use of com.sri.ai.util.base.PairOf in project aic-expresso by aic-sri-international.
the class Context method extendWith.
/**
* Extends context with index expressions, taking into account that new contextual variables may collide with existing ones.
* In this case, it renames the incoming variables to unique identifiers and replaces them in the types of remaining
* index expressions. It also renames the variables in a given expressions supposed to be in their scope (for example,
* the head and condition of an intensionally defined set).
* Returns the new context and the index expressions and expression in scope after the renaming.
* @param indexExpressions
* @param expressionInScope
* @return the new context and the index expressions and expression in scope after the renaming
*/
default default Triple<Context, ExtensionalIndexExpressionsSet, Expression> extendWith(ExtensionalIndexExpressionsSet indexExpressions, Expression expressionInScope) {
Triple<Context, ExtensionalIndexExpressionsSet, Expression> result;
if (thereExists(getIndices(indexExpressions), index -> this.containsSymbol(index))) {
// OPTIMIZATION: only kick in this entire procedure when extending with symbol in the context (previous ones could have been dealt with normally).
// the objects to be returned in the triple:
Context newContext = this;
ArrayList<Expression> newIndexExpressionsList = new ArrayList<>(indexExpressions.getList());
Expression newExpressionInScope = expressionInScope;
// Collects all existing symbols to be able to create unique symbols
Set<Expression> alreadyDefined = Util.set();
alreadyDefined.addAll(this.getSymbols());
alreadyDefined.addAll(Expressions.freeSymbols(new DefaultTuple(newIndexExpressionsList), this));
alreadyDefined.addAll(Expressions.freeSymbols(expressionInScope, this));
Predicate<Expression> isAlreadyDefined = e -> alreadyDefined.contains(e);
for (int i = 0; i != newIndexExpressionsList.size(); i++) {
Expression indexExpression = newIndexExpressionsList.get(i);
Symbol index = (Symbol) indexExpression.get(0);
Expression type = indexExpression.get(1);
PairOf<Expression> newIndexAndNewExpressionInScope = Expressions.standardizeApart(index, isAlreadyDefined, newExpressionInScope);
Expression newIndex = newIndexAndNewExpressionInScope.first;
newExpressionInScope = newIndexAndNewExpressionInScope.second;
// type should not contain the index
Expression newIndexExpression = apply(IN, newIndex, type);
newIndexExpressionsList.set(i, newIndexExpression);
alreadyDefined.add(newIndex);
for (int j = i + 1; j != newIndexExpressionsList.size(); j++) {
Expression anotherIndexExpression = newIndexExpressionsList.get(j);
Expression anotherIndex = anotherIndexExpression.get(0);
Expression anotherType = anotherIndexExpression.get(1);
Expression newAnotherType = anotherType.replaceSymbol(index, newIndex, this);
// anotherIndex is a symbols and does not contain index
Expression newAnotherIndexExpression = apply(IN, anotherIndex, newAnotherType);
newIndexExpressionsList.set(j, newAnotherIndexExpression);
}
}
ExtensionalIndexExpressionsSet newIndexExpressions = new ExtensionalIndexExpressionsSet(newIndexExpressionsList);
newContext = newContext.extendWith(newIndexExpressions);
result = triple(newContext, newIndexExpressions, newExpressionInScope);
} else {
// no collision; usual extension and the expressions do not change.
result = triple(extendWith(indexExpressions), indexExpressions, expressionInScope);
}
return result;
}
use of com.sri.ai.util.base.PairOf in project aic-expresso by aic-sri-international.
the class Expressions method standardizeApart.
/**
* Given a symbol, a predicate indicating what symbols are already defined in some situation,
* and an expression possibly containing the symbol,
* prime the symbol until it is unique,
* and return the new symbol and the result of replacing the old symbol by the new in the expression containing it.
* @param symbol
* @param alreadyDefined
* @param containingSymbol
* @return the new symbol and the result of replacing the old symbol by the new in the expression containing it.
*/
public static PairOf<Expression> standardizeApart(Symbol symbol, Predicate<Expression> alreadyDefined, Expression containingSymbol) {
Expression newSymbol = symbol;
while (alreadyDefined.apply(newSymbol)) {
newSymbol = primedUntilUnique(newSymbol, s -> !alreadyDefined.apply(s));
}
Expression newExpressionContainingSymbol = containingSymbol.replaceSymbol(symbol, newSymbol, null);
PairOf<Expression> result = pairOf(newSymbol, newExpressionContainingSymbol);
return result;
}
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