jonathan-beard/simple_wc_example

Simple Word Count Parser Example

=================

Build Status

Tested on linux and OS X

About

So this is a super simple parser example. The tutorial is located here: link

Between the tutorial and the code you should be able to get started with more advanced projects using C++ and Flex/Bison. Admittedly the example itself is a bit contrived, however it's mean to be simple and get the point across. If there are changes in Flex/Bison that prevent the example from compiling or if you just have improvements, feel free to generate a pull request or just shoot me an e-mail.

To compile just download and run make, there's a super simple test harness to make sure it runs in the test dir.

Or you use CMake.

mkdir build/
cmake ..
make

or with clang

mkdir build/
CC=clang CXX=clang++ cmake ..
make

or with clang with optimisations

mkdir build/
CC=clang CXX=clang++ cmake .. -DCMAKE_BUILD_TYPE=Release
make

To run the simple test after make call

ctest

NOTES

OS X Users I've heard of some issues compiling if you've installed command line tools, then XCode.app afterwards on Catalina (with bash). When compiling with clang++, the C++ header files aren't found. If you have this issue, exporting an environment variable, such as this, export CXX=/usr/bin/clang++, seems to be a workaround. If anybody has a better solution (aside from wiping out all build tools and reinstalling) please let me know.
OS X Users If you have this message when compiling on OS X (likely Catalina and later),
```
mc_lexer.yy.cc:675:8: error: member reference type 'std::istream *' (aka 'basic_istream<char> *') is a
  pointer; did you mean to use '->'?
```
Then this means that you've a broken cpp path. To see why this is, go to the command line, type
```
cpp -xc++ -v < /dev/null
```
to see your path included by clang. The key problem is the lack of a modern FlexLexer.h in the command line tools of OS X, which is compouned when you install a new verson of Flex and the header isn't in the path. So, your binary will be the right one, the headers the wrong ones. As an example, the header file we want on my install of OS X (fresh VM install), is in
```
/System/Volumes/Data/usr/local/Cellar/flex/2.6.4_1/include/FlexLexer.h
```
which is installed by home brew. Unfortunately, the default include path pulls in the system default version at
```
/System/Volumes/Data/Library/Developer/CommandLineTools/usr/include/FlexLexer.h
```
HOW TO FIX
1. Interestingly there's yet another version in /Library/Developer. So how do you fix? The simplest way if you have sudo access, do:
```
sudo -s 
ln -s <Path to your installed Flex Header>/FlexLexer.h
```
  As an example, here's my path:
```
ln -s /System/Volumes/Data/usr/local/Cellar/flex/2.6.4_1/include/FlexLexer.h
```
2. Second, best way for non-root is to set the CPLUS_INCLUDE_PATH like this
```
CPLUS_INCLUDE_PATH=/System/Volumes/Data/usr/local/Cellar/flex/2.6.4_1/include/:$CPLUS_INCLUDE_PATH
```
  using my path above.
Bison Version - updated the latest head to test with Bison vs. 3.5, there were a few minor changes in syntax, now reflected in the example code. Will no longer work with Bison vs. < 3.3, see notes from link.

Thanks!