notmuch/devel/schemata

This file describes the schemata used for notmuch's structured output
format (currently JSON and S-Expressions).

[]'s indicate lists.  List items can be marked with a '?', meaning
they are optional; or a '*', meaning there can be zero or more of that
item.  {}'s indicate an object that maps from field identifiers to
values.  An object field marked '?' is optional.  |'s indicate
alternates (e.g., int|string means something can be an int or a
string).

For S-Expression output, lists are printed delimited by () instead of
[]. Objects are printed as p-lists, i.e. lists where the keys and values
are interleaved. Keys are printed as keywords (symbols preceded by a
colon), e.g. (:id "123" :time 54321 :from "foobar"). Null is printed as
nil, true as t and false as nil.

This is version 2 of the structured output format.

Version history
---------------

v1
- First versioned schema release.
- Added part.content-length and part.content-transfer-encoding fields.

v2
- Added the thread_summary.query field.

v3
- Replaced message.filename string with a list of filenames.

Common non-terminals
--------------------

# Number of seconds since the Epoch
unix_time = int

# Thread ID, sans "thread:"
threadid = string

# Message ID, sans "id:"
messageid = string

notmuch show schema
-------------------

# A top-level set of threads (do_show)
# Returned by notmuch show without a --part argument
thread_set = [thread*]

# Top-level messages in a thread (show_messages)
thread = [thread_node*]

# A message and its replies (show_messages)
thread_node = [
    message|null,             # null if not matched and not --entire-thread
    [thread_node*]            # children of message
]

# A message (format_part_sprinter)
message = {
    # (format_message_sprinter)
    id:             messageid,
    match:          bool,
    filename:	    [string*],
    timestamp:      unix_time, # date header as unix time
    date_relative:  string,   # user-friendly timestamp
    tags:           [string*],

    headers:        headers,
    body?:          [part]    # omitted if --body=false
}

# A MIME part (format_part_sprinter)
part = {
    id:             int|string, # part id (currently DFS part number)

    encstatus?:     encstatus,
    sigstatus?:     sigstatus,

    content-type:   string,
    content-id?:    string,
    # if content-type starts with "multipart/":
    content:        [part*],
    # if content-type is "message/rfc822":
    content:        [{headers: headers, body: [part]}],
    # otherwise (leaf parts):
    filename?:      string,
    content-charset?: string,
    # A leaf part's body content is optional, but may be included if
    # it can be correctly encoded as a string.  Consumers should use
    # this in preference to fetching the part content separately.
    content?:       string,
    # If a leaf part's body content is not included, the length of
    # the encoded content (in bytes) may be given instead.
    content-length?: int,
    # If a leaf part's body content is not included, its transfer encoding
    # may be given.  Using this and the encoded content length, it is
    # possible for the consumer to estimate the decoded content length.
    content-transfer-encoding?: string
}

# The headers of a message or part (format_headers_sprinter with reply = FALSE)
headers = {
    Subject:        string,
    From:           string,
    To?:            string,
    Cc?:            string,
    Bcc?:           string,
    Reply-To?:      string,
    Date:           string
}

# Encryption status (format_part_sprinter)
encstatus = [{status: "good"|"bad"}]

# Signature status (format_part_sigstatus_sprinter)
sigstatus = [signature*]

signature = {
    # (signature_status_to_string)
    status:         "none"|"good"|"bad"|"error"|"unknown",
    # if status is "good":
    fingerprint?:   string,
    created?:       unix_time,
    expires?:       unix_time,
    userid?:        string
    # if status is not "good":
    keyid?:         string
    # if the signature has errors:
    errors?:        int
}

notmuch search schema
---------------------

# --output=summary
search_summary = [thread_summary*]

# --output=threads
search_threads = [threadid*]

# --output=messages
search_messages = [messageid*]

# --output=files
search_files = [string*]

# --output=tags
search_tags = [string*]

thread_summary = {
    thread:         threadid,
    timestamp:      unix_time,
    date_relative:  string,   # user-friendly timestamp
    matched:        int,      # number of matched messages
    total:          int,      # total messages in thread
    authors:        string,   # comma-separated names with | between
                              # matched and unmatched
    subject:        string,
    tags:           [string*],

    # Two stable query strings identifying exactly the matched and
    # unmatched messages currently in this thread.  The messages
    # matched by these queries will not change even if more messages
    # arrive in the thread.  If there are no matched or unmatched
    # messages, the corresponding query will be null (there is no
    # query that matches nothing).  (Added in schema version 2.)
    query:          [string|null, string|null],
}

notmuch reply schema
--------------------

reply = {
    # The headers of the constructed reply
    reply-headers: reply_headers,

    # As in the show format (format_part_sprinter)
    original: message
}

# Reply headers (format_headers_sprinter with reply = TRUE)
reply_headers = {
    Subject:        string,
    From:           string,
    To?:            string,
    Cc?:            string,
    Bcc?:           string,
    In-reply-to:    string,
    References:     string
}