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net.totietje.evaluator

AbstractEvaluator

abstract class AbstractEvaluator[R] extends Evaluator[R]

A skeletal implementation of the Evaluator class to avoid duplication of common logic.

This class is applicable if, and only if, for each character it is unambiguous whether it is part of a word or special character. That is, every character can be either a special character, or part of a word, but not both. Furthermore, neither special characters not words can contain whitespace.

A 'special character' here is a standalone character that has a special meaning. Special characters cannot be part of values or words. For example, + would be a special character.

A 'word' here is a meaningful string of characters that do not contain any whitespace or special characters. For example, the constant pi is a word, as are functions such as sin. Words cannot contain special characters or they could be mistaken for two words - the word a+b would be split into a, +, and b.

R

What the string should be evaluated to

Source
AbstractEvaluator.scala
Linear Supertypes
Evaluator[R], AnyRef, Any
Known Subclasses
ComplexEvaluator
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Inherited
  1. AbstractEvaluator
  2. Evaluator
  3. AnyRef
  4. Any
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Visibility
  1. Public
  2. All

Instance Constructors

  1. new AbstractEvaluator()

Abstract Value Members

  1. abstract def parseAfterValueChar(char: Char): Option[Token[R]]

    Determines if the character represents a token that comes after a value or close parenthesis.

    Determines if the character represents a token that comes after a value or close parenthesis.

    Operators belong here, as they come after values (for example, in 2 + 3 the + comes after the 2). Close parentheses also belong here, as do argument separators.

    In order to determine if a special character belongs here, ask yourself 'Would it make sense after a constant?'. If the answer is yes, it belongs here.

    char

    A character in the expression being parsed

    returns

    None if the input is not a special character, or the character does not belong after a value. Some(Token) otherwise, where the token represents the character's purpose.

    Attributes
    protected
  2. abstract def parseOtherChar(char: Char): Option[Token[R]]

    Determines if the character represents a token that 1) comes after an operator, 2) comes after a function, 3) follows an open parenthesis, or 4) is at the start of an expression.

    Determines if the character represents a token that 1) comes after an operator, 2) comes after a function, 3) follows an open parenthesis, or 4) is at the start of an expression. start of an expression.

    Unary operators must be defined here, as they come after operators. The unary operator token must be a Function token. A character can be both a binary operator (one that works on two operands) and a unary operator (one that works on one operand), however, they must have distinct tokens.

    Open parentheses also belong here, as they come after operators (for example, 2 * (3 + 4)) or functions (sin(2)). However, close parentheses do not, instead, they belong in the parseAfterValueChar method.

    In order to determine if a special character belongs here, ask yourself 'Would it make sense at the start of an expression?' If the answer is yes, it belongs here.

    char

    A character in the expression being parsed

    returns

    None if the input is not a special character, or does not belong in the specified positions.

    Attributes
    protected
  3. abstract def parseWord(word: String): Token[R]

    Parses a possible word.

    Parses a possible word.

    word

    The word to parse

    returns

    The token representation of the word

    Attributes
    protected
    Exceptions thrown

    net.totietje.evaluator.EvaluationException If the input string is not a valid word

Concrete Value Members

  1. final def !=(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  2. final def ##(): Int
    Definition Classes
    AnyRef → Any
  3. final def ==(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  4. final def asInstanceOf[T0]: T0
    Definition Classes
    Any
  5. def clone(): AnyRef
    Attributes
    protected[java.lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  6. final def eq(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  7. def equals(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  8. final def evaluate(expression: String): R

    Parses a string.

    Parses a string.

    First of all, this tokenizes the string using the abstract tokenize method, which must be overridden by the user. This transforms the string into an array of Tokens which represent the string in terms of its parts.

    Then, this evaluates the provided array of tokens as the user defines, producing a result of type R. For more information on how this happens, see Token.

    expression

    The input string to parse

    returns

    The result of parsing the input

    Definition Classes
    Evaluator
    Exceptions thrown

    net.totietje.evaluator.EvaluationException If there is a syntax error in the expression

  9. def finalize(): Unit
    Attributes
    protected[java.lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( classOf[java.lang.Throwable] )
  10. final def getClass(): Class[_]
    Definition Classes
    AnyRef → Any
  11. def hashCode(): Int
    Definition Classes
    AnyRef → Any
  12. final def isInstanceOf[T0]: Boolean
    Definition Classes
    Any
  13. final def ne(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  14. final def notify(): Unit
    Definition Classes
    AnyRef
  15. final def notifyAll(): Unit
    Definition Classes
    AnyRef
  16. final def synchronized[T0](arg0: ⇒ T0): T0
    Definition Classes
    AnyRef
  17. def toString(): String
    Definition Classes
    AnyRef → Any
  18. final def tokenize(expression: String): Array[Token[R]]

    Transforms an expression into a list of tokens.

    Transforms an expression into a list of tokens.

    expression

    The input string to parse

    returns

    An array of tokens containing the information needed to evaluate it

    Attributes
    protected
    Definition Classes
    AbstractEvaluator → Evaluator
    Exceptions thrown

    net.totietje.evaluator.EvaluationException If the input string contains an invalid token

  19. final def wait(): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  20. final def wait(arg0: Long, arg1: Int): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  21. final def wait(arg0: Long): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )

Inherited from Evaluator[R]

Inherited from AnyRef

Inherited from Any

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