Polish postprocess HTML script and update dependencies

Makefile

@@ -1,5 +1,7 @@
 .PHONY: help book clean serve
 
+BUIILD_DIR := "./_build"
+
 help:
 	@echo "Please use 'make <target>' where <target> is one of:"
 	@echo "  install     to install the necessary dependencies for jupyter-book to build"
@@ -16,7 +18,7 @@ install:
 
 book:
 	jupyter-book build ./
-	python3 scripts/process_build.py
+	python3 scripts/postprocess_html.py $(BUIILD_DIR)
 
 runall:
 	jupyter-book run ./content
@@ -29,7 +31,7 @@ serve:
 
 build:
 	jupyter-book build ./ --overwrite
-	python3 scripts/process_build.py
+	python3 scripts/postprocess_html.py $(BUIILD_DIR)
 
 site: build
 	bundle exec jekyll build

requirements-dev.txt

@@ -1 +1,2 @@
 jupyter-book==0.6.5
+beautifulsoup4

scripts/postprocess_html.py

@@ -0,0 +1,33 @@
+# This script santises the sympy latex in the HTML files prior to building the site
+import os
+import sys
+from bs4 import BeautifulSoup
+
+def sanitize_latex(filepath):
+    '''
+    Replace {{ with { { inside LaTeX outputs not to confuse Jekyll about what
+    should be interpolated.
+    '''
+    is_modified = False
+    soup = BeautifulSoup(open(filepath), 'html.parser')
+    for latex in soup.find_all('div', {'class': 'output_latex'}):
+        if r'{{' in latex.string:
+            sanitized_latex = latex.string.replace(r'{{', '{ {')
+            latex.string = sanitized_latex
+            is_modified = True
+    if is_modified:
+        print(f'sanitize_latex: `{filepath}`')
+        with open(filepath, 'w') as f:
+            f.write(str(soup))
+
+if __name__ == '__main__':
+    if len(sys.argv) < 2:
+        sys.exit('Usage: python3 postprocess_html.py <build-dir>')
+    base_dir = sys.argv[1]
+    for (dirpath, _, filenames) in os.walk(base_dir):
+        for name in filenames:
+            if not name.endswith('.html'):
+                continue
+            filepath = os.path.join(dirpath, name)
+            sanitize_latex(filepath)
+