private static Interval mergeAllRanges(Collection<Interval> is) throws EmptyRangeException {
Interval rv = new Interval(-Double.MAX_VALUE, Double.MAX_VALUE);
for (Interval i : is) {
rv.min = Math.max(rv.min, i.min);
rv.max = Math.min(rv.max, i.max);
}
if (rv.max < rv.min) throw new EmptyRangeException("range is unsatisfiable");
return rv;
}
/**
* Merge the two ranges. For example [-5, 4] and [2, 10] will merge to be [2, 4].
*
* @param left a range for each variable
* @param right the other range for each variable, may include more or less variables as well
* @return the merged set of constraints
* @throws EmptyRangeException if the ranges don't overlap
*/
private static TreeMap<String, Interval> mergeTreeRanges(
TreeMap<String, Interval> left, TreeMap<String, Interval> right) throws EmptyRangeException {
TreeMap<String, Interval> rv = new TreeMap<String, Interval>();
rv.putAll(left);
for (Entry<String, Interval> e : right.entrySet()) {
String key = e.getKey();
Interval val = e.getValue();
Interval i = rv.get(key);
if (i == null) rv.put(key, val);
else {
// take the tighter of the two extremes
i.min = Math.max(i.min, val.min);
i.max = Math.min(i.max, val.max);
if (i.max < i.min) throw new EmptyRangeException("range for " + key + " is unsatisfiable");
}
}
return rv;
}
/**
* Get the variable ranges and store them into ranges
*
* @param expression the expression to extract from
* @param ranges the place to store them
* @param vars a set of variables we are interested in. if null then get all variables
* @param constantMap a map of variableName -> value for all constants in the original expression
* @throws EmptyRangeException if expression is Constant.FALSE or otherwise unsatisfiable for the
* selected variables
* @throws UnsupportedConditionException if the expression contains non-interval operations on the
* desired variable
*/
private static void getVariableRangesRecursive(
Expression expression,
TreeMap<String, Interval> ranges,
Collection<String> vars,
Map<String, Double> constantMap)
throws EmptyRangeException, UnsupportedConditionException {
Operation o = expression.asOperation();
if (o != null && o.children.size() == 2) {
Expression leftExp = o.children.get(0);
Expression rightExp = o.children.get(1);
Operator op = o.op;
if (op.equals(Operator.AND)) {
TreeMap<String, Interval> left = new TreeMap<String, Interval>();
TreeMap<String, Interval> right = new TreeMap<String, Interval>();
getVariableRangesRecursive(leftExp, ranges, vars, constantMap);
getVariableRangesRecursive(rightExp, ranges, vars, constantMap);
ranges = mergeTreeRanges(left, right);
} else if (expressionContainsVariables(expression, vars)) {
double val = 0;
String varName = null;
// ignore location assignments
if (leftExp instanceof Variable && ((Variable) leftExp).name.startsWith("loc(")) return;
boolean yodaConstraint = false; // if constraint is like '5 < x' instead of the normal order
boolean shouldSkip = false;
if (leftExp instanceof Variable && rightExp instanceof Constant) {
varName = ((Variable) leftExp).name;
val = ((Constant) rightExp).getVal();
yodaConstraint = false;
} else if (leftExp instanceof Constant && rightExp instanceof Variable) {
varName = ((Variable) rightExp).name;
val = ((Constant) leftExp).getVal();
yodaConstraint = true;
} else if (leftExp instanceof Variable && rightExp instanceof Variable) {
// one of them might be an expression constant, which are given by constMap
String leftName = ((Variable) leftExp).name;
Double constVal = constantMap.get(leftName);
if (constVal != null) {
varName = ((Variable) rightExp).name;
val = constVal.doubleValue();
yodaConstraint = true;
} else {
String rightName = ((Variable) rightExp).name;
constVal = constantMap.get(rightName);
if (constVal != null) {
varName = ((Variable) leftExp).name;
val = constVal.doubleValue();
yodaConstraint = false;
} else {
// both are variables. This is only allowed it it's an alias assignment, which
// we detect by checking if the operator is '=='
if (op == Operator.EQUAL) shouldSkip = true;
else
throw new UnsupportedConditionException(
"Unsupported condition for range extraction (one "
+ "side should be variable, the other side a constant): "
+ expression.toDefaultString());
}
}
} else {
throw new UnsupportedConditionException(
"Unsupported condition for range extraction (one "
+ "side should be variable, the other side a constant): "
+ expression.toDefaultString());
}
if (!shouldSkip) {
Interval i = null;
if (op == Operator.EQUAL) {
i = new Interval(val);
ranges.put(varName, i);
} else if ((!yodaConstraint && (op == Operator.GREATER || op == Operator.GREATEREQUAL))
|| (yodaConstraint && (op == Operator.LESS || op == Operator.LESSEQUAL))) {
i = ranges.get(varName);
if (i == null) {
i = new Interval(-Double.MAX_VALUE, Double.MAX_VALUE);
ranges.put(varName, i);
}
i.min = val;
} else if ((!yodaConstraint && (op == Operator.LESS || op == Operator.LESSEQUAL))
|| (yodaConstraint && (op == Operator.GREATER || op == Operator.GREATEREQUAL))) {
i = ranges.get(varName);
if (i == null) {
i = new Interval(-Double.MAX_VALUE, Double.MAX_VALUE);
ranges.put(varName, i);
}
i.max = val;
} else
throw new UnsupportedConditionException(
"Unsupported expression during range extraction: " + expression.toDefaultString());
if (i.max < i.min)
throw new EmptyRangeException("range for " + varName + " is unsatisfiable");
}
}
} else if (expression instanceof Variable) {
Variable v = (Variable) expression;
if (v.name.equals("true")) {
// no restrictions on variable range
} else if (v.name.equals("false")) {
throw new EmptyRangeException("expression contains false");
} else
throw new AutomatonExportException(
"Unsupported expression type (variable as condition?): "
+ expression.toDefaultString());
} else if (expression == Constant.FALSE) // if any variable is false, the range for all is empty
throw new EmptyRangeException("expression contains FALSE");
else if (expression != Constant.TRUE && expressionContainsVariables(expression, vars))
throw new UnsupportedConditionException(
"Unsupported expression during range extraction: " + expression.toDefaultString());
}
