Bruno BELANYI
b5912f508e
The previous version of the algorithm did not take into account the fact that the main loop should only run while we have postfix or infix operators. This happened to work because of the small amount of operators used in the grammar. The previous version also had prefix operators hard-coded in the operand parsing function. |
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| .drone.yml | ||
| .gitignore | ||
| Makefile | ||
| README.md | ||
Evalexpr
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!
1