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Execute a Markov algorithm: Difference between revisions
→{{header|Nim}}
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Under the rules of left 4 registers, under the word has 8 character cells, the alphabet of the digits from 1 to 8. Rules are placed in "123,456", where "123" is a fragment, and "456" is to be replaced, in the registers of the РA to РD. The number of rules is stored in Р0, the initial word is in Р9. Number triggered rule is the last digit registration Р4 (0 to 3), if no rule did not work, the indicator 0, otherwise the current word to be processed. In РE is stored 10.
=={{header|Nim}}==
<lang Nim>import strutils, strscans
type Rule = object
pattern: string # Input pattern.
replacement: string # Replacement string (may be empty).
terminating: bool # "true" if terminating rule.
#---------------------------------------------------------------------------------------------------
func parse(rules: string): seq[Rule] =
## Parse a rule set to build a sequence of rules.
var linecount = 0
for line in rules.splitLines():
inc linecount
if line.startsWith('#'): continue
if line.strip.len == 0: continue
# Scan the line.
var pat, rep: string
var terminating = false
if not line.scanf("$+ -> $*", pat, rep):
raise newException(ValueError, "Invalid rule at line " & $linecount)
if rep.startsWith('.'):
# Terminating rule.
rep = rep[1..^1]
terminating = true
result.add(Rule(pattern: pat, replacement: rep, terminating: terminating))
#---------------------------------------------------------------------------------------------------
func apply(text: string; rules: seq[Rule]): string =
## Apply a set of rules to a text and return the result.
result = text
var changed = true
while changed:
changed = false
# Try to apply the rules in sequence.
for rule in rules:
if result.find(rule.pattern) >= 0:
# Found a rule to apply.
result = result.replace(rule.pattern, rule.replacement)
if rule.terminating: return
changed = true
break
#———————————————————————————————————————————————————————————————————————————————————————————————————
const SampleTexts = ["I bought a B of As from T S.",
"I bought a B of As from T S.",
"I bought a B of As W my Bgage from T S.",
"_1111*11111_",
"000000A000000"]
const Rulesets = [
#................................................
"""# This rules file is extracted from Wikipedia:
# http://en.wikipedia.org/wiki/Markov_Algorithm
A -> apple
B -> bag
S -> shop
T -> the
the shop -> my brother
a never used -> .terminating rule""",
#................................................
"""# Slightly modified from the rules on Wikipedia
A -> apple
B -> bag
S -> .shop
T -> the
the shop -> my brother
a never used -> .terminating rule""",
#................................................
"""# BNF Syntax testing rules
A -> apple
WWWW -> with
Bgage -> ->.*
B -> bag
->.* -> money
W -> WW
S -> .shop
T -> the
the shop -> my brother
a never used -> .terminating rule""",
#................................................
"""### Unary Multiplication Engine, for testing Markov Algorithm implementations
### By Donal Fellows.
# Unary addition engine
_+1 -> _1+
1+1 -> 11+
# Pass for converting from the splitting of multiplication into ordinary
# addition
1! -> !1
,! -> !+
_! -> _
# Unary multiplication by duplicating left side, right side times
1*1 -> x,@y
1x -> xX
X, -> 1,1
X1 -> 1X
_x -> _X
,x -> ,X
y1 -> 1y
y_ -> _
# Next phase of applying
1@1 -> x,@y
1@_ -> @_
,@_ -> !_
++ -> +
# Termination cleanup for addition
_1 -> 1
1+_ -> 1
_+_ -> """,
#................................................
"""# Turing machine: three-state busy beaver
#
# state A, symbol 0 => write 1, move right, new state B
A0 -> 1B
# state A, symbol 1 => write 1, move left, new state C
0A1 -> C01
1A1 -> C11
# state B, symbol 0 => write 1, move left, new state A
0B0 -> A01
1B0 -> A11
# state B, symbol 1 => write 1, move right, new state B
B1 -> 1B
# state C, symbol 0 => write 1, move left, new state B
0C0 -> B01
1C0 -> B11
# state C, symbol 1 => write 1, move left, halt
0C1 -> H01
1C1 -> H11"""
]
for n, ruleset in RuleSets:
let rules = ruleset.parse()
echo SampleTexts[n].apply(rules)</lang>
{{out}}
<pre>I bought a bag of apples from my brother.
I bought a bag of apples from T shop.
I bought a bag of apples with my money from T shop.
11111111111111111111
00011H1111000</pre>
=={{header|OCaml}}==
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