diff options
author | Christian Linhart <chris@DemoRecorder.com> | 2014-08-20 11:10:35 +0200 |
---|---|---|
committer | Peter Harris <pharris@opentext.com> | 2014-08-25 19:38:35 -0400 |
commit | 4987a5c6bcb971d851a71ec3b3d9783a4cbc7554 (patch) | |
tree | b4a976cb08b864d7e878b5707ead414beaf803ac /doc/xml-xcb.txt | |
parent | 80a79d466d1b3cb7c81c30f54035862b2d0f5f6f (diff) |
xml-xcb spec: describe switch-case
V2: patch revised according to suggestion from Peter Harris:
* add the restriction that <enumref>
inside <bitcase> can only refer to an enum's <bit> members, and
<enumref> inside <case> can only refer to an enum's <value> members.
Reviewed-by: Peter Harris <pharris@opentext.com>
Reviewed-by: Ran Benita <ran234@gmail.com>
Diffstat (limited to 'doc/xml-xcb.txt')
-rw-r--r-- | doc/xml-xcb.txt | 38 |
1 files changed, 30 insertions, 8 deletions
diff --git a/doc/xml-xcb.txt b/doc/xml-xcb.txt index 6aa789b..235958d 100644 --- a/doc/xml-xcb.txt +++ b/doc/xml-xcb.txt @@ -244,18 +244,40 @@ enum; the value is restricted to one of the constants named in the enum. <switch> instead for new protocol definitions. <switch name="identifier"> switch expression - <bitcase> bitcase expression(s), fields </bitcase> </switch> + <bitcase> bitcase expression(s), fields </bitcase> + <case> case expression(s), fields </case> +</switch> This element represents conditional inclusion of fields. It can be viewed - as sequence of multiple ifs: if ( switch expression & bitcase expression ) - is non-zero, bitcase fields are included in structure. It can be used only - as the last field of a structure. + as sequence of multiple ifs: - When a bitcase includes multiple <enumref> clauses, the contents of the - bitcase are only present once regardless of the number of bitcase expressions - that match. + <bitcase>: + if ( switch expression & bitcase expression ) is non-zero, + bitcase fields are included in structure. + + <case>: + if ( switch expression == case expression ) is true, + then case fields are included in structure. + + It can be used only as the last field of a structure. + + When a bitcase or case includes multiple <enumref> clauses, the contents + of the bitcase or case are only present once regardless of the number of + bitcase or case expressions that match. + + <enumref> inside <bitcase> can only refer to an enum's <bit> members. + <enumref> inside <case> can only refer to an enum's <value> members. + + A switch may contain multiple <bitcase> or <case> elements. + Usually it will only contain <bitcase> elements + or only contain <case> elements. + That is, mixing of <case> and <bitcase> usually doesn't make any sense. + + The same value may appear in multiple <case> or <bitcase> elements. + + New protocol definitions should prefer to use this instead of <valueparam> + and instead of <union>. - New protocol definitions should prefer to use this instead of <valueparam>. Expressions ----------- |