* markup-parse

[[https://hackage.haskell.org/package/markup-parse][https://img.shields.io/hackage/v/markup-parse.svg]]
[[https://github.com/tonyday567/markup-parse/actions?query=workflow%3Ahaskell-ci][https://github.com/tonyday567/markup-parse/workflows/haskell-ci/badge.svg]]

~markup-parse~ parses and prints a subset of common XML & HTML structured data, from and to strict bytestrings

* Development

#+begin_src haskell :results output :exports both
:r
:set prompt "> "
:set -Wno-type-defaults
:set -Wno-name-shadowing
:set -XOverloadedStrings
:set -XTemplateHaskell
:set -XQuasiQuotes
import Control.Monad
import MarkupParse
import MarkupParse.FlatParse
import MarkupParse.Patch
import Data.ByteString qualified as B
import Data.ByteString.Char8 qualified as C
import Data.Map.Strict qualified as Map
import Data.Function
import FlatParse.Basic hiding (take)
import Data.String.Interpolate
import Data.TreeDiff
import Control.Monad
bs <- B.readFile "other/line.svg"
C.length bs
#+end_src

#+RESULTS:
: Preprocessing library for markup-parse-0.1.1..
: GHCi, version 9.6.2: https://www.haskell.org/ghc/ :? for help
: [1 of 3] Compiling MarkupParse.FlatParse ( src/MarkupParse/FlatParse.hs, interpreted )
: [2 of 3] Compiling MarkupParse ( src/MarkupParse.hs, interpreted )
: [3 of 3] Compiling MarkupParse.Patch ( src/MarkupParse/Patch.hs, interpreted )
: Ok, three modules loaded.
: g
: Ok, three modules loaded.
: 7554

* Main Pipeline types

#+begin_src haskell :results output :exports both
:t tokenize Html
:t gather Html
:t normalize
:t degather
:t detokenize Html
:t tokenize Html >=> gather Html >=> (normalize >>> pure) >=> degather Html >=> (fmap (detokenize Html) >>> pure)
#+end_src

#+RESULTS:
: tokenize Html :: ByteString -> Warn [Token]
: gather Html :: [Token] -> Warn Markup
: normalize :: Markup -> Markup
: degather :: Standard -> Markup -> Warn [Token]
: detokenize Html :: Token -> ByteString
: tokenize Html >=> gather Html >=> (normalize >>> pure) >=> degather Html >=> (fmap (detokenize Html) >>> pure)
: :: ByteString -> These [MarkupWarning] [ByteString]

Round trip equality

#+begin_src haskell :results output :exports both
m = markup_ Xml bs
m == (markup_ Xml $ markdown_ Compact Xml m)
#+end_src

#+RESULTS:
: True

* MarkupParse.Patch

Obviously, patch doesn't belong here long-term but has been very useful in testing and development.

#+begin_src haskell :results output :exports both
showPatch $ patch [1, 2, 3, 5] [0, 1, 2, 4, 6]
#+end_src

#+RESULTS:
: [+0, -3, +4, -5, +6]

* wiki diff test debug

#+begin_src haskell :results output :exports both
bs <- B.readFile "other/Parsing - Wikipedia.html"
m = markup_ Html bs
m == (markup_ Html $ markdown_ Compact Html m)
#+end_src

#+RESULTS:
: True

* Reference

[[https://html.spec.whatwg.org/#toc-syntax][HTML Standard]]

[[https://stackoverflow.com/questions/3558119/are-non-void-self-closing-tags-valid-in-html5][Are (non-void) self-closing tags valid in HTML5? - Stack Overflow]]

[[https://www.w3.org/TR/xml/][Extensible Markup Language (XML) 1.0 (Fifth Edition)]]

** Prior Art

[[https://hackage.haskell.org/package/html-parse][html-parse]] is an attoparsec-based parser for HTML. The HTML parsing here has referenced this parsing logic for HTML elements.

[[https://hackage.haskell.org/package/blaze-markup][blaze-markup]] & [[https://hackage.haskell.org/package/lucid][lucid]] are HTML DSLs and printers, but not parsers.

[[https://hackage.haskell.org/package/xeno][xeno]] is an "event-based" XML parser with a more complicated base markup type.

[[https://hackage.haskell.org/package/XMLParser][XMLParser]] & [[https://hackage.haskell.org/package/hexml][hexml]] are parsec-based parsers.

* Performance

The [[https://hackage.haskell.org/package/perf][perf]] library has been used to measure performance of the library.

`cabal bench` runs the default benchmarking:

#+begin_src sh :results output :exports both
cabal bench
#+end_src

#+RESULTS:
#+begin_example
Running 1 benchmarks...
Benchmark markup-parse-speed: RUNNING...
label1 label2 old result new result change

gather time 9.33e4 7.73e4 improvement
html-parse tokenstime 1.21e6 1.17e6
html-parse tree time 6.61e4 7.59e4 slightly-degraded
markdown time 3.75e5 3.92e5
markup time 4.72e5 5.20e5 slightly-degraded
normalize time 2.80e5 3.04e5 slightly-degraded
tokenize time 8.59e5 8.67e5
Benchmark markup-parse-speed: FINISH
#+end_example

** Profiling

Profiling is used to aid library development:

#+begin_src sh :results output
cabal configure --enable-library-profiling --enable-executable-profiling -fprof-auto -fprof --write-ghc-environment-files=always --enable-benchmarks -O2
#+end_src

cabal.project.local

#+begin_example
write-ghc-environment-files: always
ignore-project: False
flags: +prof +prof-auto
library-profiling: True
executable-profiling: True
#+end_example

Profiling slow the main functions significantly:

#+begin_example
./app/speed -n 1000 --best -c +RTS -s -p -hc -l -RTS
label1 label2 old_result new_result status

gather time 2.08e4 3.01e4 degraded
html-parse tokens time 4.70e5 1.72e6 degraded
html-parse tree time 2.30e4 3.85e4 degraded
markdown time 3.51e5 5.70e5 degraded
markup time 2.10e5 1.05e6 degraded
normalize time 8.43e4 1.90e5 degraded
tokenize time 1.94e5 1.02e6 degraded
4,520,989,296 bytes allocated in the heap
2,668,887,592 bytes copied during GC
287,122,272 bytes maximum residency (21 sample(s))
1,572,000 bytes maximum slop
560 MiB total memory in use (0 MiB lost due to fragmentation)

Tot time (elapsed) Avg pause Max pause
Gen 0 1073 colls, 0 par 0.471s 0.479s 0.0004s 0.0024s
Gen 1 21 colls, 0 par 2.428s 2.575s 0.1226s 0.3303s

INIT time 0.007s ( 0.008s elapsed)
MUT time 2.142s ( 1.945s elapsed)
GC time 1.904s ( 2.071s elapsed)
RP time 0.000s ( 0.000s elapsed)
PROF time 0.995s ( 0.982s elapsed)
EXIT time 0.026s ( 0.000s elapsed)
Total time 5.074s ( 5.006s elapsed)

%GC time 0.0% (0.0% elapsed)

Alloc rate 2,110,654,040 bytes per MUT second

Productivity 61.8% of total user, 58.5% of total elapsed
#+end_example