Revision: 70875
http://sourceforge.net/p/brlcad/code/70875
Author: starseeker
Date: 2018-04-10 14:35:16 +0000 (Tue, 10 Apr 2018)
Log Message:
-----------
Add an ASCII translation and slight update of the spreadsheet Nick and Cliff
worked on specifying how search path modifiers should work.
Modified Paths:
--------------
brlcad/trunk/src/libged/TODO
Modified: brlcad/trunk/src/libged/TODO
===================================================================
--- brlcad/trunk/src/libged/TODO 2018-04-10 05:18:05 UTC (rev 70874)
+++ brlcad/trunk/src/libged/TODO 2018-04-10 14:35:16 UTC (rev 70875)
@@ -483,7 +483,78 @@
* implement -param support for 'search' command
+-------------------------------------------------------------------------------
+Thoughts on search path modifiers - this is a slight iteration on the results
+of Cliff and Nick trying to work through what "preferred" meanings and
+conventions are for path specifier modifiers.
+A path modifier is a single or multiple character pattern specified at the head
+of an object name, path, or glob pattern:
+
+[modifer]object_pattern[/object_pattern]
+
+Valid single character modifiers and their behaviors:
+
+ /object_pattern[/object_pattern]
+ .object_pattern[/object_pattern]
+ _object_pattern
+ |object_pattern[/object_pattern]
+
+ / → print option, full path. If specified without modifier, uses tops
+ objects as input list
+ . → print option, last object in path only. Default print mode if full path
+ is not specified. If specified without modifier, uses "tops" command
+ objects as input list
+ _ → modifier specifying flat object search, with no hierarchy walking. All
+ specifiers that require hierarchy are incompatible with this modifier.
+ By default it will use the tops output - if a glob pattern is supplied
+ as the object pattern, it will match all database objects against that
+ pattern and use the matching set as its input set. An object_pattern
+ including hierarchy will produce an error.
+ | → use all objects in the database as starting points for a hierarchical
+ search. Overrides default behavior of using tops objects as input list.
+ Without other modifiers, this is essentially an implicit "|." specifier,
+ since the output will default to the "." mode of printing without paths.
+
+Modifier pairs:
+
+ / . _ |
+ +---------------------
+ / | // /. /_ /|
+ . | ./ .. ._ .|
+ _ | _/ _. __ _|
+ | | |/ |. |_ ||
+
+
+Rules for pair combination and simplification:
+ // → / /. → error /_ → error /| → |/
+ ./ → error .. → . ._ → _ .| → |
+ _/ → error _. → _ __ → _ _| → |_
+ |/ → |/ |. → | |_ → |_ || → |
+
+If more than two print/modifier characters are present at the head of the
+path specifier, they will be collapsed using the above rules until either a
+single valid pairing is arrived at, a single valid character is arrived at,
+or an error condition occurs. (Any larger combination which which evaluates
+to more than two valid specification characters is defined to be erroneous.)
+
+Note: the simplification process is allowed to reorder individual characters
+within a longer specification string when attempting to collapse characters,
+since none of the valid combined behavior specifications is dependent on
+modifier position in the string under the above rules.
+
+Per the above rules, all possible valid path specifier combinations collapse
+into one of the four atomic rules, with the exception of "|/" and "|_":
+
+"|/" - this paring will produce a search output that both uses all objects in
+the database as starting points and reports full paths.
+
+"|_" - this paring will produce a search output that uses all objects in the
+database as starting points and performs a flat search. It is equivalent to
+the full pattern "_*" but may be slightly faster in that it doesn't require the
+evaluation of the glob expression to build the object set.
+
+
--- COMMAND PATTERNS ---
Here are notes on command parsing infrastructure, how to unify our
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