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api.token.raw: document it

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* doc/bison.texi: here.
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Akim Demaille
2019-08-31 19:22:32 -05:00
parent 8c18e3f18c
commit 3ca713abd0
3 changed files with 55 additions and 1 deletions
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14
NEWS
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@@ -21,6 +21,20 @@ GNU Bison NEWS
The C++ deterministic skeleton (lalr1.cc) now supports LAC, via the
%define variable parse.lac.
*** Variable api.token.raw: Optimized token numbers (all skeletons)
In the generated parsers, tokens have two numbers: the "external" token
number as returned by yylex (which starts at 257), and the "internal"
symbol number (which starts at 3). Each time yylex is called, a table
lookup maps the external token number to the internal symbol number.
When the %define variable api.token.raw is set, tokens are assigned their
internal number, which saves one table lookup per token, and also saves
the generation of the mapping table.
The gain is typically moderate, but in extreme cases (very simple user
actions), a 10% improvement can be observed.
*** Debug traces in Java
The Java backend no longer emits code and data for parser tracing if the