From 9bf422f9953cb87e3b34d458df35600457198d73 Mon Sep 17 00:00:00 2001
From: Alan Garny <agarny@hellix.com>
Date: Tue, 22 Oct 2024 14:41:34 +1300
Subject: [PATCH] Analyser: account for the case where a piecewise statement
 doesn't have any children.

---
 src/analyser.cpp | 32 +++++++++++++++++---------------
 1 file changed, 17 insertions(+), 15 deletions(-)

diff --git a/src/analyser.cpp b/src/analyser.cpp
index c3a68d105..1ebf42d13 100644
--- a/src/analyser.cpp
+++ b/src/analyser.cpp
@@ -688,30 +688,32 @@ void Analyser::AnalyserImpl::analyseNode(const XmlNodePtr &node,
 
         ast->mPimpl->populate(AnalyserEquationAst::Type::PIECEWISE, astParent);
 
-        analyseNode(mathmlChildNode(node, 0), ast->mPimpl->mOwnedLeftChild, ast, component, equation);
+        if (childCount >= 1) {
+            analyseNode(mathmlChildNode(node, 0), ast->mPimpl->mOwnedLeftChild, ast, component, equation);
 
-        if (childCount >= 2) {
-            AnalyserEquationAstPtr astRight;
-            AnalyserEquationAstPtr tempAst;
+            if (childCount >= 2) {
+                AnalyserEquationAstPtr astRight;
+                AnalyserEquationAstPtr tempAst;
 
-            analyseNode(mathmlChildNode(node, childCount - 1), astRight, nullptr, component, equation);
+                analyseNode(mathmlChildNode(node, childCount - 1), astRight, nullptr, component, equation);
 
-            for (auto i = childCount - 2; i > 0; --i) {
-                tempAst = AnalyserEquationAst::create();
+                for (auto i = childCount - 2; i > 0; --i) {
+                    tempAst = AnalyserEquationAst::create();
 
-                tempAst->mPimpl->populate(AnalyserEquationAst::Type::PIECEWISE, astParent);
+                    tempAst->mPimpl->populate(AnalyserEquationAst::Type::PIECEWISE, astParent);
 
-                analyseNode(mathmlChildNode(node, i), tempAst->mPimpl->mOwnedLeftChild, tempAst, component, equation);
+                    analyseNode(mathmlChildNode(node, i), tempAst->mPimpl->mOwnedLeftChild, tempAst, component, equation);
 
-                astRight->mPimpl->mParent = tempAst;
+                    astRight->mPimpl->mParent = tempAst;
 
-                tempAst->mPimpl->mOwnedRightChild = astRight;
-                astRight = tempAst;
-            }
+                    tempAst->mPimpl->mOwnedRightChild = astRight;
+                    astRight = tempAst;
+                }
 
-            astRight->mPimpl->mParent = ast;
+                astRight->mPimpl->mParent = ast;
 
-            ast->mPimpl->mOwnedRightChild = astRight;
+                ast->mPimpl->mOwnedRightChild = astRight;
+            }
         }
     } else if (node->isMathmlElement("piece")) {
         ast->mPimpl->populate(AnalyserEquationAst::Type::PIECE, astParent);