feat: Support nested conditionals in shuntingYard

src/core/shuntingYard.hpp

@@ -626,6 +626,27 @@ std::string calculate(const std::string & expr) {
     return result;
 }
 
+void skipBrackets(const std::string & expr, size_t & pos, const int direction) {
+    int i = pos;
+    char open = '(', close = ')';
+    if (direction == -1) {
+        open = ')'; close = '(';
+    }
+    size_t depth = 1;
+    while ((i >= 0) && (i < expr.size()) && depth > 0) {
+        if (expr[i] == open) depth++;
+        if (expr[i] == close) depth--;
+        i += direction;
+    }
+    if (depth > 0) {
+        // We didn't find the close bracket so return the end of the string
+        pos = direction == 1 ? expr.size() : 0;
+    } else {
+        pos = i - direction * 2;
+    }
+    
+}
+
 // check for multiple instances of <cond> ? <expr1> : <expr2>
 std::string compute(const std::string & expr) {
     auto expr_new = emsesp::Helpers::toLower(expr);
@@ -681,31 +702,37 @@ std::string compute(const std::string & expr) {
         f = expr_new.find_first_of('{', e);
     }
 
-    // positions: q-questionmark, c-colon
+    // <cond> ? <expr1> : <expr2>
-    auto q = expr_new.find_first_of('?');
+    // We don't allow nested conditionals in <cond> but we do in <expr1> or <expr2>
-    while (q != std::string::npos) {
+    // Therefore if you nest a conditional, it's ? is always to the right of the parent one
-        // find corresponding colon
+    // Therefore the rightmost ? never has nested conditionals
-        auto c1 = expr_new.find_first_of(':', q + 1);
+    // We will also insist that a nested conditional is surrounded by brackets
-        auto q1 = expr_new.find_first_of('?', q + 1);
+    // positions: s-start, q-questionmark, c-colon, e:end
-        while (q1 < c1 && q1 != std::string::npos && c1 != std::string::npos) {
+    size_t q;
-            q1 = expr_new.find_first_of('?', q1 + 1);
+    while ((q = expr_new.find_last_of('?')) != std::string::npos) {
-            c1 = expr_new.find_first_of(':', c1 + 1);
+        // find corresponding colon, remember we know there's no nested ones to worry about
-        }
+        size_t c = expr_new.find_first_of(':', q);
-        if (c1 == std::string::npos) {
+        if (c == std::string::npos) {
             return ""; // error: missing colon
         }
-        std::string cond = calculate(expr_new.substr(0, q));
+        // Find the start of <cond>
+        size_t s = q - 1;
+        skipBrackets(expr, s, -1);
+        // Find the end of <expr2>
+        size_t e = c + 1;
+        skipBrackets(expr, e, +1);
+
+        std::string cond = calculate(expr_new.substr(s, q - s));
         if (cond.length() == 0) {
             return "";
         } else if (cond[0] == '1') {
-            expr_new.erase(c1);       // remove second expression after colon
+            expr_new.erase(c, e + 1 - c);     // remove second expression after colon
-            expr_new.erase(0, q + 1); // remove condition before questionmark
+            expr_new.erase(s, q + 1 - s); // remove condition before questionmark
         } else if (cond[0] == '0') {
-            expr_new.erase(0, c1 + 1); // remove condition and first expression
+            expr_new.erase(s, c + 1 - s); // remove condition and first expression
         } else {
             return ""; // error
         }
-        q = expr_new.find_first_of('?'); // search next instance
     }
 
     return calculate(expr_new);

test/test_api/test_shuntingYard.hpp

@@ -80,38 +80,44 @@ void shuntingYard_test12() {
 
 void shuntingYard_test13() {
     std::string expected_result = "5";
-    std::string test_value = "1 < 2 ? (3 < 4 ? 5 : 6) : 7";
+    std::string test_value = "1<2?(3<4?5:6):7";
-    //TEST_ASSERT_EQUAL_STRING(expected_result.c_str(), compute(test_value).c_str());
+    TEST_ASSERT_EQUAL_STRING(expected_result.c_str(), compute(test_value).c_str());
 }
 
 void shuntingYard_test14() {
-    std::string expected_result = "6";
+    std::string expected_result = "7";
-    std::string test_value = "1 < 2 ? (3 > 4 ? 5 : 6) : 7";
+    std::string test_value = "1>2?(3<4?5:6):7";
-    //TEST_ASSERT_EQUAL_STRING(expected_result.c_str(), compute(test_value).c_str());
+    TEST_ASSERT_EQUAL_STRING(expected_result.c_str(), compute(test_value).c_str());
 }
 
 void shuntingYard_test15() {
-    std::string expected_result = "3";
+    std::string expected_result = "6";
-    std::string test_value = "1 < 2 ? 3 : (4 < 5 ? 6 : 7)";
+    std::string test_value = "1<2?(3>4?5:6):7";
     TEST_ASSERT_EQUAL_STRING(expected_result.c_str(), compute(test_value).c_str());
 }
 
 void shuntingYard_test16() {
-    std::string expected_result = "6";
+    std::string expected_result = "3";
-    std::string test_value = "1 > 2 ? 3 : (4 < 5 ? 6 : 7)";
+    std::string test_value = "1<2?3:(4<5?6:7)";
-    //TEST_ASSERT_EQUAL_STRING(expected_result.c_str(), compute(test_value).c_str());
+    TEST_ASSERT_EQUAL_STRING(expected_result.c_str(), compute(test_value).c_str());
 }
 
 void shuntingYard_test17() {
-    std::string expected_result = "7";
+    std::string expected_result = "6";
-    std::string test_value = "1 > 2 ? 3 : (4 > 5 ? 6 : 7)";
+    std::string test_value = "1>2?3:(4<5?6:7)";
-    //TEST_ASSERT_EQUAL_STRING(expected_result.c_str(), compute(test_value).c_str());
+    TEST_ASSERT_EQUAL_STRING(expected_result.c_str(), compute(test_value).c_str());
 }
 
 void shuntingYard_test18() {
+    std::string expected_result = "7";
+    std::string test_value = "1>2?3:(4>5?6:7)";
+    TEST_ASSERT_EQUAL_STRING(expected_result.c_str(), compute(test_value).c_str());
+}
+
+void shuntingYard_test19() {
     std::string expected_result = "44";
-    std::string test_value = "(1 > 2 ? 3 : 4) + (10 > 20 ? 30 : 40)";
+    std::string test_value = "(1>2?3:4)+(10>20?30:40)";
-    //TEST_ASSERT_EQUAL_STRING(expected_result.c_str(), compute(test_value).c_str());
+    TEST_ASSERT_EQUAL_STRING(expected_result.c_str(), compute(test_value).c_str());
 }
 
 void run_shuntingYard_tests() {
@@ -133,4 +139,5 @@ void run_shuntingYard_tests() {
     RUN_TEST(shuntingYard_test16);
     RUN_TEST(shuntingYard_test17);
     RUN_TEST(shuntingYard_test18);
+    RUN_TEST(shuntingYard_test19);
 }