additional check when converting to pari-vector

loda-lang · Oct 29, 2024 · 6003fea · 6003fea
1 parent e350c29
commit 6003fea
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Showing 3 changed files with 54 additions and 0 deletions.
diff --git a/src/form/expression_util.cpp b/src/form/expression_util.cpp
@@ -290,6 +290,44 @@ bool ExpressionUtil::isInitialTerm(const Expression& e) {
   return arg.type == Expression::Type::CONSTANT;
 }
 
+bool ExpressionUtil::isRecursionArgument(const Expression& e,
+                                         int64_t max_offset) {
+  Number offset;
+  if (e.type == Expression::Type::PARAMETER) {
+    offset = Number::ZERO;
+  } else if (e.type == Expression::Type::SUM && e.children.size() == 2 &&
+             e.children[0].type == Expression::Type::PARAMETER &&
+             e.children[1].type == Expression::Type::CONSTANT) {
+    offset = e.children[1].value;
+  } else {
+    return false;
+  }
+  return offset < Number(max_offset + 1);
+}
+
+bool ExpressionUtil::isNonRecursiveFunctionReference(
+    const Expression& e, const std::vector<std::string>& names,
+    int64_t max_offset) {
+  if (e.type != Expression::Type::FUNCTION || e.children.size() != 1 ||
+      std::find(names.begin(), names.end(), e.name) == names.end()) {
+    return false;
+  }
+  return !isRecursionArgument(e.children.front(), max_offset);
+}
+
+bool ExpressionUtil::hasNonRecursiveFunctionReference(
+    const Expression& e, const std::vector<std::string>& names,
+    int64_t max_offset) {
+  if (isNonRecursiveFunctionReference(e, names, max_offset)) {
+    return true;
+  } else {
+    return std::any_of(
+        e.children.begin(), e.children.end(), [&](const Expression& c) {
+          return hasNonRecursiveFunctionReference(c, names, max_offset);
+        });
+  }
+}
+
 bool ExpressionUtil::canBeNegative(const Expression& e) {
   switch (e.type) {
     case Expression::Type::CONSTANT:

diff --git a/src/form/expression_util.hpp b/src/form/expression_util.hpp
@@ -22,6 +22,16 @@ class ExpressionUtil {
 
   static bool isInitialTerm(const Expression& e);
 
+  static bool isRecursionArgument(const Expression& e, int64_t max_offset);
+
+  static bool isNonRecursiveFunctionReference(
+      const Expression& e, const std::vector<std::string>& names,
+      int64_t max_offset);
+
+  static bool hasNonRecursiveFunctionReference(
+      const Expression& e, const std::vector<std::string>& names,
+      int64_t max_offset);
+
   static bool canBeNegative(const Expression& e);
 
   static void collectNames(const Expression& e, Expression::Type type,

diff --git a/src/form/pari.cpp b/src/form/pari.cpp
@@ -74,12 +74,18 @@ bool PariFormula::convert(const Formula& formula, bool as_vector,
                           PariFormula& pari_formula) {
   pari_formula = PariFormula();
   pari_formula.as_vector = as_vector;
+  auto defs = FormulaUtil::getDefinitions(formula, Expression::Type::FUNCTION);
   for (const auto& entry : formula.entries) {
     auto left = entry.first;
     auto right = entry.second;
     if (as_vector && left.type == Expression::Type::FUNCTION) {
       left.type = Expression::Type::VECTOR;
     }
+    // TODO: remove this limitation
+    if (as_vector &&
+        ExpressionUtil::hasNonRecursiveFunctionReference(right, defs, 0)) {
+      return false;
+    }
     if (!convertExprToPari(right, formula, as_vector)) {
       return false;
     }