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[PATCH 7/7] news: new syntax (%gprec and %precr)
From: |
Valentin Tolmer |
Subject: |
[PATCH 7/7] news: new syntax (%gprec and %precr) |
Date: |
Thu, 1 Aug 2013 16:04:55 +0200 |
---
NEWS | 26 ++++++++++++++++++++++++++
1 file changed, 26 insertions(+)
diff --git a/NEWS b/NEWS
index 07bf5a9..a79b18b 100644
--- a/NEWS
+++ b/NEWS
@@ -2,6 +2,32 @@ GNU Bison NEWS
* Noteworthy changes in release ?.? (????-??-??) [?]
+** New syntax: partial-order precedence relationships
+
+ Formerly, the precedence order of tokens was linear, depending only on the
+ order in which they were declared. With the new syntax, all the tokens are
+ not necessarily comparable. It is possible to declare a group of tokens with
+ no links outside of the group, and to later on add only those needed.
+ The uncomparability of tokens would allow for more feedback on new conflicts
+ silently resolved via precedence.
+
+ An example of the new syntax applied to arithmetic and boolean operators,
+ with '^' serving as both numerical power and boolean XOR:
+
+ %gprec arith {
+ %left '+' '-'
+ %left '*' '/'
+ }
+ %gprec bool {
+ %left OR
+ %left AND
+ }
+ %gprec { %right '^' }
+
+ %precr '^' > arith
+ %precr OR AND > '^'
+
+ Here, AND is not comparable with '+', but '^' > '+' and AND > '^'
* Noteworthy changes in release 3.0 (2013-07-25) [stable]
--
1.7.9.5
- [PATCH 0/7] new partial order precedence syntax, Valentin Tolmer, 2013/08/01
- [PATCH 7/7] news: new syntax (%gprec and %precr),
Valentin Tolmer <=
- [PATCH 6/7] regen, Valentin Tolmer, 2013/08/01
- [PATCH 2/7] conflicts: switch to partial order precedence system, Valentin Tolmer, 2013/08/01
- [PATCH 5/7] tests: new tests for %gprec and %precr, Valentin Tolmer, 2013/08/01
- [PATCH 1/7] introduction of the new structures to prepare for partial order precedence, Valentin Tolmer, 2013/08/01
- [PATCH 3/7] syntax: introducing %gprec for precedence groups, Valentin Tolmer, 2013/08/01
- [PATCH 4/7] syntax: introducing %precr to add specific precedence relations, Valentin Tolmer, 2013/08/01