Use sphinx.ext.linkcode for more precise source code links (#821)

* switched from using sphinx-ext-viewcode to sphinx-ext-linkcode

* updated tox.ini

* removed leftover code from azure

* switched dashes to underscores

* Try fix for methods inherited by Qiskit

---------

Co-authored-by: Eric Arellano <14852634+Eric-Arellano@users.noreply.github.com>

docs/conf.py

@@ -10,6 +10,10 @@
 # copyright notice, and modified files need to carry a notice indicating
 # that they have been altered from the originals.
 
+import inspect
+import os
+import re
+import sys
 
 # -- Project information -----------------------------------------------------
 project = 'Qiskit IBM Quantum Provider'
@@ -27,7 +31,7 @@
     'sphinx.ext.napoleon',
     'sphinx.ext.autodoc',
     'sphinx.ext.autosummary',
-    'sphinx.ext.viewcode',
+    'sphinx.ext.linkcode',
     'sphinx.ext.extlinks',
     'sphinx.ext.intersphinx',
     'jupyter_sphinx',
@@ -99,3 +103,75 @@
 html_last_updated_fmt = '%Y/%m/%d'
 
 html_sourcelink_suffix = ''
+
+
+# ----------------------------------------------------------------------------------
+# Source code links
+# ----------------------------------------------------------------------------------
+
+def determine_github_branch() -> str:
+    """Determine the GitHub branch name to use for source code links.
+
+    We need to decide whether to use `stable/<version>` vs. `main` for dev builds.
+    Refer to https://docs.github.com/en/actions/learn-github-actions/variables
+    for how we determine this with GitHub Actions.
+    """
+    # If CI env vars not set, default to `main`. This is relevant for local builds.
+    if "GITHUB_REF_NAME" not in os.environ:
+        return "main"
+
+    # PR workflows set the branch they're merging into.
+    if base_ref := os.environ.get("GITHUB_BASE_REF"):
+        return base_ref
+
+    ref_name = os.environ["GITHUB_REF_NAME"]
+
+    # Check if the ref_name is a tag like `1.0.0` or `1.0.0rc1`. If so, we need
+    # to transform it to a Git branch like `stable/1.0`.
+    version_without_patch = re.match(r"(\d+\.\d+)", ref_name)
+    return (
+        f"stable/{version_without_patch.group()}"
+        if version_without_patch
+        else ref_name
+    )
+
+
+GITHUB_BRANCH = determine_github_branch()
+
+
+def linkcode_resolve(domain, info):
+    if domain != "py":
+        return None
+
+    module_name = info["module"]
+    module = sys.modules.get(module_name)
+    if module is None or "qiskit_ibm_provider" not in module_name:
+        return None
+
+    obj = module
+    for part in info["fullname"].split("."):
+        try:
+            obj = getattr(obj, part)
+        except AttributeError:
+            return None
+        is_valid_code_object = (
+            inspect.isclass(obj) or inspect.ismethod(obj) or inspect.isfunction(obj)
+        )
+        if not is_valid_code_object:
+            return None
+    try:
+        full_file_name = inspect.getsourcefile(obj)
+    except TypeError:
+        return None
+    if full_file_name is None or "/qiskit_ibm_provider/" not in full_file_name:
+        return None
+    file_name = full_file_name.split("/qiskit_ibm_provider/")[-1]
+
+    try:
+        source, lineno = inspect.getsourcelines(obj)
+    except (OSError, TypeError):
+        linespec = ""
+    else:
+        ending_lineno = lineno + len(source) - 1
+        linespec = f"#L{lineno}-L{ending_lineno}"
+    return f"https://github.com/Qiskit/qiskit-ibm-provider/tree/{GITHUB_BRANCH}/qiskit_ibm_provider/{file_name}{linespec}"

tox.ini

@@ -10,6 +10,9 @@ setenv =
   VIRTUAL_ENV={envdir}
   LANGUAGE=en_US
   LC_ALL=en_US.utf-8
+passenv=
+  GITHUB_REF_NAME,
+  GITHUB_BASE_REF
 commands =
   python -m unittest -v