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#
# Atlas Package Cloner
# (c) Copyright 2021 Andreas Rumpf
#
# See the file "copying.txt", included in this
# distribution, for details about the copyright.
#
##[
Syntax taken from strscans.nim:
================= ========================================================
``$$`` Matches a single dollar sign.
``$*`` Matches until the token following the ``$*`` was found.
The match is allowed to be of 0 length.
``$+`` Matches until the token following the ``$+`` was found.
The match must consist of at least one char.
``$s`` Skips optional whitespace.
================= ========================================================
]##
import tables
from strutils import continuesWith, Whitespace
type
Opcode = enum
MatchVerbatim # needs verbatim match
Capture0Until
Capture1Until
Capture0UntilEnd
Capture1UntilEnd
SkipWhitespace
Instr = object
opc: Opcode
arg1: uint8
arg2: uint16
Pattern* = object
code: seq[Instr]
usedMatches: int
error: string
# A rewrite rule looks like:
#
# foo$*bar -> https://gitlab.cross.de/$1
proc compile*(pattern: string; strings: var seq[string]): Pattern =
proc parseSuffix(s: string; start: int): int =
result = start
while result < s.len and s[result] != '$':
inc result
result = Pattern(code: @[], usedMatches: 0, error: "")
var p = 0
while p < pattern.len:
if pattern[p] == '$' and p+1 < pattern.len:
case pattern[p+1]
of '$':
if result.code.len > 0 and result.code[^1].opc in {
MatchVerbatim, Capture0Until, Capture1Until, Capture0UntilEnd, Capture1UntilEnd}:
# merge with previous opcode
let key = strings[result.code[^1].arg2] & "$"
var idx = find(strings, key)
if idx < 0:
idx = strings.len
strings.add key
result.code[^1].arg2 = uint16(idx)
else:
var idx = find(strings, "$")
if idx < 0:
idx = strings.len
strings.add "$"
result.code.add Instr(opc: MatchVerbatim,
arg1: uint8(0), arg2: uint16(idx))
inc p, 2
of '+', '*':
let isPlus = pattern[p+1] == '+'
let pEnd = parseSuffix(pattern, p+2)
let suffix = pattern.substr(p+2, pEnd-1)
p = pEnd
if suffix.len == 0:
result.code.add Instr(opc: if isPlus: Capture1UntilEnd else: Capture0UntilEnd,
arg1: uint8(result.usedMatches), arg2: uint16(0))
else:
var idx = find(strings, suffix)
if idx < 0:
idx = strings.len
strings.add suffix
result.code.add Instr(opc: if isPlus: Capture1Until else: Capture0Until,
arg1: uint8(result.usedMatches), arg2: uint16(idx))
inc result.usedMatches
of 's':
result.code.add Instr(opc: SkipWhitespace)
inc p, 2
else:
result.error = "unknown syntax '$" & pattern[p+1] & "'"
break
elif pattern[p] == '$':
result.error = "unescaped '$'"
break
else:
let pEnd = parseSuffix(pattern, p)
let suffix = pattern.substr(p, pEnd-1)
var idx = find(strings, suffix)
if idx < 0:
idx = strings.len
strings.add suffix
result.code.add Instr(opc: MatchVerbatim,
arg1: uint8(0), arg2: uint16(idx))
p = pEnd
type
MatchObj = object
m: int
a: array[20, (int, int)]
proc matches(s: Pattern; strings: seq[string]; input: string): MatchObj =
template failed =
result.m = -1
return result
var i = 0
for instr in s.code:
case instr.opc
of MatchVerbatim:
if continuesWith(input, strings[instr.arg2], i):
inc i, strings[instr.arg2].len
else:
failed()
of Capture0Until, Capture1Until:
block searchLoop:
let start = i
while i < input.len:
if continuesWith(input, strings[instr.arg2], i):
if instr.opc == Capture1Until and i == start:
failed()
result.a[result.m] = (start, i-1)
inc result.m
inc i, strings[instr.arg2].len
break searchLoop
inc i
failed()
of Capture0UntilEnd, Capture1UntilEnd:
if instr.opc == Capture1UntilEnd and i >= input.len:
failed()
result.a[result.m] = (i, input.len-1)
inc result.m
i = input.len
of SkipWhitespace:
while i < input.len and input[i] in Whitespace: inc i
if i < input.len:
# still unmatched stuff was left:
failed()
proc translate(m: MatchObj; outputPattern, input: string): string =
result = newStringOfCap(outputPattern.len)
var i = 0
var patternCount = 0
while i < outputPattern.len:
if i+1 < outputPattern.len and outputPattern[i] == '$':
if outputPattern[i+1] == '#':
inc i, 2
if patternCount < m.a.len:
let (a, b) = m.a[patternCount]
for j in a..b: result.add input[j]
inc patternCount
elif outputPattern[i+1] in {'1'..'9'}:
var n = ord(outputPattern[i+1]) - ord('0')
inc i, 2
while i < outputPattern.len and outputPattern[i] in {'0'..'9'}:
n = n * 10 + (ord(outputPattern[i]) - ord('0'))
inc i
patternCount = n
if n-1 < m.a.len:
let (a, b) = m.a[n-1]
for j in a..b: result.add input[j]
else:
# just ignore the wrong pattern:
inc i
else:
result.add outputPattern[i]
inc i
proc replace*(s: Pattern; outputPattern, input: string): string =
var strings: seq[string] = @[]
let m = s.matches(strings, input)
if m.m < 0:
result = ""
else:
result = translate(m, outputPattern, input)
type
Patterns* = object
s: seq[(Pattern, string)]
t: Table[string, string]
strings: seq[string]
proc initPatterns*(): Patterns =
Patterns(s: @[], t: initTable[string, string](), strings: @[])
proc addPattern*(p: var Patterns; inputPattern, outputPattern: string): string =
if '$' notin inputPattern and '$' notin outputPattern:
p.t[inputPattern] = outputPattern
result = ""
else:
let code = compile(inputPattern, p.strings)
if code.error.len > 0:
result = code.error
else:
p.s.add (code, outputPattern)
result = ""
proc substitute*(p: Patterns; input: string): string =
result = p.t.getOrDefault(input)
if result.len == 0:
for i in 0..<p.s.len:
let m = p.s[i][0].matches(p.strings, input)
if m.m >= 0:
return translate(m, p.s[i][1], input)
proc replacePattern*(inputPattern, outputPattern, input: string): string =
var strings: seq[string] = @[]
let code = compile(inputPattern, strings)
result = replace(code, outputPattern, input)
when isMainModule:
# foo$*bar -> https://gitlab.cross.de/$1
const realInput = "$fooXXbar$z00end"
var strings: seq[string] = @[]
let code = compile("$$foo$*bar$$$*z00$*", strings)
echo code
let m = code.matches(strings, realInput)
echo m.m
echo translate(m, "$1--$#-$#-", realInput)
echo translate(m, "https://gitlab.cross.de/$1", realInput)
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