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Diffstat (limited to 'docs/qapi-code-gen.txt')
| -rw-r--r-- | docs/qapi-code-gen.txt | 180 |
1 files changed, 147 insertions, 33 deletions
diff --git a/docs/qapi-code-gen.txt b/docs/qapi-code-gen.txt index 2841c5144a..7eb7be12ab 100644 --- a/docs/qapi-code-gen.txt +++ b/docs/qapi-code-gen.txt @@ -44,40 +44,154 @@ Input must be ASCII (although QMP supports full Unicode strings, the QAPI parser does not). At present, there is no place where a QAPI schema requires the use of JSON numbers or null. + +=== Comments === + Comments are allowed; anything between an unquoted # and the following -newline is ignored. Although there is not yet a documentation -generator, a form of stylized comments has developed for consistently -documenting details about an expression and when it was added to the -schema. The documentation is delimited between two lines of ##, then -the first line names the expression, an optional overview is provided, -then individual documentation about each member of 'data' is provided, -and finally, a 'Since: x.y.z' tag lists the release that introduced -the expression. Optional members are tagged with the phrase -'#optional', often with their default value; and extensions added -after the expression was first released are also given a '(since -x.y.z)' comment. For example: - - ## - # @BlockStats: - # - # Statistics of a virtual block device or a block backing device. - # - # @device: #optional If the stats are for a virtual block device, the name - # corresponding to the virtual block device. - # - # @stats: A @BlockDeviceStats for the device. - # - # @parent: #optional This describes the file block device if it has one. - # - # @backing: #optional This describes the backing block device if it has one. - # (Since 2.0) - # - # Since: 0.14.0 - ## - { 'struct': 'BlockStats', - 'data': {'*device': 'str', 'stats': 'BlockDeviceStats', - '*parent': 'BlockStats', - '*backing': 'BlockStats'} } +newline is ignored. + +A multi-line comment that starts and ends with a '##' line is a +documentation comment. These are parsed by the documentation +generator, which recognizes certain markup detailed below. + + +==== Documentation markup ==== + +Comment text starting with '=' is a section title: + + # = Section title + +Double the '=' for a subsection title: + + # == Subection title + +'|' denotes examples: + + # | Text of the example, may span + # | multiple lines + +'*' starts an itemized list: + + # * First item, may span + # multiple lines + # * Second item + +You can also use '-' instead of '*'. + +A decimal number followed by '.' starts a numbered list: + + # 1. First item, may span + # multiple lines + # 2. Second item + +The actual number doesn't matter. You could even use '*' instead of +'2.' for the second item. + +Lists can't be nested. Blank lines are currently not supported within +lists. + +Additional whitespace between the initial '#' and the comment text is +permitted. + +*foo* and _foo_ are for strong and emphasis styles respectively (they +do not work over multiple lines). @foo is used to reference a name in +the schema. + +Example: + +## +# = Section +# == Subsection +# +# Some text foo with *strong* and _emphasis_ +# 1. with a list +# 2. like that +# +# And some code: +# | $ echo foo +# | -> do this +# | <- get that +# +## + + +==== Expression documentation ==== + +Each expression that isn't an include directive must be preceded by a +documentation block. Such blocks are called expression documentation +blocks. + +The documentation block consists of a first line naming the +expression, an optional overview, a description of each argument (for +commands and events) or member (for structs, unions and alternates), +and optional tagged sections. + +FIXME: the parser accepts these things in almost any order. + +Optional arguments / members are tagged with the phrase '#optional', +often with their default value; and extensions added after the +expression was first released are also given a '(since x.y.z)' +comment. + +A tagged section starts with one of the following words: +"Note:"/"Notes:", "Since:", "Example"/"Examples", "Returns:", "TODO:". +The section ends with the start of a new section. + +A 'Since: x.y.z' tagged section lists the release that introduced the +expression. + +For example: + +## +# @BlockStats: +# +# Statistics of a virtual block device or a block backing device. +# +# @device: #optional If the stats are for a virtual block device, the name +# corresponding to the virtual block device. +# +# @node-name: #optional The node name of the device. (since 2.3) +# +# ... more members ... +# +# Since: 0.14.0 +## +{ 'struct': 'BlockStats', + 'data': {'*device': 'str', '*node-name': 'str', + ... more members ... } } + +## +# @query-blockstats: +# +# Query the @BlockStats for all virtual block devices. +# +# @query-nodes: #optional If true, the command will query all the +# block nodes ... explain, explain ... (since 2.3) +# +# Returns: A list of @BlockStats for each virtual block devices. +# +# Since: 0.14.0 +# +# Example: +# +# -> { "execute": "query-blockstats" } +# <- { +# ... lots of output ... +# } +# +## +{ 'command': 'query-blockstats', + 'data': { '*query-nodes': 'bool' }, + 'returns': ['BlockStats'] } + +==== Free-form documentation ==== + +A documentation block that isn't an expression documentation block is +a free-form documentation block. These may be used to provide +additional text and structuring content. + + +=== Schema overview === The schema sets up a series of types, as well as commands and events that will use those types. Forward references are allowed: the parser |