Add OpenQASM 3 exporter for circuits

This commit introduces an OpenQASM 3 exporter for Graphix
circuits. The functionality was originally proposed in #245 but has
not yet been merged.

The added tests verify that a round-trip through the OpenQASM 3
representation preserves Graphix circuits, using the
graphix-qasm3-parser plugin.  This plugin is therefore
added as a `requirements-dev.txt` dependency.

CI is updated so that `pip install .` can detect the current version
number of Graphix, instead of the default `0.1`: to do so, the whole
history and the tags should be available.  We removed the "-e" option
from CI because it is useless in the CI context.

In the long term the `qasm3_exporter` module will also host the
pattern exporter, but that feature is intentionally omitted from this
PR to keep the change focused.

Author: thierry-martinez

.github/workflows/ci.yml

@@ -23,7 +23,10 @@ jobs:
     runs-on: ${{ matrix.os }}
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
+        with:
+          fetch-depth: 0  # Fetch all, necessary to find tags and branches
+          fetch-tags: true
 
       - uses: actions/setup-python@v5
         with:

.github/workflows/cov.yml

@@ -14,7 +14,10 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
+        with:
+          fetch-depth: 0  # Fetch all, necessary to find tags and branches
+          fetch-tags: true
 
       - name: Set up Python
         uses: actions/setup-python@v5

.github/workflows/doc.yml

@@ -20,7 +20,10 @@ jobs:
     name: "Check documentation"
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
+        with:
+          fetch-depth: 0  # Fetch all, necessary to find tags and branches
+          fetch-tags: true
 
       - uses: actions/setup-python@v5
         with:

.github/workflows/typecheck.yml

@@ -19,7 +19,10 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
+        with:
+          fetch-depth: 0  # Fetch all, necessary to find tags and branches
+          fetch-tags: true
 
       - uses: actions/setup-python@v5
         with:
@@ -46,7 +49,10 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
+        with:
+          fetch-depth: 0  # Fetch all, necessary to find tags and branches
+          fetch-tags: true
 
       - uses: actions/setup-python@v5
         with:

CHANGELOG.md

@@ -9,6 +9,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+- #343: Circuit exporter to OpenQASM3:
+  `graphix.qasm3_exporter.circuit_to_qasm3`.
+
 - #332: New class `StandardizedPattern` that contains the decomposed
   parts of a standardized pattern.
 

noxfile.py

@@ -16,7 +16,7 @@ def install_pytest(session: Session) -> None:
 @nox.session(python=["3.9", "3.10", "3.11", "3.12", "3.13"])
 def tests_minimal(session: Session) -> None:
     """Run the test suite with minimal dependencies."""
-    session.install("-e", ".")
+    session.install(".")
     install_pytest(session)
     # We cannot run `pytest --doctest-modules` here, since some tests
     # involve optional dependencies, like pyzx.
@@ -27,7 +27,7 @@ def tests_minimal(session: Session) -> None:
 @nox.session(python=["3.10", "3.11", "3.12", "3.13"])
 def tests_dev(session: Session) -> None:
     """Run the test suite with dev dependencies."""
-    session.install("-e", ".[dev]")
+    session.install(".[dev]")
     # We cannot run `pytest --doctest-modules` here, since some tests
     # involve optional dependencies, like pyzx.
     session.run("pytest")
@@ -36,7 +36,7 @@ def tests_dev(session: Session) -> None:
 @nox.session(python=["3.9", "3.10", "3.11", "3.12", "3.13"])
 def tests_extra(session: Session) -> None:
     """Run the test suite with extra dependencies."""
-    session.install("-e", ".[extra]")
+    session.install(".[extra]")
     install_pytest(session)
     session.install("nox")  # needed for `--doctest-modules`
     session.run("pytest", "--doctest-modules")
@@ -45,14 +45,14 @@ def tests_extra(session: Session) -> None:
 @nox.session(python=["3.10", "3.11", "3.12", "3.13"])
 def tests_all(session: Session) -> None:
     """Run the test suite with all dependencies."""
-    session.install("-e", ".[dev,extra]")
+    session.install(".[dev,extra]")
     session.run("pytest", "--doctest-modules")
 
 
 @nox.session(python=["3.9", "3.10", "3.11", "3.12", "3.13"])
 def tests_symbolic(session: Session) -> None:
     """Run the test suite of graphix-symbolic."""
-    session.install("-e", ".")
+    session.install(".")
     install_pytest(session)
     session.install("nox")  # needed for `--doctest-modules`
     # Use `session.cd` as a context manager to ensure that the
@@ -67,3 +67,21 @@ def tests_symbolic(session: Session) -> None:
         # session.run("git", "clone", "https://github.com/TeamGraphix/graphix-symbolic")
         with session.cd("graphix-symbolic"):
             session.run("pytest", "--doctest-modules")
+
+
+@nox.session(python=["3.9", "3.10", "3.11", "3.12", "3.13"])
+def tests_qasm_parser(session: Session) -> None:
+    """Run the test suite of graphix-qasm-parser."""
+    session.install(".")
+    install_pytest(session)
+    session.install("nox")  # needed for `--doctest-modules`
+    # Use `session.cd` as a context manager to ensure that the
+    # working directory is restored afterward. This is important
+    # because Windows cannot delete a temporary directory while it
+    # is the working directory.
+    with TemporaryDirectory() as tmpdir, session.cd(tmpdir):
+        # See https://github.com/TeamGraphix/graphix-qasm-parser/pull/1
+        session.run("git", "clone", "-b", "fix_typing_issues", "https://github.com/TeamGraphix/graphix-qasm-parser")
+        with session.cd("graphix-qasm-parser"):
+            session.install(".")
+            session.run("pytest", "--doctest-modules")

requirements-dev.txt

@@ -20,3 +20,5 @@ pytest-mock
 # Optional dependencies
 qiskit>=1.0
 qiskit-aer
+
+graphix-qasm-parser @ git+https://github.com/TeamGraphix/graphix-qasm-parser.git@fix_typing_issues