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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.
35 lines
1.3 KiB
Markdown
35 lines
1.3 KiB
Markdown
# bistromathic - all the bells and whistles
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This example demonstrates best practices when using Bison.
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- Its hand-written scanner tracks locations.
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- Its interface is pure.
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- Its interface is "incremental", well suited for interaction: it uses the
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push-parser API to feed the parser with the incoming tokens.
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- It features an interactive command line with completion based on the
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parser state, based on `yyexpected_tokens`.
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- It uses a custom syntax error with location, lookahead correction and
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token internationalization.
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- It supports debug traces with semantic values.
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- It uses named references instead of the traditional $1, $2, etc.
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<!---
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Local Variables:
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fill-column: 76
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ispell-dictionary: "american"
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End:
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Copyright (C) 2020 Free Software Foundation, Inc.
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This file is part of Bison, the GNU Compiler Compiler.
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Permission is granted to copy, distribute and/or modify this document
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under the terms of the GNU Free Documentation License, Version 1.3 or
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any later version published by the Free Software Foundation; with no
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Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
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Texts. A copy of the license is included in the "GNU Free
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Documentation License" file as part of this distribution.
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LocalWords: bistromathic yyexpected lookahead ispell american
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LocalWords: MERCHANTABILITY
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--->
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