Expression Language

GitWire's expression language lets you write declarative rules in .gitwire.yml using a safe, sandboxed DSL. Inspired by gitStream's CM syntax but extended with pipe-style filters.

Syntax Overview

custom_rules:
  approve_safe:
    if: "files | all(extension('.css', '.md'))"
    run:
      - action: add-label
        args: { label: "safe-change" }

Operators

Operator	Meaning	Example
and	Logical AND	is.docs and is.small
or	Logical OR	is.formatting or is.tests
not	Logical NOT	not is.draft
>, >=	Greater than	changes.added > 50
<, <=	Less than	files | length < 5
==, !=	Equality	author == 'alice'
+, -, *, /	Arithmetic	changes.added + changes.deleted > 100

Pipe Syntax

The pipe operator (|) chains filter functions:

input | filter(arg1, arg2)

Multiple pipes chain left-to-right:

author | lower | contains('bot')

Built-in Filters

Filter	Input	Returns	Example
match(pattern...)	string	boolean	author | match('*[bot]')
contains(substring)	string	boolean	title | contains('fix')
startsWith(prefix)	string	boolean	branch | startsWith('feature/')
endsWith(suffix)	string	boolean	file | endsWith('.test.js')
includes(value)	array	boolean	labels | includes('bug')
some(filter)	array	boolean	files | some(match('src/**'))
all(filter)	array	boolean	files | all(extension('.md'))
length	array/string	number	files | length > 10
extension(ext...)	string	boolean	file | extension('.js', '.ts')
lower	string	string	author | lower
upper	string	string	title | upper

Context Variables

Available in every rule evaluation:

Variable	Type	Description
author	string	PR/issue author login
branch	string	Branch name (PRs only)
title	string	PR title or issue title
body	string	PR body or issue body
labels	string[]	Current labels
files	string[]	Changed file paths (PRs only)
changes		Line change counts
repo	string	Repository full name
is_new	boolean	True for newly opened items
is_draft	boolean	True for draft PRs

Named Expressions

Define reusable expressions in the expressions section:

expressions:
  is:
    docs: "files | all(extension('.md', '.rst'))"
    formatting: "files | all(extension('.css', '.scss', '.less'))"
    tests: "files | all(match('**/*.test.*'))"
    safe: "is.docs or is.formatting or is.tests"
    security: "files | some(match('src/auth/**'), match('**/secrets*'))"

custom_rules:
  approve_safe:
    if: "is.safe"
    run:
      - action: approve