Parses gas reports in different formats and outputs a Lua table in the same format. These Lua tables can be later used to produce diffs and other analysis.

• Lua 5.4
• LPEG 1.0.2

On the repository root, run the following command, where <fmt> is either forge or hardhat. If this option is not provided, the tool tries to guess the format by running each parser.

lua main.lua parse [<fmt>]

The program reads the gas report from the standard input and prints the Lua table to the standard output. You can redirect these streams to files through operating system pipes.

You can compare two gas reports that have been already parsed into Lua tables with the following command. Here, we don't need to discriminate the source of the gas report, since they all use the same Lua table scheme. Because we need two inputs, we cannot use standard input anymore. Instead, we need to read such Lua tables from files <a> and <b>.

lua main.lua diff <a> <b>

The output of this program is another Lua table which computes the absolute difference (b - a) and the relative difference ((b - a) / a) of every entry. If the absolute difference is zero, it is discarded. Also, if a table gets empty because all of its entries were discarded, the table itself also gets discarded. This is simply to minimize the size of the output and to make the end result more conscise. After all, we are only interested in what were the gas costs changes.

In the context of GitHub repositories, Markdown in the primary markup language. Because of this, we commonly format our tables using Markdown syntax. To make the process of exporting this information to Markdown simpler, you can run the following command.

lua main.lua printdiff

Similar to parse, this program reads to stdin and writes to stdout.

If you want to compare two gas reports quickly, you can use the following script.

./quickdiff.sh <a> <b>

Where <a> and <b> are text files in either Forge or Hardhat format. The tool tries to guess the format automatically.

If you want to see the program in action, you can simply run the runtests.sh Shell script. The test inputs and outputs are stored in the test/ folder. If, after running such script, none of the files were change, it is a good sign that your program is working as expected on your machine.