Future/bison
1
0
Fork 0
mirror of https://git.savannah.gnu.org/git/bison.git synced 2026-03-09 12:23:04 +00:00
Code Issues Packages Projects Releases Wiki Activity

examples: bistromathic: demonstrate the use of yyexpected_tokens

Browse Source 
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.
This commit is contained in:
Akim Demaille
2020-02-29 17:51:22 +01:00
parent b269a45fa4
commit 5789f9d91e
6 changed files with 238 additions and 60 deletions
Download Patch File Download Diff File Expand all files Collapse all files

26
examples/c/bistromathic/README.md
View File

@@ -1,7 +1,11 @@
# bistromathic - all the bells and whistles
This example demonstrates the best practices when using Bison.
- Its interface is pure.
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.
@@ -17,16 +21,14 @@ Copyright (C) 2020 Free Software Foundation, Inc.
This file is part of Bison, the GNU Compiler Compiler.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with no
Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
Texts. A copy of the license is included in the "GNU Free
Documentation License" file as part of this distribution.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
LocalWords: bistromathic yyexpected lookahead ispell american
LocalWords: MERCHANTABILITY
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
--->