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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).

How to build

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.

How to use

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!