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Custom Parsers

If you have a command or utility that you want to run pretty much as-is, but trunk doesn't natively understand how to parse it, you can inject your own custom parser to translate its output into a format that trunk does understand!
For example, let's say that we want to use grep as a linter, but we want to add more context to the matches. We could define a custom linter like so:
lint:
definitions:
- name: todo-finder
files: [ALL]
commands:
- output: regex
parse_regex: "((?P<path>.*):(?P<line>\\d+):(?P<col>\\d+): \\[(?P<severity>.*)\\] (?P<message>.*) \\((?P<code>.*)\\))" # matches the parser run output
run: grep --with-filename --line-number --ignore-case todo ${target}
success_codes: [0, 1]
read_output_from: stdout
parser:
run:
"sed -E 's/(.*):([0-9]+):(.*)/\\1:\\2:0: [error] Found todo in \"\\3\" (found-todo)/'"
The execution model that trunk follows for a parser is that it will:
  • execute the linter's run field, asserting that either:
    • the linter's exit code is in success_codes, or
    • the linter's exit code is not in error_codes;
  • execute parser.run,
    • with the read_output_from of the linter execution fed to parser.run as stdin,
    • assert that the exit code of the parser is 0, and then
  • use output to determine how it should parse the parser's stdout.
Note that you can also set parser.runtime to node or python so that you can write your parser in Javascript or Python instead, if you so prefer!

Node

lint:
definitions:
- name: todo-finder-node
files: [ALL]
commands:
- output: parsable
parse_regex: "((?P<path>.*):(?P<line>\\d+):(?P<col>\\d+): \\[(?P<severity>.*)\\] (?P<message>.*) \\((?P<code>.*)\\))" # matches the parser run output
run: grep --with-filename --line-number --ignore-case todo ${target}
success_codes: [0, 1]
read_output_from: stdout
parser:
runtime: node
run: ${workspace}/todo-finder-parser.js
#!/usr/bin/env node
'use strict';
let readline = require('readline');
let rl = readline.createInterface({ input: process.stdin });
rl.on('line', function(line){
let match = line.match(/(.*):([0-9]+):(.*)/);
if (match) {
let [_, path, line_number, line_contents] = match;
console.log(`${path}:${line_number}:0: [error] Found todo in "${line_contents}" (found-todo)`);
}
Remember to run chmod u+x todo-finder-parser.js so that trunk can run it!

Python

lint:
definitions:
- name: todo-finder-python
files: [ALL]
commands:
- output: parsable
parse_regex: "((?P<path>.*):(?P<line>\\d+):(?P<col>\\d+): \\[(?P<severity>.*)\\] (?P<message>.*) \\((?P<code>.*)\\))" # matches the parser run output
run: grep --with-filename --line-number --ignore-case todo ${target}
success_codes: [0, 1]
read_output_from: stdout
parser:
runtime: python
run: ${workspace}/todo-finder-parser.js
#!/usr/bin/env python
import re, sys
for line in sys.stdin.readlines():
match = re.match("(.*):([0-9]+):(.*)", line)
if match:
path, line_number, line_contents = match.groups()
print(f"{path}:{line_number}:0: [error] Found todo in \"{line_contents}\" (found-todo)")
Remember to run chmod u+x todo-finder-parser.py so that trunk can run it!