lapp.nim 10.8 KB
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434
import strutils
import os
import tables
export tables.`[]`

#### Simple string lexer ###
type
  PLexer = ref TLexer
  TLexer = object
    str: string
    idx: int
  TLexType = enum
    tend
    tword
    tint
    tfloat
    trange
    telipsis
    tchar

proc thisChar(L: PLexer):char = L.str[L.idx]
proc next(L: PLexer) = L.idx += 1

proc skipws(L: PLexer) =
  while thisChar(L) in Whitespace: next(L)
    
proc get(L: PLexer; t: var TLexType): string =
  skipws(L)
  let c = thisChar(L)
  t = tend
  if c == '\0': return nil
  result = ""
  result.add(c)
  next(L) 
  t = tchar
  case c
  of '-':  # '-", "--"
    if thisChar(L) == '-':
      result.add('-')
      next(L)
  of Letters: # word
    t = tword
    while thisChar(L) in Letters:
      result.add(thisChar(L))
      next(L)
  of Digits: # number
    t = tint
    while thisChar(L) in Digits:
      result.add(thisChar(L))
      next(L)
    if thisChar(L) == '.':
      t = tfloat
      result.add(thisChar(L))
      next(L)
      while thisChar(L) in Digits:
        result.add(thisChar(L))
        next(L)
  of '.': # ".", "..", "..."
    if thisChar(L) == '.':
      t = trange
      result.add('.')
      next(L)
      if thisChar(L) == '.':
        t = telipsis
        result.add('.')
        next(L)
  else: discard
    
proc get(L: PLexer): string = 
  var t: TLexType
  get(L,t)
    
proc reset(L: PLexer, s: string) =
  L.str  = s
  L.idx = 0

proc newLexer(s: string): PLexer =
  new(result)
  result.reset(s)
    
### a container for values ###
    
type
  TValueKind = enum
    vInt,
    vFloat,
    vString,
    vBool,
    vFile,
    vSeq

  PValue* = ref TValue
  TValue* = object
    case kind*: TValueKind
      of vInt: asInt*: int
      of vFloat: asFloat*: float
      of vString: asString*: string
      of vBool: asBool*: bool
      of vFile:
        asFile*: File
        fileName*: string
      of vSeq: asSeq*: seq[PValue]

proc boolValue(c: bool): PValue =  PValue(kind: vBool, asBool: c)
    
proc fileValue(f: File, name: string): PValue =  PValue(kind: vFile, asFile: f, fileName: name)
    
proc strValue(s: string): PValue =  PValue(kind: vString, asString: s) 
    
proc intValue(v: int): PValue =   PValue(kind: vInt, asInt: v)
    
proc floatValue(v: float): PValue = PValue(kind: vFloat, asFloat: v)
    
proc seqValue(v: seq[PValue]): PValue = PValue(kind: vSeq, asSeq: v)

const MAX_FILES = 30
    
type
  PSpec = ref TSpec
  TSpec = object
    defVal: string
    ptype: string
    needsValue, multiple, used: bool
var
  progname, usage: string
  aliases: array[char,string]
  parm_spec =  initTable[string,PSpec]()

proc fail(msg: string)  =
  stderr.writeln(progname & ": " & msg)
  quit(usage)

proc parseSpec(u: string) =    
  var
    L: PLexer
    tok: string
    k = 1
      
  let lines = u.splitLines
  L = newLexer(lines[0])
  progname = L.get
  usage = u
  for line in lines[1..(-1)]:
    var
      isarg = false
      multiple = false
      getnext = true
      name: string
      alias: char
    L.reset(line)
    tok = L.get
    if tok == "-" or tok == "--":  # flag
      if tok == "-": #short flag
        let flag = L.get
        if len(flag) != 1: fail("short option has one character!")
        tok = L.get
        if tok == ",": # which is alias for long flag
          tok = L.get
          if tok != "--": fail("expecting long --flag")
          name = L.get
          alias = flag[0]
        else: # only short flag
          name = flag
          alias = flag[0]
          getnext = false
      else: # only long flag
        name = L.get
        alias = '\0'
    elif tok == "<":  # argument
      isarg = true
      name = L.get
      alias = chr(k)
      k += 1
      tok = L.get
      if tok != ">": fail("argument must be enclosed in <...>")
        
    if getnext:  tok = L.get
    if tok == ":": # allowed to have colon after flags
      tok = L.get
    if tok == nil: continue
    # default types for flags and arguments
    var 
      ftype = if isarg: "string" else: "bool"
      defValue = ""
    if tok == "(": # typed flag/argument
      var t = tchar
      tok = L.get(t)
      if tok == "default":  # type from default value
        defValue = L.get(t)
        if t == tint: ftype = "int"
        elif t == tfloat: ftype = "float"
        elif t == tword:
          if defValue == "stdin": ftype = "infile"
          elif defValue == "stdout": ftype = "outfile"
          else: ftype = "string"
        else: fail("unknown default value " & tok)
      else: # explicit type
        if t == tword:
          ftype = tok
          if tok == "bool": defValue = "false"
        else: fail("unknown type " & tok)
      discard L.get(t)
      multiple = t == telipsis
    elif ftype == "bool": # no type or default
      defValue = "false"
            
    if name != nil:
      # echo("Param: " & name & " type: " & $ftype & " needsvalue: " & $(ftype != "bool") & " default: " & $defValue & " multiple: " & $multiple)
      let spec = PSpec(defVal:defValue, ptype: ftype, needsValue: ftype != "bool",multiple:multiple)
      aliases[alias] = name        
      parm_spec[name] = spec

proc tail(s: string): string = s[1..(-1)]

var 
  files = newSeq[File]()

proc closeFiles() {.noconv.} =
  for f in files:
    f.close()

proc parseArguments*(usage: string, args: seq[string]): Table[string,PValue] =
  var
    vars = initTable[string,PValue]()
    n = len(args) - 1
    i = 1
    k = 1
    flag,value, arg: string        
    info: PSpec
    short: bool
    flagvalues: seq[seq[string]]
      
  proc next(): string =
    if i > n: fail("an option required a value!")
    result = args[i]
    i += 1
      
  proc get_alias(c: char): string =
    result = aliases[c]
    if result == nil:
      n = ord(c)
      if n < 20:
        fail("no such argument: " & $n)
      else:
        fail("no such option: " & c)
      
  proc get_spec(name: string): PSpec =
    result = parm_spec[name]
    if result == nil:
      fail("no such option: " & name)

  newSeq(flagvalues, 0)
  parseSpec(usage)
  addQuitProc(closeFiles)

  # Collect failures
  var failures = newSeq[string]()
  
  # parse the flags and arguments
  while i <= n:
    arg = next()
    if arg[0] == '-':  #flag
      short = arg[1] != '-'
      arg = arg.tail
      if short: # all short args are aliases, even if only to themselves
        flag = get_alias(arg[0])
      else:
        flag = arg[1..high(arg)]
      info = get_spec(flag)
      if info.needsValue:
        if short and len(arg) > 1: # value can follow short flag
          value = arg.tail
        else:  # grab next argument
          value = next()
      else:
        value = "true"
        if short and len(arg) > 0: # short flags can be combined
          for c in arg.tail:
            let f = get_alias(c)
            let i = get_spec(f)
            if i.needsValue:
              failures.add("option " & f & " needs a value")
            flagvalues.add(@[f,"true"])
            i.used = true
    else: # argument (stored as \001, \002, etc
      flag = get_alias(chr(k))
      value = arg
      info = get_spec(flag)
      # don't move on if this is a varags last param
      if not info.multiple:  k += 1
    flagvalues.add(@[flag,value])
    info.used = true
  
  # Some options disables checking
  var enableChecks = true
  for flag,info in parm_spec:
    if info.used:
      if flag == "help" or flag == "version":
        enableChecks = false
  

  # any flags not mentioned?
  for flag,info in parm_spec:
    if not info.used:
      if info.defVal == "": # no default!
        failures.add("required option or argument missing: " & flag)
      else:
        flagvalues.add(@[flag,info.defVal])

  if enableChecks:
    # any failures up until now - then we fail
    if failures.len > 0:
      fail(failures.join(", "))

  # cool, we have the info, can convert known flags
  for item in flagvalues:
    var pval: PValue;
    let
      flag = item[0]
      value = item[1]
      info = get_spec(flag)
    case info.ptype
    of "int":
      var v: int
      try:
        v = value.parseInt
      except:
        fail("bad integer for " & flag)
      pval = intValue(v)
    of "float":
      var v: float
      try:
        v = value.parseFloat
      except:
        fail("bad float for " & flag)
      pval = floatValue(v)
    of "bool":
      pval = boolValue(value.parseBool)
    of "string":
      pval = strValue(value)
    of "infile","outfile": # we open files for the app...
      var f: File
      try:
        if info.ptype == "infile":
          if value == "stdin":
            f = stdin
          else:
            f = open(value, fmRead)
        else:
          if value == "stdout":
            f = stdout
          else:
            f = open(value, fmWrite)
        # they will be closed automatically on program exit
        files.add(f)
      except:
        fail("cannot open " & value)
      pval = fileValue(f,value)
    else: discard
    
    var oval = vars[flag]
    if info.multiple: # multiple flags are sequence values
      if oval == nil: # first value!
        pval = seqValue(@[pval])
      else: # just add to existing sequence
        oval.asSeq.add(pval)
        pval = oval
    elif oval != nil: # cannot repeat a single flag!
      fail("cannot use '" & flag & "' more than once")
    vars[flag] = pval

  return vars

proc parse*(usage: string): Table[string,PValue] =
  var 
    args: seq[string]
    n = paramCount()
  newSeq(args,n+1)
  for i in 0..n:
    args[i] = paramStr(i)
  return parseArguments(usage,args)    

# Helper proc for verbosity level.
proc verbosityLevel(args: Table[string,PValue]): int =
  if args.hasKey("verbose"):
    let verbosity = args["verbose"].asSeq
    result = verbosity.len
    if not verbosity[0].asBool:
      result = 0
  else:
    result = 0

# Helper to check if we should show version
proc showVersion(args: Table[string,PValue]): bool =
  args["version"].asBool

# Helper to check if we should show help
proc showHelp(args: Table[string,PValue]): bool =
  args["help"].asBool


# Typical usage
when isMainModule:
  let help = """
  head [flags] files... [out]
    -h,--help                     Show this help
    --version                     Show version
    -n: (default 10)              Number of lines to show
    -v,--verbose: (bool...)       Verbosity level, ignored
    -o,--out: (default stdout)    Optional outfile, defaults to stdout
    <files>: (default stdin...)   Files to take head of
  """
  # On parsing failure this will show usage automatically
  var args = parse(help)

  # These two are special, they short out
  if args.showHelp: quit(help)
  if args.showVersion: quit("Version: 1.99")
  
  # Ok, so what did we get...
  let n = args["n"].asInt
  
  # This one is a helper
  let v = verbosityLevel(args)
  
  echo "Lines to show: " & $n
  echo "Verbosity level: " & $verbosityLevel(args)
  
  let myfiles = args["files"].asSeq
  var outFile = args["out"].asFile
  
  for f in myfiles:
    for i in 1..n:
      writeln(outFile, string(f.asFile.readLine()))