Allow post-processing pipeline plugins

Makefile

@@ -88,6 +88,8 @@ all-redacted:
 
 	@cp $< $(<:.ltx=.knowngood) # for diffing broken builds to find bugs
 
+	@${PIPELINE} $< -o stage post
+
 # This builds a draft.  This only works if you're using the jinja
 # template that extends down to base.ltx.  Without that, draft
 # versions are unsupported and this should have no effect.

pipeline/pipeline.py

@@ -7,7 +7,23 @@ import os
 import pkgutil
 import sys
 
+"""
+The 'stage' option is for running this pipeline either pre- or post- latex.
+Ex: pipeline.py target.ltx -o stage post
+Ex: pipeline.py target.ltx -o stage pre
+"""
 
+def err(msg):
+    """Yeah, this is an obnoxious error message, but the user will have to
+    pick it out of a long scroll of LaTeX and make output.
+
+    """
+    sys.stderr.write("BEGIN PIPELINE ERROR MSG\n")
+    sys.stderr.write(msg)
+    sys.stderr.write("\n")
+    sys.stderr.write("END PIPELINE ERROR MSG\n")
+    sys.exit(-1)
+    
 def get_plugins(plugin_dir=None):
     """Load plugins from PLUGIN_DIR and return a dict with the plugin name
     hashed to the imported plugin.
@@ -19,10 +35,15 @@ def get_plugins(plugin_dir=None):
 
     PLUGIN API:
 
-    run_p(text, meta): (required) predicate returns True if this
+    run_p(text, meta, opt): predicate returns True if this
     plugin thinks it should run in the pipeline.
 
-    run(text, meta): (required) runs the plugin, returns text, meta
+    run(text, meta, opt): runs the plugin, returns text, meta
+
+    after_p(pdf_fname, meta, opt): predicate returns True if this plugin
+    thinks it should run after the pdf is produced.
+
+    after(pdf_fname, meta, opt): runs the plugin, returns meta.  May change the pdf
 
     """
     if not plugin_dir:
@@ -43,12 +64,23 @@ def get_plugins(plugin_dir=None):
         spec.loader.exec_module(plugins[fname])
     return plugins
 
+def tuple2dict(tup):
+    """TUP is a tuple of 2-tuples.  Return a dict where the first element
+    of each tuple hashes to the second.
+
+    """
+    ret = {}
+    for t in tup:
+        ret[t[0]] = t[1]
+    return ret
+            
 @click.command()
 @click.argument('filename')
 @click.option('--output', help="output filename")
 @click.option('--plugin', help="specify just one plugin to run (not implemented)")
 @click.option('--option', '-o', nargs=2, multiple=True, default='', help='Variables and their values.')
 def cli(filename, output, option, plugin):
+    pdf_fname = os.path.splitext(filename)[0]+'.pdf'
     doc = frontmatter.load(filename)
     text = doc.content
     meta = doc.metadata
@@ -64,17 +96,30 @@ def cli(filename, output, option, plugin):
     for o in option:
         meta[o[0]] = o[1]
 
+    # Dict is easier to work with
+    option = tuple2dict(option)
+    option['stage'] = option.get('stage', 'pre')
+    
     plugins = get_plugins()
     for p,m in plugins.items():
-        if hasattr(m, "run_p"):
-            if m.run_p(text, meta):
-                text, meta = m.run(text, meta)
-           
-    if output:
-        with open(output, 'w') as fh:
-            fh.write(text)
-    else:
-        print(text)
+        if option['stage'] == 'pre':
+            if hasattr(m, "run_p"):
+                if m.run_p(text, meta):
+                    text, meta = m.run(text, meta)
+        elif option['stage'] == 'post':
+            if hasattr(m, "after_p"):
+                if m.after_p(pdf_fname, meta):
+                    meta = m.after(pdf_fname, meta)
+        else:
+            err("Unknown stage: %s" % option['stage'])
+
+    ## Print the output or write it to a file if we're pre-latex
+    if option['stage'] == 'pre':
+        if output:
+            with open(output, 'w') as fh:
+                fh.write(text)
+        else:
+            print(text)
         
 if __name__ == '__main__':
     cli()