Migrate Mathjax detection to meson

src/meson.build

@@ -238,4 +238,5 @@ src = meson.current_source_dir()
 
 # Submodules
 subdir('sage')
+subdir('sage_docbuild')
 subdir('doc')

src/sage/env.py

@@ -19,8 +19,8 @@
     ....:     cmd += f"s1 = samefile(SAGE_ROOT, '{SAGE_ROOT}');"
     sage: cmd += f"s2 = samefile(SAGE_LOCAL, '{SAGE_LOCAL}');"
     sage: cmd += "print(s1 and s2);"
     sage: out = check_output([sys.executable, "-c", cmd], env=env).decode().strip()   # long time
     sage: out == "True"                                                               # long time
     True
 
 AUTHORS:
@@ -228,7 +228,6 @@
 
 # installation directories for various packages
 JMOL_DIR = var("JMOL_DIR")
-MATHJAX_DIR = var("MATHJAX_DIR", join(SAGE_SHARE, "mathjax"))
 MTXLIB = var("MTXLIB", join(SAGE_SHARE, "meataxe"))
 THREEJS_DIR = var("THREEJS_DIR")
 PPLPY_DOCS = var("PPLPY_DOCS", join(SAGE_SHARE, "doc", "pplpy"))

src/sage_docbuild/conf.py

@@ -28,12 +28,14 @@
 from sphinx.util.docutils import SphinxDirective
 
 import sage.version
-from sage.env import MATHJAX_DIR, PPLPY_DOCS, SAGE_DOC, SAGE_DOC_SRC
+from sage.env import PPLPY_DOCS, SAGE_DOC, SAGE_DOC_SRC
 from sage.features.sphinx import JupyterSphinx
 from sage.misc.latex_macros import sage_mathjax_macros
 from sage.misc.sagedoc import extlinks as extlinks  # noqa: PLC0414
 from sage.misc.sagedoc_conf import *  # Load configuration shared with sage.misc.sphinxify
 
+from .config import MATHJAX_PATH
+
 # ---------------------
 # General configuration
 # ---------------------
@@ -550,7 +552,7 @@ def linkcode_resolve(domain, info):
 if os.environ.get('SAGE_USE_CDNS', 'no') == 'yes':
     mathjax_path = "https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-chtml.js"
 else:
-    mathjax_path = os.path.join(MATHJAX_DIR, 'tex-chtml.js')
+    mathjax_path = MATHJAX_PATH
 
 # A list of glob-style patterns that should be excluded when looking for source
 # files. They are matched against the source file names relative to the

src/sage_docbuild/config.py.in

@@ -0,0 +1,6 @@
+"""
+Documentation configuration generated by meson
+"""
+
+# MathJax path
+MATHJAX_PATH: str = '@MATHJAX_PATH@'

src/sage_docbuild/meson.build

@@ -0,0 +1,21 @@
+# Check for system-wide MathJax installation
+mathjax_path = ''
+mathjax_found = false
+foreach dir : ['/usr/share/mathjax', '/usr/local/share/mathjax']
+  if not mathjax_found and fs.is_file(dir / 'tex-chtml.js')
+    mathjax_path = dir / 'tex-chtml.js'
+    mathjax_found = true
+    message('Found MathJax at: ' + dir)
+  endif
+endforeach
+if not mathjax_found
+  mathjax_path = 'https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-chtml.js'
+  message('Using CDN MathJax: ' + mathjax_path)
+endif
+docs_config_data = configuration_data()
+docs_config_data.set('MATHJAX_PATH', mathjax_path)
+configure_file(
+  input: 'config.py.in',
+  output: 'config.py',
+  configuration: docs_config_data,
+)