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[Gnu-arch-users] [BUG] FEATURE PLANS: selection by ID
From: |
Tom Lord |
Subject: |
[Gnu-arch-users] [BUG] FEATURE PLANS: selection by ID |
Date: |
Mon, 24 May 2004 16:56:33 -0700 (PDT) |
The little language for expressing tree selections was introduced in
the last message. This message extends it, slighly.
We've seen rules of the form:
(<outcome> <location>)
where if the <location> matches or matches a prefix of the location of
the item being tested, then the <outcome> specifies the result
produced by this rule.
So far, we've written all rule patterns just as strings, specifying a
location:
(b "./include/X11/x.h")
Such rules can be written using a list path fragments instead of a
single string:
(b ("./include" "X11" "x.h"))
or
(b ("./include/X11" "x.h"))
etc.
Any string in a rule pattern can be replaced with a list of the form:
(id STRING)
Before a set of rules is evaluated for a given tree, all "(id STRING)"
elements in patterns are replaced by suitably pruned paths.
For example, suppose that we have the rule:
(b ("./include" (id "i_x_header_file")))
Suppose that in the tree we're looking at, the file with the id
"i_x_header_file" is at the path: "./include/X11/basic/x.h".
Then the rule is rewritten:
(b ("./include" "X11/basic/x.h"))
and is therefore equivalent to:
(b "./include/X11/basic/x.h)
If a rule references an inventory id that doesn't exist, the rule is
simply discarded -- it matches nothing.
-t
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- [Gnu-arch-users] [BUG] FEATURE PLANS: selection by ID,
Tom Lord <=