commonmark-d

commonmark-d is a D translation of MD4C, a fast SAX-like Markdown parser. MD4C achieves remarkable parsing speed through the lack of AST and careful memory usage.

It passes the test suite of CommonMark 0.29 but not fully any other version, such as 0.30 or 0.31.

Usage

// Parse CommonMark, generate HTML
import commonmarkd;
string html = convertMarkdownToHTML(markdown);

// Parse Github Flavoured Markdown, generate HTML
string html = convertMarkdownToHTML(markdown, MarkdownFlag.dialectGitHub);

// Parse CommonMark without HTML support, generate HTML
string html = convertMarkdownToHTML(markdown, MarkdownFlag.noHTML);

Performance

Compile speed

In debug builds, commonmark-d compiles 3x faster than dmarkdown and 40x faster than hunt-markdown.

Timing debug build of various Markdown parsers in D:

commonmark-d:
$ time /mnt/c/d/ldc2-1.17.0-windows-multilib/bin/dub.exe -f
real    0m1.144s
user    0m0.000s
sys     0m0.016s

dmarkdown:
$ time /mnt/c/d/ldc2-1.17.0-windows-multilib/bin/dub.exe -f
real    0m3.186s
user    0m0.000s
sys     0m0.000s

hunt-markdown:
real    0m39.960s
user    0m0.000s
sys     0m0.016s

Runtime speed

commonmark-d is 2x faster than dmarkdown and 15x faster than hunt-markdown at parsing (see Benchmark below).

Benchmark

Here commonmark-d is benched against dmarkdown and hunt-markdown on a selection of Markdown blog posts. Using LDC 1.0.17, dub -b release-nobounds --combined -a x86_64.

Output:

*** Parsing file content\2015-04-07_Auburn Sounds website is now live!.md
time dmarkdown     = 108 us, HTML length = 620
time hunt-markdown = 1057 us, HTML length = 522
time commonmark-d  = 101 us, HTML length = 522

*** Parsing file content\2015-11-17_First plugin Graillon in open beta!.md
time dmarkdown     = 58 us, HTML length = 865
time hunt-markdown = 2753 us, HTML length = 779
time commonmark-d  = 48 us, HTML length = 778

*** Parsing file content\2015-11-26_Graillon 1.0 released.md
time dmarkdown     = 118 us, HTML length = 1840
time hunt-markdown = 546 us, HTML length = 1577
time commonmark-d  = 35 us, HTML length = 1577

*** Parsing file content\2016-02-04_Interested in shaping our future plugins?.md
time dmarkdown     = 85 us, HTML length = 913
time hunt-markdown = 487 us, HTML length = 872
time commonmark-d  = 32 us, HTML length = 872

*** Parsing file content\2016-02-08_Making a Windows VST plugin with D.md
time dmarkdown     = 284 us, HTML length = 9849
time hunt-markdown = 4393 us, HTML length = 8787
time commonmark-d  = 126 us, HTML length = 8775

*** Parsing file content\2016-06-22_Introducing Panagement.md
time dmarkdown     = 85 us, HTML length = 2063
time hunt-markdown = 747 us, HTML length = 1944
time commonmark-d  = 35 us, HTML length = 1944

*** Parsing file content\2016-08-22_Why AAX is not supported right now.md
time dmarkdown     = 82 us, HTML length = 1779
time hunt-markdown = 225 us, HTML length = 1691
time commonmark-d  = 49 us, HTML length = 1691

*** Parsing file content\2016-09-08_Panagement and Graillon 1.1 release.md
time dmarkdown     = 137 us, HTML length = 2016
time hunt-markdown = 914 us, HTML length = 1783
time commonmark-d  = 36 us, HTML length = 1783

*** Parsing file content\2016-09-16_PBR for Audio Software Interfaces.md
time dmarkdown     = 340 us, HTML length = 9637
time hunt-markdown = 2012 us, HTML length = 8929
time commonmark-d  = 134 us, HTML length = 8929

*** Parsing file content\2016-11-07_Panagement and Graillon 1.2 release.md
time dmarkdown     = 68 us, HTML length = 1091
time hunt-markdown = 670 us, HTML length = 980
time commonmark-d  = 41 us, HTML length = 980

*** Parsing file content\2016-11-10_Running D without its runtime.md
time dmarkdown     = 550 us, HTML length = 10362
time hunt-markdown = 4572 us, HTML length = 9056
time commonmark-d  = 157 us, HTML length = 9047

*** Parsing file content\2016-12-14_We are in Computer Music!.md
time dmarkdown     = 76 us, HTML length = 883
time hunt-markdown = 395 us, HTML length = 820
time commonmark-d  = 40 us, HTML length = 820

*** Parsing file content\2017-02-13_Vibrant 2.0 released, free demo.md
time dmarkdown     = 68 us, HTML length = 1001
time hunt-markdown = 417 us, HTML length = 943
time commonmark-d  = 44 us, HTML length = 943

*** Parsing file content\2017-07-27_Graillon 2 A New Effect for Live Voice Changing.md
time dmarkdown     = 95 us, HTML length = 1721
time hunt-markdown = 892 us, HTML length = 1574
time commonmark-d  = 38 us, HTML length = 1574

*** Parsing file content\2017-10-14_The History Of Vibrant.md
time dmarkdown     = 268 us, HTML length = 5620
time hunt-markdown = 1606 us, HTML length = 5402
time commonmark-d  = 86 us, HTML length = 5402

*** Parsing file content\2018-01-18_Bringing AAX to you.md
time dmarkdown     = 82 us, HTML length = 1841
time hunt-markdown = 1008 us, HTML length = 1576
time commonmark-d  = 56 us, HTML length = 1576

*** Parsing file content\2018-08-16_Introducing our new plug-in Couture.md
time dmarkdown     = 130 us, HTML length = 3250
time hunt-markdown = 1476 us, HTML length = 3039
time commonmark-d  = 68 us, HTML length = 3039

*** Parsing file content\2019-03-01_A Consequential Update.md
time dmarkdown     = 262 us, HTML length = 9008
time hunt-markdown = 2831 us, HTML length = 7940
time commonmark-d  = 130 us, HTML length = 7940

*** Parsing file content\2019-08-14_Introducing Panagement 2.md
time dmarkdown     = 131 us, HTML length = 3951
time hunt-markdown = 1204 us, HTML length = 3680
time commonmark-d  = 65 us, HTML length = 3680

Results can be reproduced with the benchmark tool in the bench/ directory.

Changes versus original parser

• Only UTF-8 input is supported
• (future) malloc and realloc failures will not be considered, because in Out Of Memory situations crashing is a reasonable solution.