parsecfg

The parsecfg module implements a high performance configuration file parser. The configuration file's syntax is similar to the Windows .ini format, but much more powerful, as it is not a line based parser. String literals, raw string literals and triple quoted string literals are supported as in the Nim programming language.

Example of how a configuration file may look like:

# This is a comment.
; this too.

[Common]
cc=gcc     # '=' and ':' are the same
--foo="bar"   # '--cc' and 'cc' are the same, 'bar' and '"bar"' are the same (except for '#')
macrosym: "#"  # Note that '#' is interpreted as a comment without the quotation
--verbose

[Windows]
isConsoleApplication=False ; another comment

[Posix]
isConsoleApplication=True

key1: "in this string backslash escapes are interpreted\n"
key2: r"in this string not"
key3: """triple quotes strings
are also supported. They may span
multiple lines."""

--"long option with spaces": r"c:\myfiles\test.txt"

Here is an example of how to use the configuration file parser:

import os, parsecfg, strutils, streams

var f = newFileStream(paramStr(1), fmRead)
if f != nil:
  var p: CfgParser
  open(p, f, paramStr(1))
  while true:
    var e = next(p)
    case e.kind
    of cfgEof: break
    of cfgSectionStart:   ## a ``[section]`` has been parsed
      echo("new section: " & e.section)
    of cfgKeyValuePair:
      echo("key-value-pair: " & e.key & ": " & e.value)
    of cfgOption:
      echo("command: " & e.key & ": " & e.value)
    of cfgError:
      echo(e.msg)
  close(p)
else:
  echo("cannot open: " & paramStr(1))

Examples

Configuration file example

charset = "utf-8"
[Package]
name = "hello"
--threads:on
[Author]
name = "lihf8515"
qq = "10214028"
email = "lihaifeng@wxm.com"

Creating a configuration file

import parsecfg
var dict=newConfig()
dict.setSectionKey("","charset","utf-8")
dict.setSectionKey("Package","name","hello")
dict.setSectionKey("Package","--threads","on")
dict.setSectionKey("Author","name","lihf8515")
dict.setSectionKey("Author","qq","10214028")
dict.setSectionKey("Author","email","lihaifeng@wxm.com")
dict.writeConfig("config.ini")

Reading a configuration file

import parsecfg
var dict = loadConfig("config.ini")
var charset = dict.getSectionValue("","charset")
var threads = dict.getSectionValue("Package","--threads")
var pname = dict.getSectionValue("Package","name")
var name = dict.getSectionValue("Author","name")
var qq = dict.getSectionValue("Author","qq")
var email = dict.getSectionValue("Author","email")
echo pname & "\n" & name & "\n" & qq & "\n" & email

Modifying a configuration file

import parsecfg
var dict = loadConfig("config.ini")
dict.setSectionKey("Author","name","lhf")
dict.writeConfig("config.ini")

Deleting a section key in a configuration file

import parsecfg
var dict = loadConfig("config.ini")
dict.delSectionKey("Author","email")
dict.writeConfig("config.ini")

Imports

strutils, lexbase, streams, tables

Types

CfgEventKind = enum
  cfgEof,                   ## end of file reached
  cfgSectionStart,          ## a ``[section]`` has been parsed
  cfgKeyValuePair,          ## a ``key=value`` pair has been detected
  cfgOption,                ## a ``--key=value`` command line option
  cfgError                   ## an error occurred during parsing

enumeration of all events that may occur when parsing Source Edit

CfgEvent = object of RootObj
  case kind*: CfgEventKind   ## the kind of the event
  of cfgEof:
    nil
  of cfgSectionStart:
      section*: string       ## `section` contains the name of the
                             ## parsed section start (syntax: ``[section]``)
    
  of cfgKeyValuePair, cfgOption:
      key*, value*: string   ## contains the (key, value) pair if an option
                             ## of the form ``--key: value`` or an ordinary
                             ## ``key= value`` pair has been parsed.
                             ## ``value==""`` if it was not specified in the
                             ## configuration file.
    
  of cfgError:              ## the parser encountered an error: `msg`
      msg*: string           ## contains the error message. No exceptions
                             ## are thrown if a parse error occurs.

describes a parsing event Source Edit

CfgParser = object of BaseLexer
  tok: Token
  filename: string

the parser object. Source Edit

Config = OrderedTableRef[string, OrderedTableRef[string, string]]

Source Edit

Procs

proc open(c: var CfgParser; input: Stream; filename: string; lineOffset = 0) {...}{.
    gcsafe, extern: "npc$1", raises: [IOError, OSError, Exception],
    tags: [ReadIOEffect, RootEffect].}

initializes the parser with an input stream. Filename is only used for nice error messages. lineOffset can be used to influence the line number information in the generated error messages. Source Edit

proc close(c: var CfgParser) {...}{.gcsafe, extern: "npc$1",
                               raises: [Exception, IOError, OSError],
                               tags: [WriteIOEffect].}

closes the parser c and its associated input stream. Source Edit

proc getColumn(c: CfgParser): int {...}{.gcsafe, extern: "npc$1", raises: [],
                                    tags: [].}

get the current column the parser has arrived at. Source Edit

proc getLine(c: CfgParser): int {...}{.gcsafe, extern: "npc$1", raises: [], tags: [].}

get the current line the parser has arrived at. Source Edit

proc getFilename(c: CfgParser): string {...}{.gcsafe, extern: "npc$1", raises: [],
    tags: [].}

get the filename of the file that the parser processes. Source Edit

proc errorStr(c: CfgParser; msg: string): string {...}{.gcsafe, extern: "npc$1",
    raises: [ValueError], tags: [].}

returns a properly formatted error message containing current line and column information. Source Edit

proc warningStr(c: CfgParser; msg: string): string {...}{.gcsafe, extern: "npc$1",
    raises: [ValueError], tags: [].}

returns a properly formatted warning message containing current line and column information. Source Edit

proc ignoreMsg(c: CfgParser; e: CfgEvent): string {...}{.gcsafe, extern: "npc$1",
    raises: [ValueError], tags: [].}

returns a properly formatted warning message containing that an entry is ignored. Source Edit

proc next(c: var CfgParser): CfgEvent {...}{.gcsafe, extern: "npc$1",
                                        raises: [IOError, OSError, ValueError],
                                        tags: [ReadIOEffect].}

retrieves the first/next event. This controls the parser. Source Edit

proc newConfig(): Config {...}{.raises: [], tags: [].}

Create a new configuration table. Useful when wanting to create a configuration file. Source Edit

proc loadConfig(stream: Stream; filename: string = "[stream]"): Config {...}{.
    raises: [IOError, OSError, Exception, ValueError, KeyError],
    tags: [ReadIOEffect, RootEffect, WriteIOEffect].}

Load the specified configuration from stream into a new Config instance. filename parameter is only used for nicer error messages. Source Edit

proc loadConfig(filename: string): Config {...}{.
    raises: [IOError, Exception, OSError, ValueError, KeyError],
    tags: [WriteIOEffect, ReadIOEffect, RootEffect].}

Load the specified configuration file into a new Config instance. Source Edit

proc writeConfig(dict: Config; stream: Stream) {...}{.raises: [IOError, OSError],
    tags: [WriteIOEffect].}

Writes the contents of the table to the specified stream

Note: Comment statement will be ignored.

Source Edit

proc `$`(dict: Config): string {...}{.raises: [Exception, IOError, OSError],
                                 tags: [WriteIOEffect].}

Writes the contents of the table to string. Note: Comment statement will be ignored. Source Edit

proc writeConfig(dict: Config; filename: string) {...}{.raises: [IOError, OSError],
    tags: [WriteIOEffect].}

Writes the contents of the table to the specified configuration file. Note: Comment statement will be ignored. Source Edit

proc getSectionValue(dict: Config; section, key: string; defaultVal = ""): string {...}{.
    raises: [KeyError], tags: [].}

Gets the key value of the specified Section. Returns the specified default value if the specified key does not exist. Source Edit

proc setSectionKey(dict: var Config; section, key, value: string) {...}{.
    raises: [KeyError], tags: [].}

Sets the Key value of the specified Section. Source Edit

proc delSection(dict: var Config; section: string) {...}{.raises: [], tags: [].}

Deletes the specified section and all of its sub keys. Source Edit

proc delSectionKey(dict: var Config; section, key: string) {...}{.raises: [KeyError],
    tags: [].}

Delete the key of the specified section. Source Edit