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# huddle(n) 0.2 tcllib "HUDDLE"

## Name

huddle - Create and manipulate huddle object

## Synopsis

- package require Tcl 8.4
- package require huddle ?0.2?

- huddle create key value ?key value ...?
- huddle list ?value value ...?
- huddle number number
- huddle string string
- huddle boolean expression to evaluate as true or false
- huddle true
- huddle false
- huddle null
- huddle get object key ?key ...?
- huddle gets object key ?key ...?
- huddle set objectVar key ?key ...? value
- huddle remove object key ?key ...?
- huddle combine object1 object2 ?object3 ...?
- huddle equal object1 object2
- huddle append objectVar key value ?key value ...?
- huddle append objectVar value ?value ...?
- huddle keys object
- huddle llength object
- huddle type object ?key key...?
- huddle strip object
- huddle jsondump object ?offset? ?newline? ?begin_offset?
- huddle compile spec data
- huddle isHuddle object
- huddle checkHuddle object
- huddle to_node object ?tag?
- huddle wrap tag src
- huddle call tag command args
- huddle addType callback
- callback command ?args?
- setting
- get_sub src key
- strip src
- set src key value
- remove src key value

## Description

Huddle provides a generic Tcl-based serialization/intermediary format. Currently, each node is wrapped in a tag with simple type information.

When converting huddle-notation to other serialization formats like JSON or YAML this type information is used to select the proper notation. And when going from JSON/YAML/... to huddle their notation can be used to select the proper huddle type.

In that manner huddle can serve as a common intermediary format.

    huddle-format: >
      {HUDDLE {huddle-node}}
    huddle-node: >
      {tag content}
    each content of tag means:
      s: (content is a) string
      L: list, each sub node is a huddle-node
      D: dict, each sub node is a huddle-node
    confirmed:
      - JSON
      - YAML(generally, but cannot discribe YAML-tags)
    limitation:
      - cannot discribe aliases from a node to other node.

The huddle package returns data as a Tcl dict. Either the dict package or Tcl 8.5 is required for use.

## COMMANDS

huddle create key value ?key value ...?

  Create a huddle object as a dict. It can contain other huddle objects.

huddle list ?value value ...?

  Create a huddle object as a list. It can contain other huddle objects.

huddle number number

  Create a huddle object as a number.

huddle string string

  Create a huddle object as a string.

huddle boolean expression to evaluate as true or false

  Create a huddle object as a boolean evaluating an expression as true or false-

huddle true

  Create a huddle object as a boolean true.

huddle false

  Create a huddle object as a boolean false.

huddle null

  Create a huddle object as a null.

huddle get object key ?key ...?

  Almost the same as dict get. Get a sub-object from the huddle object. key can be used to huddle-list's index.

huddle gets object key ?key ...?

  Get a sub-object from the huddle object, stripped.

huddle set objectVar key ?key ...? value

  Almost the same as dict set. Set a sub-object from the huddle object. key can be used to huddle-list's index.

huddle remove object key ?key ...?

  Almost the same as dict remove. Remove a sub-object from the huddle object. key can be used to huddle-list's index.

huddle combine object1 object2 ?object3 ...?

  Merging huddle objects given.

      % set aa [huddle create a b c d]
      HUDDLE {D {a {s b} c {s d}}}
      % set bb [huddle create a k l m]
      HUDDLE {D {a {s k} l {s m}}}
      % huddle combine $aa $bb
      HUDDLE {D {a {s k} c {s d} l {s m}}}

huddle equal object1 object2

  Comparing two huddle objects recursively. When to equal, returns 1, otherwise 0.

      % set aa [huddle create a b c d]
      HUDDLE {D {a {s b} c {s d}}}
      % set bb [huddle create c d a b]
      HUDDLE {D {c {s d} a {s b}}}
      % huddle equal $aa $bb
      1

huddle append objectVar key value ?key value ...?
huddle append objectVar value ?value ...?

  Appending child elements. When for dicts, giving key/value. When for lists, giving values.

      % set aa [huddle create a b c d]
      HUDDLE {D {a {s b} c {s d}}}
      % huddle append aa a k l m
      HUDDLE {D {a {s k} c {s d} l {s m}}}
      % set bb [huddle list i j k l]
      HUDDLE {L {{s i} {s j} {s k} {s l}}}
      % huddle append bb g h i
      HUDDLE {L {{s i} {s j} {s k} {s l} {s g} {s h} {s i}}}

huddle keys object

  The same as dict keys.

huddle llength object

  The same as llength.

huddle type object ?key key...?

  Return the element type of specified by keys. if ?key? is not given, returns the type of root node.

  string

    the node is a tcl's string.

  dict

    the node is a dict.

  list

    the node is a list.

  number

    the node is a number.

  boolean

    the node is a boolean.

  null

    the node is a null.

      % huddle type {HUDDLE {s str}}
      string
      % huddle type {HUDDLE {L {{s a} {s b} {s c}}}}
      list
      % huddle type {HUDDLE {D {aa {s b} cc {s d}}}} cc
      string

huddle strip object

  Stripped all tags. Converted to normal Tcl's list/dict.

huddle jsondump object ?offset? ?newline? ?begin_offset?

  dump a json-stream from the huddle-object.

  offset ""

    begin offset as spaces " ".

      # normal output has some indents. some strings are escaped.
      % huddle jsondump {HUDDLE {L {{L {{s i} {s baa} {s \\k} {L {{s 1.0} {s true} {s /g} {s h}}} {L {{s g}}}}} {s t}}}}
      [
        [
          "i",
          "baa",
          "\\k",
          [
            1.0,
            true,
            "\/g",
            "h"
          ],
          ["g"]
        ],
        "t"
      ]
      # stripped output
      % huddle jsondump {HUDDLE {D {dd {D {bb {D {a {s baa} c {s {d
      a}}}} cc {D {g {s h}}}}} ee {D {i {s j} k {s 1} j {s { m\a}}}}}}} "" ""
      {"dd": {"bb": {"a": "baa","c": "d\na"},"cc": {"g": "h"}},"ee": {"i": "j","k": 1,"j": " m\\a"}}

huddle compile spec data

  construct a huddle object from plain old tcl values. spec is defined as follows:

  string

    data is simply a string

  list

    data is a tcl list of strings

  dict

    data is a tcl dict of strings

  list list

    data is a tcl list of lists

  list dict

    data is a tcl list of dicts

  dict xx list

    data is a tcl dict where the value of key xx is a tcl list

  dict * list

    data is a tcl dict of lists data is plain old tcl values

      % huddle compile {dict * list} {a {1 2 3} b {4 5}}
      HUDDLE {D {a {L {{s 1} {s 2} {s 3}}} b {L {{s 4} {s 5}}}}}
      % huddle compile {dict * {list {dict d list}}} {a {{c 1} {d {2 2 2} e 3}} b {{f 4 g 5}}}
      HUDDLE {D {a {L {{D {c {s 1}}} {D {d {L {{s 2} {s 2} {s 2}}} e {s 3}}}}} b {L {{D {f {s 4} g {s 5}}}}}}}

huddle isHuddle object

  if object is a huddle, returns 1. the other, returns 0.

huddle checkHuddle object

  if object is not a huddle, rises an error.

huddle to_node object ?tag?

  for type-callbacks.

  if object is a huddle, returns root-node. the other, returns [list s $object].

      % huddle to_node str
      s str
      % huddle to_node str !!str
      !!str str
      % huddle to_node {HUDDLE {s str}}
      s str
      % huddle to_node {HUDDLE {l {a b c}}}
      l {a b c}

huddle wrap tag src

  for type-callbacks.

  Create a huddle object from src with specified tag.

      % huddle wrap "" str
      HUDDLE str
      % huddle wrap s str
      HUDDLE {s str}

huddle call tag command args

  for type-callbacks.

  devolving command to default tag-callback

huddle addType callback

  add a user-specified-type/tag to the huddle library. To see "Additional Type".

  callback

    callback function name for additional type.

## TYPE CALLBACK

The definition of callback for user-type.

callback command ?args?
  command

    huddle subcomand which is needed to reply by the callback.

  args

    arguments of subcommand. The number of list of arguments is different for each subcommand.

The callback procedure shuould reply the following subcommands.

setting

  only returns a fixed dict of the type infomation for setting the user-tag.

  type typename

    typename of the type

  method {method1 method2 method3 ...}

    method list as huddle subcommand. Then, you can call [huddle method1 ...]

  tag {tag1 child/parent tag2 child/parent ...}

    tag list for huddle-node as a dict. if the type has child-nodes, use "parent", otherwise use "child".

get_sub src key

  returns a sub node specified by key.

  src

    a node content in huddle object.

strip src

  returns stripped node contents. if the type has child nodes, every node must be stripped.

set src key value

  sets a sub-node from the tagged-content, and returns self.

remove src key value

  removes a sub-node from the tagged-content, and returns self.

strip must be defined at all types. get_sub must be defined at container types. set/remove shuould be defined, if you call them.

    # callback sample for my-dict
    proc my_dict_setting {command args} {
        switch -- $command {
            setting { ; # type definition
                return {
                    type dict
                    method {create keys}
                    tag {d child D parent}
                    constructor create
                    str s
                }
                # type:   the type-name
                # method: add methods to huddle's subcommand.
                #          "get_sub/strip/set/remove/equal/append" called by huddle module.
                #          "strip" must be defined at all types.
                #          "get_sub" must be defined at container types.
                #          "set/remove/equal/append" shuould be defined, if you call them.
                # tag:    tag definition("child/parent" word is maybe obsoleted)
            }
            get_sub { ; # get a sub-node specified by "key" from the tagged-content
                foreach {src key} $args break
                return [dict get $src $key]
            }
            strip { ; # strip from the tagged-content
                foreach {src nop} $args break
                foreach {key val} $src {
                    lappend result $key [huddle strip $val]
                }
                return $result
            }
            set { ; # set a sub-node from the tagged-content
                foreach {src key value} $args break
                dict set src $key $value
                return $src
            }
            remove { ; # remove a sub-node from the tagged-content
                foreach {src key value} $args break
                return [dict remove $src $key]
            }
            equal { ; # check equal for each node
                foreach {src1 src2} $args break
                if {[llength $src1] != [llength $src2]} {return 0}
                foreach {key1 val1} $src1 {
                    if {![dict exists $src2 $key1]} {return 0}
                    if {![huddle _equal_subs $val1 [dict get $src2 $key1]]} {return 0}
                }
                return 1
            }
            append { ; # append nodes
                foreach {str src list} $args break
                if {[llength $list] % 2} {error {wrong # args: should be "huddle append objvar ?key value ...?"}}
                set resultL $src
                foreach {key value} $list {
                    if {$str ne ""} {
                        lappend resultL $key [huddle to_node $value $str]
                    } else {
                        lappend resultL $key $value
                    }
                }
                return [eval dict create $resultL]
            }
            create { ; # $args: all arguments after "huddle create"
                if {[llength $args] % 2} {error {wrong # args: should be "huddle create ?key value ...?"}}
                set resultL {}
                foreach {key value} $args {
                    lappend resultL $key [huddle to_node $value]
                }
                return [huddle wrap D $resultL]
            }
            keys {
                foreach {src nop} $args break
                return [dict keys [lindex [lindex $src 1] 1]]
            }
            default {
                error "$command is not callback for dict"
            }
        }
    }

    # inheritance sample from default dict-callback
    proc ::yaml::_huddle_mapping {command args} {
        switch -- $command {
            setting { ; # type definition
                return {
                    type dict
                    method {mapping}
                    tag {!!map parent}
                    constructor mapping
                    str !!str
                }
            }
            mapping { ; # $args: all arguments after "huddle mapping"
                if {[llength $args] % 2} {error {wrong # args: should be "huddle mapping ?key value ...?"}}
                set resultL {}
                foreach {key value} $args {
                    lappend resultL $key [huddle to_node $value !!str]
                }
                return [huddle wrap !!map $resultL]
            }
            default { ; # devolving to default dict-callback
                return [huddle call D $command $args]
            }
        }
    }

## How to add type

You can add huddle-node types e.g. ::struct::tree. To do so, first, define a callback-procedure for additional tagged-type. The proc get argments as command and ?args?. It has some switch-sections.

And, addType subcommand will called.

    huddle addType my_dict_setting

## WORKING SAMPLE

    # create as a dict
    % set bb [huddle create a b c d]
    HUDDLE {D {a {s b} c {s d}}}
    # create as a list
    % set cc [huddle list e f g h]
    HUDDLE {L {{s e} {s f} {s g} {s h}}}
    % set bbcc [huddle create bb $bb cc $cc]
    HUDDLE {D {bb {D {a {s b} c {s d}}} cc {L {{s e} {s f} {s g} {s h}}}}}
    % set folding [huddle list $bbcc p [huddle list q r] s]
    HUDDLE {L {{D {bb {D {a {s b} c {s d}}} cc {L {{s e} {s f} {s g} {s h}}}}} {s p} {L {{s q} {s r}}} {s s}}}
    # normal Tcl's notation
    % huddle strip $folding
    {bb {a b c d} cc {e f g h}} p {q r} s
    # get a sub node
    % huddle get $folding 0 bb
    HUDDLE {D {a {s b} c {s d}}}
    % huddle gets $folding 0 bb
    a b c d
    # overwrite a node
    % huddle set folding 0 bb c kkk
    HUDDLE {L {{D {bb {D {a {s b} c {s kkk}}} cc {L {{s e} {s f} {s g} {s h}}}}} {s p} {L {{s q} {s r}}} {s s}}}
    # remove a node
    % huddle remove $folding 2 1
    HUDDLE {L {{D {bb {D {a {s b} c {s kkk}}} cc {L {{s e} {s f} {s g} {s h}}}}} {s p} {L {{s q}}} {s s}}}
    % huddle strip $folding
    {bb {a b c kkk} cc {e f g h}} p {q r} s
    # dump as a JSON stream
    % huddle jsondump $folding
    [
      {
        "bb": {
          "a": "b",
          "c": "kkk"
        },
        "cc": [
          "e",
          "f",
          "g",
          "h"
        ]
      },
      "p",
      [
        "q",
        "r"
      ],
      "s"
    ]

## LIMITATIONS

now printing.

## Bugs, Ideas, Feedback

This document, and the package it describes, will undoubtedly contain bugs and other problems. Please report such in the category huddle of the Tcllib Trackers. Please also report any ideas for enhancements you may have for either package and/or documentation.

## See Also

yaml

## Keywords

data exchange, exchange format, huddle, json, parsing, text processing, yaml

## Copyright

Copyright © 2008-2011 KATO Kanryu <kanryu6@users.sourceforge.net>
Copyright © 2015 Miguel Martínez López <aplicacionamedida@gmail.com>