Avalanche is a document generator which uses context-free grammars to generate randomized outputs for fuzz-testing. See the examples folder for some working grammars.
Define your grammar in a text file (UTF-8 encoding). 'root' is the default start symbol.
root "<html>\n" \
"<body>\n" \
content{10} \
"</body>\n" \
"</html>"
content "<" (tagname) ' style="color:' colour ';">Hello world</' @1 ">\n"
color "#" /[a-f0-9]{3}/
tagname 1 "b"
1 "blink"
1 "i"
1 "marquee"
1 "span"with open('my.gmr') as fd:
g = Grammar(fd)
result = g.generate()result from the above grammar:<html>
<body>
<i style="color:#8b2;">Hello world</i>
<marquee style="color:#d09;">Hello world</marquee>
<b style="color:#aa9;">Hello world</b>
<b style="color:#93d;">Hello world</b>
<b style="color:#ada;">Hello world</b>
<span style="color:#464;">Hello world</span>
<span style="color:#90f;">Hello world</span>
<blink style="color:#ee9;">Hello world</blink>
<marquee style="color:#661;">Hello world</marquee>
<i style="color:#a21;">Hello world</i>
</body>
</html># TextSymbol
SymName "text" # generate u"text" in the output
# ChoiceSymbol
SymName .5 Defn1 # choose between generating Defn1 (1:3 odds)
1 Defn2 # or Defn2 (2:3 odds)
SymName2 + SymName # '+' imports choices & weights from SymName into SymName2
1 Defn3 # ie. choices are Defn1 (1:5), Defn2 (2:5) or Defn3 (1:5)
SymName3 (SubSym1 | SubSym2) # inline choice, SubSym1 & SubSym2 are generated equally
# this is also a grouping and can be repeated.
# ConcatSymbol
SymName SubSym1 SubSym2 # concat, generate SubSym1 then SubSym2
SymName SubSym1 ( SubSym2 SubSym3 ) # inline concat (grouping), SubSym2 & SubSym3 can be
# repeated using RepeatSymbol or referenced later in
# the same line using RefSymbol
# RepeatSymbol
SymName SubSym{a,b} # repeat SubSym a random number of times, between a and b
SymName SubSym{a} # repeat SubSym 'a' times
SymName SubSym? # shorthand for {0,1}
# RepeatSampleSymbol
SymName SubSym<a,b> # repeatedly generate SubSym between [a,b] unique choices
# SubSym must be a choice or a concat containing exactly
# one choice
# RegexSymbol
SymName /[A-Za-z]{0,4}..?[^a-f]{2}/ # simple regex generator, generate from A-Za-z [0,4]
# times, '.' generates printable ASCII. [^] inverts
# characters. ? generates [0,1] instances, etc.
# Unicode ranges are supported.
# RefSymbol
SymName @SymName2 # returns a previously generated instance of SymName2
SymName ('abc') @1 # returns the value generated in a previous ConcatSymbol defined in the
# same line (numbered in order of opening bracket, starting at 1)
# FuncSymbol
SymName rndint(a,b) # rndint, rndflt, rndpow2, eval, id, push, pop are built-in,
# others can be passed as keyword args to the Grammar constructor
# args can be numeric literals, or symbol definitions
# Import
Blah import('another.gmr') # can use imported symnames like Blah.SymNameAvalanche is French for "Avalanche".