From 414fe24c10fb068e98c01f4a9cab0753a68d3980 Mon Sep 17 00:00:00 2001
From: Lukas Burgholzer <burgholzer@me.com>
Date: Tue, 12 Mar 2024 18:21:56 +0100
Subject: [PATCH] =?UTF-8?q?=F0=9F=90=9B=20Fix=20scientific=20notation=20in?=
 =?UTF-8?q?=20QASM=20import=20(#560)?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

## Description

This PR fixes a small bug in the QASM importer that would prevent it
from properly importing floating point numbers in scientific notation.

## Checklist:

<!---
This checklist serves as a reminder of a couple of things that ensure
your pull request will be merged swiftly.
-->

- [x] The pull request only contains commits that are related to it.
- [x] I have added appropriate tests and documentation.
- [x] I have made sure that all CI jobs on GitHub pass.
- [x] The pull request introduces no new warnings and follows the
project's style guidelines.

---------

Signed-off-by: burgholzer <burgholzer@me.com>
---
 src/parsers/qasm3_parser/Scanner.cpp | 30 +++++++++++++++++++++++-----
 test/unittests/test_qasm3_parser.cpp |  4 +++-
 2 files changed, 28 insertions(+), 6 deletions(-)

diff --git a/src/parsers/qasm3_parser/Scanner.cpp b/src/parsers/qasm3_parser/Scanner.cpp
index 2f2b8f8ba..c0946a0d2 100644
--- a/src/parsers/qasm3_parser/Scanner.cpp
+++ b/src/parsers/qasm3_parser/Scanner.cpp
@@ -1,6 +1,12 @@
 #include "parsers/qasm3_parser/Scanner.hpp"
 
+#include <cstdint>
+#include <istream>
+#include <optional>
 #include <regex>
+#include <sstream>
+#include <stdexcept>
+#include <string>
 
 namespace qasm3 {
 char Scanner::readUtf8Codepoint(std::istream* in) {
@@ -186,12 +192,26 @@ Token Scanner::consumeNumberLiteral() {
       error("Float literals are only allowed in base 10");
     }
 
-    char const sep = ch;
-    nextCh();
-    auto valAfterDecimalSeparator = consumeNumberLiteral(base);
+    std::stringstream ss{};
+    ss << valBeforeDecimalSeparator;
+
+    if (ch == '.') {
+      ss << ch;
+      nextCh();
+      const auto valAfterDecimalSeparator = consumeNumberLiteral(base);
+      ss << valAfterDecimalSeparator;
+    }
 
-    std::stringstream ss;
-    ss << valBeforeDecimalSeparator << sep << valAfterDecimalSeparator;
+    if (ch == 'e' || ch == 'E') {
+      ss << ch;
+      nextCh();
+      if (ch == '+' || ch == '-') {
+        ss << ch;
+        nextCh();
+      }
+      const auto valAfterExponent = consumeNumberLiteral(base);
+      ss << valAfterExponent;
+    }
 
     try {
       t.valReal = std::stod(ss.str());
diff --git a/test/unittests/test_qasm3_parser.cpp b/test/unittests/test_qasm3_parser.cpp
index 79093d083..be3c9b775 100644
--- a/test/unittests/test_qasm3_parser.cpp
+++ b/test/unittests/test_qasm3_parser.cpp
@@ -743,7 +743,7 @@ TEST_F(Qasm3ParserTest, ImportQasm3CPrefix) {
 TEST_F(Qasm3ParserTest, ImportQasmScanner) {
   std::stringstream ss{};
   const std::string testfile =
-      "$1 : . .5 -1. -= += ++ *= **= ** /= % %= |= || | &= "
+      "$1 : . .5 -1. 1.25e-3 1e3 -= += ++ *= **= ** /= % %= |= || | &= "
       "&& & ^= ^ ~= ~ ! <= <<= << < >= >>= >> >";
   const auto tokens = std::vector{
       qasm3::Token::Kind::HardwareQubit,
@@ -751,6 +751,8 @@ TEST_F(Qasm3ParserTest, ImportQasmScanner) {
       qasm3::Token::Kind::Dot,
       qasm3::Token::Kind::FloatLiteral,
       qasm3::Token::Kind::FloatLiteral,
+      qasm3::Token::Kind::FloatLiteral,
+      qasm3::Token::Kind::FloatLiteral,
       qasm3::Token::Kind::MinusEquals,
       qasm3::Token::Kind::PlusEquals,
       qasm3::Token::Kind::DoublePlus,