/**
* Return a set of the variables in the supplied expression. Note: Substitutions which are in the
* constant table are not included.
*/
public Set<String> getVariablesWithin(String exp) {
Set<String> all = new TreeSet<String>(String.CASE_INSENSITIVE_ORDER);
String add = null;
if (separators == null) {
StringBuilder sep = new StringBuilder(10);
for (char chr = 0; chr < operators.length; chr++) {
if (operators[chr] != null && !operators[chr].internal) {
sep.append(chr);
}
}
sep.append("()");
separators = sep.toString();
}
for (StringTokenizer tkz = new StringTokenizer(exp, separators, true); tkz.hasMoreTokens(); ) {
String tkn = tkz.nextToken().trim();
if (tkn.length() != 0 && Character.isLetter(tkn.charAt(0))) {
add = tkn;
} else if (tkn.length() == 1 && tkn.charAt(0) == '(') {
add = null;
} else if (add != null && !constants.containsKey(add)) {
all.add(add);
}
}
if (add != null && !constants.containsKey(add)) {
all.add(add);
}
return all;
}
/**
* Set a named constant (constants names are not case-sensitive). Constants are like variables but
* are not cleared by clear(). Variables of the same name have precedence over constants.
*/
public MathEval setConstant(String nam, Double val) {
if (constants.get(nam) != null) {
throw new IllegalArgumentException("Constants may not be redefined");
}
validateName(nam);
constants.put(nam, val);
return this;
}
/**
* Set a named variable (variables names are not case-sensitive). If the value is null, the
* variable is removed.
*/
public MathEval setVariable(String nam, Double val) {
validateName(nam);
if (val == null) {
variables.remove(nam);
} else {
variables.put(nam, val);
}
return this;
}
private double doNamedVal(int beg, int end) {
while (beg < end && Character.isWhitespace(expression.charAt(end))) {
end--;
} // since a letter triggers a named value, this can never reduce to beg==end
String nam = expression.substring(beg, (end + 1));
Double val;
if ((val = constants.get(nam)) != null) {
return val.doubleValue();
} else if ((val = variables.get(nam)) != null) {
isConstant = false;
return val.doubleValue();
} else if (relaxed) {
isConstant = false;
return 0.0;
}
throw exception(beg, "Unrecognized constant or variable \"" + nam + "\"");
}
private double doFunction(int beg, int end) {
int argbeg;
for (argbeg = beg; argbeg <= end && expression.charAt(argbeg) != '('; argbeg++) {;
}
String fncnam = expression.substring(beg, argbeg).trim();
ArgParser fncargs = new ArgParser(argbeg, end);
FunctionHandler fnchdl = null;
try {
if ((fnchdl = pureFunctions.get(fncnam)) != null) {
return fnchdl.evaluateFunction(fncnam, fncargs);
} else if ((fnchdl = impureFunctions.get(fncnam)) != null) {
isConstant = false; // impure functions cannot be guaranteed to be constant
return fnchdl.evaluateFunction(fncnam, fncargs);
}
fncargs = null; // suppress check for too many fncargs
} catch (ArithmeticException thr) {
fncargs = null;
throw thr;
} catch (NoSuchMethodError thr) {
fncargs = null;
throw exception(beg, "Function not supported in this JVM: \"" + fncnam + "\"");
} catch (UnsupportedOperationException thr) {
fncargs = null;
throw exception(beg, thr.getMessage());
} catch (Throwable thr) {
fncargs = null;
throw exception(beg, "Unexpected exception parsing function arguments", thr);
} finally {
if (fncargs != null) {
if (fncargs.hasNext()) {
throw exception(fncargs.getIndex(), "Function has too many arguments");
}
offset = fncargs.getIndex();
}
}
throw exception(beg, "Function \"" + fncnam + "\" not recognized");
}
/**
* Create a math evaluator with the same constants, variables, function handlers and relaxation
* setting as the supplied evaluator.
*/
public MathEval(MathEval oth) {
super();
operators = oth.operators;
constants = new TreeMap<String, Double>(String.CASE_INSENSITIVE_ORDER);
constants.putAll(oth.constants);
variables = new TreeMap<String, Double>(String.CASE_INSENSITIVE_ORDER);
variables.putAll(oth.variables);
pureFunctions = new TreeMap<String, FunctionHandler>(String.CASE_INSENSITIVE_ORDER);
impureFunctions = new TreeMap<String, FunctionHandler>(String.CASE_INSENSITIVE_ORDER);
pureFunctions.putAll(oth.pureFunctions);
impureFunctions.putAll(oth.impureFunctions);
relaxed = oth.relaxed;
separators = oth.separators;
offset = 0;
isConstant = false;
}
/**
* Set a function handler for the specific named function optionally tagging the function as
* impure, replacing any existing handler for the given name; if the handler is null the function
* handler is removed.
*
* <p>Pure functions have results which depend purely on their arguments; given constant arguments
* they will have a constant result. Impure functions are rare.
*/
public MathEval setFunctionHandler(String nam, FunctionHandler hdl, boolean impure) {
validateName(nam);
if (hdl == null) {
pureFunctions.remove(nam);
impureFunctions.remove(nam);
} else if (impure) {
pureFunctions.remove(nam);
impureFunctions.put(nam, hdl);
} else {
pureFunctions.put(nam, hdl);
impureFunctions.remove(nam);
}
return this;
}
/**
* Clear all variables prefixed by the supplied string followed by a dot, such that they match
* "Prefix.xxx".
*/
public MathEval clear(String pfx) {
variables.subMap((pfx + "."), (pfx + "." + Character.MAX_VALUE)).clear();
return this;
}
/** Clear all variables (constants are not affected). */
public MathEval clear() {
variables.clear();
return this;
}
/** Set a named variable (variables names are not case-sensitive). */
public double getVariable(String nam) {
Double val = variables.get(nam);
return (val == null ? 0 : val.doubleValue());
}
/**
* Set a named constant (constant names are not case-sensitive). Constants are like variables but
* are not cleared by clear(). Variables of the same name have precedence over constants.
*/
public double getConstant(String nam) {
Double val = constants.get(nam);
return (val == null ? 0 : val.doubleValue());
}