com.bc.jexp
Class Term

java.lang.Object
  com.bc.jexp.Term

Direct Known Subclasses:

Term.Call, Term.ConstB, Term.ConstD, Term.ConstI, Term.ConstS, Term.Op, Term.Ref

public abstract class Term
extends Object

The abstract Term class is an in-memory representation of an element within an arbitrary expression tree. The class defines a number of concrete Term implementations each representing either an an atomic leave (number constant, symbol reference) or a node (e.g. binary operator, function call) within an expression tree.

Instances of this class are normally created using an expression parser which implements the Parser interface. The ParserImpl class provides a default implementation of such a parser.

Version:

$Revision$ $Date$

Author:

Norman Fomferra (norman.fomferra@brockmann-consult.de)

Nested Class Summary

static class	Term.Add The numerical ADD operation: n-term + n-term
static class	Term.AndB The logical AND operation: b-term && b-term
static class	Term.AndI The bitwise AND operation: i-term & i-term
static class	Term.Assign The assignment operation variable-ref-term = term
static class	Term.Binary
static class	Term.BinaryB An abstract binary (= 2 operands) operation.
static class	Term.BinaryI An abstract binary (= 2 operands) operation with a return type of int.
static class	Term.BinaryN An abstract binary (= 2 operands) operation with a numeric return type.
static class	Term.Call A call of a (or reference to a) Function.
static class	Term.Cond The conditional operation b-term ?
static class	Term.ConstB A boolean constant, e.g.
static class	Term.ConstD A floating point constant, e.g.
static class	Term.ConstI An integer constant, e.g.
static class	Term.ConstS
static class	Term.Div The numerical DIV operation: n-term / n-term
static class	Term.EqB The boolean EQ operation: b-term == b-term
static class	Term.EqD The double EQ operation: d-term == d-term
static class	Term.EqI The integer EQ operation: i-term == i-term
static class	Term.GeD The double GE operation: d-term >= d-term
static class	Term.GeI The integer GE operation: i-term >= i-term
static class	Term.GtD The double GT operation: d-term > d-term
static class	Term.GtI The integer GT operation: i-term > i-term
static class	Term.LeD The double LE operation: d-term <= d-term
static class	Term.LeI The integer LE operation: i-term <= i-term
static class	Term.LtD The double LT operation: d-term < d-term
static class	Term.LtI The integer LT operation: i-term < i-term
static class	Term.Mod The numerical MOD (modulo) operation: n-term % n-term
static class	Term.Mul The numerical MUL operation: n-term * n-term
static class	Term.Neg The numerical NEG operation: - d-term
static class	Term.NEqB The boolean NEQ operation: b-term !
static class	Term.NEqD The double NEQ operation: d-term !
static class	Term.NEqI The integer NEQ operation: i-term !
static class	Term.NotB The logical NOT operation !
static class	Term.NotI The bitwise NOT operation: ~ i-term
static class	Term.Op An abstract operation.
static class	Term.OrB The logical OR operation: b-term || b-term
static class	Term.OrI The bitwise OR operation: i-term | i-term
static class	Term.Ref A reference to a Symbol.
static class	Term.Sub The numerical SUB operation: n-term - n-term
static class	Term.Unary An abstract unary (= 1 operand) operation.
static class	Term.UnaryB An abstract unary (= 1 operand) operation with return type of boolean.
static class	Term.UnaryI An abstract unary (= 1 operand) operation with return type of int.
static class	Term.UnaryN An abstract unary (= 1 operand) operation with a numeric return type.
static class	Term.XOrI The bitwise XOR operation: i-term ^ i-term

Field Summary

static int	TYPE_B The ID for the boolean type.
static int	TYPE_D The ID for the double type.
static int	TYPE_I The ID for the int type.
static int	TYPE_S The ID for the string type.

Constructor Summary

Term()

Method Summary

abstract boolean	evalB(EvalEnv context) Evaluates this term to a boolean value.
abstract double	evalD(EvalEnv env) Evaluates this term to a double value.
abstract int	evalI(EvalEnv env) Evaluates this term to an int value.
String	evalS(EvalEnv env) Evaluates this term to a String value.
Term[]	getChildren() Returns an array of terms which are children of this term.
abstract int	getRetType() Gets the term's "natural" return type.
boolean	isB() Tests whether or not this term "naturally" returns a boolean.
boolean	isD() Tests whether or not this term "naturally" returns a double.
boolean	isI() Tests whether or not this term "naturally" returns an int.
boolean	isN() Tests whether or not this term "naturally" returns a numeric value.
static boolean	toB(double value) Converts a double to a boolean.
static boolean	toB(int value) Converts an int to a boolean.
static double	toD(boolean value) Converts a boolean to an double.
static int	toI(boolean value) Converts a boolean to an int.
static int	toI(double value) Converts a double to an int.
static String	toS(boolean value) Converts a boolean to a String.
static String	toS(double value) Converts a double to a String.
static String	toS(int value) Converts a integer to a String.
abstract String	toString() Returns a string representation of this term which can be used for debugging.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

TYPE_B

public static final int TYPE_B

The ID for the boolean type.

See Also:

Constant Field Values

TYPE_I

public static final int TYPE_I

The ID for the int type.

See Also:

Constant Field Values

TYPE_D

public static final int TYPE_D

The ID for the double type.

See Also:

Constant Field Values

TYPE_S

public static final int TYPE_S

The ID for the string type.

See Also:

Constant Field Values

Constructor Detail

Term

public Term()

Method Detail

getRetType

public abstract int getRetType()

Gets the term's "natural" return type.

Returns:

the type, should always be one of the TYPE_X constants defined in this class.

evalB

public abstract boolean evalB(EvalEnv context)

Evaluates this term to a boolean value.

Parameters:

context - the application dependant environment.

Returns:

a boolean value

Throws:

EvalException - if the evaluation fails

evalI

public abstract int evalI(EvalEnv env)

Evaluates this term to an int value.

Parameters:

env - the application dependant environment.

Returns:

an int value

Throws:

EvalException - if the evaluation fails

evalD

public abstract double evalD(EvalEnv env)

Evaluates this term to a double value.

Parameters:

env - the application dependant environment.

Returns:

a double value

Throws:

EvalException - if the evaluation fails

evalS

public String evalS(EvalEnv env)

Evaluates this term to a String value. The default implementation simply returns the value of toString().

Parameters:

env - the application dependant environment.

Returns:

a String value

Throws:

EvalException - if the evaluation fails

getChildren

public Term[] getChildren()

Returns an array of terms which are children of this term.

Returns:

an array of terms, never null but can be empty

toString

public abstract String toString()

Returns a string representation of this term which can be used for debugging.

Overrides:

toString in class Object

isB

public final boolean isB()

Tests whether or not this term "naturally" returns a boolean.

Returns:

true if so

isI

public final boolean isI()

Tests whether or not this term "naturally" returns an int.

Returns:

true if so

isD

public final boolean isD()

Tests whether or not this term "naturally" returns a double.

Returns:

true if so

isN

public final boolean isN()

Tests whether or not this term "naturally" returns a numeric value.

Returns:

true if so

toB

public static boolean toB(int value)

Converts an int to a boolean.

Parameters:

value - the value to be converted

Returns:

the conversion result, which is value != 0.

toB

public static boolean toB(double value)

Converts a double to a boolean.

Parameters:

value - the value to be converted

Returns:

the conversion result, which is value != 0.0.

toI

public static int toI(boolean value)

Converts a boolean to an int.

Parameters:

value - the value to be converted

Returns:

the conversion result, which is value ? 1 : 0.

toI

public static int toI(double value)

Converts a double to an int.

Parameters:

value - the value to be converted

Returns:

the conversion result, which is (int) value.

toD

public static double toD(boolean value)

Converts a boolean to an double.

Parameters:

value - the value to be converted

Returns:

the conversion result, which is value ? 1.0 : 0.0.

toS

public static String toS(boolean value)

Converts a boolean to a String.

Parameters:

value - the value to be converted

Returns:

the conversion result, which is value ? 1.0 : 0.0.

toS

public static String toS(int value)

Converts a integer to a String.

Parameters:

value - the value to be converted

Returns:

the conversion result, which is value ? 1.0 : 0.0.

toS

public static String toS(double value)

Converts a double to a String.

Parameters:

value - the value to be converted

Returns:

the conversion result, which is value ? 1.0 : 0.0.