[Parser] Do not split numbers in scientific notation at the exponent's sign

src/quartz/parser/qasm_parser.cpp

@@ -1,5 +1,7 @@
 #include "qasm_parser.h"
 
+#include <cctype>
+
 namespace quartz {
 
 void find_and_replace_all(std::string &data, const std::string &tofind,
@@ -274,6 +276,11 @@ int ParamParser::parse_expr(std::stringstream &ss, bool is_halved) {
       if (token[pos - 1] == '*') {
         // Case: t*-e (negative sign), ignored here
         pos = token.find_last_of("+-", pos - 1);
+      } else if ((token[pos - 1] == 'e' || token[pos - 1] == 'E') && pos > 1 &&
+                 (std::isdigit((unsigned char)token[pos - 2]) ||
+                  token[pos - 2] == '.')) {
+        // Case: 1.5e-05 (sign of an exponent), ignored here
+        pos = token.find_last_of("+-", pos - 1);
       } else {
         break;
       }

src/test/CMakeLists.txt

@@ -33,6 +33,7 @@ file(GLOB_RECURSE TEST_CREATE_GRAPHXFER_FROM_QASM "test_create_graphXfer_from_qa
 file(GLOB_RECURSE TEST_PARTITION "test_partition.cpp")
 file(GLOB_RECURSE TEST_MULT "test_mult.cpp")
 file(GLOB_RECURSE TEST_PI "test_pi.cpp")
+file(GLOB_RECURSE TEST_PARSER_EXPONENT "test_parser_exponent.cpp")
 file(GLOB_RECURSE TEST_CONSTANTS "test_constants.cpp")
 file(GLOB_RECURSE TEST_QASM_PARSER "test_qasm_parser.cpp" )
 file(GLOB_RECURSE VERIFY_OPENQASM "verify_openqasm.cpp" )
@@ -73,6 +74,7 @@ add_executable(test_create_graphXfer_from_qasm ${TEST_CREATE_GRAPHXFER_FROM_QASM
 add_executable(test_partition ${TEST_PARTITION} )
 add_executable(test_mult ${TEST_MULT} )
 add_executable(test_pi ${TEST_PI} )
+add_executable(test_parser_exponent ${TEST_PARSER_EXPONENT} )
 add_executable(test_constants ${TEST_CONSTANTS} )
 add_executable(test_qasm_parser ${TEST_QASM_PARSER} )
 add_executable(verify_openqasm ${VERIFY_OPENQASM} )

src/test/test_parser_exponent.cpp

@@ -0,0 +1,64 @@
+#include "quartz/circuitseq/circuitseq.h"
+#include "quartz/context/context.h"
+#include "quartz/parser/qasm_parser.h"
+
+#include <cmath>
+#include <iostream>
+#include <string>
+#include <utility>
+#include <vector>
+
+using namespace quartz;
+
+// Rotation angles written in scientific notation (e.g. 9.5e-05, as printed by
+// many tools) must not be split at the sign of their exponent: each angle must
+// parse to the same circuit as the angle written as a plain decimal.
+int main() {
+  ParamInfo param_info;
+  Context ctx({GateType::input_qubit, GateType::input_param, GateType::add,
+               GateType::rz},
+              /*num_qubits=*/1, &param_info);
+  auto parse = [&](const std::string &angle) {
+    QASMParser parser(&ctx);
+    CircuitSeq *seq = nullptr;
+    const bool ok = parser.load_qasm_str(
+        "OPENQASM 2.0;\ninclude \"qelib1.inc\";\nqreg q[1];\nrz(" + angle +
+            ") q[0];\n",
+        seq);
+    return ok ? seq : nullptr;
+  };
+  const std::vector<std::pair<std::string, std::string>> cases = {
+      {"9.58737992428526e-05", "0.0000958737992428526"},
+      {"-4.79e-05", "-0.0000479"},
+      {"3.451511e-09", "0.000000003451511"},
+      {"1.5E+2", "150"},
+      {"2e-3", "0.002"},
+      {"0.5-1e-3", "0.5-0.001"},
+      {"pi*-0.25", "-pi/4"},
+  };
+  bool all_ok = true;
+  for (const auto &[angle, plain] : cases) {
+    CircuitSeq *seq1 = parse(angle);
+    CircuitSeq *seq2 = parse(plain);
+    bool ok = seq1 != nullptr && seq2 != nullptr;
+    if (ok) {
+      const auto mat1 = seq1->get_matrix(&ctx);
+      const auto mat2 = seq2->get_matrix(&ctx);
+      for (int i = 0; i < (int)mat1.size(); i++) {
+        for (int j = 0; j < (int)mat1[i].size(); j++) {
+          ok = ok && std::abs(mat1[i][j] - mat2[i][j]) < 1e-12;
+        }
+      }
+    }
+    if (!ok) {
+      std::cout << "rz(" << angle << ") is not parsed as rz(" << plain << ")"
+                << std::endl;
+      all_ok = false;
+    }
+    delete seq1;
+    delete seq2;
+  }
+  std::cout << (all_ok ? "All angles parsed correctly." : "FAILED")
+            << std::endl;
+  return all_ok ? 0 : 1;
+}