverseOp()
      The composite or binaryInverse operator (e.g. subtract) associated with a root or unary inverse operator
      Returns:
      the inverse operator or null if this is the inverse operator or if none defined.

    • getFlags

      public final int getFlags()
      The flags for this operator.
      Returns:
      the flags as a set of bits

    • getBinding

      @Deprecated public final int getBinding()
      Deprecated.
      When parsing how is x+y+z interpreted. Can be Operator.LEFT: x+y+z -> (x+y)+z or Operator.RIGHT: x=y=z -> x=(y=z). This is now deprecated
      Returns:
      Operator.LEFT or Operator.RIGHT
      See Also:

    • isLeftBinding

      public final boolean isLeftBinding()

    • isRightBinding

      public final boolean isRightBinding()

    • isAssociative

      public final boolean isAssociative()

    • isCommutative

      public final boolean isCommutative()

    • isBinary

      public final boolean isBinary()

    • isUnary

      public final boolean isUnary()

    • isNary

      public final boolean isNary()

    • numArgs

      public final int numArgs()

    • isTransitive

      public final boolean isTransitive()

    • isSymmetric

      public final boolean isSymmetric()

    • isReflexive

      public final boolean isReflexive()

    • isEquivalence

      public final boolean isEquivalence()

    • isPrefix

      public final boolean isPrefix()

    • isSuffix

      public final boolean isSuffix()

    • isTernary

      public final boolean isTernary()

    • isComposite

      public final boolean isComposite()

    • isSelfInverse

      public final boolean isSelfInverse()

    • useBindingForPrint

      public final boolean useBindingForPrint()

    • notInParser

      public final boolean notInParser()

    • setFlag

      public void setFlag(int flag, boolean val)
      Set the value of a specific flag. Use with care
      Parameters:
      flag - flag to set
      val - value for that flag

    • toFullString

      public String toFullString()
      returns a verbose representation of the operator and all its properties. Symbols used to represent operator are enclosed in quotes.
      Returns:
      verbose string representation

    • toString

      public String toString()
      Overrides:
      toString in class Object

    • getKey

      @Deprecated public int getKey()
      Deprecated.
      Get the key code used to identify the operator in the old OperatorTable.
      Returns:
      the key

    • setKey

      @Deprecated public void setKey(int key)
      Deprecated.
      Key code used to identify the operator in the old OperatorTable.
      Parameters:
      key - the key

    • getAltSymbols

      public List<String> getAltSymbols()
      List of alternative symbols which can represent the same operator
      Returns:
      either a list of strings or null if there are no such symbols

    • addAltSymbol

      public boolean addAltSymbol(String altSymbol)

      Adds an alternate symbol which can be used at parse time. The alternate symbol added will be recognised at parse time by configurable parser the normal symbol will be used in output.

      For example unicode U+002D the hyphen minus (-), U+2212 the unicode minus symbol (−), U+2013 then en-dash (–) may appear in some input to represent minus. Other possible alternative characters include U+2264 less-than or equals (≤), U+2264 greater-than or equals (≥), U+00D7 multiplication sign (×), U+00F7 division sign (÷), U+2044 fraction slash (⁄) and U+2215 division slash.

      Parameters:
      altSymbol - the symbol to add
      Returns:
      true if successfully added

    • duplicate

      public Operator duplicate()
      Return a copy of the operator with all fields identical.
      Returns:
      a copy of the operator
      Since:
      4.0