| # calc++ - A Flex+Bison calculator |
| |
| This directory contains calc++, a Bison grammar file in C++. If you never |
| saw the traditional implementation in C, please first read |
| examples/c/lexcalc, which can be seen as a C precursor of this example. |
| |
| Read the corresponding chapter in the documentation: "A Complete C++ |
| Example". It is also available [on |
| line](https://www.gnu.org/software/bison/manual/html_node/A-Complete-C_002b_002b-Example.html) |
| (maybe with a different version of Bison). |
| |
| To use it, copy this directory into some work directory, and run `make` to |
| compile the executable, and try it. It is a simple calculator which accepts |
| several variable definitions, one per line, and then a single expression to |
| evaluate. |
| |
| The program calc++ expects the file to parse as argument; pass `-` to read |
| the standard input (and then hit <Ctrl-d>, control-d, to end your input). |
| |
| ``` |
| $ ./calc++ - |
| one := 1 |
| two := 2 |
| three := 3 |
| (one + two * three) * two * three |
| <Ctrl-d> |
| 42 |
| ``` |
| |
| You may pass `-p` to activate the parser debug traces, and `-s` to activate |
| the scanner's. |
| |
| <!--- |
| Local Variables: |
| fill-column: 76 |
| ispell-dictionary: "american" |
| End: |
| |
| Copyright (C) 2018-2022, 2025 Free Software Foundation, Inc. |
| |
| 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. |
| |
| LocalWords: calc parsers yy MERCHANTABILITY Ctrl ispell american |
| ---> |
