mirror of
https://git.savannah.gnu.org/git/bison.git
synced 2026-03-09 04:13:03 +00:00
5789f9d91e
Let's use GNU readline and its TAB autocompletion to demonstrate the use of yyexpected_tokens. This shows a number of weaknesses in our current approach: - some macros (yyssp, etc.) from push parsers "leak" in user code, we need to undefine them - the context needed by yyexpected_tokens does not need the token, yypstate actually suffices - yypstate is not properly setup when first allocated, which results in a crash of yyexpected_tokens if fired before a first token was read. We should move initialization from yypush_parse into yypstate_new. * examples/c/bistromathic/parse.y (yylex): Take input as a string, not a file. (EXIT): New token. (input): Adjust to work only on a line. (line): Remove. (symbol_count, process_line, expected_tokens, completion) (init_readline): New. * examples/c/bistromathic/bistromathic.test: Adjust expectations.
1.3 KiB
1.3 KiB
bistromathic - all the bells and whistles
This example demonstrates best practices when using Bison.
- Its hand-written scanner tracks locations.
- Its interface is pure.
- Its interface is "incremental", well suited for interaction: it uses the push-parser API to feed the parser with the incoming tokens.
- It features an interactive command line with completion based on the
parser state, based on
yyexpected_tokens. - It uses a custom syntax error with location, lookahead correction and token internationalization.
- It supports debug traces with semantic values.
- It uses named references instead of the traditional $1, $2, etc.