Caching en el generador de cancioneros

.gitignore

@@ -1,3 +1,4 @@
 *.pyc
 public/
 audios/
+songs.dat

Makefile

@@ -22,6 +22,7 @@ public/index.html: $(ALL_TEMPLATES) $(PY_SRC)
 		--latex latex/cancionero.tex \
 		--audios audios \
 		--other-latex latex/canciones/ \
+		--use-cache \
 		--title "$(NAME)" \
 		--author "$(AUTHOR)" \
 		--links "$(SLO_LINKS)"
@@ -44,3 +45,4 @@ public/%: res/static/%
 
 clean:
 	rm -rf public
+	rm -f songs.dat

src/latex_scanner.py

@@ -1,6 +1,7 @@
 import argparse
 import os
 import re
+import pickle
 
 from django.conf import settings
 from django.template import Engine, Context
@@ -45,7 +46,7 @@ def extra_put(extra: list, index: int, the_type: str, data: dict|None = None):
 class SongLoader:
     '''Parses LaTeX files to build a collection of song objects.'''
 
-    def __init__(self, latex_file: str, audio_dir: str | None = None):
+    def __init__(self, latex_file: str | None = None, audio_dir: str | None = None):
         '''Initializes and populates a LaTeX reader.'''
         self.index: int            = 1
         self.category: str | None  = None
@@ -53,8 +54,17 @@ class SongLoader:
         self.songs: list[Song]     = []
         if audio_dir:
             self.audio_dir = audio_dir
+        if latex_file:
             self.scan(latex_file)
 
+    def populate_with_songs(self, songs):
+        for s in songs:
+            self.songs.append(s)
+            if s.category not in self.categories:
+                self.categories.append(s.category)
+            if s.number < self.index:
+                self.index = s.number
+
     def scan(self, latex_file: str) -> None:
         '''Reads through an index file and scans each song, with the same numbers.
         :param latex_file: The main latex file, which includes songs via \\input.'''
@@ -345,14 +355,35 @@ def create_argparser():
     parser.add_argument("--title", required=True, nargs=1, help="The title of the webpage")
     parser.add_argument("--author", required=True, nargs=1, help="The author for the footer")
     parser.add_argument("--links", required=False, nargs=1, default=["false"])
+    parser.add_argument("--use-cache", required=False, action="store_true",
+                        help="Whether to use a cache file if available (to use if songs haven't changed)")
     return parser
 
 
+def cache_or_parse(args):
+    loader = None
+    if args.use_cache:
+        try:
+            with open("songs.dat", "rb") as f:
+                loader = SongLoader()
+                loader.populate_with_songs(pickle.load(f))
+        except OSError:
+            pass
+    if not loader:
+        loader = SongLoader(args.latex[0], args.audios[0])
+        if args.other_latex:
+            loader.scan_others(args.other_latex[0], args.other_index[0])
+        try:
+            with open("songs.dat", "wb") as f:
+                pickle.dump(loader.songs, f)
+        except OSError:
+            pass
+    return loader
+
+
 if __name__ == '__main__':
     args = create_argparser().parse_args()
-    loader = SongLoader(args.latex[0], args.audios[0])
-    if args.other_latex:
-        loader.scan_others(args.other_latex[0], int(args.other_index[0]))
+    loader = cache_or_parse(args)
     settings.configure(USE_TZ=False, USE_I18N=False)
     e = Engine(dirs=["res/templates/"])
     loader.generate_html(args.output_dir[0], e, {