public class ConditionalExpression extends Object implements ExpressionCommand
A ConditionalExpression object holds the two expressions that are the cases in a conditional expression. Note that the boolean condition is NOT stored in the ConditionalExpression object; it is part of the ExpressionProgram for the expression in which the conditional expression occurs. A ConditionalExpression is an ExpressionCommand, meaning that it can occur in an ExpressionProgram. When the apply() method in this class is called, the boolean condition has already been evaluated, and the result is on the top of the stack. The ConditionalExpression will look at this result and replace it with the value of one of the two expressions that it contains.
It is unlikely that there will be any reason for anyone to use or understand this class, except possibly as an example of an ExpressionCommand.
Constructor and Description |
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ConditionalExpression(ExpressionProgram trueCase,
ExpressionProgram falseCase)
Create a ConditionalExpression object containing the two given expressions.
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Modifier and Type | Method and Description |
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void |
appendOutputString(ExpressionProgram prog,
int myIndex,
StringBuffer buffer)
Append the string representation of the expression (including the boolean
condition) to the buffer.
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void |
apply(StackOfDouble stack,
Cases cases)
Apply this ConditionalExpression to the stack.
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void |
compileDerivative(ExpressionProgram prog,
int myIndex,
ExpressionProgram deriv,
Variable wrt)
Add commands to deriv that evaluate the derivative of this conditional expression with
respect to the variable wrt.
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boolean |
dependsOn(Variable x)
Returns true if x occurs in either the trueCase or the falseCase expression.
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int |
extent(ExpressionProgram prog,
int myIndex)
Assume that this ConditionalExpression object occurs in prog at index myIndex.
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public ConditionalExpression(ExpressionProgram trueCase, ExpressionProgram falseCase)
public void apply(StackOfDouble stack, Cases cases)
apply
in interface ExpressionCommand
stack
- contains results of previous commands in the program.cases
- if non-null, any case information generated during evaluation should be recorded here.public void compileDerivative(ExpressionProgram prog, int myIndex, ExpressionProgram deriv, Variable wrt)
compileDerivative
in interface ExpressionCommand
prog
- program in which ExpressionCommand occurs.myIndex
- point at which ExpressionCommand occurs in the ExpressionProgram.deriv
- the derivative of the ExpressionPorgram prog, which is in the process of being computed.
Commands should added to deriv that will compute the derivative of this ExpressionCommand.wrt
- commands are added to deriv with respect to this Variable.public int extent(ExpressionProgram prog, int myIndex)
extent
in interface ExpressionCommand
prog
- ExpressionProgram in which this ExpressionCommand occurs.myIndex
- index at which ExpressionCommand occurs in prog.public boolean dependsOn(Variable x)
dependsOn
in interface ExpressionCommand
public void appendOutputString(ExpressionProgram prog, int myIndex, StringBuffer buffer)
appendOutputString
in interface ExpressionCommand