This was a small experiment in writing a precedence climbing parser, using C. I also have my reference parsing implementation, using recursive descent, to compare the parsing results.
This is mostly based on the explanation found at this address: https://www.engr.mun.ca/~theo/Misc/exp_parsing.htm (use the Wayback Machine to read it).
Simply launch the following command
42sh$ make
If you want to build an evalexpr
command using recursive descent instead, use:
42sh$ make USE_CLIMBING=0
Don't forget to use make clean
when alternating between both.
Simply launch the binary, and write an expression on its standard input. The binary can parse exactly one expression per line, and reports parsing errors if they happen.
Example use:
42sh$ ./evalexpr
1 + 2 * 3 - 3!
1