add tabulate-elements

IDEAS.md

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+
+
+- An *autofilters* filter that reads the metadata and then run several filters
+- This allows for simple executions...

filters/tabulate-elements.py

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+"""
+Count frequency of each element
+
+Sample usage:
+
+	> pandoc example.md  -F tabulate-elements.py --to=markdown
+     Element       Freqency
+     ------------- ----------
+     MetaBool      2
+     SoftBreak     1
+     Str           46
+     MetaInlines   18
+     RawInline     7
+     Doc           1
+     MetaBlocks    1
+     Emph          1
+     MetaMap       2
+     Space         24
+     Para          2
+     MetaList      2
+"""
+
+from collections import Counter
+import panflute as pf
+
+def prepare(doc):
+	doc.counter = Counter()
+
+
+def action(elem, doc):
+	doc.counter[elem.tag] += 1
+
+
+def finalize(doc):
+	c1 = pf.TableCell(pf.Plain(pf.Str("Element")))
+	c2 = pf.TableCell(pf.Plain(pf.Str("Freqency")))
+	header = pf.TableRow(c1, c2)
+	rows = []
+	for tag in doc.counter:
+		c1 = pf.TableCell(pf.Plain(pf.Str(tag)))
+		c2 = pf.TableCell(pf.Plain(pf.Str(str(doc.counter[tag]))))
+		rows.append(pf.TableRow(c1, c2))
+	table = pf.Table(*rows, header=header)
+	doc.content = [table] # bugbug?
+
+if __name__ == '__main__':
+    pf.toJSONFilter(action, prepare, finalize)