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Add a bit more commentary about regex's colormap tree data structure.

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Per an off-list question from Piotr Stefaniak.
This commit is contained in:
Tom Lane 2015-05-24 12:40:38 -04:00
parent 91e79260f6
commit 23116d5437
1 changed files with 5 additions and 0 deletions
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src/include/regex/regguts.h
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@ -162,6 +162,10 @@ typedef int pcolor; /* what color promotes to */
* deep (in the past it was shallower during construction but was "filled"
* to full depth at the end of that); areas that are unaltered as yet point
* to "fill blocks" which are entirely WHITE in color.
*
* Leaf-level tree blocks are of type "struct colors", while upper-level
* blocks are of type "struct ptrs". Pointers into the tree are generally
* declared as "union tree *" to be agnostic about what level they point to.
*/
/* the tree itself */
@ -179,6 +183,7 @@ union tree
struct ptrs ptrs;
};
/* use these pseudo-field names when dereferencing a "union tree" pointer */
#define tcolor colors.ccolor
#define tptr ptrs.pptr