fix: wrap conditional branch expression in parentheses when optimizin…

…g IF THEN ELSE (#153)

Fixes #152

models/prune/prune.dat

@@ -230,6 +230,26 @@ Test 12 Result
 10	1
 Test 12 T
 0	1
+Test 13 Cond
+0	1
+Test 13 F
+0	2
+Test 13 Result
+0	80
+1	80
+2	80
+3	80
+4	80
+5	80
+6	80
+7	80
+8	80
+9	80
+10	80
+Test 13 T1
+0	1
+Test 13 T2
+0	7
 Test 2 F
 0	2
 Test 2 Result

models/prune/prune.mdl

@@ -362,6 +362,28 @@ Test 12 Result = IF THEN ELSE(Test 12 Cond :OR: ABS(Test 12 Cond), Test 12 T, Te
 	~	:SUPPLEMENTARY 
 	|
 
+Test 13 Cond = 1
+	~	dmnl
+	~		|
+
+Test 13 T1 = 1
+	~	dmnl
+	~		|
+
+Test 13 T2 = 7
+	~	dmnl
+	~		|
+
+Test 13 F = 2
+	~	dmnl
+	~		|
+
+Test 13 Result = IF THEN ELSE(Test 13 Cond, Test 13 T1 + Test 13 T2, Test 13 F) * 10.0
+	~	dmnl
+	~	Should generate "(Test 13 T1 + Test 13 T2) * 10.0" with parentheses included.
+	~	:SUPPLEMENTARY 
+	|
+
 ********************************************************
 	.Control
 ********************************************************~

models/prune/prune_check.sh

@@ -44,17 +44,18 @@ expect_present "_constant_partial_2"
 expect_present "_initial_partial"
 expect_present "_partial"
 expect_present "_test_1_result = _IF_THEN_ELSE(_input_1 == 10.0, _test_1_t, _test_1_f);"
-expect_present "_test_2_result = _test_2_f;"
-expect_present "_test_3_result = _test_3_t;"
-expect_present "_test_4_result = _test_4_f;"
-expect_present "_test_5_result = _test_5_t;"
-expect_present "_test_6_result = _test_6_f;"
-expect_present "_test_7_result = _test_7_t;"
-expect_present "_test_8_result = _test_8_f;"
-expect_present "_test_9_result = _test_9_t;"
+expect_present "_test_2_result = (_test_2_f);"
+expect_present "_test_3_result = (_test_3_t);"
+expect_present "_test_4_result = (_test_4_f);"
+expect_present "_test_5_result = (_test_5_t);"
+expect_present "_test_6_result = (_test_6_f);"
+expect_present "_test_7_result = (_test_7_t);"
+expect_present "_test_8_result = (_test_8_f);"
+expect_present "_test_9_result = (_test_9_t);"
 expect_present "_test_10_result = _IF_THEN_ELSE(_ABS(_test_10_cond), _test_10_t, _test_10_f);"
-expect_present "_test_11_result = _test_11_f;"
-expect_present "_test_12_result = _test_12_t;"
+expect_present "_test_11_result = (_test_11_f);"
+expect_present "_test_12_result = (_test_12_t);"
+expect_present "_test_13_result = (_test_13_t1 + _test_13_t2) \* 10.0;"
 
 # Verify that unreferenced variables do not appear in the generated C file
 expect_not_present "_input_3"
@@ -88,5 +89,7 @@ expect_not_present "_test_11_cond"
 expect_not_present "_test_11_t"
 expect_not_present "_test_12_cond"
 expect_not_present "_test_12_f"
+expect_not_present "_test_13_cond"
+expect_not_present "_test_13_f"
 
 echo "All validation checks passed!"

models/prune/prune_spec.json

@@ -21,7 +21,8 @@
     "Test 9 Result",
     "Test 10 Result",
     "Test 11 Result",
-    "Test 12 Result"
+    "Test 12 Result",
+    "Test 13 Result"
   ],
   "externalDatfiles": ["prune_data.dat"]
 }

src/EquationGen.js

@@ -881,6 +881,7 @@ export default class EquationGen extends ModelReader {
       const condText = ctx.expr(0).getText()
       const condValue = Model.getConstantExprValue(condText)
       if (condValue !== undefined) {
+        this.emit('(')
         if (condValue !== 0) {
           // Emit only the "if true" branch
           this.setArgIndex(1)
@@ -890,6 +891,7 @@ export default class EquationGen extends ModelReader {
           this.setArgIndex(2)
           ctx.expr(2).accept(this)
         }
+        this.emit(')')
       } else {
         // Emit a normal if/else with both branches
         this.emit(fn)