recordjar

Documentation

Overview

Package recordjar implements the main file format used by WolfMUD. It is based on the Record Jar format as described by Eric Raymond in "The Art of Unix Programming", chapter 5:

http://www.catb.org/esr/writings/taoup/html/ch05s02.html

This implementation differs from the original in a few ways:

• Unicode is allowed in field names, data and the free text section
• Line endings can be CRLF or LF
• Comments are lines starting with "//" characters
• The free text section is separated from the field section by a blank line
• The "%%" record separator may have leading or trailing white space EXCEPT when it follows a free text section - in which case there should be no leading white space.

Record jar example

This is an example of two records taken from the recordjar defining the Zinara zone (see data/zones/zinara.wrj for the full file):

//
// The Dragon's Breath tavern. L1 to L4
//
    Ref: L1
   Type: Start
   Name: Fireplace
Aliases: TAVERN FIREPLACE
  Exits: E→L3 SE→L4 S→L2

You are in the corner of a common room in the Dragon's Breath tavern.
There is a fire burning away merrily in an ornate fireplace giving
comfort to weary travellers. Shadows flicker around the room, changing
light to darkness and back again. To the south the common room extends
and east the common room leads to the tavern entrance.
%%
    Ref: L2
   Type: Start
   Name: Common Room
Aliases: TAVERN COMMON
  Exits: N→L1 NE→L3 E→L4

You are in a small, cosy common room in the Dragon's Breath tavern.
Looking around you see a few chairs and tables for patrons. To the east
there is a bar and to the north you can see a merry fireplace burning
away.

Records

Records are separated from each other by a "%%" delimiter on a line by itself. Each record consists of an optional field section and an optional free text section. If a record has both a field section and a free text section they are separated with a single blank line.

Comment lines

Comments lines are lines that start with a "//" delimiter, optionally with leading white space. Comment lines can appear before, after or between field lines. Comment lines cannot appear in the free text section as they would be taken literally and therefore would become part of the free text data. It is valid to have a record that contains only comments.

Field section

Each record can have a field section. Each field has a name, followed by a ":" colon separator, followed by optional data. There should be no white space between the field name and the colon separator. The field name may contain Unicode but cannot contain any white space. It is a convention to use a "-" hyphen where a space would normally be used. Field names are not case sensitive, so "Aliases:" and "aliases:" are treated the same. White space after the colon separator is not required, but highly recommended to aid readability. Field names may be indented with white space - usually to align the colon separator to aid readability. A field name may be specified more than once, in which case any data will have leading and trailing white space removed, the data will then be concatenated together with a single space. For example:

Aliases: apple apples
%%
Aliases: apple
         apples
%%
Aliases: apple
Aliases: apples

All three of these records have a single field named "Aliases" with the data value of "apple apples".

The data portion of a field is free format, may contain Unicode and may continue over multiple lines. When data is continued over multiple lines it may be indented - any leading or trailing white space will be removed and the lines concatenated together with a single space. See the second record above for an example where the continuation line is indented for alignment purposes.

The recordjar format itself does not assign any meaning to field names or data values. It is only when used for a specific purpose, for example WolfMUD zone files, that specific field names and the content of the data have meaning. For example:

Exits: E→L3 SE→L4 S→L2

It is only within the context of a WolfMUD zone file that the field name "Exits" has any meaning. It is also only within that context that the data is expected to consist of pairs of values: an exit direction and location reference.

It should be noted that care should be taken when using Unicode in field names as the Unicode will not be normalized. So, for example, 'Nаme' with a Cyrillic 'а' (U+0430) and 'Name' with a Latin 'a' (U+0061) would be treated as two different, separate fields.

Free text section

Each record can have one free text section. If a record also has a field section the free text section must appear after the field section, and be separated from the field section by a blank line. The separating blank line is not considered by of the free text section and will be discarded.

If a record does not contain a field section then a separating blank line should not be used.

Within the free text section the following will be preserved:

• Blank lines
• Leading white space
• Line breaks before lines with leading white space

An example with line numbers, which are for illustration only and not part of the record:

 1  %%
 2  // Server greeting
 3
 4
 5  WolfMUD Copyright 1984-2018 Andrew 'Diddymus' Rolfe
 6
 7      World
 8      Of
 9      Living
10      Fantasy
11
12  Welcome to WolfMUD!
13
14  %%

The example shows a single record consisting of a comment (line 2) and a free text section (lines 3-13). The resulting data will have two leading blank lines (lines 3-4) and one trailing blank line (line 13). The two blank lines on lines 6 and 11 will be preserved. The indenting on lines 7-10 will be preserved. The line endings preceding each of the indented lines (7-10) will be preserved, causing the indented lines to always start on new lines.

The fee text section may contain Unicode.

Comment lines should not be placed in a free text section as they would be taken to be part of the data and not treated as actual comments.

Index

• Constants
• Variables
• type Jar
  • func Read(in io.Reader, freetext string) (j Jar)
  • func (j Jar) Write(out io.Writer, freetext string, ordering []string)
• type Record
• Bugs

Constants

const (
	FTSection = "FREE TEXT" // Internal (due to space) freetext field for reading
)

Variables

var (
	CR    = []byte("\r")
	LF    = []byte("\n")
	Empty = []byte{}
	Space = []byte(" ")
)

Types

type Jar

type Jar []Record

Jar represents the collection of Records in a recordjar.

func Read

func Read(in io.Reader, freetext string) (j Jar)

Read takes as input an io.Reader - assuming the data to be in the WolfMUD recordjar format - and the field name to use for the free text section. The input is parsed into a jar which is then returned.

For details of the recordjar format see the separate package documentation.

BUG(diddymus): There is no provision for preserving comments.

func (Jar) Write

func (j Jar) Write(out io.Writer, freetext string, ordering []string)

Write writes out a Record Jar to the specified io.Writer. The freetext string is used to specify which field name in a record should be used for the free text section. For example, if the freetext string is 'Description' then any fields named description in a record will be written out in the free text section.

Ordering is a list of field names specifying the order the fields should appear in within records if present. Fields not in the list appear at the end of the record in alphabetical order. If Ordering is nil or an empty list then all fields will be written in alphabetical order.

For details of the recordjar format see the separate package documentation.

TODO(diddymus): Uppercase character after a hyphen in field names so that we can have 'On-Action', 'On-Reset', 'On-Cleanup' automatically.

BUG(diddymus): There is no provision for writing out comments. BUG(diddymus): The empty field "" is invalid, currently dropped silently. BUG(diddymus): Unicode used in field names not normalised so 'Nаme' with a Cyrillic 'а' (U+0430) and 'Name' with a latin 'a' (U+0061) would be different fields. BUG: If a continuation line starts with ": " and we outdent it we don't refold lines even though we have two extra character positions available.

type Record

type Record map[string][]byte

Record represents the separate records in a recordjar.

Notes

Bugs

• There is no provision for preserving comments.

• There is no provision for writing out comments.

• The empty field "" is invalid, currently dropped silently.

• Unicode used in field names not normalised so 'Nаme' with a Cyrillic 'а' (U+0430) and 'Name' with a latin 'a' (U+0061) would be different fields. BUG: If a continuation line starts with ": " and we outdent it we don't refold lines even though we have two extra character positions available.