38 lines
1.2 KiB
Java
38 lines
1.2 KiB
Java
package xl.expr;
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/**
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* An <code>Expr</code> object represents a real valued expression that may contain variables. The
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* value of a variable is obtained from an <code>Environment</code> object by specifying the name of
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* the variable.
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*
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* @see Environment
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* @author Lennart Andersson
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*/
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public abstract class Expr {
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/**
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* The <code>toString</code> method returns a <code>String</code> representation of this
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* expression without unnecessary parentheses.
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*
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* @return the <code>String</code> representation of this expression.
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*/
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public String toString() {
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return toString(0);
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}
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/*
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* toString(prec) returns a string representation of this expression without
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* unnecessary parentheses. The prec argument specifies the precedence level
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* enclosing expression and is used to control the precedence of
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* parentheses.
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*/
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public abstract String toString(int prec);
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/**
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* The <code>value</code> method returns the value of this expression.
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*
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* @param env is the <code>Environment</code> containing the values of variables.
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* @return the <code>double</code> value of this expression.
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*/
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public abstract double value(Environment env);
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}
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